ISS cargo deliveries:

The year 2011 was a highly successful year in terms of cargo flights to the ISS, with January’s launch of Japan’s H-II Transfer Vehicle-2 (HTV-2), February’s launch of Europe’s Automated Transfer Vehicle-2 (ATV-2), and the successful launches of Space Shuttle missions STS-133, STS-134 and STS-135, as well as numerous Russian Progress flights.

The delivery and installation of the Permanent Multipurpose Module (PMM) to the ISS on STS-133 in February increased the amount of stowage space available on the station for cargo, which paved the way for STS-135 to deliver a massive stockpile of crew provisions to the station on the final Shuttle mission in July.

The stockpile of crew provisions from STS-135 will enable the station to make it to mid-2012 without any additional deliveries of cargo, and make it to 2013 when supplemented with deliveries of cargo from Europe’s ATV and Japan’s HTV. Thus, successful commercial and non-commercial resupply flights to the ISS are essential in order to maintain a crewed presence on the station throughout 2012.

The late-addition of STS-135 to the Shuttle’s manifest in order to shore up ISS’ supplies is already being seen as an excellent decision, given the delays of commercial resupply flights to the ISS and recent failures of Russian rockets.

Non-commercial cargo vehicles:

This year’s non-commercial cargo vehicle flights to the ISS will see two large deliveries made to the station by both Europe and Japan.

Europe’s ATV-3 spacecraft, named “Edoardo Amaldi”, is currently set to launch to the ISS atop an Ariane V rocket from the Kourou space center in French Guiana, on 9th March, and arrive at the ISS for a docking to the Service Module (AM) Aft port ten days later on 19th March. It is scheduled to undock from the ISS on 27th August.

ATV-3 will carry more “dry” cargo (i.e. internal items) than ATV-2 carried to the station in 2011, due to numerous internal structural modifications that have been made that will allow ATV to carry additional internal payload.

This will mean that less “wet” cargo (i.e. propellants) will be carried by ATV-3, however this will not be of big impact to the ISS since ATV-2 performed four “big boosts” of the ISS in 2011 that boosted the station’s altitude to a mean of around 400km, meaning less reboosts will be needed in future, and thus less requirements for propellants. (L2 Link)

The next large non-commercial delivery of ISS cargo will be via Japan’s HTV-3 spacecraft, currently scheduled to launch on 26th June atop an H-IIB rocket from the Tanegashima space center in Japan, arriving at the ISS five days later for a 1st July rendezvous, capture and berthing.

HTV-3 will depart the ISS on 15th August. The HTV-3 mission was originally scheduled for the first quarter of 2012, but was pushed back to mid-2012 due to delays in hardware processing caused by the Japanese earthquake in 2011.

In additional to bringing a large volume of internal cargo to the station, HTV-3 will also carry two external payloads for the ISS – the Space Communication and Navigation (SCaN) testbed, which will be attached to ExPrESS Logistics Carrier-3 (ELC-3), and the Multi-mission Consolidated Equipment (MCE), a payload for the Japanese Exposed Facility (JEF). (L2 Link)

Five Russian Progress flights to the station are also planned in 2012 – Progress M-14M on 25th January, M-15M on 25th April, M-16M on 25th July, M-17M on 23rd October, and M-18M on 26th December. (L2 Link)

Progress flights, however, will be of particular interest to the ISS Program over the course of 2012 due to the multiple failures of Russian launch vehicles in 2011, including two third stages of Soyuz rockets – a Soyuz-U with Progress M-12M/44P on 24th August, and a Soyuz 2-1b with the Meridian satellite on 23rd December.

However, the Progress M-12M third stage failure was attributed to a problem in the RD-0110 engine, while the third stage failure of Meridian used a newer RD-0124 engine.

If any further Soyuz rockets fail in 2012, it will not only have implications for Progress cargo flights, but also Soyuz crewed flights, which could lead to a de-crewing of the station since the ISS partners now depend on the Soyuz for crewed access to the station.

As such, successful launches of both Progress and Soyuz spacecraft are vital for a continued crewed presence on the ISS throughout 2012.

Commercial cargo vehicles:

This year will also mark the first of two long-awaited commercial cargo vehicles visit the station – SpaceX’s Dragon, and Orbital’s Cygnus.

The first commercial spacecraft to attempt to reach the ISS will be SpaceX’s Dragon, which is currently scheduled to launch on the combined COTS-2/3 (C2/C3) mission atop a Falcon 9 rocket from Launch Complex-40 (LC-40) at Cape Canaveral Air Force Station (CCAFS) on 7th February.

Preliminary timelines show that COTS-2 objectives (rendezvous and communication tests) will be performed the day following launch, with COTS-3 objectives (rendezvous, capture & berthing) being performed two days after launch on 9th February. These timelines, however, are not confirmed at this time.
Following a two week stay at the ISS, during which some non-critical supplies will be transferred to the ISS, Dragon will be unberthed from the ISS on 23rd February, for a re-entry and splashdown off the coast of California. (L2 Link)

While Dragon was originally scheduled to reach the station in 2011, ongoing setbacks from the Progress M-12M launch failure and subsequent ISS crew impacts, ISS hardware and software upgrades, Dragon software testing, and Dragon flight review processes delayed the flight into 2012.

With the successful docking of Soyuz TMA-03M/29S to the ISS on 23rd December, which delivered US astronaut Don Pettit to the station, all crewmembers trained to capture and berth Dragon are now aboard the ISS.

ISS hardware and software upgrades, notably the Enhanced Processor & Integrated Communications (EPIC) and X2_R10 software transition, got underway aboard the ISS last week and will continue throughout this week, so far with success.

Dragon software testing and flight reviews are currently ongoing, as much a big hurdle – deployment of an ORBCOMM secondary payload – has now been removed from the C2/C3 mission so that SpaceX can concentrate on Dragon’s flight to the ISS, and not have to worry about ISS conjunction concerns from the ORBCOMM.

Assuming the C2/C3 mission is a success, SpaceX are schedule to fly at least one more Dragon to the ISS in 2012 as an operational resupply spacecraft.

The next commercial cargo craft to attempt to reach the ISS after Dragon will be Orbital’s Cygnus spacecraft, currently scheduled to launch No Earlier Than (NET) June due to ongoing delays with launch pad readiness. A hot-fire test and a test launch with a dummy payload of Cygnus’ Antares (formerly Taurus II) launch vehicle need to be performed prior to the Cygnus C1 mission.

Since ISS can make it only as far as 2013 without any commercial cargo deliveries (assuming successful deliveries of cargo by non-commercial vehicles), this means that at least one commercial resupply vehicle must successfully reach the ISS in 2012 in order to maintain a crewed presence in 2013.

The margin for failure of this year’s COTS vehicle test flights is tight, with sources noting that even with the stockpiles of supplies from STS-135, ISS will struggle to sustain a failure of any COTS vehicle to reach the station.

As such, retirement of the Space Shuttle and its large up/downmass before an operational commercial resupply capability was available has placed additional risk on the ISS, since test flights of new, and in the case of Orbital, untested launch vehicles and spacecraft are now on the critical path for sustained ISS operations.

Although the commercial vehicles in question have yet to reach the station at the start of the year in which they must become operational, the due diligence displayed thus far by both NASA and its commercial partners enables is an encouraging sign.

While the commercial resupply vehicles have been a long time coming, the end is now in sight for the COTS (Commercial Orbital Transportation Services) development program and the transition to the operational Commercial Resupply Services (CRS) program. Due to both the high risks and high payoffs involved, 2012 is likely to be the make-or-break year for COTS and CRS.

–

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Robotics and EVA activities:

Opening the ISS systems status review was an update on the robotics and EVA systems on the International Space Station. Specifically, the robotics and EVA division noted an amazingly clean performance of all related systems in the preceding months, with no issues being reported.

This, coupled with no upcoming robotics activities on the ISS until December, will make for a relatively quiet period of time for the three-person ISS crew through the remainder of October and the month of November.

The next scheduled robotics activity on the ISS, in fact, is set to be the walk-off of the SSRMS (Space Station Remote Manipulator System) arm to Node-2/Harmony for “support of the Dragon mission and high-res LEE snare cable photography,” notes the MOD Robotics operations presentation – available for download on L2.

EVA systems and support structures also received little mention in the “preceding months” category. However, internal NASA documentation indicated that GMT days 290-292 (Oct. 17-19) and 298 (Oct. 25) were/will be spent by performing system and equipment maintenance in the EVA realm.

Specifically, GMT days 290-292 were spent performing maintenance on the NiMH batteries, EMU (Extravehicular Mobility Unit – spacesuit) water maintenance, and crewlock cleanout.

Airlock switch recongifuration verification will take place tomorrow, GMT day 298.

Click here for ISS News Articles: http://www.nasaspaceflight.com/tag/iss/

EMU water maintenance specifically included “extra iodination in preparation for possible de-crewing of ISS” – an added precaution as Russian space agency officials continue to work recovery efforts from the failed Progress resupply craft launch in August of this year.

Currently, ISS de-crew is not considered likely as Russian officials track a mid-November (~Nov. 14th) launch of the next ISS crew increment to the Station in a Soyuz spacecraft. The Nov. 14th launch of Soyuz will mark the 111th Soyuz flight since flight operations began in 1967 and the 22nd and final flight of the Soyuz TMA spacecraft – which is being replaced with the upgraded Soyuz TMA-M series.

ISS Systems Status: Failures and completed/upcoming work:

While robotics and EVA operations have been light in recent and upcoming months, general upkeep and maintenance of the International Space Station has continued along with science and research objectives.

Specifically, the ISS Systems Status presentation reviewed ISS systems failures and recovery/investigation results from these failures.

The first such failures mentioned were two EPS system anomalies.

“Failure: On September 23rd, AR 5543 – RPCM LA1A4A_C RPC 4 Trip. Impact: Loss of redundant power feed to Express Rack 2 (LAB1O1 Rack). Rack contains Ku-Band receiver.”

On October 17, crewmembers R&Red (removed and replaced) the RPCM LA1A4A unit to recover redundant power to the Stations’ Ku-band antenna receiver. Likewise, the RPCM LA1B-H was then R&Red the following day to “recover second of two smoke detectors in Lab” (Destiny module),” notes the ISS System overview presentation – also available for download on L2.

This resulted in the recovery of all systems from the September 23rd failure.

The second EPS failure was an Oct. 12th event in which six of the eight lights in the Permanent Multipurpose Module (PMM) Leonardo turned off because of a recurring software “overcurrent FDIR” unique to the PMM General Luminaire Assembly.

The problem was resolved by temporarily disabling the FDIR and repowering all the lights. However, this repowering failed to illuminate any of the six failed lights.

A forward plan was developed to replace the failed Lamp Housing Assembly “as crew desire/timeline allows.”

The presentation further notes a failure of the Urine Processing Assembly, specifically the Fluids Control Pump Assembly (FCAP).

