CRO

American military strategic defense satellite. Chemical release in orbit satellite built by DSI for SDIO, USA. Launched 1991.

The CRO (Chemical Release Observation) satellites were part of an SDIO program designed to test the ability of space-based, ground-based, and airborne sensors to track incoming ICBMs.

The experiment was designed to determine how the intentional release of rocket propellants from an incoming ICBM would mask the missile's signature. Managed by the Los Alamos National Laboratory, the 3 CRO satellites were deployed from Get-Away-Special (GAS) canisters carried by STS-39. After release, the satellites' chemical payloads were released by ground command, and were subsequently tracked by a number of sensors, including sensors carried aboard STS-39. These sensors were used to study the chemicals' optical, infrared, and RF characteristics. All three satellites performed as designed and decayed approximately one week after deployment. The spacecraft 's command and data handling system used an 1805 microprocessor interfacing to a UHF receiver and an S-band transmitter. Stabilization was provided by atmospheric drag on a large corner reflector on the end of a deployable boom. CRO-C released 6.8 kg of nitrogen tetroxide, CRO-B released 23.6 kg of UDMH, and CRO-A released monomethyl hydrazine.