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Questions tagged [safety]

Questions regarding space exploration safety issues and procedures.

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How many nuclear fission reactors have been launched into space? How many are still there?

I remember p@Hobbes's answer to Which countries have built RTGs and used them in Earth orbit and/or beyond? mentioning that the US has put one nuclear fission reactor in space, and that not much was ...
uhoh's user avatar
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28 votes
4 answers
3k views

Are there any safe-to-launch alternatives to RTG's for outer solar system exploration?

In the past two decades, NASA has launched at least three missions that use RTG's: Cassini Mars Science Laboratory New Horizons Those launches include plutonium, which is a reason for some to oppose ...
gerrit's user avatar
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14 votes
9 answers
3k views

Tiny emergency propulsive device if stuck floating in a large volume in microgravity

The questions here in SXSE Can you swim in space? and in Physics SE How to escape the center of a room without gravity? [closed] both address aspects of how to move if stuck floating in the center of ...
uhoh's user avatar
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32 votes
4 answers
11k views

Why would a box full of 1cm balls released into LEO be so scary to an engineer supporting the ISS?

update March 2018: I just saw this in Buzzfeed (Google sent me there, I don't normally read it): Rich People Will Soon Be Able To Buy Fake Meteor Showers On Demand. It seems this might happen in 2018. ...
uhoh's user avatar
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19 votes
1 answer
6k views

What is the "ISS's Keep Out Sphere" and what is its radius?

The comment: In a similar vein, it would be interesting to know if going around the moon rather than to the ISS removes any legal hurdles. Do we have any questions covering the legal ramifications (...
uhoh's user avatar
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4 votes
2 answers
811 views

Was this large pieces of "space junk" just released from the ISS in the "nadir and retrograde" direction?

According to Space.com's 02-Feb-2018 article Cosmonauts Break Russian Spacewalk Record During Space Station Antenna Repair: The cosmonauts spent the day replacing an electronics box for a high-gain ...
uhoh's user avatar
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17 votes
1 answer
2k views

What does it mean for a launcher to be 'nuclear-certified'?

This article says NASA has booked a nuclear-certified Atlas 5 for the launch of the Mars 2020 rover, and says this: currently, Atlas 5 is the only launch vehicle that holds a NASA certification ...
kim holder's user avatar
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24 votes
3 answers
3k views

How are cryogenic rocket propellants delivered to the launch pad?

I work at a university that gets LN2/LHe (liquid nitrogen and helium) delivered a couple times a week by a large tanker truck outside my office. It seems to work well enough to deliver a couple tons ...
Nick T's user avatar
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18 votes
3 answers
6k views

Is the EU really banning "toxic propellants" in 2020? How is that going to work?

This comment links to an archived presentation by Tesseract "The space transportation company offering revolutionary propulsion" says on slide 8: Timing is right Small satellite ...
uhoh's user avatar
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11 votes
2 answers
1k views

Will a computer be allowed to "self-destruct" astronauts (or passengers)?

In the video clip of this interview, captioned: General Wayne Monteith, 45th Space Wing Commander, talks about the Autonomous Flight Safety System, or AFSS -- a new, automated way of having a ...
uhoh's user avatar
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8 votes
2 answers
754 views

What first aid options do astronauts have during an EVA?

If an astronaut gets unconscious or ill I suppose the colleague will help her to the airlock. But are there any other measures that could be taken already outdoors? Do they have duct tape to seal a ...
LocalFluff's user avatar
6 votes
1 answer
2k views

Any potential downside to throwing personal life support out the door on the Moon?

I found this really interesting description of the ALSEP instrumentation placed on the moon during the Apollo 11 landing, written by Hamish Lindsay, (also, author of Tracking Apollo to the Moon). One ...
uhoh's user avatar
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4 votes
1 answer
872 views

Is 45 km unusually close to pass the ISS and deploy a microsatellite without warning?