“Failure: UPA Fluids Control Pump Assembly (FCPA) failure. FCPA was able to be restarted several times, but eventually high current draw prevented subsequent re-starts. Impact: Loss of Urine processing function. The UPA cannot operate without the FCPA,” notes the ISS systems presentation.

The FCPA was subsequently replaced on September 23rd and the UPA regained full operational capabilities.

The final failure mentioned in the ISS systems presentation was a September 30th failure of the Russian Contingency Telemetry asset.

“On September 30th, MCC-H performed a command and telemetry test via the Russian assets. Following a successful test, MCC-M was unable to command Russian Contingency Telemetry (RCT) on or off.

“It was determined that all commands originating from the Russian Segment sent to the US Segment were being rejected by the C&C MDM (Command and Control Multiplexer/Demultiplexer) due to a ‘Time Authentication’ bit set in commands from the SMCC.”

This failure meant that Mission Control Moscow (MCC-M) could not command RCT enabled or inhibited and that the crew could not silence a caution and warning tone from the C&W panel in the Russian Segment of the ISS.

Station Mode transitions could also not be executed if sent from the SMCC to CCS.

To counter this failure, Mission Control Houston commanded the RCT enabled and inhibited for Moscow and the crew was “informed to use the PCS laptops to silence tones in the RS segment.”

Preparations were also made to use the US operating segment of the ISS to send station mode transition commends if needed until the issue could be fully resolved.

Mission Control Moscow developed and sent a command to “reverse the ‘Time Authentication’ bit in the SMCC to turn off time authentication for commands being sent from the RS segment to the US segment” on Oct. 5 – which corrected the on-orbit problem.

A root cause investigation is still ongoing at this time.

To the end of the year: preparing for Dragon, Cygnus, and HTV-3:

As ISS operations move into their final phase for calendar year 2011, preparations are also continuing for the first approach and rendezvous of SpaceX’s Dragon resupply craft, the first test flight of Orbital’s Cygnus resupply craft, and the third mission of JAXA’s (Japan Aerospace Exploration Agency’s) HTV resupply craft to the International Space Station.

Dragon:

In preparation for the upcoming Dragon flight, NASA is in the process of updating all procedural handbooks and procedures themselves to reflect the Dragon configuration that is scheduled to fly the ISS rendezvous mission in December. (45 proc handbooks from the ISS side of operations are available in L2).

“Dragon Demo will fly on CCS R9/MSS 6.3/PCS R13. Updating procedures to be consistent with this configuration,” notes the presentation.

Testing and certification are scheduled to be completed today, October 24, and work is ongoing to “determine how newly-certified PCS and CDDT can be available for Dragon Demo mission.”

Additionally, teams are looking at synchronization issues between Dragon and RWS.

“In Stage test risk mitigation/dry-run, saw RWS data drop in and out on crew overlay displays. RWS looking for consecutive, incrementing values of Dragon time (1-2-3-4, not 1-3-4-6) to confirm good link (and therefore valid data) between Dragon and ISS.”

A short-term mitigation plan for this issue is to include a filter on RWS which will result in an informational hold until three invalid counts have been received before data drops begin.

A more long-term solution is being worked to update the RWS software. This update was supposed to have already taken place; however, Expedition 29 crew prioritizations with only a three-person crew have delayed the software update until at least November 28.

The requirement for the software update is for it to be in place No Later Than 30 days before the scheduled launch of Dragon. That launch is currently targeted for Dec. 19 – just 21 days after the software update is scheduled to be installed.

Cygnus:

While preparations for Dragon’s flight continue, work is also progressing on readiness operations for the first test flight of Orbital’s Cygnus spacecraft.

“Cygnus Demo flying on new CCS R9/MSS 7.1/R11 Recon/PCS R13 configuration,” notes the Expedition Vehicle Division presentation to MOD – available for download on L2.

Open work ahead of this flight, scheduled for January 2012, includes ICATT re-work to “ensure CCS R9 vehicle data path cmds/tlm available with R11 recon and updating procedures affected by data path configuration and PCS R13 navigation changes.

“Orbital’s command/telemetry ground system unable to send valid IPCL and Sendback data, which affects ability to verify displays, and eventually, to sim.”

End to end testing on these data paths is expected in November. Additional testing will take place in February 2012.

HTV-3:

Finally, preparations are also underway for the February 18, 2011 launch of the HTV-3 (H-II Transfer Vehicle 3) resupply craft from the Tanegashima Space Center in southern Japan.

Only standard open work remains for this flight at this time: updating procedures from this year’s HTV-2 mission to account for flight rule updates and vehicle design changes.

The flight of HTV-3 will also mark the first time when FOR will not be required for HTV.

(Images: NASA, Space X, Orbital and L2 Documentation) (As the shuttle fleet retire, NSF and L2 are providing full transition level coverage, available no where else on the internet, from Orion and SLS to ISS and COTS/CRS/CCDEV, to European and Russian vehicles. 

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HTV-2′s Successful Visit:

HTV-2 delivered approximately 6,000kg of supplies to the ISS via its Pressurised Logistics Carrier (PLC), including two brand new science racks – the Multipurpose Small Payload Rack (MSPR) and Kobairo, which contains the Gradient Heating Furnace (GHF). Both new racks were transferred to the ISS’s Japanese Pressurised Module (JPM) “Kibo” in the days following HTV-2′s arrival at the station. Aside from the new racks, many Cargo Transfer Bags (CTBs) of dry cargo, including food, spare parts, and scientific materials were also delivered.

HTV-2 also delivered two Orbital Replacement Units (ORUs) for the station’s exterior via its Exposed Pallet (EP), mounted inside its Unpressurised Logistics Carrier (ULC). The two ORUs were the Flex Hose Rotary Coupler (FHRC) and Cargo Transportation Container-4 (CTC-4).

In early February, the EP was extracted from HTV-2′s ULC via the SSRMS, and installed onto the Japanese Exposed Facility (JEF) via the JEM RMS (Japanese Experiment Module Remote Manipulator System). Once the EP was installed onto the JEF, the Special Purpose Dextrous Manipulator (SPDM) “Dextre” removed the FHRC and CTC-4 from the EP. The empty EP was then removed from the JEF and re-inserted into HTV’s ULC.

The SPDM still remains the temporary home of the FHRC and CTC-4, nearly two months after it took ownership of them from the EP. Now that the ExPrESS Logistics Carrier-4 (ELC-4) is attached to the ISS following the highly successful STS-133 mission, the SPDM will install the FHRC onto its final home (ELC-4) sometime next week, according to an ISS Specialist Status presentation available to download on L2.

Click here for all HTV news articles: http://www.nasaspaceflight.com/tag/htv/

The SPDM will keep hold of CTC-4 for a while longer yet, as CTC-4 contains some new Remote Power Control Modules (RPCMs). The SPDM was due to Remove & Replace (R&R) a faulty RPCM on the P1 Truss last year, until its operations were cut short due to the infamous Pump Module failure/R&R. As the SPDM already has a hold of CTC-4, an “R&R of opportunity” will be performed on the RPCM in question in the coming months.

HTV-2 was shuffled around on the ISS twice during its two month stay – once prior to the arrival of Space Shuttle Discovery/STS-133, when it was relocated to the Node 2 Zenith port to clear the way for Discovery, and once after the STS-133 mission when it was relocated back to its original home on Node 2 Nadir. The fact that HTV-2 was present on Node 2 Zenith during STS-133 provided for some unique views of HTV-2 during Discovery’s flyaround of the ISS.

Once HTV-2′s new cargo was completely unloaded, it began to take on its new role as a glorified trash can, as the ISS crew slowly filled HTV-2 with discarded items that have been cluttering up the station for the past few months. In December 2010, NASA managers decided to extend the HTV-2 mission by an additional month, so that HTV-2 could dispose of some unneeded cargo from the Permanent Multipurpose Module (PMM), which was recently delivered to the station on STS-133.

During the STS-133 mission, the decision was taken to grant Discovery an extra two days docked to the ISS in order to allow the STS-133 crew to make a significant dent into the PMM reconfiguration work planned for the Expedition 26 and 27 crews. 

STS-133 News Articles (over 110 articles): http://www.nasaspaceflight.com/tag/sts-133/

In total, the mission extension gave the STS-133 crew an extra 65 hours to reconfigure the PMM, which had to be complete prior to HTV-2′s departure in order to allow HTV-2 to dispose of the unneeded PMM hardware. 30 hours of reconfiguration and trash loading work still remained upon Discovery’s departure, including 12 hours for the Expedition 26 crew, and 22 hours for the Expedition 27 crew.

A total of 55 percent of HTV-2′s trash items have come from the PMM, which included two unneeded Resupply Stowage Platforms (RSPs) and two Integrated Stowage Platforms (ISPs). The ISPs were installed in HTV-2 during the STS-133 mission, and the RSPs were transferred from the PMM to HTV-2 by the Expedition 27 crew last week.

The two RSPs occupy the rack spaces that were previously occupied by the MSPR and Kobairo racks (Forward 1 and Aft 1), and the two ISPs are strapped to the front of two HTV Resupply Racks (HRRs) at the Starboard 1 and Port 2 locations.

A massive 85 percent of HTV-2 trash consists of discarded packing foam, the majority of which comes from the PMM. Most of the hardware launched in the PMM was large spare parts for ISS which needed to be protected inside large foam “clamshell” boxes.

These foam boxes are not needed on-orbit and take up valuable volume. The cargo was removed from the foam boxes during the STS-133 mission, and the Expedition 27 crew spent last week transferring and stowing the foam boxes in HTV-2.

Click here for ISS news articles: http://www.nasaspaceflight.com/tag/iss/

The large foam “clamshells” to be trashed on HTV-2 come from PMM-delivered hardware including the Pump Package Assembly, Inlet ORU, V-Guides, Water Tank, Waste Water Tank, and Robonaut 2′s (R2′s) Structural Launch Enclosure to Effectively Protect Robonaut (SLEEPR), which consists of a large metal box and surrounding packing foam.

According to NASA, other cargo to be trashed on HTV-2 includes: “6 large foam boxes inside the RSP locations, 4 M-01 bags worth of RFTA foam, 6 CTBEs of ISP launch foam, RSP filler foam, 2 large JAXA foam boxes, 3 CTBEs of common trash, 6 CTBEs of KTOs, HTV2 M-bags of launch foam, foam box from the cylinder flywheels, filler foam pulled from inside NASA CTBs, HTV-2 rack filler foam, 6 CTBEs of CWC-I foam, 1 CWC-I metal box, RSP fences from the racks remaining on ISS and 17 CTBEs of ballast”.

HTV-2 is filled to its volumetric limit for its departure, with cargo quite literally packed right up to the hatch. This will not cause a Center of Gravity (CG) issue for HTV-2 however, since most of the cargo is low-mass foam. JAXA have performed precise CG calculations to ensure that HTV-2′s thrusters will be able to handle the mass, and have also performed analysis to verify that none of the cargo will pose a threat during its burn-up in the atmosphere and splashdown into the Ocean.

