Phase 1 RRM was designed with four tools, each with electronics and two cameras and lights. Additionally, it had pumps and controllers and electrical systems such as electrical valves and sensors. The RRM payload was transported to the
Kennedy Space Center in early March 2011, where the GSFC team performed the final preparations for space flight. Once up on the International Space Station, RRM was planned to be installed into the ELC-4. The
Dextre robot was planned to be used in 2012 and 2013 during the refueling demonstration experiments. The RRM phase 1 experiment platform was launched to the
International Space Station (ISS) on 8 July 2011, transported by
Space Shuttle Atlantis on
STS-135, the 135th and final flight mission of the
American Space Shuttle program. The experiment suite included a number of
propellant valves,
nozzles and
seals similar to those used on a wide variety of
commercial and
U.S. government satellites, plus a series of four
prototype tools that could be attached to the
distal end of the Dextre
robotic arm. Each tool was a prototype of a device that could be used by future satellite servicing missions to refuel spacecraft in orbit. RRM is the first in-space refueling demonstration using a platform of fuel valves and spacecraft plumbing representative of most existing satellites, which were not designed for refueling. The Phase 2 hardware complement consists of: In February 2014 the ground-based 'Remote Robotic Oxidizer Transfer Test' (RROxiTT) transferred
nitrogen tetroxide (NTO) via a standard satellite-fueling valve at the satellite fuelling facility,
Kennedy Space Center (KSC), using a robot
controlled remotely from the
Goddard Space Flight Centre, away in
Greenbelt, Maryland. On March 26, 2015, The RRM On-orbit Transfer Cage was loaded into the Kibo airlock and picked up by the JEM Robotic Arm who handed it off to Dextre for installation on the main module. On April 30, 2015, The RRM On-Orbit Transfer Cage was installed on the main module and the Phase 1 hardware was removed and placed in the cage for disposal on HTV-4. The experiment was then activated that same day. Phase 2 experiments over some days were successful? February 2016 the Phase 2 experiment was deactivated and all fuel and cooling lines were turned off in preparation for disposal of the RRM payload and its fuel on SpaceX Dragon CRS-10. On February 23, 2017, The main module of the RRM experiment and the Phase 2 hardware were removed and stored in the trunk of
SpaceX CRS-10 for disposal and the STP H5 experiment with Raven was activated beginning Phase 3.
Phase 3 Phase 3 testing needed the delivery of Raven (autonomous space navigation demonstration) on
CRS-10. The new Phase 3 module was delivered to the station on December 8, 2018, on
SpaceX CRS-16 and installed on the ELC 1 on December 19, 2018. Zero boil off storage of cryogens (methane) was demonstrated for 4 months, but following a cryocooler failure the methane was vented in April 2019. Remaining tests were deferred; these include plugging a fuel nozzle into a refuelling port. In Oct 2020 the 2nd set of robotic tool operations for RRM3 was completed using the Dextre robot manipulators. Having completed its mission, RRM3 was transferred to ELC-3 in June 2022. On October 26, 2023, it was installed on an external mounting point on the
Cygnus NG-19 cargo spacecraft for eventual disposal when Cygnus departed the ISS and reentered several months later. ==See also==