The two most recent payloads to be exposed to the LEO environment are: ICA (Instrument Comrade Active) and PIE (Particle Impact Experiment) both located on the Mir space station. PIE has been returned to Earth currently undergoing detailed analysis, whereas ICA remains on the Spektr module of Mir.

The ICA experiment is an active payload attached to the ESEF (European Scientific Exposure Facility) platform on the Spektr module of the Mir space station. It was installed as part of the ESA/Russia EUROMIR 95 mission in September 1995 via an EVA by Thomas Reiter. Data can still be received from ICA, although due to the recent Mir power problems and the depressurization of the Spektr module, ICA is currently switched off.

There are plans in hand to re-activate ICA and continue it's role as the only real time environmental detector in operation in LEO. The main objectives of ICA are:

• Hypervelocity Impact flux measurements using MOM sensors
• AO erosion measurement using Carbon coated QCM
• Mir local contamintion using QCM
• Sun sensor, radiometer and temperature sensors

ICA is positioned on the ESEF platform with an unhindered view out to space on 3 directions. In addition to ICA, ESEF hosted experimental casettes each holding a variety on surfaces for measuring the particulate environment and the intact capture of particulates. The schematic below shows the realtive positions of ICA and the casettes on ESEF:

ESEF Schematic showing ICA at the end.

The ICA is self contained and all electronics are housed in the external unit. There is a power unit inside Spektr that deals with the basic On/Off power to ICA and the data transmission into the Mir system for data relay to Earth every 6 hours.

The results from ICA have been widely presented to the Space community at conferences in the USA, Europe and Japan.

Two of the most valuable results obtained from ICA and that are currently changing the international perspective for the coming International Space Station are:

• High levels of contamination in the Mir vacinity
• The re-affirmation of Space Debris clouds in LEO orbits

Contamination data as determined from ICA, showing high contamination deposition.

Impact data as determined by ICA showing debris clouds

The PIE experiment payload contains surfaces to measure and capture hypervelocity impactors intact. PIE was be retrieved via EVA May 1997 and returned to Earth via STS-84. This payload is part of the ongoing Shuttle/Mir program and the results of the analysis will be presented shortly.

PIE payload prior to experiment surface integration.