Also installed in HTV-2 is the Re-Entry Breakup Recorder (REBR). REBR is the spacecraft equivalent of a black box typically found in most aircraft, and will be used to transmit breakup and re-entry data back to Earth using its GPS, temperature sensors, accelerometers, data recorder and Iridium modem.

HTV-2′s operations were affected by the devastating earthquake in Japan, which caused damage to the Space Station Integration & Promotion Center (SSPIC) in Tskuba, Japan. The earthquake severed an undersea communications line between Japan and the US mainland, which was utilised by the SSPIC. The prime communication line was recovered between the 16th and 17th March, and a back-up line was also established. Full command, telemetry and voice capabilities were fully restored, meaning that the SSPIC is able to support the HTV-2 unberthing and re-entry.

As a sign of support for the victims of the tragedy in Japan, the ISS crew conducted a voluntary activity called “Cranes for Japan”, which involved making paper cranes (Orizuru) using the traditional Japanese activity of Origami (paper folding). Paper cranes are a symbol of hope and good luck in Japan, and they will ride inside HTV-2 during its “falling star” descent through the atmosphere as a message of support to all the victim of the disaster. Cranes can also been see in the ISS Flight Control Room (FCR).

In preparation for the unberthing, HTV-2 was closed out yesterday, with close-out steps including scavenging items from HTV-2 that could be used on ISS, such as Restraint & Mobility Aids (R&MAs), a Portable Fire Extinguisher (PFE), a Portable Breathing Apparatus (PBA), and a Smoke Detector (SD). HTV’s General Luminaire Assembly (GLA) “lights” were previously removed.

Following close-out activities, the hatch into HTV-2 was closed and HTV’s vestibule connections were unplugged from the ISS yesterday. Final vestibule activities, Multi Layer Insulation (MLI) installation, Center Disc Cover (CDC) installation, and Node 2 Nadir hatch closure was completed this morning. Grappling of HTV-2 by the SSRMS was also completed Monday morning.

Once all sixteen Common Berthing Mechanism (CBM) bolts have been released, the SSRMS manoeuvred HTV-2 to a point below the ISS, whereupon HTV’s thrusters were activated and the SSRMS ungrappled HTV. SSRMS release of HTV-2 was at 3:46 PM GMT.

During HTV-2′s approach to the station on 27th January, an overlay on the Robotics Workstation (RWS) video monitors aboard the station did not match the vehicle location in the Mobile Base System (MBS) camera view.

A camera calibration was executed on 7th February, which resulted in pointing offsets that matched the offsets seen during approach. The camera has since been re-calibrated, which should correct the overlay offset issue for HTV-2′s departure.

Following release, HTV-2 will conduct two engine burns to set up for the de-orbit burn on Wednesday (30th March). Re-entry will occur at 3:10 AM GMT on Wednesday, following which the remains of HTV-2 will safely splash down in the Southern Pacific Ocean, bringing to end a flawless mission by the HTV-2 team.

HTV-3 is set to arrive at the ISS in January 2012 – only ten months away from now.

(Images via NASA.gov, L2 documentation and @carbon_flight (Ed Van Cise – ISS FD)

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Visiting Vehicle Docking Port Shuffle:

The major task accomplished by the crew last week was the relocation of Japan’s H-II Transfer Vehicle-2 (HTV-2) “Kounotori” from the Nadir port of Node 2 to the Zenith port of Node 2. The purpose of the relocation was to clear the way for payload extractions from Shuttle Discovery’s Payload Bay (PLB) when Discovery docks to Pressurised Mating Adapter-2 (PMA-2), located on Node 2 Forward.

Following on from hatch closure between HTV-2 and Node 2 Nadir last Thursday (17th February) evening, Friday (18th February) morning saw Flight Engineer-5 (FE-5) Paolo Nespoli and FE-6 Cady Coleman unberth and remove HTV-2 from Node 2 Nadir and began the six hour robotics sequence to manoeuvre HTV in between the Japanese Pressurised Module (JPM) and the Port 1 (P1) Truss.

The never-before-performed manoeuvre, executed flawlessly by the Space Station Remote Manipulator System (SSRMS) and controlled from the station’s Cupola, was completed successfully when HTV arrived at the Node 2 Zenith port later in the afternoon.

Once the berthing sequence had been completed, Node 2′s Zenith hatch was opened on Friday evening. A new, specially-constructed contingency power jumper was installed in order to provide backup power to HTV, should it be needed.

Such backup power was not an issue when HTV was on Node 2 Nadir, as that port was designed for Visiting Vehicles (VVs) and so all the necessary connections to support those vehicles were present at the module’s launch. However, Node 2 Zenith was never intended to be a VV port under original ISS plans, and so a contingency power supply is not available.

Since its launch in 2007, Node 2 Zenith has been designated as a backup VV port, and ISS managers identified the lack of a contingency power supply as an issue and subsequently manifested contingency jumpers on the STS-133 mission. The contingency jumpers provide back-up power to VVs on Node 2 Zenith by connecting them to power supplies on Node 2′s Forward-Overhead bulkhead.

STS-133 was originally scheduled to arrive at the ISS ahead of HTV-2, but due to repeated delays to the STS-133 mission, HTV-2 has arrived at the ISS ahead STS-133 and the contingency jumpers. Discovery’s docking has facilitated the need for HTV-2′s relocation to Node 2 Zenith, and so a situation arose where the required jumpers were on the ground inside the Permanent Multipurpose Module in Discovery’s PLB.

Retrieving the jumpers from the PMM, in order to deliver them to the ISS ahead of the HTV-2 relocation via a Russian Progress vehicle, was not an option as no access to the PMM is available while it is secured in Discovery’s PLB. Therefore, ISS engineers developed a plan to construct a jumper from scavenged parts already present on ISS.

Although the Node 2 Zenith hatch was opened last Friday evening, HTV-2′s hatch will not be opened until today (Monday 21st February). HTV-2 will be relocated back to Node 2 Nadir on 7th March, following the departure of Shuttle Discovery.

Following on from the successful HTV-2 relocation, Russia’s Progress M-07M/39P vehicle, which had been docked to the Service Module (SM) Aft port since 12th September last year, undocked from the ISS yesterday (Sunday 20th February) at 1:12 PM GMT.

During the undocking, Russian thrusters were in control of the station’s attitude control. US Control Moment Gyroscopes (CMGs) resumed control of the ISS later on Sunday. Following the undocking, 39P was commanded to conduct it’s de-orbit burn for a destructive re-entry over the Pacific Ocean at 4:12 PM GMT on Sunday.

Click here for ISS news articles: http://www.nasaspaceflight.com/tag/iss/

The 39P undocking has cleared the SM Aft port for the arrival of Europe’s Automated Transfer Vehicle-2 (ATV-2) “Johannes Kepler”, which is currently chasing down the ISS following its launch from Kourou in French Guiana last Wednesday (16th February).

Due to the one day slip of ATV’s launch (from Tuesday to Wednesday), ATV’s automatic docking to the SM Aft port also slipped by one day, to this Thursday (24th February) – the same day as the scheduled launch of Discovery on STS-133. This creates some schedule issues, due to the fact that ATV-2′s successful docking is a Launch Commit Criteria (LCC) for STS-133.

In the unlikely event that ATV-2 should fail to dock with the ISS, Shuttle and ISS managers would be faced with a decision for which there would be very little time for discussion. As such, pre-defined options have already been put in place to aid the decision making process.

Should ISS managers determine that ATV’s docking failure is a simple issue that can be easily resolved, STS-133 and Discovery will stand down for 48 hours in order to give ATV time to make a second docking attempt at the station.

However, should ISS managers determine that ATV’s docking failure is a more complex issue, requiring further study and analysis before a second docking attempt can be made, the ATV will be sent into a parking orbit and Discovery will launch as planned.

The time-critical decision is driven by the fact that ATV-2′s docking to the ISS will occur roughly two hours after External Tank (ET) fuelling is scheduled to begin for Discovery’s launch. As such, if a docking failure occurs, a decision will need to be made extremely quickly as to whether to park ATV and proceed with fuelling and launch, or re-attempt a docking in the following days and stand Discovery down.

STS-133 Specific – Including ET Stringer Issue – Articles: http://www.nasaspaceflight.com/tag/sts-133/

If the decision to stand down was taken, then ET-137 would need to be drained of propellants, thus using up another of the ET-137′s limited number of cryogenic cycles (although 11 cryo cycles still remain before ET-137 reaches its limit).

If ATV docks successfully on Thursday as planned, the ISS crew will ingress ATV that same day, in order to have it “open for business” by the time Shuttle Discovery arrives two days later. ATV-2 was scheduled to perform a test reboost of the ISS on Friday (25th February), one day prior to the scheduled STS-133 docking. However, due to the one day delay of ATV-2′s docking, it is not currently known whether this reboost will be performed or not.

In preparation for the docking, FE-5 Paolo Nespoli and Russian cosmonaut FE-1 Alexander Kaleri have been conducting Onboard Training (OBT) aboard the ISS last week. The OBT consisted of a computer-based program that simulates ATV’s approach to the station, including failures and anomalies in the approach.

Although ATV’s approach and docking to the ISS is fully automated, Both Nespoli and Kaleri will be on hand during the docking to assume manual control in the event of a problem occurring in the approach.

ISS Reconfiguration for STS-133:

Following the successful relocation of the HTV last Friday, the Mobile Servicing System (MSS) was reconfigured to support the STS-133 mission.

These reconfigurations consisted of the SSRMS “walking off” from the Mobile Base System (MBS), where it had been located for the HTV relocation, to Node 2′s Power & Data Grapple Fixture (PDGF). Following the SSRMS walk-off, the Mobile Transporter (MT), with MBS attached, translated from Worksite-5 (WS-5) to WS-3. The Special Purpose Dextrous Manipulator (SPDM), based on the Lab PDGF and holding onto HTV-2′s external payloads, then completed a body roll manoeuvre.

The Expedition 26 crew will be hard at work this week reconfiguring the interior of the ISS to support STS-133, according to an Increment 26 Status document obtained by L2.

Tasks to be completed this week include swapping over two Minus Eighty-degree Laboratory Freezer for ISS (MELFI) racks. MELFI-2, currently located in the Lab Starboard 1 location, will be swapped with MELFI-3, which is currently located in the JPM Aft 1 location.

The Centerline Berthing Camera System (CBCS), which aids ISS robotics operators by providing them with live video views of modules approaching their berthing ports, will be installed and checked out at the Node 1 Nadir port this week in order to support PMM berthing during STS-133. PMA-2, to which Space Shuttle Discovery will dock, will be pressurised and leak checked this week. A great deal of stowage relocation and “pre-pack” for STS-133 will also be conducted this week.

