Bother

[james_davis_nicoll]

We don't know how to safely land a large payload on Mars.

Nicked from the Bad Astronomer

Comments

[illian.livejournal.com]

I'm struck by the following bit:

But what about airbags, parachutes, or thrusters that have been used on the previous successful robotic Mars missions, or a lifting body vehicle similar to the space shuttle?

None of those will work, either on their own or in combination, to land payloads of one metric ton and beyond on Mars.

I'm probably missing something obvious (at least to someone in the field) but I wonder why they can't do multiple payloads for most of landing? Is it that 1 ton or less is just too small a load to be economical to land, even if there is more than one?

[twoeleven.livejournal.com]

i have the same question, so if there's a rocket scientist in the house...

[anton-p-nym.livejournal.com]

I can see one issue; scattering. The article discussed how Mars' atmosphere made decent paths somewhat unpredictable. Dropping a large number of small packages means huge dispersion. (Think of parachute drops during World War Two... now scale that up to supersonic speeds of decent.) It could be ruinous to have all that equipment strewn randomly over a drop zone the size of Nebraska.

-- Steve has this horrible mental image of astronauts scattered hither and yon over the Martian landscape, trying to find the bulk containers of breathing mix...

[jamesenge.livejournal.com]

There's a good story in that.

[daveon.livejournal.com]

1 tonne is just too small to be useful for a human landing. As they said the Lunar Lander was 10 tonnes (although I think it was more) and that didn't need any heat shield etc... Not to mention you're going to be on the Mars surface a lot longer than they were on the moon.

I've also worried about the ability to land payloads close together which is essential for any of Zubrin's Mars Direct scenarios.

One of the things which struck me when I read the case for Mars, that there were a lot of "in a bound he was free" elements to the engineering and, in reality, there's a lot of problems with a manned Mars mission that we've not cleared up yet.

I'm sure we can, I just question how easy it'll be without some trial runs.

[sunshaker.livejournal.com]

The problem is that many small vehicles take up more space than a few big ones (plus you need to factore in pilots/computers, fuel, etc.).

Think of it like trying to ship 100 pigs from New York to LA, you could do it by using 100 cars or 2 Tractor Trailers. Now think about how much 100 cars cost compared to 2 Tractor Trailers, how much material is used in the cars compared to the tractor trailers, compare the amount of Gas used by the cars to that used by the tractor trailers. Now think about shipping the pigs, the vehicles, the drivers and all the gas they will need, in the smallest cheapest ship possible from Cape Town South Africa to New York and then offloading them so they can drive to LA.

[james-nicoll.livejournal.com]

Suddenly the idea of establishing a base in Deimos or Phobos looks more attractive. At least we could actually do that.

[felis-sidus.livejournal.com]

Assuming, for the sake of discussion, that everything we need to land, including astronauts, could be packaged in multiple units each weighing 1 metric ton or less, would tethering the units together address the scattering problem? (Please be kind if this is a ridiculous question. I'm only a wannabe space geek, not someone who actually knows anything about the subject.)

[keithmm.livejournal.com]

Last thing you'd want to do. Aside from the...interesting...aerodynamic issues there's also the possibility of failure. Say there's a 2% chance of the landing system failing to work. For a single lander, that's acceptable risk. Now say you wanted to land 25 tons in ton lots. That's a 50% chance at least one of them won't make it. Tether them together and that's a 50% chance *all* of them won't make it.