CT2 Incident:

The two 3,000 ton tracked vehicles have a storied history, responsible for carrying the NASA fleet of vehicles from the Vehicle Assembly Building (VAB) to the launch pads, ever since the Saturn IB and right through to today’s Space Shuttles.

The CTs would live on past the end of the Shuttle era, by transporting Ares I – after successfully debuting with the Ares I-X test vehicle – or a proposed Shuttle Derived Heavy Lift Launch Vehicle (SD HLV).

With at least two more shuttle missions to go, the Constellation Program (CxP) added a task that was set to take place ahead of STS-133′s rollout – to weigh and relocate the newly constructed Ares I ML.

The Ares I ML test and relocate involves both CTs – with the ML being weighed by the Crawler Transporter (CT-1) at its current location at the Mobile Launcher Platform (MLP) refurbishment site, while CT-2 works in tandem by freeing up the new location by moving MLP-1 to the VAB.

CT-1 will then move the Ares I ML the relatively short distance to its new home at the east refurb site, where it will be lowered down on to mounts. The entire operation – which was scheduled for late August – would be spread out over five days.

However, CT-2 was recently struck by lightning – it is believed, though still under an official investigation as to an exact root cause – after the recently installed special electrical equipment was damaged. The issues with the CT were found after a recent checkout, with problems associated with the control boards for the servo valve on the JEL system. The repair work will take around four to six weeks.

“Crawler Transporter-2: Engineering is evaluating an issue with all eight of the Jacking Equalization & Leveling (JEL) servo valves,” noted the NASA Test Director (NTD) in an opening report on the problem (L2). “The four electronic control boards for these valves were removed and sent to the Malfunction Lab for evaluation.

“The Servo valves (have been removed) and valves shipped to the Vendor for evaluation and rebuild. Turnaround estimate is 4-6 weeks. A timeline is being built of events/tasks that have taken place on CT-2 from 1 April through 31 July. Included are: PM’s, repairs, welding, lightning events, and anything else that may help explain the event. Investigation continues as to possible causes of the failure.”

“The investigation continues with further troubleshooting as to the possible cause of the failures,” added a later update. “The failure analysis lab has been asked to do some additional analysis on the circuit cards to look for any data that would support a lightning strike or power supply failure.”

With CT-2 under investigation, CT-1 has also been grounded for the interim. However, it is likely the results of the lab testing will allow for the release of CT-1 in time to support STS-133′s rollout from the VAB, currently scheduled for September 28.

“Once all parts are received back from the vendor and re-installed, testing will be performed to verify no other CT systems were affected,” added the latest NTD update. “The use of CT-1 is currently being constrained by the CT-2 investigation. CT-1 may be released back into service when the failure analysis of the control cards is completed.”

Crawlerway Testing for HLV:

The home track of the CTs is also undergoing a study, as the prospect of a HLV riding down the crawlerway sooner than outlined in the FY2011 budget proposal increasing as the political refinements move forward.

Under what is still the current Program of Record (POR), Ares I is/was to be joined by Ares V – Constellation’s HLV. The Ares V program was rumored to be considering a larger type of Super Crawler, with six tracks, to carry the Ares V to the pad. (Left: Notional image based on early L2 information).

However, the first references to the challenge of ensuring such a heavy vehicle – one with two full fuelled five segment Solid Rocket Boosters (SRBs), as opposed to solely liquid-fuelled vehicles, tanked after arriving at the pad – were provided in this week’s review of construction at the Kennedy Space Center (KSC).

“Study involves testing of various crawlerway rock surfaces to better understand the feasibility of operating a tracked transporter for a heavy-lift program,” noted KSC Construction’s August presentation (L2). “Similar testing was last conducted in the mid-1960s in support of the Apollo Program.”

Initial testing has already been completed on an area of crawlerway just outside of Constellation’s Pad 39B, via a strange looking contraption which aimed to test the impact of over 25 million pounds on the rock surface of the track.

“This compatibility testing was conducted on the crawlerway just outside of LC-39B and was performed at the equivalent anticipated Ares V rollout weight of 25,200,000 pounds versus the Shuttle/Apollo rollout weight of 18,000,000 pounds,” added the presentation.

