H|1|louvers|thermal control louvers|387|409|218,32,272,174,
H|0|mms|MMS|286|288|
H|0|satsys|systems|94|100|
The TOPEX/Poseidon Instrument Module (IM) is comprised of all the scientific sensors and systems that provide the spacecraft with its mission-specific data collection, communication, and solar power gathering capabilities.
The IM is a large aluminum box which attaches to the MMS. Since many of the instruments within the IM operate best within a controlled temperature range, thermal control louvers in the IM walls open and close to maintain the desired temperature as the sun shines on the spacecraft from different directions.