• Question: How many times would somebody be able to travel around earth in a rocket before they died?

    Asked by to Becky, Clara, Daniel, Simon, Thomas on 13 Mar 2014. This question was also asked by .
    • Photo: Simon Albright

      Simon Albright answered on 13 Mar 2014:

      That would depend on how fast the rocket was going, how close to the earth it was, how much food etc was on board and probably a dozen other things I can’t think of…

      Assuming you had everything on board you needed to survive and weren’t orbiting a million light years away probably more times than you’d want to.

      The astronauts on board the ISS orbit about 16 times per day and can stay for as long as 18 days meaning they’ll orbit about 288 times!

    • Photo: Clara Nellist

      Clara Nellist answered on 13 Mar 2014:

      Interesting question. I think it depends on the rocket they were in. If it had everything they need to live, like food, water, a toilet, a shower and computer games (or some form of entertainment 😉 ). Then they could probably live for a long time. But without gravity, they won’t be exercising their body enough and the muscles will start to wither away. Astronauts have machines they take on their rockets to try to slow this withering down, but it still happens. There’s also the problem of radiation from space. On Earth, we’re protected by a magnetic field that surrounds us and stops a lot of radiation from the sun getting to us. But in space the rocket won’t protect the humans on board as much and they could get cancer from all of the radiation.

      The longest time anyone has ever spent in space is for 437.7 days which was a Russian guy called Valeri Polyakov. I’m not sure how many times he travelled around the earth, because it depends which way the rocket is going and how fast it’s travelling, but let’s say that’s hundreds of times. Now if we wanted to go to Mars, the people will have to be in the rocket for about 200 days just to get there (and so the same to get back).

    • Photo: Thomas Elias Cocolios

      Thomas Elias Cocolios answered on 13 Mar 2014:

      Beyond the obvious needs for food, water, oxygen, … (and mental health!), I think that there are 2 main issues:
      1) the gravity pull, otherwise known at the centripetal force which goes like v^2 / r, where v is the velocity of the rocket and r the distance from the center of the Earth. As such, the closer to the Earth or the faster the rocket, the more pull you feel. Considering the Earth radius is 6,371 km, the altitude won’t matter much (let’s take 29 km for simplicity!). With such big number to start with, you see that you need v=8 km/s to get 1G (i.e. like on Earth), or 28510 km/h.
      2) the radiation exposure, which depends on your altitude and whether you are shielded by the Earth’s magnetic field or not, but that might be a question better answered by Becky!

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