NASA managers have been presented with a working plan and completed assessments on the potential for a Soyuz flyaround of the Shuttle/Station stack during Endeavour’s docked mission. With many of the hurdles from the cancelled STS-133 flyabout plan removed, the unique event has a high potential of being approved by the International Space Station (ISS) partners.
**UPDATE APRIL 8 PER L2: OFFICIALLY “TURNED OFF” FOR STS-134 due to Russian schedule decision. More later in a new article**
The original opportunity for the flyabout – during Discovery’s STS-133 mission at the ISS – suffered from two crucial issues.
Firstly, the amount of time between the proposal and putting the plan into work was short, meaning evaluations were still ongoing even after Discovery’s mission was being carried out.
Secondly, the Soyuz to be used was on its debut mission, with the ultimate Russian decision based on the risk of undocking their new 700 series Soyuz to and from the Station – which is classed as test vehicle – prior to the capturing of photography of the orbiting outpost, before redocking shortly after.
(Click here for more amazing model photography by NSF member Keith McNeill)
With the potential STS-134 flyabout back on the table, as listed in Flight Readiness Review (FRR) documentation (L2) for Endeavour’s mission, there is a large amount of hope a positive decision will be forthcoming for STS-134.
Although the flyabout would provide stunning imagery of the Station, the engineering data gathered on the health of the orbiting outpost would be helpful for engineers on the ground. Carrying out the flyabout with a docked shuttle, however, would be lost if an agreement can’t be reached for either STS-134 or STS-135.
“With Shuttle flights winding down, this being the second to last one, this represents a unique opportunity to get photo documentation of the entire configuration with the Shuttle attached,” noted Derek Hassmann, Lead ISS Flight Director for ULF-6.
The flyabout trajectory and maneuvers would likely be similar to what was evaluted during analysis prior to STS-133, this time using the soon-to-be-launched Soyuz TMA-21 spacecraft.
The Russian vehicle would undock from its planned port on the Poisk module – which is attached to the zenith port of Zvezda module – back straight out to a distance of about 200 meters and hold position.
The ISS would then change its orientation to provide a different perspective of the station complex to the Soyuz and also a first-time look at a Shuttle Orbiter docked to the station from that perspective.
The Soyuz crew would then fly their ship to align with the re-oriented location of the docking port on Poisk, move back in and redock. Crew members would take video and still imagery of the Station during most of these maneuvers.
Hassmann added that if approved, the operations team would likely use the mission extension day (the “plus one” day) to allow for the event to fit into the schedule.
“At a high level, what we would plan to do is use that ‘plus one’ day – we’d insert that plus one day in order to provide some margin to support this activity,” Hassmann added. “I would expect the Soyuz flyabout to be done later in the mission rather than earlier – something on the order of Flight Day 12 (or) 13. We haven’t finalized what that day would be, but that’s what we’re working towards.”
Previous articles on the Soyuz Flyabout Evaluations:
Documentation and memos are now starting to flow on the assessments created for the flyabout with the Soyuz, all showing positive evaluations into what would be a historic event.
Most of the documentation shows the STS-133 planning as the baseline (Image left from set of L2 hi res images, photoshopped by NSF member Lee Jay Fingersh), with tweaks for the actual manevers involved and the slight change to the configuration of the Station, such as the lack of the HTV-2 being docked, which – for the STS-133 evaluations – provided some level of protection for the orbiter’s windows from potential thruster firing contamination.
“STS-134 Dual Docked Ops (aka Soyuz flyabout) – The Soyuz undock/redock is the same scenario as evaluated for STS-133 except that HTV will not be present. The Windows (Team) evaluated the STS-134 environment and showed good results even without HTV being present,” noted an 8th Floor MOD memo (L2).
The update also noted that it is now likely the decision will be taken ahead of the mission, instead during the docked phase of the flight, with a placeholder for the event to take place on Flight Day 13 (FD13). The Space Shuttle Program (SSP) FRR and Agency FRR are being consulted on the evalautions.
“The decision to add the flyabout is needed no later than FD9 since the +1 day would be added after FD9 to accomplish some of the prep activities and offload some of the activities from the actual flyabout day. The extra day is added before docked late inspection to keep that as late as possible,” added the memo.
“The flyabout would be performed on the morning of FD13. Hatch closure is at the end of this day with undock the next morning. This subject will be taken to the SSP FRR and to the Agency FRR as a special topic. The plan is to continue to keep this as an option and make a decision during the mission.”