“Testing results will provide degradation characteristics, rate of deterioration, expected lifecycle of various materials, coefficients of friction and reaction forces exerted upon a crawler-transporter shoe.

“Several surfaces were tested and included rock expected to be optimal for a tracked transporter, rock anticipated to be optimal for a dual-use crawlerway (supporting both a tracked and wheeled transporter), and resilient surfaces targeted to reduce excessive loading of a crawler shoe as it crosses roadways and VAB transitions.”

The findings of the testing, which was conducted by NASA, the United Space Alliance (USA), Architect and Engineering firm Jones Edmunds and Associates (JEA) and a couple of additional contractors, are expected sometime in September. Additional testing will take place, with STS-133′s rollout also aiding the results.

“Testing and site demobilization at LC-39B are now complete, with a report from JEA targeted for September 2010, although there are plans to conduct some additional testing and instrumentation of the crawlerway during the next shuttle rollout,” added the notes.

The iconic 100-foot wide double pathway is made up of a seven foot deep bed of stones, which lies beneath a layer of asphalt and a river rock surface. The surface requires constant maintenance to ensure the smooth passage of the Shuttle during its ride on the CT to the pad.

The latest construction news noted that a major project will be undertaken to repair areas of crawler that lead up to Pad 39A, requiring 32,000 tons of the specialised Alabama river rock to be used.

“This project involves removing and replacing the severely degraded river rock along the surface of the LC-39 crawlerway from Ordnance Road to the Pad A surface. The uniformly rounded river rock surface provides the necessary cushioning and low-friction coefficient characteristics that are critical to all crawler-transporter operations,” added the presentation.

“While the crawlerway foundation includes a minimum of 3 feet of compacted limestone, the minimum depth of the rock surface varies between just 4 inches on the crawlerway straight sections to 8 inches on the curves. The estimated total amount of new rock necessary to complete this project is 32,000 tons.

“All the excavated rock is being stockpiled at the Diverted Aggregate Reclamation and Collection Yard (DARCY) site within the landfill and will be screened into separate piles of fine and larger rock for future reuse throughout KSC as decorative borders, road base and crawlerway repairs.”

Other major work is also listed, including news that Pad 39B will undergo major demolition work, as planned via the Constellation Program. Sources note this work is likely to be placed on hold due to large costs. An article will be published when inquires into the project’s status are addressed.

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JDTV:

The first test of the giant parachutes that will be tasked with easing Ares I’s five segment Solid Rocket Motor First Stage’s return to earth for splashdown in the Atlantic didn’t go fully to plan, with damage sustained to the JDTV – which mimics the Ares I First Stage, if not by appearance – during its debut drop test last summer.

An Integrated Product Team (IPT) conducted a design and analysis review of modifications to the JDTV, which resulted an increase to the strength of the buckled components, following its hard landing, and the inclusion of break-away fins – which were re-manufactured prior to the upcoming test.

This should avoid future damage to the reusable test vehicle, which is deployed out of the back of a US Air Force C-17 transport on an extraction pallet.

Teams successfully completed the tow tests of the new C-17 air drop extraction (pallet) system to be used on the upcoming JDTV parachute drop tests. A new extraction system was required since the standard extraction system utilized by the Air Force has a 60,000-lb extraction limit.

“The new extraction system uses Vectran rope, along with modified standard Army 15-ft drogue, and 28-ft extraction parachutes that have been structurally reinforced with Kevlar radials,” noted Ares Program information.

“The test consisted of towing the modified drogue and extraction chutes with the Vectran rope behind a C-17. The test objectives were to measure and record the tow forces of the parachutes at various air speeds and parachute reefing positions and visually record their proper deployment.”

The drop will take place at 10am on February 26 – weather permitting – at the US Army Yuma Proving Ground, located close to the Arizona-California border, which has been the site for most of the drop tests for the Constellation program.

Last summer, the Orion Parachute Test Vehicle (PTV) – a truncated looking Orion – suffered a failure, ripping off its parachutes and crashing to the ground, after it became inverted following extraction from a C-17 aircraft.

The vehicle is now scrapped, located in the “boneyard” of the Army base.

In 2007, the third Parachute Drop Test (PDT) – which was testing a pilot parachute for the Constellation program – resulted in the Drop Test Vehicle (DTV) being destroyed.

