The FINAL Space Shuttle Spacewalk: STS-134 EVA-4 – Completed

by Chris Gebhardt

As Endeavour heads into the sunset portion of her historic final voyage to space, her crew have completed one of the biggest lasts in the Shuttle Program: the 162nd and FINAL Space Shuttle spacewalk. This historic day concluded all scheduled EVA activities for the Space Shuttle Program and its astronauts since EVAs on Shuttle missions began on the STS-6 (1983) mission by Shuttle orbiter Challenger.

The Final Space Shuttle Spacewalk:

With Flight Day 12 (FD-12) for Endeavour and her STS-134 crew come four important and truly historic milestones: the final EVA/Spacewalk of the Space Shuttle Program, the final Station construction EVA by non-ISS crewmembers (as currently scheduled), the permanent transfer of Endeavour’s Orbiter Boom Sensor System from the Shuttle itself to the International Space Station, and the 1000th hour of spacewalking time dedicated to construction of the International Space Station.

After waking up at 1956 EDT, Mike Fincke and Greg Chamitoff emerged from the Quest Airlock where they spent the night “camping out” for their final foray into the vacuum of space.

After a brief, 30-minute hygiene break, Fincke and Chamitoff returned to Quest to begin final preparations for their spacewalk, or EVA – Extra-Vehicular Activity. Once the crew lock of Quest was depressurized to 10.2 psi, spacesuit purge was conducted as the spacewalking duo donned their tell-tale white EMUs (Extravehicular Mobility Units).

Once the crew lock was completely depressurized, Fincke and Chamitoff took their EMUs to battery power and officially began the final Space Shuttle crew spacewalk in history at 4:02 Central time.

However, per the mission timeline, just before the duo took their spacesuits to battery power, the Space Station Remote Manipulator System (SSRMS), or robot arm, reached out from the Station and grappled Endeavour’s OBSS – which itself was grappled by the Shuttle Remote Manipulator System (SRMS).

Fincke and Chamitoff began their EVA excursion with an egress from the Quest Airlock on the Station. At this same, per the written EVA timeline, the Endeavour crew commanded the SRMS to ungrapple the OBSS – marking the official handoff of Endeavour’s long-serving and extremely important OBSS from Endeavour to the Station, and by extension from the Space Shuttle Program to the International Space Station Program.

Interestingly enough, the handoff of Endeavour’s OBSS to the ISS marked the final element of Space Shuttle flight hardware to be permanently deployed on and attached to the ISS – bringing a full circle to Endeavour’s career as the Space Shuttle orbiter that both began construction of the International Space Station and completed U.S. assembly of the iconic orbiting laboratory.

Moreover, this marked Endeavour, two times over, the only Space Shuttle orbiter to launch with an OBSS and not return with it.

STS-134 Specific Articles:

The previous mission to do so was STS-123/Endeavour in March 2008. During that flight, Endeavour’s crew (of which Greg Johnson was a part of as well) also performed a docked late-inspection of OV-105’s Wing Leading Edge Reinforced Carbon-Carbon panels before deploying their OBSS on the Station for use by the next Shuttle mission: STS-124/Discovery.

After exiting the ISS, Fincke and Chamitoff moved out to the S0/S1 truss and provide visual and audio commentary/directions as the SSRMS is used to lower and berth the OBSS to its already installed stanchions.

Once SSRMS manoeuvring ops were complete, Fincke and Chamitoff began OBSS post-berth securing operations.

Unlike the similar STS-123 EVA to attach the OBSS to the station, this mission will not feature OBSS “keep alive” activities for the dedicated sensor packs on the boom’s scanning end. Since the sensors will no longer be needed for any Space Shuttle orbiter TPS evaluations, the sensors will be allowed to “die” and decay.

After initial securing operations are complete, Fincke and Chamitoff translated over to the P6 truss and retrieved a stowed Power Data Grapple Fixture (PDGF), which they brought back to the OBSS at the S0/S1 truss.

Once back at the OBSS, Fincke and Chamitoff started to remove the boom’s End Effector Grapple Fixture – the grapple fixture which, until now, allowed the Endeavour’s SRMS to grapple and control and interface with the OBSS.

However, this Shuttle-ready interface unit on the OBSS is not compatible with requirements of the Station’s SSRMS. Thus, the EFGF was removed from the OBSS and stowed on the Station’s Tool Stowage Assembly.

Chamitoff was then tasked with installing the PDGF onto the OBSS – which will allow the SSRMS to grapple the OBSS at its end point and allow for maximum reach and utility of the OBSS as a Station-based asset for future ISS crews.

After this, Greg Chamitoff began an inspection of the OTP before joining Mike Finke at Canadian-built Dextre (or the Special Purpose Dexterous Manipulator). During their work on Dextre, Fincke and Chamitoff released a retention system on the spare robotics arm.

