To date, more than 600 astronauts have gone into space, and they are all heroes of humanity, and while we are proud of them, we also fear for their safety. A common question is: how do astronauts return to the spacecraft if they accidentally fall into space during extravehicular activities?
The first condition for astronauts to carry out extravehicular activities is that the spacecraft must operate very stably, and in order to achieve this standard, the spacecraft must not have acceleration at this time, which means that when the astronaut and the spacecraft are actually in synchronous motion during extravehicular activities, the relative velocity between the two is very small and usually negligible.
In such a situation, even if the astronaut accidentally falls into space, his relative speed with the spacecraft will not be very fast, generally on the order of several meters per second, because the drag in space is almost zero, so it only takes a little extra thrust for the astronaut to return to the spacecraft, how to do it? In addition to waiting for the spacecraft to rescue by its own power, the following three methods may be tried.
The first method is to use a jetpack, in fact, a jetpack can be said to be a must for every astronaut to carry out out-of-cabin activities, as the name suggests, this kind of backpack is to use the jet to generate thrust.
The jetpack usually has two working modes, one is the automatic mode, which can detect the attitude and movement of the astronaut and automatically adjust the switch of the fumale to keep the astronaut's attitude stable in space, and the other is the manual mode, which allows the astronaut to manually control the direction and strength of the fumarole, so that the astronaut can move in the direction he wants.
If an astronaut accidentally falls into space, he can choose to adjust his direction and speed in manual mode to move himself in the direction of the spacecraft. You must know that the jetpack has fumaroles in all directions, which can be called "360 degrees without dead ends", and its theoretical maximum speed can be tens of kilometers per hour, so as long as it is operated properly, the astronauts can completely return to the spacecraft with the help of the jetpack.
Of course, we can't completely rule out the possibility that the jetpack will "drop the chain" at a critical time, so if the jetpack doesn't work, will the astronauts still be able to return to the spacecraft?
The second method is simply to use the gas in the spacesuit. Astronauts must wear special spacesuits during extravehicular activities, which contain gases that the astronauts can breathe.
So in an emergency, the astronaut can open the air valve of the spacesuit, let a part of the gas eject from the spacesuit, and then obtain thrust in the opposite direction, although this thrust is much smaller than the jetpack, and not durable enough, if the astronaut is not very far away from the spacecraft, and the relative speed with the spacecraft is not very large, then the astronaut still has the opportunity to return to the spacecraft.
If the astronaut has something that can be thrown, such as some maintenance tool or a part that can be removed from a spacesuit, then try to use a third method, which is to throw these things out and get the reverse thrust.
The principle of the thrust that a jetpack obtains through the jet in space can be explained by the law of conservation of momentum, which simply means that the total momentum of a system remains constant when it is not acted upon by an external force or the sum of the vectors of the external force is zero.
It can be concluded that in the case where a system is divided into two parts, "A" and "B", due to internal interactions, if "A" moves in a certain direction, then "B" will have a momentum equal to it but in the opposite direction, and we all know that the direction of momentum is the same as velocity, so "B" will have a velocity in the opposite direction of motion to "A".
When a jetpack jets in space, it can be simply regarded as a system because of the internal interaction divided into two parts, "A" and "B", in which the ejected gas can be regarded as "A" as a whole, and the jetpack can be regarded as "B", so when the jetpack ejects gas, it itself has the opposite velocity to the ejected gas, and then gains thrust.
By the same token, if an astronaut can throw something, he can use the principle of conservation of momentum to gain reverse thrust, in which case the astronaut also has a chance to return to the spacecraft.
It should be pointed out that the above three methods can only be said to be theoretically feasible, and in practice, in fact, it will face great risks and various unpredictable accidents, so we should start with prevention, through a series of measures such as strict training, quality control and safety inspection of spacecraft, to ensure the safety of astronauts to the greatest extent, in fact, in the past days, this aspect has been done very well, and there has never been such a thing as "astronauts accidentally falling into space".