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The Dragon Capsule by SpaceX can contaminate the ISS



In February 2017 a SpaceX Falcon 9 rocket lifted through deep clouds and pushed a dragon capsule towards orbit. Among the spare parts and food, an important scientific cargo named SAGE III rumbled up. Once installed on the International Space Station, SAGE would measure and measure ozone molecules and aerosols in the Earth's atmosphere. His older siblings (SAGEs I and II) had shown both the growth of the gaping ozone hole and the subsequent recovery of humans after they decided not to spray Freon anymore.

So this third child had a lot to do. Like its eco-conscious predecessors, SAGE III is extremely sensitive. Because it requires unpolluted conditions for optimal operation, it contains pollution sensors that monitor whether and how its environment might upset the measurements. These sensors soon proved useful: as the next three dragons docked at the space station over the following months, SAGE experienced unexplained spikes in contamination. Something on this dragon was outgassing ̵

1; releasing molecules above expected and potentially acceptable levels. And these molecules were attached to SAGE.

From an earthly point of view, that's what a new car smells like a new car. "There are volatile chemicals in these new materials that come to the surface through the material," says Alan Tribble, author of Fundamentals of Contamination Control . They smell of escaping seating ingredients, in other words. [19659002] Outgassing also forms as a greasy film on the inside of the windows of your new car – or the outside of your space station. This mess is a problem especially for instruments that measure light, but it can also reduce the efficiency of solar panels and cause surfaces to be hotter than they should. To avoid all this, engineers in cleanrooms build space station complements and satellites, only use prequalified materials, moisturizing impurities before take off and setting strict limits on the proverbial smell of new car craft can be published. "It's an intense process that is considered extremely critical," says Meg Abraham of the Aerospace Corporation, which advises on a number of space projects. "Everyone thinks about it."

But this pre-planning does not always work. For example, when astronauts brought some of the space telescope's early Hubble instruments back to Earth, they found that the body of the $ 1.5 billion telescope was $ 2.88 billion 2018 dollars would have cost. They had sprayed enough molecules on them to severely degrade their ability to detect ultraviolet light-one of the telescope's outstanding capabilities.

NASA has been dealing with this filth for decades – but so far the filth is largely from the agency's own creations. Dragon is different. It belongs to SpaceX. Today, the company plans to bring another Dragon capsule full of cargo and possibly contaminants to the space station. This launch will be the company's sixteenth commercial resupply mission.

As NASA outsources operations to private companies such as SpaceX, Orbital ATK (now part of Northrop Grumman) and Boeing, it must respond if its children misbehave. And that's a big deal: new ISS instruments show us how our planet and the universe work, at prices in the tens of millions and with years of development. With these inserts, scientists, engineers and citizens want the last time that the capsule of a private company makes measurements.

SAGE III went as part of a NASA aboard the tenth NASA SpaceX mission to the Space Station SpaceX contract for agency local supplies. Once SAGE was on board, the contaminating crystals registered Dragon's excessive outgassing.

These crystals do not belong to the healing variety (spoiler alarm: none), but are "thermoelectric quartz crystal microbalances". Eight such sensors have two twin crystals. Together they form two "Contamination Monitoring Packages". These crystals oscillate at a certain frequency that matches their mass. When a crystal gains mass, such as when a spaceship re-transmits – car smells its way – its frequency changes.

When the twin crystals start their missions, they are exactly the same, but on the space station, one of them is exposed to the outside environment. Others remain protected, it's a kind of twinship in psychology: scientists can tell by measuring the twins' frequency difference how much contamination was on the exposed, although this is not the case The nature of the layers.

Following the arrival of the Eleventh Dragon, the frequency of a Contamination Monitoring Package has steadily shifted, according to a presentation published on September 1, on NASA's Technical Reports Server, a database of documents created or funded by the agency. The data was notable because NASA sets contamination limits for sensitive surfaces containing some of the more sensitive parts of the ISS. The crystals served as canaries in this case and warned of possible damage to these exquisite instruments.

The results are preliminary, but Dragon may have been down to 21 times the allowable contamination level on a sensor. The frequency of the crystals also changed significantly when the next dragon was docked, and the report estimates that this mission may have left 32 times more than the regular amount of additional material on a sensor.

The presentation was by the Space Environments team, a collaboration between NASA and Boeing, which deals with understanding the harsh reality of space using instruments and people. With the annoying data in hand, the people of Space Environments developed an experiment to find out what was going on. The problem may have been in the solar system or the materials on the outside of the capsule. To narrow down the list of suspects, the engineers positioned the solar arrays during the thirteenth kite flight with their edges facing the space station. When the panels gassed, they did not dump the spacecraft . The mass would build up more slowly on the crystals and keep their frequency relatively constant.

