Effects of chemical releases by the STS 3 Orbiter on the ionosphere

Abstract

The Plasma Diagnostics Package, which was flown aboard STS 3 as part of the Office of Space Science first shuttle payload (OSS 1), recorded the effects of various chemical releases from the orbiter. Changes in the plasma environment were observed to occur during flash evaporator system releases, water dumps, and maneuvering thruster operations. During flash evaporator operations, broadband orbiter‐generated electrostatic noise was enhanced, and plasma density irregularities (ΔN/N) were observed to increase by 3–30 times with a spectrum which rose steeply and peaked below 6 Hz. Ions with energies up to several hundred eV were also observed during one flash evaporator operation. In the case of water dumps, background electrostatic noise was enhanced at frequencies below about 3 kHz and suppressed at frequencies above 3 kHz during the dump, and ΔN/N was also seen to increase by 5–6 times. Various changes in the plasma environment were effected by primary and vernier thruster operations, including increases in electron density by as much as 3 orders of magnitude, neutral pressure increases to as high as 10−4 torr from the nominal 10−7 torr, and perturbations in the spacecraft potential by several volts, particularly when measured in relation to the plasma potential in the wake. Thruster activity also stimulated electrostatic noise with a spectrum which peaked at approximately 0.5 kHz. In addition, ions with energies up to 1 keV were seen during some thruster events.