Jet Propulsion Laboratory (U.S.). Interactions Measurements Payload for Shuttle (IMPS) Project.

The Interactions Measurement Payload for Shuttle (IMPS) was designed to be a shuttle experiment by the Air Force Geophysics Lab (AFGL) and JPL's role was to prepare preliminary plans and to provide project management support. As a polar-auroral environment was felt to be a threat to spacecraft systems, the IMPS experiments were designed to study these threats, especially: Spacecraft Charging, Contamination, Plasma Interactions, Material (Bulk and Surface) Property Changes, Solar UV/IR Ambient and Induced Fields.

Based on past missions into space, it was expected that as spacecrafts "evolved" into larger, more complex objects, the following problems might occur: Logic Upsets, Circuit/Device Latch-Up, Arc Discharges, Power Loss, Electromagnetic Interference, High Sensor-Background Levels, Efficiency Loss in Solar Cells, Loss of Thermal Control, Mechanical Damage, Spurious Light Flashes, and Loss of Structural Control.

IMPS was designed to study these problems in an effort to understand what could be done to alleviate such difficulties on future spacecraft.

IMPS was designed to fly on a Shuttle Pallet Satellite (SPAS). SPAS was developed by Messerschmitt-Bolkow-Blohm (MBB) to be carried in the Shuttle's payload bay. In orbit, the cargo doors of the shuttle would be opened and the SPAS, with experiments attached, would be ejected. The SPAS could then be retrieved on the same mission. In effect, the SPAS was a "holder" for the experiments -a platform.

SPAS first flew successfully on the Challenger, 18-24 June 1983. Subsatellites were developed based on the original SPAS technology and body plan. The SPAS-01 was the first of these subsatellites. As of December 1986, the SPAS-02 was under development by MBB for the SDIO sponsored Infrared Background Signature Survey (IBSS) program. IMPS was to be mounted on SPAS-03 which was under study by the Space Test Program (STP). The Kitty Hawk (KH) was to be a second generation SPAS class carrier designed against STP performance requirements only.

The experiments slated for the IMPS were as follows: Space Based Radar Antenna (SBR): SBR was to operate a portion of a prototype space based radar antenna in the polar auroral environment so its operation could be characterized.

Photovoltaic Array Space Power (PASP): PASP was to evaluate planned elements of the new generation of large solar arrays in the polar-auroral environment.

Transient Pulse/Surface Potential Monitors (TPSP): Transient Pulse Monitor (TPM) was to record electrical transients on selected SPAS systems, PASP cables and on the outer surface of the SPAS. Surface Potential Monitor (SPM) was to investigate variations in differential surface potential and bulk currents of representative spacecraft surface materials.

Optical Effects Module (OEM): OEM was to provide data on contamination hazards likely to be encountered by the optical components of a potential space based radar system by exposing candidate mirror materials to the polar-auroral environments.

Fluxgate Magnetometer (MAG): MAG was to measure the geomagnetic field in situ and DC offsets due to currents and low frequency oscillations.

Search Coil Magnetometer (SCM): SCM was to determine the nature of occurring disturbances, whether electrostatic or electromagnetic, by measuring the high frequency magnetic field variations.

Langmuir Probe (LP): LP was to determine the thermal characteristics of the thermal electron population.

Plasma Probes (PP): PP was to measure the high frequency (100Hz to 5MHz) electric field near IMPS.

Electric Field Antenna (EFA): EFA was to characterize the orbiter induced environment through two-axis measurements of the generated DC and low frequency AC electric fields along with measurements of the ambient Energy fields.

Ion and Electron Electrostatic Analyzer (ESA): ESA was to provide a primary source of data on the variations in the polar-auroral environment by measuring the characteristics of the precipitating charged particles in the auroral zones and polar cap.

Pressure Gauge (PG): PG was to measure the spatial and temporal variations of the neutral gas density within the payload bay and in the near region of the orbiter.

Quadrupole Ion/Neutral Mass Spectrometer (QMS): QMS was to identify sources and types of contamination and measure the spatial extent of such contamination.

Differential Ion Flux Probe (DIFP): DIFP was to characterize the complex orbiter wake during IMPS transitions.

Suprathermal Electron Spectrometer (SES): SES was to characterize the cold electron population by measuring suprathermal electrons.

The IMPS, a polar mission, was scheduled to fly at 150Nmi and 62 degrees. To reach a 62 degree orbit, only a west coast launch was possible; for to reach a 62 degree orbit from the east coast, an overland flight was necessary. Vandenberg Air Force Base (VAFB) was very near completion of a launch facility when the Challenger disaster occurred (January 28, 1986). The Air Force then decided that they wanted nothing to do with the the Space Transportation System (STS) and both the launch facility and the IMPS were scrapped. By December 1986, the Space Test Program (STP) backed out of IMPS. It was decided that the money for IMPS would be diverted to the carrier (SPAS). By January of 1988, JPL began the phasing out of the IMPS project and by February of that same year, the Kitty Hawk was canceled due to budget cuts.

From the description of Records of the Interactions Measurements Payload for Shuttle (IMPS) Project, 1966-1988. (Jet Propulsion Laboratory Library and Archives). WorldCat record id: 733099935