Report: SpaceX Dragon Spacecraft Contaminating Space Station

Dragon on the end of Candarm2. (Credit: NASA)

Wired has a fascinating story that details how SpaceX’s cargo Dragon spacecraft have been contaminating the International Space Station during their stays there – and how NASA has tried to hide the fact.

The contamination was discovered by the Stratospheric Aerosol and Gas Experiment (SAGE) III Earth observing instrument, which was launched to the station aboard SpaceX’s CRS-10 resupply mission in February 2017. The instrument has crystals in it capable of detecting contamination at the space station.

The results are preliminary, but Dragon may have deposited, according to this presentation, up to 21 times the allowed amount of contamination on one sensor. The crystals also significantly changed in frequency when the next Dragon docked, and the report estimates that this mission may have left behind up to 32 times the rule-abiding amount of extra matter on one sensor….

During this thirteenth mission, one sensor may have been sprayed with up to 73 times more than what’s allowed during a sojourn. And for the month or so that Dragon was docked at the Station, two of the sensors individually detected more contamination than is allowed—total, from everything on the Station—in a whole year.

Among the space assets at risk from the capsule’s outgassing is the U.S. Laboratory Science Window, a porthole through which astronauts and instruments can gaze out on Earth. On the more scientific side, there’s CATS, an instrument that measures smoke, pollution, dust, and other particles in the planet’s atmosphere. In total, seven sensitive areas or instruments on the ISS, including SAGE, could be contaminated beyond the limit.

“NASA has communicated with the Station payload community its findings, and payload developers have responded either that their instruments have experienced no impact or they have taken precautions to mitigate impacts to their science,” says Space Environments in a statement. The SAGE III team closes the instrument’s “contamination door,” as a standard operating procedure, when any spacecraft visit to protect its optical instrument, although the resulting measurements aren’t as sensitive .

SpaceX said it is working with suppliers to develop low outgassing materials for use in future Dragon spacecraft. It said NASA pre-approved the materials used in the resupply ships. (The story, however, says that it’s possible materials such as paint are not being applied and cured properly.)

The information came from a presentation marked unclassified and unlimited public distribution that was posted on the NASA Technical Reports Server in September. A day after the Wired writer requested an interview about it with NASA officials, the document disappeared from the server. A NASA official said the report is “under review” and told Wired to submit a Freedom of Information Act request for it.

 

  • windbourne

    Paint was just a guess. The fact is, this could also be the cargo.

  • Aerospike

    Don’t think so, seems too consistent to be related to the unpressurized cargo in the trunk (which is never the same on any two missions).

  • Robert G. Oler

    its been a bad week or so for SpaceX they need to get their QC under control..

  • Steve

    I would assume this problem disqualify the Dragon for the 6-month long crew trips. This type of outgassing can’t be allowed to continue.

  • windbourne

    Iff this is the real issue. The fact that it has not been outgassing all this time and only recently started, makes me suspect a common cargo.

  • windbourne

    I did not suggest trunk, but the massive cargo in pressurized area. The fact that only a few of the missions, and fairly recent, makes me think that some common cargo is doing it. Otherwise, SpaceX has changed proceedures for building dragon, and needs to back.

  • Aerospike

    And how would pressurized cargo inside dragon outgas to the outside of the station?

  • Douglas Messier

    They only recently became aware of it after SAGE III was installed in Feb. 2017. The instrument detected outgassing from CRS-10 Dragon that transported it.

  • Douglas Messier

    How would cargo inside Dragon’s pressure vessel outgas into space?

  • duheagle

    SpaceX hasn’t built any new Dragon 1’s in some time. All the recent missions have been re-flies.

  • ThomasLMatula

    Yep, and if they installed elsewhere it would have probably detected it from the Soyuz..,

  • duheagle

    Seems as though the cheapest and fastest fix would be to move any particularly sensitive instrumentation to locations on ISS more remote from where the visiting vehicles dock.

  • ThomasLMatula

    You are assuming it’s a QC issue with zero evidence. It might be a sensor issue instead. You do know that the SAGE III is new.

  • duheagle

    The outgassing only seems to adversely affect a few instruments. If it’s a genuine problem, move the finicky instrumentation elsewhere on ISS away from visiting vehicle ports. Longer-term, changing materials or fabrication processing to reduce outgassing might be undertaken, but only if the “standards” actually make sense and are achievable. It would also be interesting to know what the outgassing “profiles” of Progress, Soyuz, Cygnus and HTV are – and the upcoming Dragon 2 and Starliner. Would Dragon 2, in particular, still evidence the problem? Is the problem just a matter of Dragons always berthing closest to the affected instrumentation?

  • Robert G. Oler

    I think it might be the vehicle itself

  • Robert G. Oler

    the vast majority of hydraulic pump failures particularly ones that use “gas” are contaminants brought on by improper servicing…

  • duheagle

    RGO does that a lot.

    Even assuming the SAGE III is accurate, my question would be was there ever a NASA spec for maximum outgassing permitted while berthed/docked for visiting vehicles? If not, then there is certainly no QC issue as there would have been no “quality” parameter against which to measure.

    NASA’s seeming attempt at a cover-up might be motivated by pure bureaucratic reflex, guilty/embarrassed knowledge that its visiting vehicle specs were incomplete in at least one respect, pro-SpaceX partisanship by some within NASA or some other reason(s).

    One would also like to know if this alleged problem is unique to Dragon or whether other visiting vehicle types also outgas significantly. Is the SAGE III measurement simply a matter of proximity to the Dragon berthing hatch?

    Given that the Sage III instrument has only been on ISS since sometime after the arrival of the CRS-10 Dragon in Feb. 2017, there would also seem to be some additional obvious questions to be answered along the lines of “what was known and when was it known?”

