It is no secret that NASA is seeking out private space contractors to help bring some of its current plans to fruition. Naturally, these involve restoring indigenous launch capabilities to the US, but also include the more far-reaching goal of sending astronauts to Mars. Towards that end, NASA and SpaceX participated in an unprecedented data-sharing project that will benefit them both.
The project took place on Sept. 21st when, after multiple attempts,and the U.S. Navy used a series of IR tracking cameras to capture footage of one of SpaceX’s Falcon 9 reusable rockets in flight. The cameras recorded the rocket as the second stage engine ignited and the first stage, having detached and fallen away, reignited its engines to lower itself back to Earth for a zero-g touchdown on the sea surface.
The resulting data is being shared between the two parties and will benefit them both.
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For SpaceX, the benefit comes in the form of the detailed information NASA is providing on temperatures and aerodynamic loading on the Falcon 9 rocket, which will help them in their efforts to develop a reusable rocket system. For NASA, engineers are getting a chance to collect data on supersonic retro-propulsion that may one day help them to lower massive, multi-ton payloads onto the surface of Mars.
“Because the technologies required to land large payloads on Mars are significantly different than those used here on Earth, investment in these technologies is critical,” said Robert Braun, principal investigator for NASA’s Propulsive Descent Technologies (PDT) project and professor at the Georgia Institute of Technology in Atlanta. He’s also NASA former Chief Technologist. “This is the first high-fidelity data set of a rocket system firing into its direction of travel while traveling at supersonic speeds in Mars-relevant conditions. Analysis of this unique data set will enable system engineers to extract important lessons for the application and infusion of supersonic retro-propulsion into future NASA missions.”
Supersonic retro-propulsion basically means generating supersonic thrust to shed velocity after atmospheric entry. Alongside aerobraking, this is one of the proposed means of landing heavy equipment and habitats on Mars.
Braun is certainly no stranger to the concept. After returning to Georgia Tech, Braun – a specialist in entry, descent and landing (EDL) – worked with engineers from the university and various NASA centers to develop a proposal for a program to flight-test this concept.
At the time, NASA’s Space Technology Mission Directorate (STMD) rejected the plan for being too expensive, but the agency still needs a way to land payloads in excess of 20 tons if ever it wants to mount a human expedition to Mars. And given that the proposed mission is due to take place within the next 16 years, the more information they obtain now, the better.
Hence the decision to partner with SpaceX. Basically, the PDT Project struck a deal to use airborne infrared-imaging techniques – developed to study the Space Shuttle in flight after the Columbia accident – to gather data on the supersonic retro-propulsion SpaceX is currently using for its reusable launch vehicle development.
This sort of collaboration is without precedent, and as Braun told Universe Today via email, stands to benefit both participants immensely:
“This is the first high-fidelity data set of a rocket system firing into its direction of travel while traveling at supersonic speeds in Mars-relevant conditions. The synergy between NASA’s interest in improving its Mars entry, descent and landing capability and Space X’s interest and experimental operation of a reusable space transportation system provided a unique opportunity to obtain this data at low cost. Analysis of this unique data set will enable system engineers to extract important lessons for the infusion of supersonic retropropulsion into future NASA missions that may one day lower large payloads to the Mars surface while providing SpaceX with engineering insight to advance its development of a reusable space transportation system.”
After unsuccessful attempts to image the rocket on two previous missions – April 18 and July 14 – the project succeeded with the CRS-4 flight on Sept. 21st. Launched at night, NASA relied on two aircraft – a WB-57 and a NP-3D Orion – equipped with mid-wave IR sensors to document re-entry of the rocket’s first stage.
The first stage is the part of the rocket that is ignited at launch and burns through the rocket’s ascent until it runs out of propellant, at which point it is discarded from the second stage and returns to Earth. It was during its return, or descent, that NASA captured quality infrared and high definition images and monitored changes in the smoke plume as the engines were turned on and off.
Watch the video of the footage:
For NASA, the period of the flight most relevant for future operations over Mars came when the first stage was traveling at about Mach 2 some 30,000 – 45,000 meters (100,000-150,000 ft.) above the surface. The two midwave IR sensors – mounted in a nose pod on the WB-57 and internally on the NP-3D – were about 60 nautical miles from the rocket when it reignited its engines for supersonic retro-propulsion.
That produced raw images in which the stage appeared 1 pixel wide and 10 pixels long, but subsequent enhancing by specialists at the Johns Hopkins University Applied Physics Laboratory improved the resolution dramatically.
“NASA’s interest in building our Mars entry, descent and landing capability and SpaceX’s interest and experimental operation of a reusable space transportation system enabled acquisition of these data at low cost, without standing up a dedicated flight project of its own,” said Charles Campbell, PDT project manager at NASA’s Johnson Space Center in Houston.
Engineers at NASA and SpaceX are now correlating that data with company telemetry from the Sept. 21st Falcon 9 launch of a Dragon cargo carrier to the International Space Station to learn exactly what the vehicle was doing in terms of engine-firing and maneuvering when it generated the signatures collected by the aircraft.
Further Reading: NASA