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Comment by Cthulhu_ | Hacker News Reader

It's theoretically possible, it'd just require a lot of fuel to slow the craft down enough to survive a landing.

source: I've played Kerbal Space Program. If you speak maths (I don't), you could probably do them; the calculations are relatively simple: https://en.wikipedia.org/wiki/Delta-v.

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No, it is much much harder. Especially the survival part

Delta-v is literally Physics 101

Landing on Mars is hard, but feasible. Because it has a thick atmosphere to help with the braking

Sure, it adds a lot of complications as well, but it is a very good way of slowing your craft enough for other braking systems to work (like rockets, parachutes, etc)

Of course, bodies with little atmosphere also have a small gravity, so that makes things easier as well (like landing on the Moon)

> No, it is much much harder. Especially the survival part

Please elaborate. What is dangerous about a braking burn? Sure, it's harder (because you need to carry that fuel), but not impossible in principle.

> Sure, it adds a lot of complications as well, but it is a very good way of slowing your craft enough for other braking systems to work (like rockets, parachutes, etc)

I'm sorry, when do rockets not work?

But it is not some fuel, it is more or less the same amount of fuel you need to accelerate the thing. And now you have to accelerate twice as much mass at liftoff requiring even more fuel. Of course requiring even more fuel itself. The tyranny of the rocket equation.

Yes, it's hard. I understand that. But not impossible.

Same arguments apply to Saturn, but "we" managed to get Cassini in orbit. It's a matter of scale, not principle.

It is of course possible but difficultly and costs will probably explode ruining the cost benefit ratio. Fly by ten times or try landing once? Or fly by once and spend the remaining money exploring something else - there is so much else. And entering an orbit seems still vastly simpler than landing on the surface.

Yeah, but Saturn is at approx. 1/4 of the distance to Pluto and it used a different process to intersect to Saturn's orbit, taking more time to get there

New Horizons got to Jupiter after ONE year

There was a good xkcd what-if on this a while back. http://what-if.xkcd.com/38/

in part it's more dangerous than correction or passive braking system because you need a high twr motor and the explosive to go with it to have a way to correct for unforeseen consequences.

see what happened with philae, they got two redundant system to land and both failed.

if the scan reveal pluto to have an usable atmosphere, it will be much much easier to land

however, if you look at the trajectory they used it's an orthogonal encounter [1]

that means the speed they have relative one another is quite much more than when you approach calmly from behind using a hoffman transfer or the like - however if you go that route, instead of waiting 10 years you have to wait a load more, probably more like hundreds (exactly what they did with phila, they approached from the closest orbit possible to minimize the correction burn needed [2])

and let us not forget that having anything in space surviving for soo long is a challenge by itself, as having equipment on earth funded for so long to be maintained operational - remember this story about the other spacecraft that was sent to a comet flyby and was out of gas due leaks on its way back? [3] they had to work a great deal just to rebuild the communication equipement in time

[1] https://upload.wikimedia.org/wikipedia/commons/c/cb/New_Hori... [2] http://i.imgur.com/TUkKuhf.gif [3] http://blogs.nature.com/news/2014/07/attempt-to-retrieve-nas...

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