Eight years ago, on September 27, 2008, the Shenzhou-7 carying three taikonauts deployed the microsatellite Banxing-1 for testing maneuvers and external imaging. A few hours later at 15:07 UTC the ...
uhoh's user avatar
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3 votes
1 answer
521 views

When were Shuttle crew absolutely required to have their seat belts fastened and their tray tables in their full upright position?

@OrganicMarble's comment says: Rhea Seddon describes in her bio standing and walking around in the shuttle middeck in the early part of entry when g's were low. "...I had this funny sensation of ...
uhoh's user avatar
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2 votes
1 answer
316 views

Why not turn off the main engines while using the launch escape system on liquid fuelled engines?

I've seen a couple of launch escape systems firing and the rockets main engines are on, isn't it more safe if you turn off the engines? Edit: i agree that the engines turning off might be not so ...
FRaNKU's user avatar
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118 votes
6 answers
27k views

What makes (or at least made) Ada the language of choice for the ISS's safety-critical systems?

We have it on good authority that Ada is widely used for "safety critical software" on at least the US side of the International Space Station. Of all the possible languages to choose from, ...
uhoh's user avatar
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26 votes
1 answer
4k views

How did sloshing prevent the Apollo Service Module from moving safely away from the Command Module and how was this fixed?

The Insider.com article 'We could have lost the Apollo 11 crew:' A once-classified anomaly nearly killed NASA's first moon astronauts, a new book reveals describes a problem during reentry of several ...
uhoh's user avatar
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19 votes
2 answers
15k views

Is the overall mortality rate for being in a spacecraft in space or bound for space about 4%?

I just read this answer in astronomy.stackexchange, where a sobering point was made that the overall to-date chance of losing ones life in a spacecraft is about 4%. While I don't want to dwell on ...
uhoh's user avatar
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16 votes
2 answers
840 views

How does the launch risk posed by plutonium compare to the launch risk posed by propellants?

For outer solar system exploration, virtually the only feasible power subsystem are Radioisotope thermoelectric generators (RTGs). These include plutonium, which may carry considerable risks (see ...
gerrit's user avatar
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14 votes
3 answers
2k views

Has any spacecraft had a way for the crew to escape during reentry?

All manned spacecraft to date have come back to Earth eventually, and when they do it's through a flaming ball of plasma. It seems too probable that this plasma would have a way of breaking things ...
user avatar
13 votes
4 answers
1k views

How are SRBs and solid rocket motors transported safely? Do they ever end up on trucks driven down public highways?

The BBC News article The Rocket Scientists Mixing Up a Giant Firework begins with: In a remote corner of tropical South American jungle, French scientists are mixing a ‘cake’ with a difference – a ...
uhoh's user avatar
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10 votes
1 answer
10k views

Can astronauts wear eyeglasses inside their helmets during launches and landings?

Are astronauts allowed to wear their eyeglasses inside their helmets during launches and landings?? Are there any special considerations or rules? During spaceflight (launches and landings) there can ...
uhoh's user avatar
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8 votes
1 answer
1k views

How much jerk do astronauts experience? Is there a safety limit?

From Wikipedia: In physics, jerk is the rate of change of acceleration; that is, the derivative of acceleration with respect to time, and as such the second derivative of velocity, or the third ...
uhoh's user avatar
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7 votes
1 answer
2k views

What exactly does it mean to human-rate a rocket? As opposed to the escape system?

The escape system is that thin pointy part at the very top of the rocket. It has powerful solid rockets that basically act as an "ejection seat" for the entire crew capsule. So when we talk about "...
DrZ214's user avatar
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6 votes
1 answer
2k views

Why are lightning towers at launch pads topped with big hollow tubes with spiral windings and not "lightning rod-shaped" lightning rods?

https://xkcd.com/2107/ Why are the lightning towers around launch pads topped with big hollow tubes with spiral windings? Why not conventional lightning rods - big metal rods with pointy things at ...
uhoh's user avatar
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5 votes
1 answer
489 views

Does the ISS have any ability to detect or sense unexpected/unscheduled objects in close proximity?

