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Arsia Mons Anomaly?, Recent Mars Express Imagery shows odd feature
ectoterrestrial
post Nov 16 2018, 06:02 AM
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Changing course...

Is there a limitation on conventional landings with chutes happening near one of the Tharsis 4? Atmosphere must be extra thin up there.

The huge flat caldera on Arsia seems to beckon for a lander or rover. The "spiral cloud" (caldera confined circulating aerosol suspension) might make things interesting as an engineering challenge.

What use is there for a high altitude station on Mars?


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mcaplinger
post Nov 16 2018, 07:08 AM
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QUOTE (ectoterrestrial @ Nov 15 2018, 10:02 PM) *
Is there a limitation on conventional landings with chutes happening near one of the Tharsis 4?

https://marsnext.jpl.nasa.gov/scieng_eng.cfm says that the Mars2020 landing site, for example, has to be below -0.5 km MOLA elevation, with respect to the MOLA geoid. So you can forget about landing on the volcanoes unless you are using purely propulsive landing (no parachutes.)


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mcmcmc
post Nov 16 2018, 10:40 AM
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QUOTE (mcaplinger @ Nov 16 2018, 08:08 AM) *
https://marsnext.jpl.nasa.gov/scieng_eng.cfm says that the Mars2020 landing site, for example, has to be below -0.5 km MOLA elevation, with respect to the MOLA geoid. So you can forget about landing on the volcanoes unless you are using purely propulsive landing (no parachutes.)

why don't landers make aerobraking in orbit rather than landing directly? There would be much less energy to dissipate (just potential energy from 100km altitude rather than all the energy produced by the launcher).
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Gerald
post Nov 16 2018, 02:06 PM
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The do, as far as possible, first with the heat shield, later with parachutes. But with a few hPa, it's hard to slow down to subsonic velocities by mere aerobreaking.
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mcaplinger
post Nov 16 2018, 02:36 PM
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QUOTE (mcmcmc @ Nov 16 2018, 02:40 AM) *
why don't landers make aerobraking in orbit rather than landing directly?

It would require a large engine and a lot of fuel to get into orbit first, but Viking did do that. You still need a parachute.

If you're talking about aerocapture to get into orbit, I'm not sure why you think it would help landing.


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ectoterrestrial
post Nov 16 2018, 09:28 PM
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QUOTE (mcaplinger @ Nov 16 2018, 12:08 AM) *
https://marsnext.jpl.nasa.gov/scieng_eng.cfm says that the Mars2020 landing site, for example, has to be below -0.5 km MOLA elevation, with respect to the MOLA geoid. So you can forget about landing on the volcanoes unless you are using purely propulsive landing (no parachutes.)


Hmm. Not much (unvisited) terrain left with those constraints.. A visit to Beagle 2 crater in Isidis? A slow climb up Elysium Mons maybe?


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atomoid
post Nov 17 2018, 02:00 AM
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QUOTE (mcaplinger @ Nov 16 2018, 06:36 AM) *
...If you're talking about aerocapture to get into orbit, I'm not sure why you think it would help landing.

aerocapture orbits take quite an extended time to slow the velocity and round out the orbit (adding operations cost to the budget), when that energy can be dispersed much quicker via the well-proven heatsheild method. I'd assume the orbital speed will still be high enough that you'd have use a heatshield for the orbital-to-atmopspheric entry anyways but i am only guessing... I was curious to find the relative velocities of direct atmospheric entry modes vs the slowest possible option for orbital insertion trajectories but ran out of time, here are some starter resources though.
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