HOUSTON — The development team for ’s Morpheus prototype precision planetary lander is prepping for a late July return to , where engineers plan to resume the free-flight test campaign that was abruptly suspended last August with a fiery crash of the test vehicle.
The liquid oxygen/methane-fueled replacement test vehicle and launch pad are being substantially enhanced with the addition of redundant inertial measurement units (IMUs) and a flame trench to address the loss of guidance data and a buildup of destructive vibro-acoustic forces identified as the most likely cause of the Aug. 9, 2012, crash.
If this summer’s three-month campaign achieves all of its goals, Morpheus will close out a graduated series of test objectives at Kennedy by rising 500 meters above a simulated lunarscape at the north end of Kennedy’s Shuttle Landing Facility. Morpheus would then fly a 1-km trajectory using laser guidance supplied by its equally experimental Autonomous Landing Hazard Avoidance Technology (ALHAT) system to dodge a network of boulders and craters to achieve a soft landing.
“Testing so far here has been going really well,” said Jon Olansen, who manages Morpheus from’s , in a June 12 interview. “If that continues, then by the end of July we should be back at KSC.”
Evaluations of the second Morpheus lander at Johnson, where development is limited to static or tethered test flights, began in April 2011 as part of a NASA initiative to develop an autonomous, multi-purpose lander/testbed for a range of planetary mission assignments and deep-space technology demonstrations. Morpheus might contribute to the testing of Orion/Multi-Purpose Crew Vehicle guidance systems; deliveries of robotic hardware to the surface of an asteroid, Mars or the Moon; or perhaps transporting an in-situ resource utilization plant to the lunar surface for oxygen production.
The lander’s use of non-toxic methane could prove attractive to mission planners beyond the comparative ease of ground handling. Methane could prove favorable as a storable in-space propellant, especially to those who advocate a network of space fuel depots. Unlike liquid hydrogen and oxygen, methane would not require extensive thermal conditioning.
During a May 29 test firing at Johnson while suspended from a crane by a tether, Morpheus demonstrated the simultaneous combustion of LOX/methane in the main engine as well as its reaction control system (RCS), another new feature.
“That is the first time we know of that anyone carried out an integrated main engine/RCS test using LOX/methane,” Olansen said. “That was a nice step forward.”
The methane-fueled RCS addition is one of 70 upgrades to the second test vehicle following the crash.
In the 2012 mishap, the lander lost IMU data less than a second after lifting off on an early unrestrained flight test at Kennedy. It crashed 8 sec. later. The single IMU had flown on 27 previous test flights without an issue. Though much of the vehicle was destroyed, making the forensics difficult, the project team reached a consensus on the most likely cause: destructive vibro-acoustics from the main engine at ignition.
Morpheus is now equipped with four IMUs, and all of the devices have been moved outboard from the previous location at the center of the lander. Two are designed for functional redundancy. The others will be flown as data-generating developmental hardware.
At Johnson, a flame trench was added at the test site before post-crash static and tethered firings resumed with the replacement lander in April. Meanwhile, the Morpheus project is assembling a third flight-test vehicle.