Mars trips may involve less radiation exposure than previously thought:
There's no question that the first human mission to Mars will be extremely dangerous. Some studies have suggested that the radiation levels would exceed the maximum career dose for a given astronaut, greatly increasing the risk of cancer and other illnesses. It might not be quite so bad as it sounds, though. Newly presented ESA ExoMars orbiter data indicates that astronauts would receive "at least" 60 percent of their maximum recommended career radiation exposure on a round trip to Mars that takes six months both ways. That's still several times what ISS crew members receive, but it's relatively gentle compared to what some had feared.
(Score: 2) by c0lo on Thursday September 20 2018, @11:16AM (1 child)
Yes, for sure, it will be a significant saving in comparison with lifting that fuel from Earth surface.
Not such a big advantage for the rest... the brake into Sun's gravity's well will cost the same energy as the escape from Sun's gravity well.
True, between the asteroid belt and somewhere close to Earth you'll have Mars to do a gravity assist braking, but you could do only once for a reasonable transit time - will save you some energy, but not a significant percentage.
(Remember that solar probe [soylentnews.org] they sent "down" recently? No less that 7 Venus gravity assist braking needed to slow down [wikipedia.org] over 7 years duration)
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by bzipitidoo on Thursday September 20 2018, @03:01PM
The plan I heard years ago, from Zubrin, was to first send an unmanned fuel generator to the Martian surface, several months ahead of the manned space ship. The manned ship carries enough fuel for a one way trip.
As to refueling en route, it seems the refueling ship should be the one that does almost all the work of matching position and velocity.
Anyway, I still think colonizing Mars is one of those seductive ideas that a cold, rational cost benefit analysis will show is so not worth doing in the immediate future. It's like the flying car that we've been dreaming about since the 1940s. Sounds great, but it's still not practical. A big problem with flying cars is they're heavy and simply take too much energy. A helicopter can get about 7 miles per gallon. They also take a lot more space than a car. Then there's the problem of piloting them, and not getting yourself and your passengers killed in a crash. Takes a lot of training to handle a flying craft safely. Maybe next century on flying cars and Mars.