The Expedition 26 crew will also spend time this week bringing themselves up to speed on the STS-133 mission by reviewing procedures and timelines uplinked to them from the ground, and holding conferences with ground controllers to discuss STS-133 mission activities. A conference with the STS-133 crew was held last week.

Crews will also conduct Rendezvous Pitch Manoeuvre (RPM) training, which involves reviewing heat shield photography targets and practising photographing an imaginary Shuttle through the ISS SM windows.

ISS ECLSS Status:

An ISS Systems Status document, obtained by L2, gave an overview of the current status of the ISS Environmental Control & Life Support System (ECLSS), which will be needed to support the STS-133 crew during their stay on the station.

The Oxygen Generator Assembly (OGA), located in the Oxygen Generation System (OGS) rack at Node 3 Aft 5, will be down during the STS-133 mission, as it is currently under investigation by ground specialists due to concerns regarding the pH levels in the system.

The document notes that the OGA was activated at 50% mode for four days from 31st January to 4th February. Recirculation loop samples were taken and initial analysis showed that the pH levels of the samples were “in family with expected results”.

Another item mentioned in the document related to the station’s Water Processor Assembly (WPA), which is located within the Water Recovery System-1 (WRS-1) and WRS-2 racks, installed at Node 3 Deck 5 and Deck 4 respectively. The WPA converts urine and condensate into drinkable water for the station crew.

On 8th February, the WPA’s Mostly Liquid Separator (MLS) failed during a process cycle, which meant that the WPA was unable to process condensate or urine. As such, the ISS crew was required to redirect condensate collection from the WPA to the condensate tank in the Lab.

The WPA’s waste water tank was used to collect Urine Processor Assembly (UPA) distillate. The crew also used an Iodinated Contingency Water Container (CWC-I) to fill the WPA’s water storage tank, for delivery to the Portable Water Dispensed (PWD) to be used for crew consumption.

This configuration would create issues for STS-133 – not because of lack of water – but because of the difficulties associated with keeping track of water in the Lab condensate tank, which collects condensate, the WPA’s waste water tank, which collects UPA distillate, and the WPA’s water storage tank, which provides drinking water for the crew.

The issue of keeping track of all these water locations would be even more challenging during the STS-133 mission, as Discovery’s crew would be using the Waste & Hygiene Compartment (WHC), thus producing more urine and increasing UPA processing, and because the extra crewmembers would be producing more condensate in the ISS’s atmosphere, requiring collection by the condensate tank in the Lab.

Also, some of the STS-133 crewmembers may wish to use the ISS’s PWD for drinking water, but without the WPA to convert UPA distillate and condensate into drinking water, the PWD tanks would be emptied at a faster rate than normal, requiring more manual filling by the ISS crew.

Following a quick study by the Flight Investigation Team (FIT), all evidence pointed to the Pump/Separator Orbital Replacement Unit (ORU) as the failed component. The Pump/Separator ORU had been Removed & Replaced (R&Rd) on a previous occasion, and a new ORU was recently delivered to the ISS inside Japan’s HTV-2.

The FIT instructed the ISS crew to command the WPA to standby mode, which would activate the Pump/Separator so that it could be checked out. The pump turned on at the expected speed, and so the WPA was commanded to process mode, which was again nominal. The WPA was thus considered to be back to normal operational mode.

The WPA continued to operate nominally for two to three process cycles, however, on 17th February, the WPA Pump/Separator again failed in a similar manner to the first failure. The WPA was power-cycled and the pump turned back on as expected. On the morning of 18th February, the WPA processed nominally.

The failure occurred on the same day that HTV-2′s hatch was due to be closed for its upcoming relocation to Node 2 Zenith, and so ground control teams had FE-5 Paolo Nespoli retrieve the spare Pump/Separator ORU from HTV before the hatch was closed, so that it would be available should the FIT deicide to R&R the pump.

Teams met to discuss the WPA failures and possible plans of action to rectify the problem, should they be needed. Teams also worked to develop a plan for STS-133 that does not involve using water converted from UPA distillate – thus protecting against a UPA failure during STS-133.

However, at the STS-133 Flight Readiness Review (FRR) last Friday, it was decided that the ISS ECLSS would not impact STS-133′s target launch date.

Soyuz Flyaround Latest:

The Soyuz TMA-01M/24S flyaround, also being referred to as a flyabout by NASA, is still not certain to happen, as managers at the FRR on Friday decided to make a GO/NO-GO decision for the flyaround during the STS-133 mission.

The decision would be made by Flight Day-6 (FD-6), and would be dependent upon completion of all EVA tasks and no requirement for a Focused Inspection (FI) of Discovery’s heat shield. The Russian space agency, Roscosmos, would have the final say in the decision.

The desire to perform the flyaround manoeuvre seems to be strong, as noted by Associate Administrator for Space Operations Bill Gerstenmaier during last Friday’s post-FRR press conference. According to Gerstenmaier, the images taken during the flyaround would serve engineering purposes, as well as provide for some stunning views.

Gerstenmaier said that never-before-seen views of the ISS’ Truss, Multi Layer Insulation (MLI), and potential Micro Meteoroid Orbital Debris (MMOD) strikes would be gained during the flyaround.

Gerstenmaier also said that Soyuz flyarounds would become more common in the future, when the Shuttle will no longer be available to perform flyarounds of the ISS and gather much-needed images of potential damage to the station’s exterior.

As such, performing a Soyuz flyaround during STS-133 would be good practice for future operations.

The latest proposal for the flyaround would likely involve a one day to extension to the STS-133 mission, with the flyaround occurring on FD-10/Saturday 5th March – one day prior to Discovery’s undocking from the ISS.

NASA sent their proposal for the flyaround to Roscosmos last Saturday (12th February). The proposal that Roscosmos sent back to NASA differed wildly from the proposal that NASA sent to Roscosmos. The new Roscosmos proposal was seen in a stunning Soyuz Flyaround CGI Video, available to download on L2.

At the start of the flyaround manoeuvre, the ISS would be in its standard attitude for Shuttle docked operations, the negative X axis in Velocity Vector (-XVV) Torque Equilibrium Attitude (TEA). For the flyaround, the ISS would first manoeuvre to the Soyuz undocking attitude, which would place the Zenith, or -Z side of the ISS in the Velocity Vector (-ZVV).

The Soyuz TMA-01M/24S spacecraft would then undock from Mini Research Module-2 (MRM-2) and back away from the ISS. This would provide for some views of the Zenith side of the ISS with the curvature of the Earth as a backdrop.

The ISS would then conduct a roll manoeuvre on the negative Y axis, in order to put the station the correct attitude for the Soyuz redocking. During this manoeuvre, the 24S crew would gain some spectacular side-on views of the ISS, its VVs and Shuttle Discovery, with the curvature of the Earth as a backdrop.

24S would then flyaround to line back up with MRM-2′s docking port, and initiate the approach to re-dock. Views of the Zenith side of the ISS with the surface of the Earth below would be available during this manoeuvre.

Once 24S re-docked to MRM-2, the hatches would be opened and the spectacular historical images would be downlinked to the ground for release to the public.

(Numerous articles will follow. L2 members refer to STS-133 live coverage sections for internal coverage, presentations, images and and updates from engineers and managers – which will ramp up into full Flight Day coverage during the mission. Images used, via NASA.gov/NASA TV, and L2).

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SPDM overview:

The SPDM is part of Canada’s Mobile Servicing System (MSS), which also includes the Space Station Remote Manipulator System (SSRMS), Mobile Base System (MBS), and Mobile Transporter (MT).

It was launched to the ISS as a “flat-pack” kit aboard STS-123 in March 2008. Upon its arrival at the ISS, Extravehicular Activity (EVA) crewmembers assembled the SPDM’s individual parts, which rode up to space on a modified Spacelab Pallet (SLP).

The primary purpose of the SPDM is to perform dextrous tasks that require fine, minute control. In the past, such tasks have been performed by EVA crewmembers, as the Shuttle and Station RMS’s are unable to provide fine control due to their large Latching End Effectors (LEEs), which are used to grapple payloads.

Being able to perform these tasks with the SPDM removes the risk to EVA crewmembers, and enables the ISS crew to concentrate on science while ground controllers operate the SPDM.

The SPDM’s construction consists of a LEE, which the SPDM uses to attach itself to grapple fixtures, and a Power & Data Grapple Fixture (PDGF), which the SSRMS uses to grapple the SPDM.

The Enhanced ORU Temporary Platform (EOTP), which was installed on the SPDM during STS-132 in May 2010, is used to hold ORUs in place on the SPDM. Four tool holsters and a video camera are also present.

The SPDM’s manipulation control is provided by two seven-jointed arms, which are both terminated with ORU/Tool Changeout Mechanisms (OTCMs).

The OTCMs are what provide the SPDM with its fine dextrous control. The OTCMs attach to specially designed micro fixtures on the Orbital Replacement Units (ORUs).

The OTCMs feature a retractable motorised socket wrench used to torque bolts, a retractable umbilical connector used to provide electrical, data and video connections to payloads, and a camera and lights used for close-up viewing and to align the OTCMs with the micro fixtures.

The OTCMs also feature Force/Moment Sensor (FMS) and Force/Moment Accommodation (FMA) systems. The FMS and FMA provide the OTCMs with a “sense of touch”, which allows the SPDM to apply precise amounts of force in exactly the right place and direction. The FMS monitors the forces, which are applied and corrected using the FMA.

Checkout period:

Following its delivery to the ISS in March 2008, the SPDM, never before tested in space, has been put through a rigorous set of checkout procedures, which culminated in an operational demonstration in late December 2010.

On 22nd December, the SPDM removed Cargo Transportation Container-3 (CTC-3) from ExPrESS Logistics Carrier-2 (ELC-2) Flight Releasable Attachment Mechanism-1 (FRAM-1), and installed it on the EOTP. On the 23rd, the SPDM removed CTC-3 from the EOTP, and installed it onto ELC-2 FRAM-2.

The results of the December 2010 were detailed in a “lessons learned” document, available to download on L2.

The document provided a more detailed summary of the demonstration operations.

CTC-3 uses the FRAM interface to attach to ELC-2. The Active FRAM (AFRAM) is on CTC-3, with the Passive FRAM (PFRAM) being on ELC-2. FRAMs feature a magnetic soft dock system.

Four protruding magnets in each corner of the PFRAM fit into four magnetic slots in each corner of the AFRAM. The magnets provide 17 pounds of force (lbf) to draw the two sides together.

The force falls to zero when the two sides come within 1.25 inches of each other. Once the soft docks are engaged, the two sides are bolted together. Electrical and data connections are automatically made upon bolt engagement.

For the CTC-3 extraction from ELC-2 FRAM-1, the OTCM first released the FRAM bolt with nominal torque settings. The SSRMS then backed away, taking the SPDM & CTC-3 with it. The removal went smoothly, with the FRAM soft dock reading only ~6 lbf through the FMA.

