Endeavour’s ongoing legacy: AMS-02 proving its value

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The first exciting results from the AMS-02 (Alpha Magnetic Spectrometer -02) were released this week, providing what may be the first tangible clues in the ongoing investigation into Dark Matter in the universe. However, the $2 billion experiment only made it into space thanks to the addition of a mission for Shuttle Endeavour, STS-134.


Originally, the plan was to end the Space Shuttle Program (SSP) with the STS-133 flight. Indeed, the last two planned missions – STS-132 and STS-133 – began life on the Flight Assignments Working Group (FAWG) manifests (full set from STS-1 onwards in L2) as CLF (Contingency Logistics Flight) missions, prior to what became a mini-extension of the Shuttle fleet’s swansong.

AMS-02 Oveview, via L2STS-134 came to life via the Flight Definition and Requirements Directive (FDRD) process as a mission for Discovery, based on strong political support to extend the life of the International Space Station (ISS), and to facilitate a ride uphill for AMS-02.

Initially, funding for STS-134 had yet to be secured. However, MOD teams were able to begin their traditional “Plan/Train/Fly – PTF” approach to the mission, via the support of a NASA Authorization Bill in September of 2008, which directed NASA to “take all necessary steps” to add STS-134’s delivery of AMS to the Station into the schedule.

The mission was still lacking certainty, not least because the Bill contains a caveat for the NASA Administrator to cancel the flight, within one year ahead of its launch, if it was determined that it could cost significantly more than the existing estimate, or that it would create an unacceptable safety risk.

STS-134 coming to life via the FAWG Manifests, via L2Had NASA’s leadership taken such a route, Congress would have had to reauthorize the flight, or the President would have had to certify that it is in the national interest to fly the mission.

Thankfully, STS-134 soon matured into a baselined mission – as seen in its progression on the FAWG manifests – as it moved from a Launch On Need (LON) support mission, to an actual mission in its own right.

With a Change Request (CR) swapping the STS-134 mission from Discovery to Endeavour, the youngest orbiter in the fleet was baselined to carry to the Alpha Magnetic Spectrometer 2 (AMS-02), Express Logistics Carrier 3 (ELC-3), Materials on International Space Station Experiment 8 (MISSE 8), an Orion Rendezvous Detailed Test Objective (DTO) kit, and a GLACIER freezer module for one of the Station’s science laboratories.

Click here for the full range of STS-134 News Articles: http://www.nasaspaceflight.com/tag/sts-134/

Endeavour would also return the MISSE 7a and 7b experiments to Earth as well as perform four Department of Defense payloads of opportunity: MAUI, SEITI, RAMBO-2, and SIMPLEX.

Title Page for the STS-134 FDRD Presentation, via L2The STS-134 FDRD document (available in L2) provided an overview of Endeavour’s final – and rather large payload – up-mass, totaling 36,740lbs, including middeck payload and crew equipment weight.

The star of the show as the primary payload was AMS-02 – weighing 15,300lbs.

Tagged as a “particle physics detector”, designed with a large, cryogenic super-fluid helium superconducting magnet, the AMS-02 unit was constructed to “search for antimatter and the origin and structure of dark matter.”

Ironically, it was that magnet that became a problem ahead of the launch date – relating to a vastly reduced lifetime estimation that was observed during testing in Holland, as engineers worked on finding a solution that would allow AMS to enjoy a lifetime that would match the extension of ISS operations until at least 2020.

AMS-2 Magnet Change, via L2A decision to changeout the hardware for a permanent magnet, as noted by the STS-134 Mission Integration Manager (MIM) at the time, which in turn slipped the launch date deeper into 2011.

Getting AMS-02 uphill to the ISS was also a challenge, with mission documentation (L2) noting the need for four longeron payload latches and one active keel latch for its attachment to the payload bay sidewalls of Endeavour.

Additionally, once on orbit, Remotely Operated Electrical Umbilicals (ROEU) would provide AMS-02 with 124V of power for its heaters and avionics – required to keep it alive in the cold of space.

Prior to liftoff, this power was provided via the T-0 umbilicals on the launch pad. These T-0 umbilicals also allowed launch personnel to monitor the health of AMS-02 prior to liftoff and make sure that Launch Commit Criteria for the AMS-02 was not breached.

STS-134 LaunchEndeavour had an eventful final flow at the launch pad, with her first launch attempt scrubbed due to problems with heaters on her Auxiliary Power Units (APUs).

Launching on May 16, 2011Endeaovur enjoyed a successful trip to the ISS, kicking off the docked phase with the transition of AMS-02 from the orbiter’s payload bay to its new home on the Station.

The robotic ballet involved the Shuttle Remote Manipulator System (SRMS) unberthing the AMS from the payload bay, before handing AMS to the SSRMS (Space Station Remote Manipulator System).

AMS-02 on ISSThe crew then ungrappled the SRMS from AMS, officially handing the experiment over to the ISS, before it was maneuvered to its attachment point on the Starboard 3 Upper Inboard Command Attach System (CAS).

This was followed by stage one installation/first stage capture. Stage two installation was completed, before the umbilical mates were then secured. The SSRMS then ungrappled AMS, marking the completion of its permanent installation on ISS.

STS-134 Animation via photo sequence on L2Endeavour completed her final mission and returned home on June 1, 2011.

(Animated image resized from hires/full screen version and sequence photo dumps on L2′s STS-134 Flight Day image section – several hundred megabytes strong – L2 Link.) 

She was then placed into a Transition & Retirement (T&R) flowmarked by her final powerdown in May, 2012

Endeavour was then given an emotional farewell tour on the back of the Shuttle Carrier Aircraft, prior to her handover to her retirement home at the California Science Center (CSC).

However, her final primary payload lives on, with Wednesday’s announcement of AMS-02’s first set of results on the ISS causing interest from around the world.

The results noted that since its installation, AMS-02 has measured over 30 billion cosmic rays at energies up to trillions of electron volts.

Its permanent magnet and array of precision particle detectors collect and identify charged cosmic rays passing through AMS from the far reaches of space. Over its long duration mission on the ISS, AMS will record signals from 16 billion cosmic rays every year and transmit them to Earth for analysis by the AMS Collaboration.

AMS-02 on ISSImportantly, the results note that AMS-02 has seen evidence of what may be proven to be the elusive “dark matter” – the mysterious element that accounts for most of the mass in the Universe – colliding with itself.

“The AMS cosmic ray particle results announced today could help foster a new understanding of the fields of fundamental physics and astrophysics,” noted NASA administrator Charlie Bolden. “I am confident that this is only the first of many scientific discoveries enabled by the station that will change our understanding of the universe.

“Multiple NASA human spaceflight centers around the country played important roles in this work, and we look forward to many more exciting results from AMS.”

A lot more work and research will be required to advance the findings, but the value of the AMS-02 is now becoming more obvious – all made possible by some political will, some clever scientists, the orbital outpost that is the ISS, and the capable baby of the Shuttle fleet, Endeavour.

(Images: Via NASA and L2 content from L2’s Expansive STS-134 specific section, which includes vast amount of FRR/PRCB level presentations, photos, graphics, videos, flow and mission updates – compelte coverage available on no other site.)

( To join L2, click here: http://www.nasaspaceflight.com/l2/)

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