title: Spacelab-2 plasma depletion experiments for ionospheric and radio astronomical studies.
abstract: The Spacelab-2 Plasma Depletion Experiments were a series of studies to examine shuttle-induced perturbations in the ionosphere and their application to ground-based radio astronomy. The space shuttle Challenger fired its orbital maneuvering subsystem engines on 30 July and 5 August 1985, releasing large amounts of exhaust molecules (water, hydrogen, and carbon dioxide) that caused the electrons and ions in Earth's upper atmosphere to chemically recombine, thereby creating so-called "ionospheric holes." Two burns conducted over New England produced ionospheric peak depletions ranging from 25 to 50 percent, affected the ionosphere over a 200-kilometer altitude range, and covered 1 degrees to 2 degrees of latitude. Optical emissions associated with the hole spanned an area of several hundred thousand square kilometers. A third burn was conducted over a low-frequency radio observatory in Hobart, Australia, to create an "artificial window" for ground-based observations at frequencies normally below the natural ionospheric cutoff (penetration) frequency. The Hobart experiment succeeded in making high-resolution observations at 1.7 megahertz through the induced ionospheric hole.
authors.forename: M
authors.initials: M
authors.lastname: Mendillo
authors.forename: J
authors.initials: J
authors.lastname: Baumgardner
authors.forename: D P
authors.initials: DP
authors.lastname: Allen
authors.forename: J
authors.initials: J
authors.lastname: Foster
authors.forename: J
authors.initials: J
authors.lastname: Holt
authors.forename: G R
authors.initials: GR
authors.lastname: Ellis
authors.forename: A
authors.initials: A
authors.lastname: Klekociuk
authors.forename: G
authors.initials: G
authors.lastname: Reber