During the CTC-3 installation onto the EOTP, there were no issues with alignment techniques over the coarse alignment guides.

However, the CTC-3 insertion manoeuvre with the FMA was terminated after 102 seconds due to an FMA timeout. Real-time monitoring of FMA data showed that Y and Z forces were low and stable, at less than 10 Newtons.

The roll was low and the pitch appeared to be stabilising. The yaw was 30 N, so the FMA was likely still working on this axis. Yaw and pitch corrections were required due to termination of the insertion manoeuvre prior to the FMA completing load alleviation.

On the second day of operations, the OTCM released the FRAM bolt/connector with nominal torque. CTC-3 was successfully extracted from the EOTP with the FMA reading only ~6 lbf.

For the CTC-3 installation onto ELC-2 FRAM-2, the installation manoeuvre was attempted without the use of the FMA. The manoeuvre from -14 cm was stalled at -6 cm with an induced pitch error of ~2.5 degrees.

The pitch was corrected, CTC-3 was pushed back into ELC-2, but was stalled at -5 cm with an induced Z error of ~1 cm. The Z error was corrected, CTC-3 was pushed back in, but stalled with no X motion and an induced Z error of ~2 cm.

Due to time constraints, the decision was taken to install using the FMA. With the FMA enabled, the manoeuvre from 5 cm was allowed to run for 93 seconds. All forces were low and stabilised, and the installation was a success.

As the FRAM bolt drives structural pins and a power umbilical, an inhibit is required so that a “hot” connector is not mated. It was discovered that powering off the body for the power inhibit caused the loss of FMS data input to the FMA.

Correction manoeuvres were performed with the FMA active, but because all FMS data was zero, the FMA was effectively inaccurate.

The lessons learned were: “Allow install manoeuvre to run longer giving FMA opportunity to correct misalignments”, “Perform FRAM attachment to EOTP as two stage operation with Body powerdown prior to connector mate to prevent FMA data interruption”, “FRAM install without FMA is best effort and can require significant additional time to accomplish”, and “Consider using FMA Mate payload file with generic manoeuvre timer values for non-FMA install”.

HTV-2 operations:

Following on from the successful demonstration in December, ISS Managers gained confidence in the SPDM’s ability to perform its first ever operational tasks in support of the HTV-2 mission this week. A major overview of HTV-2 robotics operations were detailed in an expansive set of presentations acquired by L2.

Click here for ISS news articles: http://www.nasaspaceflight.com/tag/iss/

The operations kicked off on Tuesday 1st February, when the SSRMS grappled and extracted the Exposed Pallet (EP) from HTV-2′s Unpressurised Logistics Carrier (ULC). The SSRMS then manoeuvred the EP over to the Japanese Experiment Module Remote Manipulator System (JEM RMS), which grappled the EP. The SSRMS then released the EP, and the JEM RMS installed the EP onto the Japanese Exposed Facility.

Attached to the EP are two new ORUs for the station – the Flex Hose Rotary Coupler (FHRC), which facilitates the transfer of ammonia coolant across the station’s Thermal Radiator Rotary Joint (TRRJ), and the CTC-4, which contains smaller items including Remote Power Control Modules (RPCMs) and a Video Distribution Unit (VDU). These two ORUs are attached to the EP via the FRAM interface.

The FHRC and CTC-4 are destined to be installed on ELC-4 FRAM-5 and FRAM-1 respectively. However, ELC-4 currently resides in the Payload Bay (PLB) of Space Shuttle Discovery on LC-39A at KSC, awaiting delivery on the STS-133/ULF-5 mission in February.

Under original plans, ELC-4 would have arrived at the ISS in December, prior to the FHRC and CTC-4 arrival. Due to the delays of the ULF-5 mission, the two ORUs have arrived at the ISS before their install site. Due to this fact, a plan was devised to temporarily store the ORUs on the SPDM until Discovery arrives with ELC-4.

The three-day ORU transfer operation began on Wednesday, when the SSRMS walked-off from the Node 2 PDGF to MBS PDGF-3. The MT with MBS attached then translated from Worksite-5 (WS-5) to WS-7. Upon arrival at WS-7, the SSRMS grappled the SPDM and removed it from MBS PDGF-2, and manoeuvred it into position near the EP.

On Thursday, the second day of operations, the SPDM arm 1 grappled the FHRC’s micro fixture, and released the FRAM bolt. The SSRMS then backed away, pulling the SPDM and FHRC with it. SPDM arm 1 then manoeuvred the FHRC to EOTP side 1 and torqued the FRAM bolt to secure it in place.

The SSRMS then manoeuvred the SPDM into position so that SPDM arm 2 could grapple and remove CTC-4 from the EP. Once arm 2 had a hold of CTC-4, arm 1 moved in to grapple CTC-4′s second micro fixture, whereupon the umbilical was mated to provide electrical power to CTC-4.

CTC-4 will remain attached to arm 1′s OTCM until its installation onto ELC-4 post ULF-5. The reason for leaving CTC-4 on arm 1 instead of EOTP side 2 is because having it on the arm will better distribute the heater power draw from the two ORUs, by putting less electrical load on the EOTP.

Friday’s third and final day of operations started a few hours late due to the snow at Mission Control Center-Houston (MCC-H). The MT translated from WS-7 to WS-5, the SSRMS installed the SPDM onto the Lab PDGF, and SPDM arm 2 then released its grasp of CTC-4. The SSRMS then walked off to the Node 2 PDGF in preparation for Monday’s operations.

On Monday 7th February, the JEM RMS will grapple the EP, remove it from the JEF, and hand it off to the SSRMS. The SSRMS will then re-insert the EP into HTV-2′s ULC.

On Friday 18th February, the SSRMS will again change its base to MBS PDGF-1, in order to grapple and relocate HTV-2 from Node 2 Nadir to Node 2 Zenith, in support of ULF-5.

The MSS will then be configured for ULF-5. For this, the SSRMS will change its base once more to Node 2′s PDGF. The MT will also translate from WS-5 to WS-3.

An SPDM body roll maneuverer will be performed, in order to allow for access by ULF-5 EVA crewmembers, who will install a CLPA lens cover and remove some Multi Layer Insulation (MLI) blankets from the SPDM.

Following the installation of ELC-4 onto the ISS during the ULF-5 mission, and Discovery’s departure from the ISS, the SSRMS will retrieve the SPDM from the Lab PDGF, and the MT will translate to the Starboard side of the station’s Truss.

The SPDM will then install the FHRC and CTC-4 onto ELC-4 using the same method as was used during the December demonstration.

Future operations:

The SPDM has an interesting future ahead of it, with two demonstrations already approved by NASA.

Following the official baselining of STS-135, NASA has confirmed that the Robotic Refuelling Dexterous Demonstration (R2D2) payload will ride up to the ISS on the LMC. R2D2 will demonstrate the feasibility and ability to refuel a satellite in space.

For the test, the SPDM’s OTCMs will be equipped with tools that can cut through a satellite’s exterior, allowing a hose to be inserted into the satellite to pump fuel into its tanks. Tests will include locating, accessing and uncapping valves and transferring simulated liquid fuel. The tools and a demonstration satellite will both be launched on STS-135.

In December 2010, NASA awarded Lockheed Martin Space Systems Company (LMSSC) a contract for Systems Engineering for In-Space Servicing (SEISS). SEISS will include two demonstration tasks, the first being R2D2, and the second being evaluation of a variety of tools, sensors and instruments to support autonomous rendezvous and capture capabilities for orbiting spacecraft systems.

Robotics operations will play a large part in future human spaceflight missions, as current human operations are handed over to robots with increasing dextrous capability. The tests and operations performed by the SPDM will provide much needed data that will be used in the development of these future robotic systems.

(Images used: Lead Image via NASA.gov. Images within the article via L2 Presentations).

Related posts:

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Potential Communication Issues/Dropouts during Rendezvous PROX Ops:

Following launch and several days on orbit, HTV-2 was grappled by the ISS crew at 0641 EST. In preparation for the arrival of HTV-2, a potential problem that flight controllers and ISS crewmembers were trained for during the approach of HTV was a communications dropout through the Command Connection.

As reported in the Mission Operations Directorate Flight Readiness Review (FRR – over 50 presentations for HTV-2 available on L2), “Problem: AR 079240, MCCS – Command Connection for Clients Dropped, Major, 4/20/09.

“Description: Anomaly causes the interface to terminate with all clients connected via EIS. Most external client’s systems initiate an automatic recovery of their connection. SSIPC recovery time could take up to 1.5 minutes due to manual method.”

This could potentially mean a loss of HTV PROX Ops Commanding from SSIPC, but not a loss of HTV telemetry to SSIPC.

The probability of such and occurrence is low as there were only 5 occurrences of this issue in 2009 and 8 in 2010 – none of which occurred during a spacecraft rendezvous with ISS. The occurrences are random and not predictable, and the last occurrence of this issue was on November 4, 2010.

Nonetheless, should the issue present itself during HTV-2 rendezvous, the ISS crew could abort or hold HTV-2’s approach to the station until the Command Connection can be reestablished.

HTV-2 commands transmitted over the HTV/TDRS network would not be affected by any Command Connection issues and “Recovery has been reviewed with JAXA to minimize potential disconnect time during HTV critical commanding.”

In addition to this issue, JAXA has also flagged an MCC-H (Mission Control Center Houston) Dropbox issue.

“The MCC-H dropbox will not receive/deliver files sent from International Partners at the time they are sent because those files have a future timestamp with the large time zone differences,” notes the Mission Operations Directorate FRR, available for download on L2.

“A polling software limitation issue occurs at the beginning of each month between MCC-H and SSIPC using local time stamps with large time zone differences.

“This is a limitation until Efficiency 2.3.2 replaces polling software with COTS.”

To date, JAXA is the only International Partner to flag this as an issue, mainly due to the potential 15-hour lag time between the receipt of the file on the MCC-H server and the processing of that file.

Engineers devised a short-term workaround to process files by “changing the polling configuration real-time until 0000L (midnight local time) and then restoring the default configuration drop box.”

In the end, the arrival of HTV-2 was without issue.

Post-Rendezvous Robotics and Contingency EVAs:

Following the STS-133/ULF5 flight of Discovery to the ISS – currently targeted for launch on 24 February 2011 – the ISS crew will use the now two-year-old SPDM (Special Purpose Dexterous Manipulator) robot, affectionately known as Dextre, to transfer the FHRC and CTC external payloads from the HTV-2 to the newly delivered/installed ELC-4 pallet – a move representing a new robotic operations procedure for the ISS crew.

However, as with all things in the business of space travel, there is a possibility the SPDM could experience a failure that would prevent its use in transferring the FHRC and CTC from HTV-2 to ELC-4.

