![]() ![]() STS-125 would also see an increase in the concentration of MMOD, due to the region of Low Earth Orbit (LEO) Atlantis flew in for the majority of her mission. This mission held the largest risk to the orbiter, given it was the only post Return To Flight mission that did not have the “safe haven” option of docking with the ISS, ahead of a rescue orbiter being flown to pick up the crew. Such strikes – however minor, were always taken seriously, given they are the third biggest threat to losing a vehicle during a mission – second only to launch and re-entry.Įxtensive evaluations took place ahead of each shuttle mission, not least Atlantis’ STS-125 flight into space, a mission that provided one final servicing mission to the Hubble Space Telescope. Such MMOD strikes were observed on a large amount of Space Shuttle missions, especially late into the mission when the orbiter had undocked from the protection of the ISS and was preparing to head home. The debris panes can be replaced individually, via EVAs. ![]() The window is made up of four panes – an inner scratch pane to protect the pressure pane from accidental damage, two pressure panes 25mm thick to maintain cabin pressure, and finally an outer debris pane. Such a replacement would require an EVA to fit an external pressure cover to allow for the changeout, with a pressure cover requiring a flight up to the ISS – likely aboard a SpaceX Dragon spacecraft. Per the resulting contingency evaluations, it was noted that in the event of the damage being more serious, on-orbit replacement of an entire window is an inbuilt design feature. It is understood that this was the first MMOD strike to be suffered by a Cupola window. While the flight rules are naturally cautious, in order to ensure a large amount of margin for crew safety, the window was soon cleared by the subsequent evaluations. “The shutter for window 2 is closed now, as required by flight rules, until the MMOD strike has been evaluated.” The crew reported an MMOD strike on Cupola window 2 and downlinked photos (full set available on L2) of it,” noted L2 level ISS Status (LINK). MMOD strikes on space hardware are not uncommon and continue to be a major risk factor all spacecraft have to deal with.Īlthough exposed windows are built to withstand such impacts, a strike to Window 2 on the Cupola – back in 2012 – was one example of how even tiny strikes are noticeable. “At this time no indications of a leak have been observed, but teams will continue to monitor for impacts.” “A preliminary analysis indicates that visible damage to the cover sheet may be up to 12 inches in length,” added the L2 status. So far, the ISS does not appear to be suffering any ill effects of the damage, while no leaking from the panels has been observed at this time. “Initial observations based on this imagery ( acquired by L2), and subsequent imagery obtained using external cameras, suggest that the damage may be from an MMOD strike. “Potential P4 Photovoltaic Radiator (PVR) Micrometeoroid/Orbital Debris (MMOD) strike: During a recent review of downlinked imagery, the Image Science and Analysis Group noticed an anomalous feature on the third panel of the P4 PVR,” noted L2 ISS Status this week. ![]() It was via the regular assignment of taking photography of the ISS that resulted in observations of the damage that was been caused by what appears to be a MMOD strike. The launch of the first PVRs was conducted by Space Shuttle Endeavour during her STS-97 mission in November 2000, with their successful deployments occurring on December 3 and 5, 2000, and February 14, 2001. The PVRs also internally flow liquid ammonia coolant and are capable of rejecting at least nine kilowatts of excess heat. panels, deployed by an electric motor driven “scissor” mechanism. The four 1650-pound PVRs consist of seven 6 ft. The hardware in question is one of the key elements of the heat rejection systems utilized by the orbital outpost. ![]() While the situation is being monitored, data suggests there isn’t a leak from the system as a result of the 12 inch long puncture to the cover sheet. International Space Station (ISS) managers are currently evaluating what appear to be MicroMeteoroid and Orbital Debris (MMOD) impact to a panel on the Potential P4 Photovoltaic Radiator (PVR). ![]()
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