[X] My Assistant

[cIclops]

In his recent long piece on spacedaily.com Bruce Moomaw reports:

... JPL's Pete Theisinger and Mike Meyer (chief engineer and scientist of the 2009 Mars Surface Lab) confirmed that the current plan is to have MSL land using a strange, Rube Goldbergian system called "Skycrane".

Skycrane is a very innovative landing system and now that MSL appears to be planning to use this approach there are lots of open questions, such as: How exactly does it work? What advantages does it have over legs, airbags or pallets? What the heck is it anyway?

Some background info:

JPL note

Space.com article

[Guest_BruceMoomaw_*]

The weigth of the rover (say 1000 kg with some kind of pallet to withstand impact) can be supported on Mars by a helium balloon of...100 m diameter (roughly).

You're right, it is a stupid idea 

____________________

Well, if I may provide you with a little consolation: the idea of a Martian hot-air balloon (a "Montgolfiere") that can make repeated landings on and takeoffs from the Martian surface with a small instrument payload has been very seriously considered by JPL, and specifically by engineer Jack Jones in several JPL Technical Reports. I may try to track down the Reports' URLs (I've got some of them on CD-ROM). The trouble starts when you try to use balloons to land BIG payloads. (Ditto for airbags, which still look very promising for small Martian network landers.)

[dvandorn]

The weigth of the rover (say 1000 kg with some kind of pallet to withstand impact) can be supported on Mars by a helium balloon of...100 m diameter (roughly).

You're right, it is a stupid idea 

____________________

Well, if I may provide you with a little consolation: the idea of a Martian hot-air balloon (a "Montgolfiere") that can make repeated landings on and takeoffs from the Martian surface with a small instrument payload has been very seriously considered by JPL, and specifically by engineer Jack Jones in several JPL Technical Reports. I may try to track down the Reports' URLs (I've got some of them on CD-ROM). The trouble starts when you try to use balloons to land BIG payloads. (Ditto for airbags, which still look very promising for small Martian network landers.)

Whatever happened to the concept of a deployable winged Martian flier? I have heard of the balloon concept, and heard it criticized because you have no control of the direction of travel with a Montgolfier-type balloon, no ability to target specific, interesting targets to land "on top" of (within arm's reach, so to speak) and analyze.

The argument I've heard against winged vehicles is that they're a lot harder to land on (much less take off again from) the vast majority of surfaces you find on Mars. And if you're just going to stay in the air, flying around taking very-high-resolution images from a mile or two above the surface, you're not getting that much more significant data than you'll be able to get from orbiters. Being *on* the surface and able to verify "ground truth" of orbital images by phsyically examining the minerology of the rocks and soils is a required part of the process. But I've heard it argued that the resolution of remote sensing data from a mile (or even less) in the air just won't be significantly more valuable than the resolution that can be achieved from orbit. And it's a lot easier to design, fly and operate an orbiter than it is to try to deliver a winged vehicle to Mars' atmosphere...

If you didn't have the kind of capability that the MERs and (hopefully) the MSL give you, then I could see how picking up images from low altitude might be interesting, or hopping indiscriminately from place to place with a *very* small science package might be interesting... but if you're going to spend money to put really small science packages on and around Mars, why not put a bunch of netlander-type probes around to establish meteorological, seismological and radiation detection networks (and do some really basic site investigations), and leave the mobile exploration to wheeled vehicles more suited to the task?

-the other Doug

[Stephen]

The argument I've heard against winged vehicles is that they're a lot harder to land on (much less take off again from) the vast majority of surfaces you find on Mars.  And if you're just going to stay in the air, flying around taking very-high-resolution images from a mile or two above the surface, you're not getting that much more significant data than you'll be able to get from orbiters.  Being *on* the surface and able to verify "ground truth" of orbital images by phsyically examining the minerology of the rocks and soils is a required part of the process.  But I've heard it argued that the resolution of remote sensing data from a mile (or even less) in the air just won't be significantly more valuable than the resolution that can be achieved from orbit.  And it's a lot easier to design, fly and operate an orbiter than it is to try to deliver a winged vehicle to Mars' atmosphere...

If you didn't have the kind of capability that the MERs and (hopefully) the MSL give you, then I could see how picking up images from low altitude might be interesting, or hopping indiscriminately from place to place with a *very* small science package might be interesting... but if you're going to spend money to put really small science packages on and around Mars, why not put a bunch of netlander-type probes around to establish meteorological, seismological and radiation detection networks (and do some really basic site investigations), and leave the mobile exploration to wheeled vehicles more suited to the task?

What about marrying a Montgolfier-type balloon with a small rover? The balloon does most of the travelling, snapping pics etc from aloft, but lands at interesting sites to release a small (Sojourner-style?) rover. The rover does its business (with the balloon's own instrument package acting as a basestation Pathfinder-style), then returns, gets back onboard its cradle (or whatever), and off they fly to another site.

[djellison]

What about marrying a Montgolfier-type balloon with a small rover? The balloon does most of the travelling, snapping pics etc from aloft, but lands at interesting sites to release a small (Sojourner-style?) rover. The rover does its business (with the balloon's own  instrument package acting as a basestation Pathfinder-style), then returns, gets back onboard its cradle (or whatever), and off they fly to another site.

How do you stop the balloon just drifting away in the mean time?

Doug