Phys.org
Aerobraking
Using a planet's atmosphere as a brake, over months, to save enormous amounts of fuel.
A spacecraft arriving at Mars enters a long ellipse, then dips into the upper atmosphere at each closest approach. Each pass sheds a little energy, and after a few hundred of them the orbit has been circularised without a large burn. It saves so much propellant that missions are designed around it, and it takes patience — Mars Reconnaissance Orbiter spent five months doing nothing else. The risk is that atmospheric density varies with the weather and the season, so each pass is targeted with a margin and adjusted afterwards.
Where it has come up lately
Related terms
Gravity assist
Stealing a fraction of a planet's orbital momentum to go faster for free.
Regolith
The layer of broken rock and dust covering an airless world — and a serious engineering problem.
Sample return
Bringing a piece of somewhere else back to a laboratory on Earth.
Opposition and conjunction
The two alignments that decide when a planet is worth looking at and when it is unreachable.
Questions
What is Aerobraking?
Using a planet's atmosphere as a brake, over months, to save enormous amounts of fuel.
Why does it matter?
It saves so much propellant that missions are designed around it, and it takes patience — Mars Reconnaissance Orbiter spent five months doing nothing else. The risk is that atmospheric density varies with the weather and the season, so each pass is targeted with a margin and adjusted afterwards.