Should this happen, two ISS crewmembers would have to undertake an unplanned contingency EVA (spacewalk) to manually move the two components to ELC-4. Should this EVA become necessary, a minimum of two weeks lead time would be necessary to adequately prepare and uplink/review the necessary EVA materials to the ISS crew.

As the EVA/Robotics presentation to the HTV-2 FRR states, “Large amount of open work necessary to complete the EVA, most of which will not be started until an EVA is deemed necessary.”

While the likelihood of SPDM failing and the contingency EVA being necessary is slim, the fact remains that this flight of HTV-2 will be one of numerous firsts and previously unplanned events.

A portion of HTV-2’s mission will bridge the ISS indirect crew handover in March, the HTV will be directly mated to Node-2 Zenith before and during Shuttle Discovery’s visit in February/March,  and the ISS crew will be tasked with transferring two new racks from HTV-2 to the JEM-PM (Japanese Experiment Module Pressurized Module): the KOBAIRO and MSPR.

Furthermore, should Discovery’s STS-133 mission be delayed further, beyond its currently planned NET (No Earlier Than) 24 February launch date, the ELC-4 would not be available for the FHRC and CTC external payloads from HTV-2, and HTV-2 itself would not be available for disposal of several PMM (Permanent Multipurpose Module) RSP supply transfer racks.

Additional new HTV-2 internal payloads include the International Space Station Agricultural Camera (ISSAC), Re-Entry Breakup Recorder (REBR), and Amine Swingbed (only a portion of the hardware on HTV-2).

The remaining items in HTV-2 are resupply items for existing payloads. All these payloads are unpowered and carry no transfer constraints.

Additionally, the PMM on Discovery is also launching the permanent power jumpers that will be required for HTV-2’s berthing on Node-2 Zenith. 

Click here for all HTV news articles: http://www.nasaspaceflight.com/tag/htv/

Since Discovery will be launching after the HTV-2 is berthed to Node-2 Zenith, this initially left NASA/JAXA with four options: retrieve the already packed power jumpers from the PMM and launch them on HTV-2, build a new set of jumpers and launch on HTV-2, build a Pin Kit version of jumpers and launch on HTV-2, or build Pin Kit jumpers on orbit.

Option one, to retrieve the jumpers from the PMM, was not possible due to a Space Shuttle Program directive to leave the PMM installed in Discovery’s payload bay for the vehicle’s rollback and stay in the VAB for ET intertank stringer inspections and repairs.

(Refer to live coverage threads linked above. L2 members refer to HTV sections for a vast array of presentations and handbooks, etc. Images used, NASA.gov and via L2 acquired PRCB presentations).

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Launch/On-Orbit Comm & Radar Tracking Ops:

The H-IIB launch vehicle is a two-stage rocket using liquid oxygen and liquid hydrogen as propellant and has four strap-on solid rocket boosters (SRB-A) powered by Polybutadiene.

The H-IIB has two liquid rocket engines (LE-7A) in the first-stage, instead of one for the H-IIA. It has four SRB-As attached to the body, while the standard version of H-IIA had two SRB-As. In addition, the H-IIB’s first-stage body has expanded to 5.2m in diameter from 4m of H-IIA.

The vehicle is extended by the total length of the first stage by 1m from that of H-IIA. At the result of such enhancement, the H-IIB requires 1.7 times more propellant than the former.

To support the launch and initial on-orbit phases of HTV-2′s flight, several ground-based radar tracking stations will be available to ground controllers in Japan.

In fact, HTV-2 will have four C-band radar passes during its first 6 orbits: one during launch and post-insertion activities, one from Kwajalein atoll during orbit 1 ops, one from Wallops field in Virginia, USA on orbit 5 ops, and a final ground pass from Wallops during the craft’s sixth orbit.

As the JSC (Johnson Space Center) MOD (Mission Operations Directorate) presentation to the HTV-2 FRR states, “Four (4) C-band radar passes will be available to support the HTV-2. In the event of a contingency, all available C-band radars would be brought up for support.”

Additionally, ground controllers will have near-permanent comm contact with HTV-2 from launch to docking, and then again from undocking -1 hr until reentry – a capability made possible via continuous S-band Single Access coverage and augmented by Multiple Access (MA) Forward/Return and S-band Multiple Access data channels.

Continuous S-band Single Access support will be routed, at times, through the TDRS (Tracking & Data Relay Satellite) system (TDRS-4, TD171, and TDZ) from pre-launch until ISS grapple and berthing. Likewise, MA service will be available through TDRS-4, TDW, and TDZ.

Nonetheless, TDRS-4′s battery #1 is failed and, while there were no battery issues during the last “eclipse” from 24 July 2010 – 25 September 2010, the next “eclipse” period runs from 21 January 2011 – 23 March 2011… nearly the entire duration of HTV-2′s mission. As the JSC MOD presentation (available for download on L2) notes, “TDRS-4 downlink experiencing irregular, apparently random telemetry errors (hits).”

This could result in telemetry errors from HTV-2. A backup system, Spare Traveling Wave Tube Amplifier (TWTA) is available for use should this issue be realized in flight.

Likewise, “Full utilization on the Eastern and Western TDRS satellites” will be available to HTV-2 teams, but the TDRS 275 satellite will be available for SSA only through its SA2 antenna.

The SA1 antenna will not be available for use except during docking and undocking only and even then must be limited and preapproved by the NASA Network Director.

TDRS support will not be required during HTV/ISS docked ops.

Click here for all HTV news articles: http://www.nasaspaceflight.com/tag/htv/

Flight Dynamics/Automated Vehicles/Orbit Analysis:

After its insertion into LEO (Low Earth Orbit), HTV-2 will begin a seven (7) day phasing period where its orbit will be gradually adjusted (at the same time the spacecraft itself is put through a series of post-launch/pre-docking tests) to more precisely align the craft with the International Space Station.

Unique to HTV-2 is its relatively wide margin in terms of rendezvous altitudes, with a capability to rendezvous with the ISS at altitudes between 350 and 460 km. As noted by the Flight Dynamics, Automated Vehicles & Orbit Analysis presentation to the HTV-2 FRR, “The 350 km minimum altitude is the actual ISS altitude (i.e. ISS perigee requirement) and not average altitude.”

A unique consideration for HTV-2′s docking, however, quickly became the need to set up both HTV-2 and Shuttle Discovery rendezvous opportunities in late-January/early-February following the delay of STS-133/ULF5 to a penciled in “work to” date of 3 February.

“ISS trajectory will be optimized to meet requirements for STS-133/ULF5 and HTV-2,” notes the FRR presentation – available for download on L2. Since APM (Ascent Performance Margin) for STS-133 became a driving factor for the rendezvous altitude of Discovery’s mission, the ISS team devised a plan to lower the Station’s orbit to 348 km (188nm) to assist with STS-133′s APM needs.

This initial strategy allowed for the set-up of FD-3 (Flight Day 3) rendezvous capability for Discovery for the week-long early-February launch window while still preserving HTV-2 launch and docking ops in late-January.

To this end, ISS reboost maneuvers were planned for December 22 and January 12. “TIG for the ISS reboosts on December 22 and January 12 will be optimized to minimize the eccentricity and keep the ISS perigee as high as possible” for HTV-2.

HTV-2/Discovery SIMO Ops:

Moreover, the shift in NASA’s launch schedule for Discovery led to direct impacts on HTV-2 mission planning. With Discovery’s launch suddenly falling within the time span of HTV-2′s docked mission – an occurrence which at first was not possible due to HTV-2′s berthing location and the payload needs of Discovery’s 133/ULF5 mission – a plan was devised to allow both vehicles to be docked simultaneously.

Under the initial planned outlined in the December 2010 FRR for HTV-2, HTV-2 would launch on January 20 and be grappled and berthed to ISS Node-2 Nadir via the SSRMS (Space Station Remote Manipulator System) on January 27.

The following day, the External Platform on HTV would be removed and installed onto the JEM EF (Japan Experiment Module Exposed Facility). On January 30, HTV power would then be deactivated and the HTV-2 itself relocated to the Node-2 Zenith port.

The following day, on January 31, the Russian Progress 41P spacecraft would dock to the Russian segment of the station and therefore pave the way for the STS-133/Discovery launch on 3 February.

However, as noted by the Mission Operations Directorate presentation to the HTV-2 FRR, the power and data cables needed to ingress HTV after its relocation to Node-2 Zenith had already been packed and stowed inside the PMM (Permanent Multipurpose Module) in Shuttle Discovery’s payload and would therefore not be aboard Station prior to FD-7 of Discovery’s mission – the day the PMM would be ingressed.

Therefore, a “Plan to provide temporary keep-alive power using old JLP cable, and comm via Prox RF; also building back-up power cable” was devised by ground teams to enable the relocation of HTV and its ingress by the crew prior to the arrival of Discovery and the PMM.

While the dates for this relocation operation have now changed given the alterations to Discovery’s launch date, they will still be performed prior to Discovery’s now-schedule NET (No Earlier Than) launch on 24 February.

With Discovery launching in February, HTV-2 will still be able to serve as the disposal vehicle for 2 RSP racks, 2 ISP (Integrated Stowage Platforms), and several large foam blocks from the PMM that will no longer be needed once the equipment they are carrying to orbit is removed.

In fact, 55-percent of HTV-2′s return trash content is scheduled to be from the PMM hauled to orbit by Discovery. To accomplish this, the ISS crew will devote nearly 210 hrs to the reconfiguration of the PMM to pull out all the equipment scheduled for burn up in Earth’s atmosphere on HTV-2.

Some of the trash, specifically the foam material from the PMM, will be stowed in “non-standard return stowage locations (center volumes, end-cone, PBA/PFE volumes).”

Resolution of HTV-1 In-Flight Anomalies:

Finally, as with all space missions, JAXA thoroughly reviewed all IFAs (In Flight Anomalies) from the HTV-1 mission in 2009 and developed workarounds or fixes to those issues. In all, only four IFAs gained mention in the HTV-2 FRR, the first being a loss of telemetry during HK1 preemption or packet swap.

As noted by the FRR, “SSIPC lost telemetry during HK1 preemption or packet swap. SSIPC ground system requires BIU minor frame counter in order to process telemetry.”

The presentation goes on to explain that this parameter (BIU minor frame counter in order to process telemetry) is only present – in HTV-1 – in HK1 packets 2 and 4, not in packets 1 and 3. Therefore, an HK1 swap between packets 1 and 3 “would mean SSIPC could not see Ess data. HK1 preemption while in 2 or 4 meant SSIPC could only see half of HTV telemetry.”

The necessary telemetry has been placed in all HK1 packets for HTV-2; however, preemption is still classified as an issue and “will be solved by avoiding preemption during critical HTV ops (handled in planning process).”

Further action on this topic will result in HTV-3 and subs having the BIU counter telemetry in the Ess packet so that preemption will not affect data in the SSIPC.

The second IFA identified from HTV-1 related to a MCU loss of sync caution annunciation.

