A few questions about the mass of the ISS (1, 2, 3) have got me thinking about mass change of the ISS due to natural processes.

The ISS has quite a large area exposed to space, and is subject to both the solar wind and micrometeoroids.

Protons and other nuclei in the solar wind can both sputter surfaces causing permanent mass loss, and implant, causing mass gain which may be either temporary or permanent depending on several details (species, energy, nature of the surface).

Various other particles impinge on surfaces as well.

Likewise micrometeoroid and meteoroid impacts will both add some mass and will disperse some as well (analogous to ejecta).

Are there any theoretical estimates of mass gain or loss of the ISS due to each of these processes? After two thirds of a billion seconds over several thousand square meters of surface area, could it be of the order of a gram? A kilogram?

  • 2
    $\begingroup$ There is also a mass loss by venting not needed gases like hydrogen. Will the mass change due to meteorites or solar wind smaller or larger than those by venting of gases? $\endgroup$
    – Uwe
    Jun 22, 2018 at 15:14
  • $\begingroup$ @Uwe "...have got me thinking about mass change...due to natural processes." First sentence. $\endgroup$
    – uhoh
    Jun 22, 2018 at 15:16
  • $\begingroup$ Evaporation of the ISS construction materiel in vacuum is natural process too :) But I have no numbers.. $\endgroup$
    – Heopps
    Jun 23, 2018 at 7:01
  • 1
    $\begingroup$ At LEO, the dominant process is mass loss via atomic oxygen erosion. $\endgroup$
    – user71659
    Jul 3, 2018 at 19:30
  • 1
    $\begingroup$ @user71659 atomic oxygen is so important that I've added "and other particles" to the question. Thanks! $\endgroup$
    – uhoh
    Jul 3, 2018 at 20:38


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