Lithobraking

Source: Wikipedia, the free encyclopedia.

Lithobraking is a whimsical "

Ancient Greek: λίθος [líthos], "rock")[4] substituted to indicate the spacecraft is intersecting the planet's solid lithosphere
rather than merely its gaseous atmosphere.

According to

apoapsis
height to zero instantly, but with the unfortunate side effect that the spacecraft does not survive. Originally a whimsical euphemism, but increasingly a standard term."

End-of-mission lithobraking

Lithobraking is used to refer to the result of a spacecraft crashing into the rocky surface of a body with no measures to ensure its survival, either by accident or with intent. For instance, the term has been used to describe the impact of MESSENGER into Mercury after the spacecraft ran out of fuel.[2][3] More recently, the term has also been used to describe the successful completion of the Double Asteroid Redirection Test (DART), when a probe crashed into Dimorphos to test lithobraking as a method of planetary defense.[5]

Intact lithobraking

Successful lithobraking requires a spacecraft capable of impacting the planet or moon at high velocity, or protecting the probe with sufficient cushioning to withstand an impact with the surface undamaged. Incoming angles are made shallow enough such that the impact has the characteristic of a glancing blow, rather than a direct impact on the surface. Lithobraking can be combined with other braking techniques, where the velocity of a lander can be reduced using retrorockets or parachutes, and it can be protected from the force of impact by cushioning air bags or shock absorbers.[citation needed]

In the absence of a thick atmosphere, lithobraking is difficult due to the extremely high orbital velocities of most bodies. However, the orbital velocity of small moons (for example, Phobos), asteroids, and comets can be sufficiently small for this strategy to be feasible. For example,

MASCOT lander from Hayabusa2 landed on asteroid 162173 Ryugu in a similar manner.[7]

Instead of attempting to slowly dissipate the incoming velocity, it can be used to enable the probe to penetrate the surface. This can be tried on bodies with low gravitation, such as

LUNAR-A probe would have carried penetrators to the Moon.[citation needed
]

Related concepts

train, and the train then slowing.[8] This technique requires extremely precise guidance and control, in addition to a large infrastructure, and is thus not yet a viable option – although it may be in the future.[citation needed
]

See also

References

  1. ^ a b McDowell, Jonathan (2020). "Lithobraking", Astronautical Glossary. Retrieved May 16, 2022.
  2. ^ a b Whitwam, Ryan (April 30, 2015). "NASA's MESSENGER probe is crashing into Mercury today". Extreme Tech. Retrieved September 13, 2020.
  3. ^ a b Chappell, Bill (April 30, 2015). "Kill The Messenger: NASA Orbiter Crashes Into Mercury". NPR.org. Retrieved September 13, 2020.
  4. ^ "litho". Dictionary.com.
  5. ^ Glaze, Lori S. (October 2022). "First Line of Defense". Lunar and Planetary Institute. Archived from the original on November 17, 2022. Retrieved November 17, 2022. ... the live feed dropped out at the heartbreaking/lithobraking moment of impact ...
  6. ISSN 0273-1177
    .
  7. ^ Howell, Elizabeth (October 2, 2018). "Tiny German Spacecraft Poised for Hopping Landing on Asteroid Ryugu". Space.com. Retrieved 2020-09-13.
  8. Bibcode:1988LPICo.652...26B
    .
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