China Launches An Emergency Lifeboat To Bring Three Astronauts Back To Earth (arstechnica.com) 26
China launched an uncrewed Shenzhou 22 spacecraft to serve as an emergency lifeboat for three astronauts aboard the Tiangong space station after a docked return craft was found to have a cracked window likely caused by space debris. "A Long March 2F rocket fired its engines and lifted off with the Shenzhou 22 spacecraft, carrying cargo instead of a crew, at 11:11 pm EST Monday (04:11 UTC Tuesday)," reports Ars Technica. "The spacecraft docked with the Tiangong station nearly 250 miles (400 kilometers) above the Earth about three-and-a-half hours later." From the report: Chinese engineers worked fast to move up the launch of the Shenzhou 22, originally set to fly next year. On November 4, astronauts discovered one of the two crew ferry ships docked to the Tiangong station had a damaged window, likely from an impact with a small fragment of space junk. [...] Now, 20 days after the saga began, the Tiangong outpost again has a lifeboat for its long-term residents. Astronauts Zhang Lu, Fu Wei, and Zhang Hongzhang will return to Earth on the Shenzhou 22 spacecraft next year, soon after the arrival of their three replacements.
The Tiangong astronauts will head outside the station on a spacewalk to inspect the damaged window on Shenzhou 20. Eventually, Shenzhou 20 will depart Tiangong and reenter the atmosphere with cargo. Assuming a smooth landing, Chinese engineers will have an opportunity to get a closer look at the damage on the ground to inform the design of future spacecraft. A preliminary assessment of the window indicates the crack is in the outermost layer of heat-insulating glass in Shenzhou 20's porthole window, according to Chinese state media. Engineers on the ground conducted simulations and wind tunnel ablation tests to determine whether the window might fail during reentry. "The results showed that the cracks would still propagate further," reported CCTV, China's government-run television network. "We held review meeting, and everyone agreed that ensuring the safe return of the astronauts was too risky with the glass damaged," Zhou said.
While this crew is just one month into their planned six-month expedition, an emergency could force them to leave the station and return home at any time. Although remote, another collision with space junk, a major systems failure, or a medical emergency involving one of the astronauts could trigger an evacuation. That's why Chinese officials wanted to quickly launch Shenzhou 22 to give the crew a ticket home.The International Space Station follows the same policy, with SpaceX's Dragon spacecraft and Russian Soyuz ships serving as lifeboats until their crews' scheduled return to Earth.
The Tiangong astronauts will head outside the station on a spacewalk to inspect the damaged window on Shenzhou 20. Eventually, Shenzhou 20 will depart Tiangong and reenter the atmosphere with cargo. Assuming a smooth landing, Chinese engineers will have an opportunity to get a closer look at the damage on the ground to inform the design of future spacecraft. A preliminary assessment of the window indicates the crack is in the outermost layer of heat-insulating glass in Shenzhou 20's porthole window, according to Chinese state media. Engineers on the ground conducted simulations and wind tunnel ablation tests to determine whether the window might fail during reentry. "The results showed that the cracks would still propagate further," reported CCTV, China's government-run television network. "We held review meeting, and everyone agreed that ensuring the safe return of the astronauts was too risky with the glass damaged," Zhou said.
While this crew is just one month into their planned six-month expedition, an emergency could force them to leave the station and return home at any time. Although remote, another collision with space junk, a major systems failure, or a medical emergency involving one of the astronauts could trigger an evacuation. That's why Chinese officials wanted to quickly launch Shenzhou 22 to give the crew a ticket home.The International Space Station follows the same policy, with SpaceX's Dragon spacecraft and Russian Soyuz ships serving as lifeboats until their crews' scheduled return to Earth.
Contingency planning (Score:1)
Contingency planning is important for any hostile environment, whether it is for underwater habitats, mountain climbing, or space habitats. I'm glad they had a spare crew vehicle ready so they can bring the damaged capsule back for troubleshooting.
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Windows are cool but (Score:2, Insightful)
Why do they have a porthole window with crackable glass? I get having them on the space station but do they need one on their return craft? I mean, if space junk hits your vessel its bad even if its not glass, but in this case it seems like it might have been better not to have a window.
Re: Windows are cool but (Score:3)
The relative speed of various bits of space debris in relation to manned objects can carry significant potential energy, even for something as small as a screw.
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Why do they have a porthole window with crackable glass?
What other material would you suggest?