The test vehicle hit the ground with such velocity, special excavation equipment was required to recover the nose of the DTV – which was buried 30 feet below the surface. All other tests have been deemed a success.

MLAS (Max Launch Abort System):

Specially funded outside of the Constellation program, under the leadership of former Constellation head Scott Horowitz and NASA Engineering and Safety Center (NESC), the MLAS is confirmed to be just a month away from an opening salvo of tests.

First revealed by NASASpaceflight.com last year, several presentations on L2 outline the concept that appears to have grown out of the LAS trade studies in 2007.

During that trade study, three candidates were evaluated, namely the Multiple External (x4) Service Module (SM) Abort Motor concept, the Crew Module Strap On Motors (x4) concept, and the In-Line Tandem Tractor (Tower) concept – with the latter then baselined into Ares I/Orion design.

The trade study presentation – also on L2 – shows a ‘hand drawn sketch’ by former NASA administrator Mike Griffin, dated March 22, 2006, that is believed to be the origin of MLAS.

The “alternative” Launch Abort System was originally set to carry out a pad abort test in September, 2008. However, concerns the system is far too heavy for Ares I, and the continued push to baseline the traditional “tower’ LAS, initially led to rumors the project had been cancelled.

Although never specifically noted as anything other than an alternative “fall back position” system, it is possible MLAS is part of a backup plan for a Human Rated Ares V, given initial studies into man-rating the huge vehicle note it would be impossible to stack with the current LAS tower, due to height restrictions regarding vehicle integration inside the Vehicle Assembly Building (VAB).

With MLAS on top of Ares V, the vehicle could be stacked within current restrictions. A Human Rated Ares V would only become a reality if Ares I development was ceased, and the alternative options of EELV and Direct’s Jupiter vehicles failed to win approval under such a scenario.

For now, the Constellation program are only classing MLAS as an “alternative” to the LAS tower, even though it would be near unthinkable to make such a large change to Ares I at this stage of development.

“Like the leading NASA launch abort concept, MLAS offers a safe, reliable method of pulling the spacecraft capsule and crew out of danger in the event of an emergency on the launch pad or during the climb to Earth orbit,” noted NASA in releasing the date of the pad abort test.

“A NASA team is preparing to demonstrate an alternate escape system design to explore different technological approaches. Named after Maxime (Max) Faget, a Mercury-era pioneer, the Max Launch Abort System (MLAS) concept will be validated by conducting an unmanned pad-abort test in March at NASA’s Wallops Flight Facility, Wallops Island, Va.”

The dates listed involve a parachute drop test of the MLAS on March 5, followed by the pad abort test on March 27.

Representatives from the Sounding Rockets Program Office and NASA Sounding Rocket Operations Contract, (NSROC), have provided technical support associated with the solid rocket motor systems used by MLAS. NSROC also play a major role in vehicle hardware and mechanical GSE (Ground Support Equipment) fabrication.

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The program has initiated a study to look at the feasibility of maintaining the SSME after shuttle retirement, for potential use with Constellation, in turn allowing a move that would also hold benefits for spares support requirements in the event of a shuttle extension.

Currently, the Ares V baseline is a 10m core stage with six RS-68B engines and 5.5 segment solid boosters derived from Ares I. The upper stage is 10m in diameter with a single J2-X engine. However, the program is looking for additional margin on lunar exploration missions, and to trim the budget at the same time. This effort resulted in numerous studies to refine the Ares V vehicle.

The original 2005 ESAS (Exploration Systems Architecture Study) Cargo Launch Vehicle (CaLV or Ares V) was an 8.4m core with five expendable SSME’s, two 5 segment SRBs, and two J2-S engines on the upper stage. This originally mirrored a more powerful version of what was known as the “Magnum” vehicle in the July 2005 AIAA Joint Propulsion Conference Document.

The CaLV was to share the SSME with the Crew Launch Vehicle (CLV or Ares I), which would use it as its upper stage power plant.

After the expendable SSME was found to be too difficult to airstart on the CLV upper stage, and also too expensive to be used on the CaLV core stage, Constellation adopted a single J2-X for both upper stages, with Ares V utilizing the RS-68 on a 10m core (a more powerful “Longfellow” type vehicle).

