The Endeavour and International Space Station crews bid one another farewell early Sunday, setting the stage for an five hour undocking and re-rendezvous test of two relative navigation sensors developed for NASA's Orion spacecraft, the four-person deep space capsule recently re-designated as the Multi-Purpose Crew Vehicle.
However, the availability of one of the two sensors, the high definition docking camera, appeared unlikely because of a data recorder issue that surfaced during the nearly 11 days of docked activities.
The Sensor Test for Orion Relative Navigation Risk Mitigation (STORRM) exercise marks an unprecedented leveraging of shuttle and station assets to advance the development of of a future spacecraft, said Howard Hu, NASA's manager of MPCV system performance and analysis.
The hardware, which is under development for future robotic as well as crewed spacecraft on planetary encounters or docking missions, has already caught the attention of NASA's Origins Spectral Interpretation Resource Identification Security Regolith Explorer team. The 2016 OSIRIS-REx asteroid sample return mission was previewed by agency officials last week.
"We've had a very successful mission," declared Endeavour commander Mark Kelly, as the hatches between the two spacecraft were secured on Sunday, just after 7 a.m., EDT.
"We're just in awe of the finely oiled machine that was STS-134," said NASA's Ron Garan, one of two station crew members under the command of Russian Andrey Borisenko. "You've really left us in good shape."
Endeavour's six astronauts were scheduled to undock at Sunday 11:55 p.m., EDT.
Endeavour and station crews assemble for a final time. Station commander Andrew Borisenko,
Alexander Samokutyaev and Ron Garan, pictured left to right, form the front row. Shuttle
astronauts Greg Chamitoff, Roberto Vittori, Mark Kelly, Drew Feustel, Greg H. Johnson and Mike
Fincke look on. Photo Credit/NASA TV
Several hours before the hatches were closed, Kelly and pilot Greg. H. Johnson lit Endeavour's vernier thrusters long enough to raise the station's altitude by 3,100 feet. The re-positioning of the orbiting science lab was intended to accommodate future docking and undocking activities, including the June 9th arrival of the three-member Soyuz 27S crew.
The STORRM hardware -- an eye-safe Visual Navigation System flash LIDAR and Hi-Definition television sensors as well as a data recorder secured near Endeavour's docking system -- will be activated ahead of the shuttle's departure. As the orbiter undocks and retreats to a distance of 400 feet, Johnson will initiate a traditional 45 minute fly around of the orbital outpost that will take Endeavour out to a separation of 600 feet.
If working, the Hi Def sensor will record the range of lighting conditions.
As the looping maneuver concludes, Kelly will then take the controls for a 3 1/2 hour series of maneuvers that will steer the orbiter over and behind the station. At a distance of almost 30,000 feet behind and 4,000 feet below the orbital outpost, Kelly will initiate an MPCV rendezvous trajectory, a gradual increase in altitude along the velocity vector, rather than the normal final shuttle approach along the radius and velocity vectors.
The test, in which Endeavour's trajectory control system sensors will provide the actual guidance, will conclude with Endeavour 1,000 feet below and 300 feet behind the station.
STORRM was functional during Endeavour's May 18 station docking, providing the NASA/Lockheed Martin/ Ball Aerospace & Technologies development team with a third of the performance data they are seeking, said Lisa Hardaway, Ball's Orion chief engineer for the project.
The flash LIDAR established a lock with five pre-positioned sensors on Endeavour's station docking port at between 18,500 and 18,800 feet. The goal was lock at 16,500 feet.
While developed as part of an autonomous docking system, the STORM sensors would permit manual piloting.
During the flight testing, the Hi Def camera is archiving lighting conditions that will contribute to future ground-based MPCV docking simulations.
Endeavour's 16-day flight is scheduled to conclude on Wednesday with a pre-dawn landing at NASA's Kennedy Space Center.
The STORRM data and hardware will be retrieved and sent to Lockheed Martin's new Space Operations Simulator Center in Denver by the end of June.
During July, the Denvertest team will focus on an detailed recreation of the last 200 feet of the docking environment, followed by work in August and September to integrate the results into guidance, navigation and control simulation software.