    Lots of questions. Not many answers yet.

  • duheagle

    Hydraulic systems use liquid working fluids. If any kind of gas is used, then the system is pneumatic, not hydraulic.

    But you put quote marks on the word “gas.” So did you mean to indicate the F9’s kerosene propellant as double-duty hydraulic fluid? The engine gimbal hydraulics use RP-1 as working fluid, but the engines are located down low just below the RP-1 tank. The grid fin actuators are way up in the interstage above the LOX tank. I think the actuators for the latter run on a more usual type of hydraulic fluid and that the whole system, including accumulator, is localized. Running RP-1 lines up to the interstage would be less reliable and definitely more massive than the localized system in use. It would probably even be more massive than adding a backup pump to the current system.

    If contaminants are an issue, that should be discovered once the recovered system is torn down and autopsied. The grid fin actuator system might well be filled and sealed at Hawthorne and not further messed with prior to launch. Or it could be shipped, unfilled, to McGregor, filled there and then either sent on to the launch site without further attention or perhaps is drained at McGregor and refilled at the launch site. The last of these three scenarios would provide the most latitude for contaminants to creep in. That would likely be true even were there a backup hydraulic pump added to the system.

    It will be interesting to see what, if anything, Elon tweets about this affair in coming days.

  • duheagle

    It certainly would be useful to know the chemical composition of whatever is being outgassed.

  • Robert G. Oler

    I am told by my blue suit friends in CA at the plant that the grid fins use He as a “fluid” .

    Elon is using “hydraulics” your argument is with him

  • Robert G. Oler

    Boeing uses bleed air as a working fluid in Thrust reversers and they address it as “hydraulics” there is no chance SpaceX is using RP1

  • Fred Chauvière

    1st, it could be He in a liquid form if cold enough. 2nd it used to be He in previous version of Falcon, but they stopped using it in block 5. Can’t remember what they use now…

  • Emmet Ford

    They probably do repaint them, though. Maybe they got a really good deal on an odd lot of extra gassy paint.

    I sounds to me like NASA is not sure how much of a problem this is, and how much effort to solve it is warranted. Because surely the technology exists to solve this mystery. NASA has vacuum chambers. They have spectrometers. Contractually, it’s probably on SpaceX to comply with the published contamination restrictions, but actual long term working relationships involve a lot of give and take.

    The paper may have been pulled from the public server because the NASA folks figured that politicizing the issue was not going to help them deal with it, which is what they are interested in. They make plenty of anodyne 2 minute videos for public consumption. If you prefer longer form material, they produce some truly mind numbing podcasts. Watch or listen to those, you cretinous liberal arts majors.

  • Ohya Yasunori

    well this isn’t such a big deal, the gamma-ray altimeter on the Soyuz spacecraft’s been contaminating the MAXI instrument on Kibo module for years, and the Russian’s done nothing to deal with it.
    https://arxiv.org/pdf/1410.6245.pdf

  • windbourne

    If so, then implication is that pollution is coming from cargo.

  • windbourne

    Wow. I though instrument was inside. Just checked and yeah, I’m wrong.

  • Mr Snarky Answer

    This Is is a routine challenge for ISS, not unique.

  • Mr Snarky Answer

    Your blue suit friends are wrong or at least misleading. If the grid fins were actuated by He pressure they woudn’t need a pump, nobody is pumping up He to pressurize it in flight, they would just store in COPVs (As they already do). They may use pressurized He to turn the hydraulic pump which then pressurizes a more conventional hydraulic loop, it’s that or an electric motor. The pump and loop are clearly visible in multiple some photos.

  • duheagle

    That would depend upon the chemical assay of the contamination.

  • duheagle

    The F9 Block 5 still uses He pressurant for the same things as previous versions did. It’s Super Heavy and Starship that are going to be He-free.

  • Fred Chauvière

    Reading that tweet (https://mobile.twitter.com/elonmusk/status/1070388894875545600), I highly doubt He is still used on F9 Block 5 for the grid fin actuating : why will you need a pump (and a backup pump) if it’s an open system pressurised with He?

  • Fred Chauvière

    But yeah, if you meant that F9 Block 5 is still using He in general (and not for that specific purpose), I agree 😉

  • Robert G. Oler

    unlikely.

    taking the He as high pressure from the COPV’s would only work if the system were open loop…meaning that the “working fluid” under pressure is used and then vented…

    if you want a closed loop system than you can take it under pressure from “some pressure source” but at some point you have to have return lines which bring the working fluid back to a “pressurizing source”..

    SpaceX had an open looped hydraulic system until they ran out of “fluid” andlost a vehicle on recovery because of that. so they closed the loop…that is why you have the “pump”

    I dont know what they use for fluid…but as I say I am told its He…and well you would need a pump to close the system…

  • Robert G. Oler

    I am certain they use He…

  • Mr Snarky Answer

    Yes, and they aren’t pumping He, so your point is moot. I am well aware of the original open loop design.

    https://twitter.com/elonmusk/status/556105370054053889

    https://twitter.com/elonmusk/status/878839825473822720?lang=en

  • Robert G. Oler

    lol stop talking until you learn something 🙂 otherwise I will have to mock you 🙂 fan boy

  • Mr Snarky Answer

    Going completely ad hominem…nice touch.

  • Robert G. Oler

    fan boy

  • Mr Snarky Answer

    So you concede my point. Thanks

  • Robert G. Oler

    that you are a fan boy yes

    sorry off to bed. more B77X class tomorrow (I am teaching) be cool Mr. Fan Boy

  • Mr Snarky Answer

    That was your point not mine. Follow along.

  • Aerospike

    Can happen to anyone 🙂