In a recent science fiction movie there was a space station similar to the ISS, and it had a "proximity alert". This made me wonder; in the real world, does the real ISS have any capability to ...
The Hawk's user avatar
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26 votes
3 answers
2k views

August 30th 2018 Soyuz leak, any dangers for re-entry?

On August 30th 2018, Soyuz MS-09 had a leak that was fixed by the ISS crew (source). Does the leak/fix have any consequences on using the Soyuz for returning to Earth? Would the fix hold the stress ...
Thibault D.'s user avatar
21 votes
5 answers
12k views

Is it safe to observe the ISS with the naked eye?

As far as I understand, when we view the ISS, it is because the sunrays get reflected from the solar panels of the ISS and reach us at the appropriate angle. So that would be equivalent to viewing the ...
User Not Found's user avatar
20 votes
4 answers
2k views

Any possible setbacks in deorbiting larger space junk and let it burn up upon reentry into atmosphere?

Space junk, orbital debris, or space waste pose a risk on functional satellites and space laboratories / stations in orbit around Earth. According to Wikipedia: Currently about 19,000 pieces of ...
TildalWave's user avatar
15 votes
1 answer
2k views

How does the launch risk for a plutonium RTG and a uranium fission reactor compare?

I was looking at this answer that talks about how a good alternative to Radioisotope Thermoelectric Generators would be fission reactors. It makes a number of good points, but in the comment thread ...
kim holder's user avatar
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15 votes
2 answers
2k views

How long were the Apollo astronauts allowed to breathe 100% oxygen at 1 atmosphere continuously?

This answer explains that from the time they suited up "in the Suit Lab before launch" until the time the capsule started depressurizing during ascent, the Apollo astronauts were breathing 100% oxygen ...
uhoh's user avatar
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14 votes
1 answer
4k views

How is the periscope port on Soyuz spacecraft secured for the atmospheric reentry?

Soyuz Backup Periscope (ВСК-4) is used in Soyuz spacecraft to align itself for orbital corrections, deorbit burn, and rendezvous with the International Space Station. Here is a cute closeup photograph ...
TildalWave's user avatar
12 votes
1 answer
1k views

Was this a rapid SCHEDULED disassembly? How was it done?

The new Curious Droid video Apollo's Forgotten Computer - The LVDC discussed the Saturn V flight computer that's also discussed in answers to Is this really the Saturn V computer only, or are there ...
uhoh's user avatar
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11 votes
1 answer
2k views

Did the Apollo missions fly "over the top" of the Van Allen radiation belts?

In the video The Moon Trees That Flew To The Moon On Apollo 14 after about 08:47 Scott Manley says that Apollo 14 "flew up over the top" of the Van Allen radiation ...
uhoh's user avatar
  • 149k
11 votes
3 answers
1k views

Where does space travel rank in per-passenger-mile safety?

Air travel is the safest method of transportation, with 0.07 deaths every billion passenger-miles. While space travel certainly has a higher fatality rate per-space-traveller (~3%)1, 2, where does it ...
w8ite's user avatar
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10 votes
1 answer
2k views

Why would the Apollo Lunar Module pressure dump (to space?) valve have a bacterial filter?

This answer to Why did they bother closing the hatch on the LM while doing EVA? links to a transcript of Apollo 11 which contains the following (find it there by searching for "radiative"): 109:41:...
uhoh's user avatar
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8 votes
0 answers
751 views

ISS - Tiangong 2 minimum safe distance

Using the SGP4 propagator, I calculated the minimum distance between ISS and Tiangong-2 for this year. I obtained 12.32 km for 2017-09-27 17:29:36.376 UTC (which ...
Cristiano's user avatar
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8 votes
1 answer
6k views

Were ejection seats on the Space Shuttle a practical safety system?

The first four STS missions were flown by Columbia with two pilots and had ejection seats as an option. These seats were eventually disabled (by STS 5) and removed (by STS-61-C). They could only be ...
Ezra Bailey's user avatar
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5 votes
1 answer
447 views

Why end-of-life GPS satellites given orbits that seemingly still intersect active satellite orbits but with a different period? Recipe for disaster?