This is not the case. As the array was tilted away, the frequencies of the crystals continued to increase. The Dragon capsule itself seemed to be the problem – a problem that got worse as more sunlight shone on it. During this thirteenth mission, a sensor may have been sprayed up to 73 times more than allowed during a stay. And for the month Dragon was docked at the station, two of the sensors individually detected more contaminants than anything else – all on the station – in a full year .

Space objects endangered by outgassing of the capsule is the US Laboratory Science Window, a porthole through which astronauts and instruments can look at the earth. On the scientific side, there is CATS, an instrument for measuring smoke, pollution, dust and other particles in the atmosphere of the planet. In total, seven sensitive areas or instruments on the ISS, including SAGE, could be contaminated beyond the limit.

"NASA has communicated its findings with the station-payload community, and the payload developers have either responded that their instruments had no impact or have taken precautions to mitigate the impact on their science," says Space Environments in a statement. The SAGE III team closes the instrument's "mud flap" as a standard procedure if a spacecraft is to protect its optical instrument, although the resulting measurements are not as sensitive.

And at least SAGE III, whose optics this is "susceptible to molecular contamination deterioration", knows if care must be taken. The SAGE III team only knows these exact values ​​because it carries contamination monitors that were not previously available on the station.

SpaceX checks the ingredients. "SpaceX has scrutinized Dragon's external materials selection and is working with suppliers to individually develop low-emission, low-gassing variants to improve the molecular deposition rate," the company says, adding that NASA is all in the US used materials pre-approved first dragon design.

Antonius de Rooij, author of the Space Materials Database, believes that the color of the capsule is the probable problem. First, he says, "The white painted surface is very large, which means that even low-gassing products can have a strong contaminant effect."

He is also curious as to why the Space Environments team considered solar heat and radiation. But not the human or earthly factors. "Is the paint applied correctly? Is it cured right? ", He says. "I was a little surprised that these points were not mentioned." Paint does not behave as advertised if the surface it was hit on is not ultra-pure or if the moisture is not Goldilocks-correct during drying. Maybe the stews were not exactly alike. "This batch variation can be the cause of different outgassing and different optical properties between batches," he says.

Or the surface could have been contaminated after curing the paint . This contamination could cause more pollution. While the exact paint for these three Dragon missions is not public information, at least one of the earlier missions used Alion Z-93c55, a variant of Alion Z-93. When contaminated after curing, Alion Z-93 tends to deteriorate when exposed to UV rays, a phenomenon that was documented as early as 1971. It then absorbs more sunlight, gets hotter than expected, and emits more. "I wonder why they did not mention that in their report," says de Rooij.

However, part of the problem here is NASA's reluctance to talk about the problem as well as the plans to solve the problem. The presentation, which was shared during the Payload Operations Integration working group meeting in April, was approved for unclassified and unlimited public release and filed on the NASA Technical Reports Server in early September. On September 25, I asked for an interview. The presentation was over the next day. "The record detail page you wanted to access can not be found on this server," says the page. I inquired about the dead link and more than three weeks later I received an answer: "The document is under review," wrote Meagan Storey of NASA's Scientific and Technical Information Program, "and we recommend that you submit a FOIA request for the article.

Statistically, this is probably a prospect lost. When we use FOIA requests as a proxy for transparency, NASA is one of the most veiled government agencies. In 2017, it rejected more FOIA applications than the US Department of Defense, the Securities and Exchange Commission, the US Department of Energy, the Environmental Protection Agency, the Nuclear Regulatory Commission, and the Office of the National Intelligence Director, organizations that do so to a large extent to protect more than the nation's space agency. To cope with NASA, which has rejected 71 percent of applications, the CIA has rejected 78 percent. I had seen a previous document that said, "The Dragon Trunk particle background is uncharacterized, but publications have been observed." That's why I asked NASA's SAGE III team, knowing that gassing could affect their instrument, if they had changed. None of their plans because of concerns over Dragon. "No negative contamination effects or concerns about the science of SAGE III," they replied by e-mail. "In addition, nothing to add."

As I would learn from the case of the disappearance of the presentation and three missions of measurements that the team had made, there was much more to add.

The agency not only protects itself, but also its private, profitable partner, SpaceX, whose capsule, in turn, has implications for federally supported ISS tools.

This lack of transparency will soon become more relevant as private companies force not only astronauts but also astronauts ce cream and atmospheric instruments, but also people back and forth from space, as part of the agency's commercial crew program , Another iteration of Dragon will take some of these future astronauts. "SpaceX uses the data to improve its Dragon 2 crew and cargo vehicles," says the Space Environments team.

Today's contamination problems may pose no major problem, but if there's a big problem with tomorrow's kite or tomorrow's jet. Another company airline points out in this case study that they may be behind closed bay windows or hazy windows becomes.



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