NASA’s Mars Science Laboratory spacecraft inspired millions of people worldwide a year ago when its unprecedented “sky crane” landing system successfully landed the Curiosity rover in a crater on the red planet on Aug. 6, 2012 (Aug. 5, 2012, PDT).
On the first anniversary of Curiosity’s landing near the base of Mount Sharp on Mars, engineers at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif., are testing an even more sophisticated flight control algorithm that could allow for precise, pinpoint landings of future Martian spacecraft.
Flight testing of the new Fuel Optimal Large Divert Guidance algorithm – G-FOLD for short — for planetary pinpoint landing is being conducted jointly by JPL engineers in cooperation with Masten Space Systems in Mojave, Calif., using Masten’s XA-0.1B “Xombie” vertical-launch, vertical-landing experimental rocket.
NASA’s Space Technology Mission Directorate is facilitating the tests via its Game-Changing Development and Flight Opportunities Programs; the latter managed at NASA’s Dryden Flight Research Center at Edwards Air Force Base. The two space technology programs work together to test game-changing technologies by taking advantage of Flight Opportunities’ commercially provided suborbital platforms and flights.
“The Flight Opportunities Program supports both the development of innovative space technology and the emerging suborbital industry by using commercial suborbital vehicles to test concepts that could further mankind’s exploration and understanding of the universe,” said Christopher Baker, a campaign manager for the program. “The collaboration between JPL and Masten to test G-FOLD is a great example of how we hope to further the exploration of the solar system while building up the industrial base needed to advance future space endeavors.”
Current powered-descent guidance algorithms used for spacecraft landings are inherited from the Apollo era. These algorithms do not optimize fuel usage and significantly limit how far the landing craft can be diverted during descent. The new G-FOLD algorithm invented at JPL autonomously generates fuel optimal landing trajectories in real time and provides a key new technology required for planetary pinpoint landing. Pinpoint landing capability will allow robotic missions to access currently inaccessible science targets. For crewed missions, it will allow increased precision with minimal fuel requirements to enable landing larger payloads in close proximity to predetermined targets.
Masten Space Systems launched the Xombie July 30 from the company’s test pad at the Mojave Air and Space Port. JPL and Masten are planning to conduct a second flight test with a more complicated divert profile later in August, pending data analysis.
To simulate a course correction during a Martian entry in the July test, Masten’s Xombie was given a vertical descent profile to an incorrect landing point. About 90 feet into the profile, the G-FOLD flight control software was automatically triggered to calculate a new flight profile in real-time and the rocket was successfully diverted to the “correct” landing point some 2,460 feet away.
“This flight was an unprecedented free-flying demonstration of the on-board calculation of a fuel-optimal trajectory in real time,” said Martin Regehr, acting task lead for the Autonomous Descent Ascent Powered-Flight Testbed at JPL.
Masten Space Systems is one of seven suborbital reusable launch companies contracted by NASA’s Flight Opportunities Program to fly experiments in sub-orbital space to verify new technologies work as expected in this harsh environment.
NASA Dryden also aided development of Curiosity’s “sky crane” landing system by conducting two series of pre-launch flight tests of its landing radar, the first under a helicopter in 2010 and a follow-on series with the radar housed in a Quick Test Experimental Pod mounted under the wing of a Dryden F/A-18 in June 2011. The 2011 tests focused on the on-chute acquisition portion of the MSL’s entry into the Martian atmosphere, when the spacecraft was suspended from its parachute. Data collected from the flights was used to finesse the MSL’s landing radar software to ensure that it was calibrated as accurately as possible prior to Curiosity’s landing.
To date, Curiosity has already achieved its main science goal of revealing that ancient Mars could have supported microbial life. Curiosity has provided more than 190 gigabits of data, returned more than 36,700 full images and 35,000 thumbnail images, fired more than 75,000 laser shots to investigate the composition of targets, collected and analyzed sample material from two rocks and traveled more than a mile on Mars’ surface.