“During activation of HTV-1, C&W (caution and warning) event 16415 ‘Primary INT MDM (multiplexer/Demultiplexer) Detected Loss of Sync with HTV MCU 2 – LAB’ was Enabled per step 8.4 in 1.100 HTV Activation (HTV OPS/HTV1). This event was in alarm, which rang tones onboard.”

Investigation into this issue revealed that an alarm during HTV activation was unavoidable for HTV-1 due to the default settings of the INT MDM – a setting that “would have been discovered preflight if HTV 1553 connection was modeled in SSTF.”

For HTV-2, “Event 16415 will remain inhibited during HTV attached ops unless a swap to MCU2 is required for a failure. In that case, event 16415 will be enabled and the loss of comm message for MCU1 (event 16414) will be inhibited,” notes the FRR presentation.

Finally, the last two IFAs both dealt with the GPS system aboard HTV-1.  As noted by the FRR, the HTV-1 GPS Absolute Kalman filter diverged once every 18 to 24hrs. This has been corrected for HTV-2 via a fix to the clock management module that “had a software bug causing the SIGI Kalman filter to periodically reject measurements and the filter to diverge.”

Moreover, the HTV-1′s GPS receiver experienced spontaneous resets every few days. To correct this issue, HTV-2′s GPS receiver firmware has been modified.

(Images via JAXA and L2 HTV presentations – over 50 FRR, FOR and Overview presentations).

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ISS Visiting Vehicle Status for ATV-2/HTV-2:

ATV-2 is dictating the choice between Discovery’s February 24th and 27th launch dates, with the deciding factor being the length of time between ATV-2′s launch and docking to the ISS. ATV-2 is currently planned to launch on February 15th, and dock to the ISS at the Service Module (SM) Aft port on February 26th.

That means an eleven day free flight for ATV-2 – eight days of minimum free-flight time which covers any phase angle in the ISS’s orbit, and three extra days to allow for three consecutive launch attempts for ATV-2 without having to adjust the docking date.

If Discovery were to launch on the 24th February, then under current plans, Discovery and ATV-2 would be docking to the ISS on the same date – 26th February. This is not doable due to the amount of work that would be placed on the ISS crew.

As such, the ISS Program (ISSP) is currently in discussions with the European Space Agency (ESA) with a view to eliminating the three extra days from ATV-2′s free flight, which would allow ATV-2 to dock on 23rd February, instead of the currently planned 26th. Should this agreement be made, this would allow Discovery to launch on the 24th – one day after ATV-2′s docking.

The major issue with this plan is that if ATV-2′s launch is scrubbed by one day, then Discovery’s launch will also need to be delayed by one day, due to the fact that the three extra days have been removed from ATV-2′s free flight, and so no time exists in the free flight for launch slippage.

If no agreement can be made, Discovery will launch on February 27th – one day after ATV-2′s docking.

Discovery’s launch slip has also affected the robotics operations for HTV-2, currently planned to launch on 20th January, for a rendezvous and berthing to the ISS on 27th January. The launch window, however, extends from the 20th to the 28th January, with launch attempts to be made every three days.

HTV-2 will be a challenging mission from a robotics perspective, with multiple operations planned that include use of the Space Station Remote Manipulator System (SSRMS) “Candarm2″, the Special Purpose Dextrous Manipulator (SPDM) “Dextre”, the Mobile Base System (MBS), the Mobile Transporter (MT), and the Japanese Experiment Module Remote Manipulator System (JEM RMS).

ISS Specific Articles: http://www.nasaspaceflight.com/tag/ISS/

Shuttle Discovery is dictating the robotics operations due to the fact that she is carrying the ExPrESS [Expedite the Processing of Experiments to Space Station] Logistics Carrier-4 (ELC-4) in her Payload Bay (PLB), which is the install site for both of HTV-2′s external Orbital Replacement Unit (ORU) payloads – the Flex Hose Rotary Coupler (FHRC) and Cargo Transportation Container-4 (CTC-4).

Due to the fact that Discovery’s launch date has been pushed into the late February window, there will now be insufficient time to complete all ORU transfers to the ISS prior to HTV-2′s departure date on 28th March. If STS-133′s launch date is pushed beyond the late February window, then both ORUs will have no install location on ISS prior to HTV-2′s departure.

A full overview of HTV-2 robotics operations was detailed in an expansive set of HTV-2 Mission Operations Directorate (MOD) Flight Readiness Review (FRR) documents, available to download on L2.

On HTV-2 Flight Day-7 (FD-7), the HTV will be captured and berthed to the Node 2 Nadir Common Berthing Mechanism (CBM) by the SSRMS, which will be based on the Node 2 Power and Data Grapple Fixture (PDGF).

A few hours after the berthing, the SSRMS will grapple the Exposed Pallet (EP) in HTV-2′s Unpressurised Logistics Carrier (ULC), in order to provide power to the EP’s two ORU payloads.

A few days after the berthing, the SSRMS will extract the EP from HTV-2′s ULC and hand it off to the JEM RMS. The JEM RMS will then attach the EP to the Japanese Exposed Facility (JEF) via the JEF’s Exposed Facility Unit (EFU), and the EP’s Payload Interface Unit (PIU).

When connected together, the EFU and PIU become an Equipment Exchange Unit (EEU).

A few days later, the SSRMS will retrieve the SPDM from MBS PDGF number 2. The SPDM, on the end of the SSRMS, will then retrieve the FHRC and CTC-4 from the EP on the JEF.

Two plans are being considered that would either place both ORUs on the SPDM’s Enhanced ORU Temporary Platform (EOTP), which was delivered during STS-132 last May, or one ORU on the EOTP and another on one of the SPDM’s “arms”, which may better distribute the heater power draw of the two ORUs.

The SPDM will then be placed on the MBS. Having ORUs on the SPDM during STS-133 may carry some issues, however, as one of STS-133′s EVA tasks is to install a CLPA lens cover over the SPDM’s video camera.

In the days following the ORU transfers to the SPDM, the JEM RMS will grapple and remove the EP from the JEF, and hand it off to the SSRMS. The SSRMS will then re-insert the empty EP into the ULC.

This plan ensures that both ORUs are transferred to ISS and the EP re-inserted into the ULC before HTV-2 has to depart the station.

The next task for the SSRMS, still based on the Node 2 PDGF, will be to grapple HTV-2 and relocate it from the Node 2 Nadir CBM to the Node 2 Zenith CBM. The relocation is a Launch Commit Criteria (LCC) for STS-133, as HTV-2 would preclude payloads from being removed from Discovery’s PLB if it were berthed to Node 2 Nadir.

This means that Discovery cannot launch until the relocation has been performed, due to the fact that, should a problem arise during HTV-2′s unberthing from the ISS, Discovery would be unable to perform her mission objectives of installing the Permanent Multipurpose Module (PMM) and ELC-4 onto the ISS.

The Mobile Servicing System (MSS), which includes the Mobile Transporter, MBS, SSRMS, and SPDM, will then be reconfigured to support the STS-133 mission. All of the aforementioned operations are time-critical, as they must be completed before Discovery launches. If any problems or issues arise during these robotics operations, very little time will exist to perform troubleshooting.

Following the successful installation of ELC-4 onto the S3 Nadir Inboard Payload Attach System (PAS), and Discovery’s departure from the ISS, the SSRMS will position itself on the MBS, and the MT (with MBS attached) will then translate from Worksite 5 (WS-5) to WS-2. The SSRMS will then grapple the SPDM, and the SPDM will install the FHRC and CTC-4 onto ELC-4.

On the third and final day of the ORU transfer operations, the SSRMS will place the SPDM back onto the MBS, the MT will translate from WS-2 to WS-5, and the SSRMS will then be relocated to the Node 2 PDGF.

It is unclear at this time as to whether HTV-2 will be relocated back to Node 2 Nadir prior to unberthing. Whichever option is chosen, the final task for the SSRMS will be to unberth HTV-2 from Node 2 Nadir or Zenith, and release it to free-fly once again.

(Images used: Lead – NASA.gov. Within the article  – via L2 presentations).

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General Overview:

In the 20-page MOD (Mission Operations Directorate) presentation (available for download on L2), a comprehensive overview of the three proposed software changes is outlined, as well as the MOD’s specific role in “integration of current and future visiting vehicles.”

Among the software changes – one of which will be implemented prior to the launch of JAXA’s (Japan Aerospace Exploration Agency’s) HTV automated resupply spacecraft to the ISS in the middle of next month (January 2011) – are software specific changes for the accommodation of multiple visiting vehicles (including commercial vehicles) at a single time, projected alterations to the COTS UHF Communication Unit and upgrades to HTV2′s Caution and Warning system.

Issue #1: How to Support Multiple Vehicles on ISS (Software):

Currently, the software architecture on the ISS is “static,” using shared C&C (Command and Communication) MDM (Multiplexer Demultiplexer) memory to handle visiting vehicle telemetry. Using JAXA’s HTV as an example, “two different command routing logical destination codes exist: HTV_1553 and HTV_PROX both send commands to the HTV but through different paths” – a system that will not be able to handle certain visiting vehicle requirements in the future.

Specifically, “Data routing is accomplished with two commands that have the potential to conflict with each other: Select HTV Data Path and Select Dragon (SpaceX)/Cygnus (Orbital) Data Path.”

Presently, these data paths are managed in real-time by ISE, and APID (Applications Process Identification) takes responsibility for “command routing.”

However, this “static” operation is scheduled to change in 2012 with the uplink of the CCS (Command Communication Software) R12 updates/upgrades and the introduction of “dynamic command routing to ISS for visiting vehicles.”

According to the MOD presentation from earlier this month, the 2012 CCS R12 uplink will reconfigure the handling systems on the ISS so that “Command and telemetry routing will be grouped into the same category and both will be configured with a new data path selection command.”

This will enable different “memory areas” in the ISS’s computer system to be selected and used during multiple visiting vehicle operational times. In turn, each “memory area” can be connected to/linked to a specific visiting vehicle via a visiting vehicle designator: HTV-A, Dragon-A, Dragon-B – all of which will enable data to reach its intended destination in an efficient manner.

Under the new dynamic command routing software, “Single destination code ‘HTV’ would send command to the appropriate destination based on the data mapping configuration commands.”

Furthermore, no changes to APID tables for currently operational visiting vehicles will be required for this upgrade, therefore eliminating the need to update all HTV PCS (Procedure Completion Sheet) pages and crew and joint ground procedures.

However, there maybe a need to update some ground segment architecture at visiting vehicle partner centers and MCC-H (Mission Control Center – Houston).

Moreover, there are four Ops related issues that have been raised as a result of this planned software upgrade.

“Load shed causes commands to visiting vehicles; undesirable while in free flight,” notes the MOD presentation. “Current architecture has load shed commands to power down visiting vehicle components built with the command instances that are designed to static route only to the 1553 hardline connection.”