Interestingly enough, the final Space Shuttle crew to perform work on Dextre was a crew of Endeavour. Endeavour was the orbiter that delivered Dextre to the International Space Station on the STS-123 mission.

After this, Fincke and Chamitoff performed a few “get ahead” tasks before cleaning up and ingressing the Space Station, but not before Chamitoff paid tribute to Endeavour, the ISS and the thousands of workers involved in constructing the orbital outpost.

“This is the last flight of Space Shuttle Endeavour and it’s also the last spacewalk of shuttle crewmembers and for station assembly,” noted the spacewalker from the “top” of the Station.

“It’s kinda fitting that Endeavour is here, ’cause Endeavour was the first shuttle to begin construction of the station, and so it’s fitting that she’s here for the last mission for station assembly. 

“During this EVA we passed collectively over 1000 hours of spacewalks that is part of station assembly.

“Mike and I have the honor here to share this last spacewalk and of course for all the folks working on the ground, thousands of people helped build this – working in the shuttle and station program – we’re floating here on the shoulders of giants.

“This space station is the pinnacle of human achievement and international cooperation. Twelve years of building and 15 countries and now it’s a cornerstone in the sky and hopefully the doorstep to our future.

“So congratulations everybody on assembly complete. Ok, time to go home.”

At the completion of EVA-4, officially marking the end of a 7 hour and 24 minute EVA, Mike Fincke is ~13hrs shy of breaking the all-time American/NASA astronaut endurance record for cumulative time spent in space. Currently, the record is held by now-Chief of the Astronaut Office Peggy Whitson. Fincke is due to surpass her 377-day record at ~8pm EDT Friday.

Space Shuttle EVA History:

Since Space Shuttle EVA operations began on the STS-6/Challenger mission in April 1983, astronauts have spent thousands of hours building a space station, helping maintain MIR, saving/upgrading/servicing the Hubble Space Telescope, servicing satellites in orbit, and learning new and innovative ways to work in the confines of a large, bulky pressure suit.

Of the 162 spacewalks performed over the life of the Space Shuttle Program, 121 of those have been performed since the STS-88/Endeavour mission in December 1998 – the mission that began construction of the International Space Station.

Before the era of the ISS, only 41 Space Shuttle spacewalks were performed: a handful in support of joint Shuttle/MIR operations, a few designed to test concepts for Space Station construction, and numerous EVAs to retrieve, repair, and re-release satellites in Low Earth Orbit – including 10 dedicated to Hubble.

However, not all of the 121 ISS-era spacewalks were in support of ISS construction. In fact, 108 of those 121 spacewalks have been conducted in support of construction of the International Space Station over the course of only 36 missions.

The remaining 13 (still a whopping number) were performed over the course of three missions (STS-103/Discovery, STS-109/Columbia, and STS-125/Atlantis) in support of maintenance and upgrades to the Hubble Space Telescope.

In all, a whopping 23 EVAs were undertaken by the crews of just five Space Shuttle missions to save, service, repair, and upgrade the Hubble – our window on the universe.

But more striking here at the completion of EVA-4 for STS-134, is the coincidence – once again – with Endeavour.

Today’s spacewalk marked the 4th and final spacewalk of Endeavour’s STS-134 mission. The first time four spacewalks were conducted on a single mission was back on STS-49 in May 1992 – the maiden voyage of Endeavour.

Similarly, Endeavour was the first Space Shuttle orbiter to perform five back-to-back spacewalks on single mission – an achievement that has never been topped, only equalled.

Click here for Endeavour’s full history:
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Moreover, 161 of these 162 historic walks in space have been conducted with only two astronauts. Only one has ever been conducted with more than two astronauts; STS-49 (Endeavour’s maiden voyage) saw a three-person spacewalk on EVA-3 of that mission.

And while today represents a Shuttle crew’s last foray into the vacuum of space, we remember the skill and dedication of all individuals – both those in space and especially those on the ground… the hundreds of unnamed planners and trainers and supporters of our EVA undertakings – involved in all the spacewalks across the program.

But most importantly, as we mark the closing of another highly visible and significant chapter of the Space Shuttle Program, we take with us the lessons we have learned from our spacewalking enterprises, and we thank the thousands of men and woman around the world who have supported these valiant efforts in Low Earth Orbit.

(Images via L2 presentations, videos and images – plus L2 Historical and Extensive coverage is being provided on the news site, forum and L2 special sections – the latter of which is the world’s best front row seat to Shuttle missions. With specific and extensive flight day coverage, from interactive “one stop” FD live coverage in the open forum, to internal documentation, photos, videos and content in the specific L2 FD areas).

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