This answer to Where are MEO satellites put at the end of their operational life? says (currently in full): This is an active area of research. As you noted, the main satellites that are in MEO are ...
uhoh's user avatar
  • 149k
5 votes
2 answers
580 views

What are some common (but non-obvious) materials that are particularly unsuitable for spaceflight?

If a product was to be made for use in space, there may be certain materials or certain combinations of materials that might work well on Earth, but be particularly unsuitable for spaceflight ...
P.Watkin's user avatar
4 votes
2 answers
371 views

Do standard procedures for securing the ISS before an orbital boost burn include making sure that at least large objects are securely "strapped down"?

In discussions on previous posts it was debated whether ISS crew would need to "batten down the hatches" and confirm all objects were "lashed to the deck" before an orbital boost ...
uhoh's user avatar
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2 votes
0 answers
189 views

How often are fewer than three astronauts present when moving a Soyuz spacecraft from one docking port to another?

CNN's Astronauts relocated a spacecraft outside the International Space Station (was it inside before?) says: Russian cosmonauts Sergey Ryzhikov and Sergey Kud-Sverchkov, along with NASA astronaut ...
uhoh's user avatar
  • 149k
2 votes
1 answer
204 views

How will space suit computers likely be radiation hardened?

Writing this comment inspired the following question: Space suits are critical to life, so if there's a solar storm and the astronaut has received a less-than-lethal dose of radiation, they'll be ...
uhoh's user avatar
  • 149k
1 vote
1 answer
78 views

Are there currently any spacecraft in orbit around Venus that might (or might not) be at risk of meteoric dust from comet Leonard C/2021 A?

Astronomer Shreyas Vissapragada @astroshrey ​tweeted Check out the latest from @aciqra, @Yeqzids, et al (including myself!) on C/2021 A1 (Leonard) and its close approach to Venus: Preview of Comet C/...
uhoh's user avatar
  • 149k
1 vote
0 answers
153 views

Do ISS crews have to worry about the ionosphere? Have hazards to EVAs or surface arcing/functional anomalies happened due to ionospheric charing?

Comments below this answer tell us that the International Space Station always remained in Earth's atmosphere. It orbits in the thermosphere and simultaneously the ionosphere. This answer to How do ...
uhoh's user avatar
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1 vote
1 answer
156 views

How are airborne particulates monitored on the ISS? Are they distinguished at all by size and/or type?

The question What kinds of activities, experiment and, procedures done on the ISS must be done in chambers vented to space? links to and quotes from this answer to the 3D Printing SE question How is ...
uhoh's user avatar
  • 149k
0 votes
1 answer
329 views

What support equipment is necessary to maintain a falcon 9 booster during transport after recovery?

This file photo shows a Falcon 9 first stage being transported by truck after landing. There is some equipment at the end of the truck, which includes dials, knobs, and an exhaust stack, which ...
uhoh's user avatar
  • 149k
24 votes
1 answer
703 views

What were the Top 10 Shuttle Risks in John Young's "famous letter"?

Whilst reading A Technical History of the External Tank I ran across this comment: Although the problem has not recurred, John Young, in his famous top ten Shuttle risk letter ...
Organic Marble's user avatar
23 votes
2 answers
7k views

How intrusive was the Apollo Master Alarm system?

During the Apollo 11 landing, a misconfiguration caused the guidance computer to activate the 1201 and 1202 program alarms, signifying that the computer was overloaded and dropping low-priority tasks. ...
Russell Borogove's user avatar
21 votes
5 answers
6k views

Why is dust such a problem in microgravity? Wouldn't proper air circulation and filtration take care of it?

Dust and small particles in microgravity environments are generally regarded as bad, and items prone to generating these tend to be discouraged: Bread should be prepared quite differently, so that it ...
Vikki's user avatar
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