NOAA Satellite Information System

August 2012

Low Density Supersonic Decelerator

As NASA plans ambitious new robotic missions to Mars, laying the groundwork for even more complex human science expeditions to come, the spacecraft needed to land safely on the red planet's surface necessarily becomes increasingly massive, hauling larger payloads to accommodate extended stays on the Martian surface. NASA has used its current, parachute- based deceleration system since the Viking Program, which put two landers on Mars in 1977. New technology is needed to slow larger, heavier landers from the supersonic speeds of atmospheric entry to subsonic ground-approach speeds. NASA seeks to use atmospheric drag as a solution, saving rocket engines and fuel for final maneuvers and landing procedures. The heavier planetary landers of tomorrow, however, will require much larger drag devices than any now in use to slow them down -- and those next-generation drag devices will need to be deployed at higher supersonic speeds to safely land vehicle, crew and cargo. NASA's Low Density Supersonic Decelerator (LDSD) Technology Demonstration Mission, led by NASA's Jet Propulsion Laboratory in Pasadena, Calif., will conduct full-scale, stratospheric tests of these breakthrough technologies high above Earth to prove their value for future missions to Mars. Three devices will be developed. The first two are supersonic inflatable aerodynamic decelerators -- very large, durable, balloon-like pressure vessels that inflate around the entry vehicle and slow it from Mach 3.5 or greater to Mach 2. These decelerators are being developed in 6-meter-diameter and 9-meter-diameter configurations. Also in development is a 30-meter- diameter parachute that will further slow the entry vehicle from Mach 2 to subsonic speeds. All three devices will be the largest of their kind ever flown at speeds several times greater than the speed of sound. Together, these new drag devices can increase payload delivery to the surface of Mars from our current capability of 1.5 metric tons to 2 to 3 metric tons, depending on which inflatable decelerator is used in combination with the parachute. They will increase available landing altitudes by 2-3 kilometers, increasing the accessible surface area we can explore. They also will improve landing accuracy from a margin of 10 kilometers to just 3 kilometers. All these factors will increase the capabilities and robustness of robotic and human explorers on Mars.

To thoroughly test the system, the LDSD team will fly the drag devices several times -- at full scale and at supersonic speeds -- high in Earth’s stratosphere, simulating entry into the atmosphere of Mars. The investigators will conduct design verification tests of parachutes and supersonic inflatable aerodynamic decelerators in 2012 and 2013. The first supersonic flight tests are set for 2014 and 2015. Once tested, the devices will enable missions that maximize the capability of current launch vehicles, and could be used in Mars missions launching as early as 2018. The test campaign will be flown out of PMRF in Hawaii. Each LDSD test vehicle will be lifted to ~120k feet via high altitude balloon, dropped and propelled up to ~ mach 4.5 to simulate a mock Mars entry. The soft good test articles will be tested, and the test vehicle will then descend to the Pacific ~100 miles off-shore from PMRF. The Argos/GPS beacons will be used as tracking aid to locate the test vehicle. The test vehicle is being recovered for two reasons:

1) Recover data recorders that have all science and forensic data stored on board the vehicle.

2) Remove flight vehicle from the ocean to minimize any environmental impacts.

The initial unit will be used for engineering qualification purposes. Up to 10 units will be used on this program which include one more engineering qual unit with some modifications for triggering and then four flight vehicles with two units per flight vehicle. No more than two would be used simultaneously.

 

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