Mars inSight Mission
Discussion
Eric Mc said:
MartG said:
Surface roughness does affect radar return signals, but I suspect the device carried by the lander is a simple altimeter
I'd say it isn't that different to the reversing sensor system on modern cars.
But at what cost in weight penalties? The equipment itself would be heavier plus the need to carry additional fuel and (possibly) thrusters to allow all that hovering and manoeuvering.
I'm sure NASA and JPL take all these things into consideration when specifying these landers. On balance, I would say they know what they are doing - and the success rate for the landers seems to prove that.
I'm sure NASA and JPL take all these things into consideration when specifying these landers. On balance, I would say they know what they are doing - and the success rate for the landers seems to prove that.
RizzoTheRat said:
They mentioned on the live stream that the radar was a modified version of the one in the F16, but presumably they mean the F16's radar altimeter not its main radar.
Maybe they expect to have to shoot down some hostile Martians (or a rival lander from some other space agency) 
RizzoTheRat said:
They mentioned on the live stream that the radar was a modified version of the one in the F16, but presumably they mean the F16's radar altimeter not its main radar.
I'm pretty sure that was just a throwaway comparison to explain it to non-techie people - the radar ( even the altimeter ) on an F-16 would take far too much power for the lander's batteries to copeEric Mc said:
But at what cost in weight penalties? The equipment itself would be heavier plus the need to carry additional fuel and (possibly) thrusters to allow all that hovering and manoeuvering.
I'm sure NASA and JPL take all these things into consideration when specifying these landers. On balance, I would say they know what they are doing - and the success rate for the landers seems to prove that.
The reduction in risk of losing the entire mission due to an inconveniently placed rock could be worth it - maybe they've just been lucky so farI'm sure NASA and JPL take all these things into consideration when specifying these landers. On balance, I would say they know what they are doing - and the success rate for the landers seems to prove that.
MartG said:
Eric Mc said:
But at what cost in weight penalties? The equipment itself would be heavier plus the need to carry additional fuel and (possibly) thrusters to allow all that hovering and manoeuvering.
I'm sure NASA and JPL take all these things into consideration when specifying these landers. On balance, I would say they know what they are doing - and the success rate for the landers seems to prove that.
The reduction in risk of losing the entire mission due to an inconveniently placed rock could be worth it - maybe they've just been lucky so farI'm sure NASA and JPL take all these things into consideration when specifying these landers. On balance, I would say they know what they are doing - and the success rate for the landers seems to prove that.
MartG said:
RizzoTheRat said:
They mentioned on the live stream that the radar was a modified version of the one in the F16, but presumably they mean the F16's radar altimeter not its main radar.
I'm pretty sure that was just a throwaway comparison to explain it to non-techie people - the radar ( even the altimeter ) on an F-16 would take far too much power for the lander's batteries to copehttps://mars.nasa.gov/news/8390/nasa-insight-landi...
Beati Dogu said:
MartG said:
RizzoTheRat said:
They mentioned on the live stream that the radar was a modified version of the one in the F16, but presumably they mean the F16's radar altimeter not its main radar.
I'm pretty sure that was just a throwaway comparison to explain it to non-techie people - the radar ( even the altimeter ) on an F-16 would take far too much power for the lander's batteries to copehttps://mars.nasa.gov/news/8390/nasa-insight-landi...
The craft just doesn't have the fuel capacity to allow it to dick about in the hover. It really is a bit of a gamble getting these things down. However, they did select a fairly smooth area for this mission and the images they have of potential landing sites are way better than what they had to go on decades ago - so far less of a gamble than in the days of Viking.
No doubt they'll eventually develop an electronic Neil Armstrong to pick the perfect spot, but there will always be a calculated risk.
If you want to know how carefully they plan: They have an identical lander back on earth and they're going to model the sand & rocks around it to match what's around InSight on Mars. They'll using photos and augmented reality glasses to do this. Once they've happy with that, they're going to test deploy the experiments before telling InSight exactly where to place them.
If you want to know how carefully they plan: They have an identical lander back on earth and they're going to model the sand & rocks around it to match what's around InSight on Mars. They'll using photos and augmented reality glasses to do this. Once they've happy with that, they're going to test deploy the experiments before telling InSight exactly where to place them.
Edited by Beati Dogu on Thursday 29th November 19:40
I dont know how big a boulder it could cope with landing on, but the legs look pretty short, and it landed at a decent speed so presumably they need to give a fair bit.
Einion Yrth said:
And I don't get the feeling that there was much "site selection and hovering to get there" going on. The system appears to have been "find the ground and make sure that velocity is zero when you get there"; certainly the altitudes called out during the final descent, and their timing, suggested a "suicide burn", to me.
That's how I do it in KSP Eric Mc said:
JPL should always consult the experts on PH first - or so it seems.
I don't see much offering of advice, just questions and/or amateur analysis. Hell I've landed loads of things in both KSP and Orbiter, but I don't think I'm ready for the multi-million dollar hardware gamble...It's just all the suggestions that maybe NASA/JPL should do this or that - or that there was a bit too much "gamble" in what they do regarding these Mars landers.
I like to think they DO know what they are doing and they have had a very good success rate when it comes to Mars probes, ESPECIALLY when it comes to Mars landers.
I like to think they DO know what they are doing and they have had a very good success rate when it comes to Mars probes, ESPECIALLY when it comes to Mars landers.
Eric Mc said:
It's just all the suggestions that maybe NASA/JPL should do this or that - or that there was a bit too much "gamble" in what they do regarding these Mars landers.
I like to think they DO know what they are doing and they have had a very good success rate when it comes to Mars probes, ESPECIALLY when it comes to Mars landers.
FFS Eric - it's a simple discussion about the technology used I like to think they DO know what they are doing and they have had a very good success rate when it comes to Mars probes, ESPECIALLY when it comes to Mars landers.
I often agree with you but this time you're taking pickiness to a new level 
MartG said:
FFS Eric - it's a simple discussion about the technology used I often agree with you but this time you're taking pickiness to a new level
I just thought that there was implied criticism of NASA and the JPL for not using "obvious" technology. I often agree with you but this time you're taking pickiness to a new level I love discussing this stuff - but I balk at concluding that an organisation that has done such amazing things when it comes to Mars somehow could have done better.
On the other hand, both the Soviet/Russian and European attempts at landers have been singularly unsuccessful - so maybe we should look at why they kept/keep getting it wrong - all the time.
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