Please make a donation to support Gunter's Space Page.
Thank you very much for visiting Gunter's Space Page. I hope that this site is useful and informative for you.
If you appreciate the information provided on this site, please consider supporting my work by making a simple and secure donation via PayPal. Please help to run the website and keep everything free of charge. Thank you very much.



IRT canister [NASA]

The IRT (Integrated Rendezvous Target) was an inflatable rendezvous target, to be ejected in a canister from Space Shuttle mission STS-41B, then to be inflated with nitrogen.

IRT was scheduled as a pathfinder to the SolarMax Repair Mission (STS-41C), the rendezvous, capture and on-orbit repair of the SMM satellite. IRT was a 2 m diameter balloon that was to be deployed from a rack bolted to the forward end of the Space Shuttle Challenger's longeron on the port side of the payload bay. The target and its canister were ejected from the Challenger in a retrograde direction. One minute after ejection from the payload bay the canister was scheduled split in half and inflate automatically with nitrogen to a pressure of 0.3 psia. Built of one-mil thick aluminized Mylar, the IRT balloon was flat white in color except for one of the 24 gores painted infrared black. The balloon, inflation equipment and sintered tungsten ballast results in a total weight of 90.7 kg.

But the mechanism to open the canister was not activated, because the lanyards pulled loose from the orbiter instead of pulling out of the canister. The nitrogen inflation cartridge did fire as scheduled, and the balloon burst as it began to inflate inside its canister. The remaining pieces of the balloon provided enough of a target for three rendezvous instruments to provide data important in verifying their capabilities.

Nation: USA
Type / Application: Rendezvous target
Operator: NASA
Equipment: None
Configuration: Balloon
Propulsion: None
Power: Batteries
Orbit: 269 km × 283 km, 28.46
Satellite COSPAR Date LS Launch Vehicle Remarks
IRT 1984-011C 03.02.1984 CCK LC-39A Shuttle with Challenger F4 (STS 41-B), Westar 6, Palapa B2, SPAS 01A


  • NSSDC Master Catalog: IRT