Aerocapture
Additional small burns may be required to correct apoapsis and inclination targeting errors before the initial science orbit is established.
[2][3] Aerocapture has been shown to be feasible at Venus, Earth, Mars, and Titan using existing entry vehicles and thermal protection system materials.
[4] Until recently, mid-L/D (lift-to-drag) vehicles were considered essential for aerocapture at Uranus and Neptune, due to the large uncertainties in entry state and atmospheric density profiles.
[5] However, advances in interplanetary navigation and atmospheric guidance techniques have shown that heritage low-L/D aeroshells such as Apollo offer sufficient control authority for aerocapture at Neptune.
[citation needed] Cruz's 1979 article was the first to use the word aerocapture, and was followed by a series of studies focusing on its applications to Mars Sample Return (SR).
The project resulted in a number of significant developments, including guidance flight software, but was eventually cancelled due to cost overruns and was never flown.
The ASAT team led by Mary Kae Lockwood at the NASA Langley Research Center studied in substantial detail aerocapture mission concepts to Venus, Mars, Titan, and Neptune.
[14] Since 2016, there is renewed interest in aerocapture particularly with respect to small satellite orbit insertion at Venus and Mars,[15] and Flagship-class missions to Uranus and Neptune in the upcoming decade.
[18][19] Although there are similar constraints on trajectories for robotic missions, the human limits are typically more stringent, especially in light of the effects of prolonged microgravity on acceleration tolerances.
Entering within the corridor allows the vehicle guidance scheme to achieve the desired exit conditions for a capture orbit around the planet.
The third major design option is of an inflatable, trailing ballute—a combination balloon and parachute made of thin, durable material towed behind the vehicle after deployment in the vacuum of space.
The most recent example is the Mars Exploration Rovers, Spirit and Opportunity, which launched in June and July 2003, and landed on the Martian surface in January 2004.
Just prior to entering the atmosphere, the inflatable aeroshell extends from a rigid nose-cap and provides a larger surface area to slow the spacecraft down.
This can be seen as a special effect in the movie version in which only a Russian spacecraft undergoes aerocapture (in the film incorrectly called aerobraking).
In the television serial Stargate Universe, the ship Destiny's autopilot employs aerocapture within the atmosphere of a gas giant at the edge of a star system.
Aerocapture is part of a family of "aeroassist" technologies being developed by NASA for science missions to any planetary body with an appreciable atmosphere.
