Lithobraking is a term used by spacecraft engineers to refer to a spacecraft reducing its velocity by impacting the surface of a planet or moon.
[McDowell, Jonathan (2020)]
"Lithobraking"
''Astronautical Glossary''. Retrieved May 16, 2022.[ Originally coined as whimsical euphemism for a " crash landing", it is now also used when the collision is deliberate.]aerobraking
Aerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit (apoapsis) by flying the vehicle through the atmosphere at the low point of the orbit (periapsis). The resulting drag slows the spacecraft. Aerobraking is ...
", slowing a spacecraft by intersecting the atmosphere
An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...
, with "lithos" ( [], "rock") substituted to indicate the spacecraft is intersecting the planet's solid lithosphere rather than merely its gaseous atmosphere.
According to Jonathan McDowell,[ "Lithobraking reduces the ]apoapsis
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values.
Apsides perta ...
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."
The term Lithobraking has been popularised by the video game ''Kerbal Space Program
''Kerbal Space Program'' is a 2015 Space flight simulation game, space flight simulation video game developed by Mexican studio Squad for Linux, macOS, Windows, PlayStation 4, PlayStation 5, Xbox Series X/S and Xbox One. In the game, players dir ...
'' as a euphemism for spacecraft crashes.
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
Messenger, Messengers, The Messenger or The Messengers may refer to:
People
* Courier, a person or company that delivers messages, packages, or mail
* Messenger (surname)
* Bicycle messenger, a bicyclist who transports packages through cities
* M ...
'' into Mercury after the spacecraft ran out of fuel.Dimorphos
Dimorphos (formal designation (65803) Didymos I; provisional designation S/2003 (65803) 1) is a natural satellite or minor-planet moon, moon of the near-Earth object, near-Earth asteroid 65803 Didymos, with which it forms a Binary asteroid, bina ...
to test lithobraking as a method of planetary defense.
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.
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.comet
A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...
s and asteroid
An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...
s, or on planets with atmospheres (by using only small parachutes, or no parachutes at all). Several such missions have been launched, including penetrators on the two Phobos probe landers targeted for Mars' moon Phobos and ones for Mars itself on Mars 96
Mars 96 (sometimes called Mars-8) was a failed Mars mission launched in 1996 to investigate Mars by the Russian Space Forces and not directly related to the Soviet Mars probe program of the same name. After failure of the second fourth-stage ...
and Deep Space 2,
See also
{{Portal, Spaceflight
*Aerocapture
Aerocapture is an Orbital maneuver, orbital transfer maneuver in which a spacecraft uses
aerodynamic drag force from a single pass through a planetary
atmosphere to decelerate and achieve orbit insertion.
Aerocapture uses a planet's or moon's at ...
* Aerogravity assist
*Asteroid capture
Asteroid capture is an orbital insertion of an asteroid around a larger planetary body. When asteroids, small rocky bodies in space, are captured, they become natural satellites, specifically either an irregular moon if permanently captured, or a ...
*Atmospheric reentry
Atmospheric entry (sometimes listed as Vimpact or Ventry) is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet, or natural satellite. Atmospheric entry may be ''uncontrolled entry ...
*Skip reentry
Non-ballistic atmospheric entry is a class of atmospheric entry trajectories that follow a non-ballistic trajectory by employing aerodynamic lift in the high upper atmosphere. It includes trajectories such as skip and glide.
Skip is a flight tr ...
References
Spacecraft propulsion
21st-century neologisms
Euphemisms