Non-crackable glass? /s
OK but seriously, since cost isn't a big deal, perhaps this might be a good application for transparent aluminum (aluminium oxynitride). [wikipedia.org]
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The fracture toughness quoted for that material is about 3 times higher than that for soda glass. Which is "better". But not compellingly better. Replacing the porthole with a metal panel matching the rest of the skin, and maybe a CCTV external port for communication between ground crew and contents of the spacecraft would probably be better value for money.
Which is a parameter everyone pays attention to. It might not be an overwhelming factor, but it is considered.
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maybe a CCTV external port for communication between ground crew and contents of the spacecraft would probably be better value for money.
While this is an option, reliability would go waaay down for multiple reasons.
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It's about time they deployed PDCs on space stations. They can shoot a stream of ice pellets at space debris to slow it down or deflect it. Radar would tell it what's approaching from thousands of miles out.
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It appears from what I read here that the debris hit the glass and now, in their study, scientists have determined that the crack caused by the debris may expand upon reentry.
So presumably if it had hit something else that doesn't crack so easily they might be in a better position to patch it up. I suspect a hole in the metal skin of the craft would have been easier to deal with.
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They need to be able to see outside, and glass is the most reliable way to facilitate that.
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Do the Taikonauts have to steer the capsule themselves?
Or is it controlled by the ground (and computers)
Re:Windows are cool but (Score:5, Informative)
Automated but they have options for manual control and setting parameters of the autopilot. The window helps them be sure it is working as expected, and that instruments match what they can see. It's also very useful when they land.
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What a weird question !
Why would it be different to any other modern spacecraft, capable of both automatic and manual control ?!
The Chinese aren't exactly a newcomer to space - they have their own space station, are currently exploring Mars with their own rover, and look likely to beat the USA to building a moon station unless we get our act together.
You see to be imagining these "taikonauts" in some primitive Chop Suey powered craft built using 1950's technology.
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They need to be able to see outside, and glass is the most reliable way to facilitate that.
You're not wrong but there are other passive options that could be more structurally robust like using several optical fibers to create a composite image. You could also use optical elements to radically compress and magnify a larger area. Both of these options minimizes the size of the area needed to transmit the light from outside to inside the capsule using components that require no resources to operate and are more mechanically robust.
I don't know if port windows a generally problematic in space capsul
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Desirable to see outside, I'd agree - for your various reasons. "Need" on the other hand is a much steeper challenge.
But considering the relatively low stresses encountered when on orbit, and the presence of five robotic arms already on the station, the option of fitting a protective cover while the "lifeboat" is docked would be one to consider. 3 magnets and a metal (aluminium, or titanium ; or even a tough polymer composite) plate would do it, if there are conveniently located ferrous metal nodes on the e
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Since we're discussing cracked Windows, does OpenBSD count?
Re:Windows are cool but (Score:5, Interesting)
You don't seem to be thinking very logically.
What is more likely to be hit by a piece of space junk or micro meteorite, a space station sitting there for years, or a transport vessel just making a quick run up or down ?!
You also seem not to realize the kinetic energy and destructive power of these impacts - some of the most powerful weapons on earth are rail-guns using nothing other than kinetic energy to punch though multiple layers of steel, maybe pass straight through a tank.
FWIW the windows on this Chinese craft are triple layer, and the impact only cracked the outer one, so it must have been an extremely small object which is why they wouldn't have picked it up on radar and maneuvered out of the way which is normal practice.
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What is more likely to be hit by a piece of space junk or micro meteorite, a space station sitting there for years, or a transport vessel just making a quick run up or down ?!
To be fair, it depends on the altitude of the space station. If the ISS was kept at an altitude of 4000 km then the vessel making a quick trip would be more likely to be struck because most of Earth's orbital debris is found below an altitude of 2,000 km. However, the ISS is kept at 400 km and it only becomes more risky up to that altitude.
So, while you are incidentally correct, it is not a mere matter of logical thinking that you present it to be.
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The "lifeboats" aren't there for years on end. They come and go with cargo and/ or crew. (Tiangong isn't operated with permanent crew, so they have mothballing and de-mothballing procedures. Meh.) So the exposure profiles you suggest are not really correct.
I believe the relevant dimension for being "trackable" is around 1cm. Above that, trackable ; below
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I imagine it's actually acrylic, not silica glass. But acrylic can crack in the same way. Scratches are stress risers and cracks can propagate from areas where they're under unequal pressure.
Space debris (Score:3, Informative)
a docked return craft was found to have a cracked window likely caused by space debris. "
In space, no one can hear your karma [slashdot.org].
Different (Score:3, Insightful)
China may have a different view of safety and of reporting and a host of other things. But dead spacenaughts are not a good look, and so a rescue mission is the right thing to do. Fair play on them for rushing it together to solve their problem.