The Effects of Hypervelocity Impacts on Spacecraft

Hypervelocity impacts can affect spacecraft
in various ways. Micron sized particles
can degrade sensitive spacecraft surfaces
and equipment, like mirrors and
optical sensors. Larger particles with
sizes ranging from tens to hundreds of
microns can penetrate coatings and foils
as well as solar cells. Damage such as
this has been observed on satellite surfaces
returned to Earth (LDEF, HST
solar arrays, EURECA) and on the windows
of the U.S. Space Shuttle which
have been replaced many times due to
impact damage. Millimeter-sized parti-

cles can penetrate satellite structure
walls or shielded walls of manned spacecraft,
posing a serious threat to equipment,
astronauts, or both. To reduce the
destructive effects of impacts, all modules
of the International Space Station
have debris shields to defeat sub-cm
objects. Impacts of such large particles
may also induce considerable changes in
the satellite’s attitude through transfer of
momentum. The impact of centimeteror
decimeter-sized particles will typically
lead to complete destruction of
important spacecraft parts or even to disintegration
of the spacecraft. Prominent
examples of collisions involving large
fragments with spacecraft are the 1996
collision between the French CERISE
military satellite and a 1 m fragment that
was generated from the explosion of an
Ariane 4 upper stage 10 years prior, and
the 2005 collision between an American
Thor rocket motor with a large fragment
of the third stage of a Chinese CZ-4
launcher. Many satellites and manned
space-stations are known to have performed
collision avoidance manoeuvres
with catalogued Space Debris parts, such
as ESA’s ERS-1 and ENVISAT satellites,
the U.S. Shuttle, the MIR station
and the ISS, to name only a few. Besides
the effects of structural damage, every
hypervelocity impact generates metal
vapour plasma that can result in electromagnetic
interference or result in
plasma-induced discharges: The
European Space Agencies’ (ESA)
OLYMPUS communication satellite
may have failed as a consequence of
hypervelocity impact of a Perseid meteoroid
in 1993.