ISS is at an altitude of about 400 km (approximately). But there will be some of space debris at that altitude (since some of the space debris orbits decay over time). So the debris has a probability of coming in contact (colliding) with the ISS. So, how does the ISS avoid those collisions?


1 Answer 1


I will assume you are asking about collision risk management. As usual, it comes in several guises:

  • Avoidance
  • Protection
  • Mitigation

See this reference: http://www.nasa.gov/mission_pages/station/news/orbital_debris.html

The key assets in Collision Avoidance are:

When Debris Avoidance Maneuvers cannot be performed due to late detection of the threat, risk avoidance procedures force the ISS crew to go for the boats (err, Soyuz vehicles).

Protection is indeed Whipple shields, as TildalWave graciously noted.

Mitigation comes into play after the collision. As discussed elsewhere (Are there any safety procedures in place on the ISS in case of puncture?), if there is time to isolate leaking compartments, the crew may do so. However, repairing the station is considered to be the job of followup expeditions.

Broadly speaking, there are three other possible solutions to the problem that have not been implemented on the ISS:

  • Prevention of debris generation (by responsible design)
  • Debris collection
  • Active defense (with kinetic interceptors or laser ablation)

A hat tip to osgx for references on ideas on installing a debris detection telescope and a laser on the ISS:

  • Toshikazu Ebisuzaki, Mark N. Quinn, Satoshi Wada et al. Demonstration designs for the remediation of space debris from the International Space Station. Acta Astronautica, July 2015. DOI 10.1016/j.actaastro.2015.03.004
  • Wolfgang O. Schall. Laser requirements for the removal of space debris from orbit. Proceedings of SPIE 3574 (1998) pp. 426–436. DOI 10.2514/2.3785 - the first paper proposing an ISS-based laser.
  • $\begingroup$ "Active defense (with kinetic interceptors or laser ablation)" This I want to see! $\endgroup$
    – Scott
    Commented Oct 15, 2014 at 13:21
  • 3
    $\begingroup$ Scott, there are plans to install debris tracking telescope (mini EUSO, then something like JEM-EUSO) and small laser ("CAN" fiber laser, 10J pulse, 20-60 kilometers) on ISS: gizmodo.com/… "Demonstration designs for the remediation of space debris from the International Space Station" in Acta Astronautica Volume 112, July–August 2015, Pages 102–113 doi:10.1016/j.actaastro.2015.03.004 It will be tesetd on 2-3 debris objects per year $\endgroup$
    – osgx
    Commented May 2, 2015 at 15:44

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