This means that during dynamic routing, an ISS power failure/spike (or general power issue) holds the potential to send a “load shed” command to a free-flying visiting vehicle.

To work around this issue, a software inhibit will be added to allow any automated C&C MDM commands to visiting vehicles during pathway configuration to be “masked,” thus preventing any inadvertent commands from reaching the visiting vehicle while it’s in free-flight.

A second issue raised by the software change is the potential “undesired response” by the ISS computers in the event of a fire in a free-flying visiting vehicle.

“Emergency event such as fire in a free-flying vehicle may cause undesired ISS automated response,” notes the software change presentation. “Current architecture uses INT (Internal) MDM for emergency response; free-flying visiting vehicle comm systems bypass the INT.”

To counter this problem, the presentation notes that a new docking hub “may require emergency response software to be elevated to C&C since the docking hub systems will likely have their own MDM.”

Furthermore, if the CCS were to handle an emergency response, steps would need to be taken to ensure that the software could properly distinguish if a visiting vehicle was in free-flight or not. This would be necessary to determine if “automatic safing on the ISS” would be required.

The same inhibit command for the “load shed” issue would most likely be used to ensure this free-flight/non-free-flight distinction is made.

The third of four Ops issues identified relates to the unique PROX GPS data path that will not be accommodated in the new software upgrades.

“New architecture does not accommodate unique PROX GPS data path currently available in CCS. Due to CB-EXT bus bandwidth limitations, a set of “extended” PROX GPS data is available only when HTV data is turned off.”

Current thinking to mitigate this problem is to configure the software to recognize this extended GPS data as a “dummy” visiting vehicle and assign it a unique ID and specific data path.

Finally, the last Ops issue is the configuration of RMAD data to RWS. As the MOD presentation states, “Two data pipes exist to send visiting vehicle data to the RWS overlays: one for HTV and one for Dragon/Cygnus.”

Given that both the PROX and CUCU (COTS UHF Communication Unit) links could be active at the same time under the software upgrades, a new command to set the RMAD data pipes will be required since there will be no way for the software to automatically determine which path to use.

Over the coming year, ISS engineers will continue to refine the software changes planned for 2012, updating procedures for configuring data paths in rendezvous and docked phases, updated PCS to include new data path configuration commands, retesting interfaces and MCC/ops team support, and assisting with the planning for the installation of new 1553 jumper installation on Node-2 zenith to “support second visiting vehicle hardline data path.”

Issue #2: Fixing Problems with CCS Response to CUCU Failures:

As originally conceived during COTS (Commercial Orbital Transportation Services) – Dragon or Cygnus capsule – vehicle docked missions, CUCU (COTS UHF Communication Unit) RIO 1 would always be selected as the primary communications channel, with RIO 2 serving only as a backup in the event of RIO 1 failure.

However, this configuration is now out of spec with the latest operations concept for the COTS vehicles.

“Operationally may be desirable to have RIO2 as the Primary due to better comm antenna coverage. In this case, FDIR (Fault Detection Identification/Isolation and Recovery/Recognition) would not be available,” notes the MOD presentation.

As such, ISE has requested an FDIR implementation change to favor RIO 2 as the primary channel and, in a failure scenario, automatically switch to RIO 1.

While it is hoped that this change can be implemented prior to SpaceX’s Dragon C3 mission, there remains the possibility that this changeover could produce high rates of unnecessary retreat maneuvers by Dragon (either through its own software or as commanded by the ISS crew) during its approach to the ISS.

Currently, though, the MOD does not believe the RIO 1 to RIO 2 changeover prior to Dragon C3 would be a safety hazard to the ISS crew since they will still have command capability to Dragon.

Issue #3: HTV Injector Overheat Response:

“During HTV1 (September-November 2009), there was a thruster overtemp issue caused by a high duty cycle when performing 300 m hold. Team worked around this by swapping thruster strings multiple times and bypassing some demo objectives to quickly get closer to ISS where thruster duty is lower,” notes the ISS software presentation.

During post-flight analysis, it was discovered that more temperature margin existed than was baselined prior to the HTV1 mission. Therefore, “Even though the probability [was] small, there [was] a chance that if HTV [held] outside of 300 m, injector temperature might approach catastrophic limits.”

As such, ISE has coordinated an upgrade of the injector overtemp advisory. This upgrade will involve a warning event with planned crew action to abort HTV approach to ISS should the crew receive a injector overtemp warning message while the HTV is out of contact (LOS – Loss Of Signal) with MCC.

These upgrades, along with crew procedure deltas and crew familiarization with the new ops will be implemented prior to the launch of HTV2 next month (January 2011).

Meanwhile, JAXA has already updated HTV2′s software to set the warning message trigger at 320-degrees C. The previous limit was 260-degrees C.

Additionally, ground control crews will automatically switch propulsion strings – during periods of direct contact/communication with HTV2 – if the injector temperatures reach 320-degrees C.

No related posts.

STS-133 Delay:

With the root cause into what caused two stringers to crack on Discovery’s External Tank (ET-137) during tanking continuing, managers decided to take the “next step” via demonstrations, such as building a test rig with a stringer set-up – likely to be located at the Marshall Space Flight Center (MSFC) – along with an instrumented Tanking Test out at the Pad.

A preliminary schedule for the instrumented Tanking Test has already been created, with a plan to conduct the test on December 15, replacing an original plan to press forward with a non-instrumented tanking next week – as much as that was only a preliminary option.

“An option to perform an un-instrumented tanking test is (was) being considered. CTS (Call To Stations) NET Monday, 12/6, and tanking NET Wednesday, 12/8. The plan is to go down to T-31 seconds and secure,” noted the NASA Test Director on Friday morning (L2).

“While the team prepares for a tanking test, the PRCB (Program Requirements Control Board) yesterday did not provide direction as to when the tanking test would occur.”

Space Shuttle Program (SSP) manager John Shannon addressed the media on Friday, noting that on consideration a non-instrumented Tanking Test would be “too gross”.

Discussions over the coming days will decide on the forward plan for setting up ET-137′s flange regions with instrumentation – which will include the removal and replacement of BX-265 Thermal Protection System foam from the tank – along with a pad flow schedule to refine the date the of the test.

This effort will be the major focus of Discovery’s flow for the interim, with ordnance disconnects – originally scheduled for the weekend – cancelled, while Backscatter imaging of the ET LH2 flange is continuing.

STS-133 Specific – Includes all ET issue content – Articles: http://www.nasaspaceflight.com/tag/sts-133/

Several in-depth articles will follow in the coming days on the continuing root cause evaluations.

ISS Fallout:

The STS-133 delay will have major impacts on Japan’s H-II Transfer Vehicle-2 (HTV-2) “Kounotori”, that is scheduled to launch to the ISS on 20th January 2011.

Inside HTV-2′s Unpressurised Logistics Carrier (ULC) will be an Exposed Pallet (EP), which will be carrying two Orbital Replacement Units (ORUs) for the US segment of the station. The first ORU is the Flex Hose Rotary Coupler (FHRC), and the second is the Cargo Transportation Container-4 (CTC-4).

The FHRC and CTC-4 will be installed onto the ISS’s ExPrESS Logistics Carrier-4 (ELC-4), which currently resides in the Payload Bay of Space Shuttle Discovery on LC-39A at KSC. Under original plans, ELC-4 was set to arrive at the ISS months ahead of HTV-2, when Discovery was planned to visit in late 2010. However, now that STS-133 has been pushed into February 2011, HTV-2 will arrive at the ISS before ELC-4.

As such, ISS Program Managers have devised a plan that enables the FHRC and CTC-4 to be installed directly onto ELC-4, without having to adjust the launch date of HTV-2.

Following HTV-2′s launch on 20th January and a seven day free flight, HTV-2 will be captured by the Space Station Remote Manipulator System (SSRMS) and berthed to the Nadir port of Node 2 on 27th January. Node 2 Nadir is currently the primary port for all Common Berthing Mechanism (CBM) compatible Visiting Vehicles (VVs).

In the days following the HTV-2 berthing, the ORU-laden EP will be extracted from HTV-2′s ULC with the SSRMS, and attached to the Japanese Exposed Facility (JEF) on the Port side of the station. Following the completion of this procedure, the SSRMS will un-berth HTV-2 from the Node 2 Nadir port, and transfer it to the Node 2 Zenith port directly above the Nadir port.

The Node 2 Zenith port is currently reserved as a back-up port in case the primary VV port is unusable.

The reason for re-locating HTV-2 to the Node 2 Zenith port is to provide clearance for Space Shuttle Discovery when it docks to the ISS on 5th February. If HTV-2 were berthed to the Node 2 Nadir port during the STS-133 mission, it would preclude payloads from being removed from Discovery’s Payload Bay by the SSRMS.

Following Discovery’s visit and the installation of ELC-4 onto the Nadir side of the Starboard 3 (S3) Truss, the two ORUs will be removed from the EP, still attached to the JEF, with the Japanese Experiment Module (JEM) RMS.

They will then be handed off to the Special Purpose Dextrous Manipulator (SPDM) “Dextre” on the end of the SSRMS, and installed onto ELC-4. HTV-2 will then be relocated back to Node 2 Nadir, and the EP removed from the JEF and reinserted into the ULC.

In the midst of all these external activities, an intense period of reconfiguration will also be taking place inside the ISS.

The Permanent Multipurpose Module (PMM) being launched on STS-133 contains many racks used to retain cargo during launch, but that are useless on-orbit. The Expedition 26 crew will be working hard to unload these racks quickly, so that they can be transferred to HTV-2 for disposal before it is un-berthed from the ISS in mid-March.

We may also see Robonaut 2 (R2), being launched in the PMM on STS-133, being unpacked soon after launch, as its Structural Launch Enclosure to Effectively Protect Robonaut (SLEEPR) is planned to be disposed of on HTV-2.

In order to accomplish all these extra objectives, the HTV-2 mission will be extended to 60 days. This busy period of work aboard the ISS will be further complicated by the arrival of Europe’s Automated Transfer Vehicle-2 (ATV-2) on 27th February, two Russian Progress undockings, one Progress docking, and two Russian Orlan spacewalks.

ISS Specific Articles: http://www.nasaspaceflight.com/tag/iss/

On 20th December, a test of the SPDM will be conducted in order to verify that it is ready to perform ORU ops. during HTV-2. For this test, the SPDM will pick up a CTC, and manoeuvre it around in order to test its dexterity.

Endeavour’s STS-134 mission has also been slipped from its February launch date, moving to a placeholder of April 1 – a date which will continue to be refined based on the status of her older sister’s successful completion of her mission.

(Further updates and articles will follow. Refer to live coverage threads linked above. L2 members refer to STS-133 live coverage sections for internal coverage, presentations, images and and updates from engineers and managers. Images used, Lead: NASA.gov. Within the article: via L2 acquired presentations and NASA.gov).

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