Comments on: Europe’s Trace Gas Orbiter achieves operational orbit around Mars

By: Edward

Edward — Thu, 12 Apr 2018 23:22:58 +0000

I’m with Tom D on this one. After the loss of Mars Climate Orbiter in 1999, NASA may be a little more cautious for a while.

By: Localfluff

Localfluff — Wed, 11 Apr 2018 16:34:30 +0000

@Tom D
Aerobraking actually happens at very high altitude where the atmosphere is very thin. So thin that there are no aerodynamics, just an average of particles hitting the spacecraft’s profile as it goes through the very thin gas of the exosphere. Aerobraking is as effective at Earth as at Venus or Mars. One just chooses the appropriate altitude and thus air density. Why this exomars orbiter has taken so long, I don’t know. I’ll probably look into it once it starts doing science. I suspect that the guys involved don’t mind ensuring themselves longer employments on the project and that it is therefor little opinion against delaying stuff.

It has even been suggested that a spacecraft could aerobrake at Pluto. A planet with no real atmosphere, but the exosphere, the particles leaving the surface without really hitting each other, could be enough to help a probe enter orbit.

By: Tom D

Tom D — Wed, 11 Apr 2018 15:46:14 +0000

I understand that Mars’s extremely thin atmosphere is quite variable in density and height. Aerobraking at Mars is much less useful and much riskier than aerobrake at Earth (or Venus). I am not surprised that they were very cautious about this maneuver.

By: Localfluff

Localfluff — Tue, 10 Apr 2018 17:50:43 +0000

It took a year for this ExoMars orbiter to aerobrake itself into science orbit. ESA tried out aerobraking at Venus with Venus Express. I would have hoped for this to have had greater potential.