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InSight probably landed with some fuel margin.

Unless it was vented/burned on landing (maybe not a bad idea considering potential leaks down the road), is there some left ?

Do we know the ISP of InSight thrusters (and therefor it's potential time of flight) ?

Related: Could InSight lift off and move somewhere else?

DrSheldon
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Antzi
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  • ISP is the easy part — about 225 seconds (Aerojet’s datasheets list other MR-107 submodels). Good luck finding out how much propellant it expended in the landing... – Russell Borogove Nov 30 '18 at 02:56
  • InSight is based on the Phoenix lander. I've read through its website http://phoenix.lpl.arizona.edu and there is no mention of a fuel level sensor or the actual remaining fuel. They do note that they avoided burning extra fuel, as it would interfere with water detection (an issue for Phoenix but not InSight). So, we may never know how much InSight has, or at best a very crude estimate. – DrSheldon Nov 30 '18 at 04:32
  • Also, "Over the course of the mission, as propellant is expended, tank and feed pressures will decline and cause engine thrust and specific impulse to decrease – requiring detailed analysis of the thruster response to decreasing inlet pressure to ensure accurate maneuvering over the course of the mission." http://spaceflight101.com/insight/insight-spacecraft/ – DrSheldon Nov 30 '18 at 04:34
  • @DrSheldon maybe we could extrapolate from the time burn; or even the seismometers from the landing ? – Antzi Nov 30 '18 at 05:43
  • @Antzi -- The burn was pulsed at the end to maintain a constant rate of descent - so the time of the burn isn't known (but it may be possible to derive from the telemetry) –  Nov 30 '18 at 08:01
  • I'd be surprised if it was not included one way or an other in the telemetry – Antzi Nov 30 '18 at 08:18
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    @Antzi -- I'd be surprised if it was. That would entail an extremely high data rate. Regarding your previous comment about the seismometers, I doubt they were powered up until sometime after landing. They're rather power-hungry. – David Hammen Dec 01 '18 at 10:33
  • @DrSheldon -- A bit strange that the propulsion system was in blowdown mode. But that it was is another argument against InSight's to lift off and move somewhere else. – David Hammen Dec 01 '18 at 10:37

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