CRO-A, -B, -C
Chemical Release Observation

The CRO 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 payoads 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.

Spacecraft
Command and data handling system used an 1805 microprocessor interfacing to a UHF receiver and an S-band transmitter. Stabilization provided by atmospheric drag on a large corner reflector on the end of a deployable boom

Payload
CRO-C released 6.8 kg of nitrogen tetroxide, CRO-B released 23.6 kg of UDMH, and CRO-A released monomethyl hydrazine.

Country of Origin	United States
Customer/User	SDIO (USAF)
Manufacturer(s)	Defense Systems Inc. (now CTA)
Orbit	260 km, 57.0 deg inclination
Design Life	1 week

Launch Facts

Name	Int'l Desig.	Date	Site	Vehicle	Orbit	Mass(kg)
Notes
CRO C	1991-031D	4/28/91	ESMC	STS 39	LEO	197
Chemical Release Observation; deployed 5/2/91; released gases for observation by IBSS
CRO B	1991-031E	4/28/91	ESMC	STS 39	LEO	197
Chemical Release Observation; deployed 5/2/91; released gases for observation by IBSS
CRO A	1991-031F	4/28/91	ESMC	STS 39	LEO	197
Chemical Release Observation; deployed 5/3/91; released gases for observation by IBSS