Russian Progress M-21M re-tests new Kurs-NA system

by Chris Bergin

A Russian Progress went on a short excursion this week, resulting in a redocking to the International Space Station (ISS) on Friday. The two day free-flying trip for Progress M-21M was used to re-test the Kurs-NA system that misbehaved when the vehicle first docked to the orbital outpost last November, resulting in Oleg Kotov having to grapple manual control of the little ship ahead of a successful docking.

Progress M-21M:

Following its liftoff from the Baikonur Cosmodrome a top of a Russian Soyuz-U rocket, Progress M-21M spent several days in orbit, unlike a number of its predecessors that have been using the well-practised four-orbit fast rendezvous with the ISS, conducted over a period of around six hours.

In fact, the trip was even longer than usual, involving four days on orbit, allowing for flybys of the Station to test the new system.

Unlike recent Progress vehicles that used the 2AO-VKA and AKR-VKA antennas of KURS-A system, M-21M sported a AO-753A antenna of the KURS-NA system instead.

This new system is noted to be lighter and has a lower power consumption than its predecessor – while the accuracy of the system is understood to have been greatly improved.

Once the Progress reached its preliminary orbit last November, it conducted a series of automated engine burns to put it on track to fly within one mile of the station, allowing for the test of the more efficient KURS automated rendezvous system hardware for upgraded Soyuz and Progress vehicles.

The tests were all classed as successful.

Following the flyby, the Progress looped above and behind the station, ahead of preparations for its docking.

Z78However, despite a good approach and flyaround, the KURS system suffered a failure at just 60 meters distance during final approach.

The Progress immediately halted its approach, allowing for Oleg Kotov to take control of the vehicle via the manual TORU system.

Using a joystick and a control panel on the ISS, the Expedition 38 commander guided the Progress into the docking port with a large amount of skill, as the vehicle started to move around the docking target.

Docking was confirmed, followed by hard mate, resulting in a welcome array of food and cargo for the ISS crewmembers.

It total, the vehicle delivered 1,763 pounds of propellant, 48 pounds of oxygen, 57 pounds of air, 925 pounds of water and 3,119 pounds of spare parts and experiment hardware, as it took up residency at the aft port of the Zvezda service module.

A Russian Arrival at the ISSHowever, because the test of the Kurs-NA didn’t achieve its goals, a retest was planned for this week, resulting in the Progress undocking on April 23 at 08:58 UTC – heading out on a two day flight, prior to re-docking on April 25 at 12:16 UTC.

“Progress 53P (M-21M)  Undock: 53P undocked at ~4am.  This is in support of a Kurs-NA test.  Separation and preliminary Kurs-NA test were nominal.  Re-Dock is planned for Friday ~7:15am,” noted ISS status information, as the Progress headed out before making its second trip back to the Station.

The return, closely following what the initial attempt was supposed to do, appears to have been successful. However, Russian teams on the ground will likely spend the next few days reviewing the data.

ISS Dragon Ops:

During Friday’s events, the Progress re-joined with its new neighbor, SpaceX’s CRS-3 Dragon, which successfully arrived at the Station on Easter Sunday.

“SpaceX-3 Capture: The approach and capture of the Dragon vehicle was mostly nominal on Sunday.  Capture occurred at about 6:15am Sunday morning,” confirmed L2 ISS status.

4f5518b15ac4e3ac1c74dff2f7496f32“Four instances of Dragon UHF / CUCU swaps were seen during approach with no significant loss of communication and no impacts. No swaps occurred after the 200m point.  No issues with ISS hardware were observed.”

(Animation created by Artyom Zharov, via L2’s huge collection of CRS-3 arrival hi res images)

The CRS-3/SpX-3 brought with her a complement of 1,580kg/3,476lb of payload, an increase from the previous limit of 800kg, afforded by the increased upmass capabilities of the Falcon 9 v1.1.

Z77A multitude of cargo included a GLACIER and two MERLIN freezers for transporting ISS experiment samples.

The external payload in Dragon’s trunk includes the Optical Payload for Lasercomm Science (OPALS) – which will demonstrate high-bandwidth space to ground laser communications, and the High Definition Earth Viewing (HDEV) package consisting of four commercial HD video cameras.

The CRS-3 mission also involves the delivery of a replacement Extravehicular Mobility Unit (EMU), allowing for the return of a faulty suit on the same vehicle when it returns to Earth. This spacesuit relay is enabled by a specially built rack inside the Dragon.

While the ISS crew continue to unload the pressurized cargo from the Dragon, next week will highlight the spacecraft’s payload in her trunk, as the Station’s robotic assets prepare to remove them for an installation on the ISS.

The trunk is an unpressurized element of the Dragon, allowing for additional cargo – such as Orbital Replacement Units (ORUs) – to ride uphill with the spacecraft.

“On Wednesday and Thursday next week, the High Definition Earth Viewing (HDEV) hardware will be installed on Columbus, and the Optical Payload for Lasercomm Science (OPALS) hardware will be installed on the Special Purpose Dexterous Manipulator (SPDM) Enhanced ORU Temporary Platform (EOTP) (to be installed later on ELC1),” noted L2 ISS Status.

Work to prepare for this meeting between the Station’s Canadian assets and SpaceX’s spacecraft have proceeded nominally.

“MT (Mobile Transporter) Translation and SSRMS (Space Station Remote Manipulator System) Status for Space X Trunk Operations: The MT was translated from Work Site 2 to Work Site 6 to support removing two sets of research hardware from the Space X Trunk next week,” added L2 ISS Status.

In support of next week’s activities, the SSRMS released its grip on the Dragon, which was since firmly secured on the Station, as much as there was a slight issue during the securing of the bolts, after the spacecraft was latched on to the Common Berthing Mechanism (CBM).

Z7“SpaceX-3 Berth – ND2 Nadir CBM Bolt 3-1 Failure – The Berthing operations were mostly nominal except for the CBM bolt 3-1 that would not engage,” added L2 ISS Status information.

“This particular bolt had been trending toward needing higher torques in past operations and on Sunday during Dragon Berthing it exceeded the software limit of 33 N-m for sequence 4.  The other bolts were torqued to the final required values.  15 of 16 bolts is approved for all loads except Dragon solar Array rotation.  Bolt 3-1 was successfully retracted.

“This configures the bolt for remove and replacement (R&R) which will likely be scheduled before Dragon departure. Vestibule pressurization, leak check, equalization, and ingress were all completed successfully without further issue. There are 2 spare CBM Portable Bolt Assemblies on-orbit.”

ISS engineers have set up Failure Investigation Team (FIT) to discuss impacts and forward plan.

(Images: via L2’s SpaceX Special Section, which includes over 1,000 unreleased hi res images from Dragon’s four flights to the ISS. Other images via NASA and SpaceX)

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