F. Buhler et al., First detection of He-4 in a sample of interstellar neutral gas collected onboard Mir station, ASTRO SP SC, 274(1-2), 2000, pp. 19-24
For the first time, the method of collecting impinging atoms in pretreated
foil surfaces during exposure from a spacecraft allowed to detect in the la
boratory, after retrieval of the foils, He-4 gas of interstellar origin in
the expected concentration.