However, that original configuration wasn’t powerful enough to meet performance requirements, and Ares V eventually grew a 10m upper stage, with six RS-68B engines. The baseline boosters are now 5.5 segment variants of the shuttle SRB, with the option to build new lighter composite casings for additional performance.

Constellation is now interested in re-evaluating the SSME option for the Ares V core, with five or six expendable SSMEs, and two 5 segment SRB’s powering the new variant, should the option be selected.

The switch back to the $50-$60 million per engine SSME would be traded against the development costs of the 5.5 segment booster and modification of the $20 million RS-68B for Ares V.

A documented reference to the SSME potentially living on post-shuttle was recently revealed via a note of pre-emption on a shuttle memo in December, which initially did not give clarification on its potential requirement, until sources passed on clarification of its Ares V relevance.

“A study on retaining flight ready block II engines/LRUs (Line Replaceable Unit) and the flight capability after Shuttle retirement was discussed,” noted the memo on L2. “This preserves the option of using SSME assets as risk mitigation for Cx (Constellation) and other NASA or external flight and test applications. This presentation identified the items that would need to be retained.

“A potential location for storage is the engine processing facility which is attached to OPF-3 (Orbiter Processing Facility) but OPF-3 is later scheduled for demolition. SSME and Ground Ops need to study this in further detail. The PRCB (Program Requirements Control Board) agreed the study should be pursued.”

Should shuttle receive an additional two years worth of flights – which is deemed as the favored option – one additional SSME will be built and added to the current manifest of engines.

The additional requirements will be based on spares supports, with the shutdown of SSME contractor assets now frozen until a decision on the retirement date is finalized, as required in the recent Senate Bill that included the protection of shuttle extension. Plans to shutdown the key hardware elements of the SSME had been ongoing up to that point.

Notably, an expanded production capability would be required to support the number of SSME’s that would be needed for Constellation, should the option be taken. Past studies have estimated the cost of building a new production line at roughly $500 million.

When the engine has been looked at in the past for expendable use, it has been estimated that the complexity of the engine can be reduced by eliminating the reuse requirement. This would drive down costs by reducing the number of parts, simplifying the manufacturing, and eliminating the labor required per engine for post flight servicing. All of this will factor in to the decision to go with RS-68B and 5.5 segment SRB or SSME and 5 seg SRB.

With the potential shuttle extension, the SSME will be used by the shuttle far longer than originally anticipated. The infrastructure to support the SSME is already in place at KSC, and the personnel are already trained and equipped to handle the SSME.

With the potential for a shorter gap between the decommissioning of the shuttle and the first tests of Ares V it may be possible to retain the capability to fly the SSME, which is an option that was previously not on the table.

Another major factor that the study is likely to consider is that the SSME may be better suited to mitigating the plume impingement and base heating issues on Ares V, which is currently a major issue that is being worked on Ares V.

The exhaust plumes of six RS-68 engines, combined with the two SRBs, interact to reduce the efficiency of the engines, and cause extreme heating on the base of the core stage.

This has led to an ongoing evaluation into the realignment of engine placement on the base of the Ares V, with several options still being studied.

The regenerative nozzle of the SSME may have an advantage over the ablative RS-68 by providing a more resistant nozzle in the extreme environment of the core stage cluster.

The regenerative nozzle protects both the inside and the outside of the nozzle, versus the ablative nozzle which is designed to deal with heat from only the inside. In a cluster of engines, the nozzle must withstand both the heat from its own exhaust in addition to the outside exhaust plumes of the other engines in the cluster.

Because of the regenerative nozzle, the SSME may be more resilient to plume interaction and base heating in this area.

Although a change back to the SSME is not believed to be imminent, the study into a potential switch will likely be completed by early 2009.

At that time, Constellation program engineers will know if the shuttle manifest has been extended past 2010, and if the plume impingement issue with the RS-68s is still a troublesome factor – all of which will play into the hands of favoring a lifeline to the workhorse engine that has proved to be a huge success over the 25 years-plus use on the space shuttle.

L2 members: All documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, now over 4000 gbs in size, which includes the world’s largest collection of  unrestricted Constellation documentation and video outside of NASA computers.

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