The largest evaluation – from a STS-134 standpoint – was seen at the Program Requirements Control Board (PRCB) level, where an expansive 44 page overview was discussed.
“Soyuz undock/redock during the mated mission to capture imagery of the unique vehicle configuration (similar to STS-133 less HTV). Fly-about will be performed by 26S Crew (model 200 Soyuz). Fly-about duration approx 1 hr,” opened the PRCB presentation, available on L2 – noting that should the flyabout suffer a major issue, the newly arrived Soyuz crew would have to deorbit and return home – a major consideration for the ISS partners.
NASA astronaut and Expedition 27 Flight Engineer Ron Garan and Russian cosmonauts Alexander Samokutyaev and Andrey Borisenko will launch from the Baikonur Cosmodrome in Kazakhstan on April 4 at 5:18 pm CDT, for a scheduled six month tour on the ISS.
“Soyuz crew will be suited and prepared for a contingency deorbit if required. Crew will use still camera and camcorder to capture imagery from Habitation Module window once at 180-200 meter range. On board ISS, MRM-2 hatch will be closed, but other ISS hatches will be open and ISS/STS crew will be scheduled for nominal activities.”
The presentation’s operation plan outline elaborates on the baseline of STS-133’s flyabout discussions, the mission timeline – taking into account STS-134’s Docked Late Inspections (DLI) given Endeavour’s Orbiter Boom Sensor System (OBSS) will be left on Station – and the contingency evaluations, which are listed as forward work, pointing to what is likely the only remaining obsticle for the green light to proceed with the flyabout.
“Team is leveraging off of our known experience base where applicable to meet this Agency objective. Utilizing as much information as possible from the STS-133 fly-about work. Nominal plan is developing with open work remaining,” the presentation continued.
“Vehicle orientations (ISS and Soyuz) for undock, photos, and docking are to be provided by the Russians which enables other analysis and assessments to begin. Contingency planning considerations forward work. ‘What if’ scenarios for emergencies during the event that result in Orbiter undock requirements (JEUS). Soyuz Failure to redock.
“Add a +1 day after FD9 to accomplish some of the prep activities as well as offload some of the activities from the actual fly-about day. Before the Docked Late Inspection (DLI). DLI relative to entry remains the same as the nominal plan (as late as possible). Perform the fly-about on morning of FD13. Hatch closure is at the end of this day and undock the next morning (FD14). Fly-about performed by 26S crew (Borisienko, Garan, Samokutayuv).”
The key points of this current plan note the Flyabout decision is required no later than FD9, given most major mission objectives complete by then (AMS, ELC, EVAs 1-3), whilst also reserving the +1 day as late as possible for other needs that may arise. Thus, it is likely the flyabout will recieve an initial go, pending no issues during the bulk of Endeavour’s docked mission.
STS-134 Specific Articles: http://www.nasaspaceflight.com/tag/sts-134/
The plan also keeps the Docked Late Inspections as late as possible to minimize MMOD (Orbital Debris) risk, and keeps all crewmembers sleep shifted together.
For the Russian vehicle, the Soyuz activation, leak check, and prep will occur on daily orbits 1 and 2, with the Flyabout scheduled on daily orbit 3.
The presentation also notes a large amount of work has been completed, successfully, as per the Technical Work Executive Summary, citing the SSP/ISS mated Soyuz dynamic un-dock and docking loads analysis is complete, whilst no issues were found in relation to the Soyuz to Shuttle Radio Frequency Compatibility.
Trajectory Control System, payload bay cameras, elbow camera and RSC camera will be sufficiently shielded from, and/or pointed away from, the 26S plume environment, with a large section dedicated to the evaluations on the small risk of contamination on the orbiter’s windows from the Soyuz’s thruster firings.
Again, evaluations are based on mitigating the potential worst case scenarios, which the presentation lists – though notes the findings show no concern for Endeavour’s windows.
“Worst Case Consequences. Window would shed slivers of glass after failure. Glass debris could impact OMS pod, Rudders speed brake. Crew Module pressure would not be affected. Reduced CDR/PLT (Commander/Pilot) visibility through the windows.”
The thermal analysis has also been completed, with no orbiter passive thermal issues noted. The orbiter has an ‘any attitude’ capability of three to five hours depending on beta. Also, the OBSS will be stowed on ISS given current operational timeline scenario.
It is likely that a decision point on at least proceeding towards a go/no go during the docked mission will be announced at the Agency FRR next week.
(Images used, all via L2 presentations, imagery and L2 acquired flyabout video – plus as accredited within the article).