Mars Science Laboratory Entry, Descent & Landing Instrumentation (MEDLI)
"The heights by great men reached and kept were not attained by sudden flight, but they, while their companions slept, were toiling upward in the night."
-- Henry Wadsworth Longfellow, 19th-century American poet
When the Mars Science Laboratory mission, or MSL -- the latest entry in NASA's Mars Exploration Program -- reached the red planet in August 2012 to deliver an advanced new science rover, Curiosity, to the surface, NASA researchers also were closely studying a complex instrumentation payload in the entry vehicle's heatshield. Its successful results could significantly influence how we send future robotic and human missions to Mars.
The MSL Entry, Descent, & Landing Instrument suite, or MEDLI, is a NASA Technology Demonstration Mission, a set of engineering sensors designed to measure the atmospheric conditions and performance of the entry vehicle's heatshield during atmospheric entry and descent. While not part of the core scientific payload of the Mars Science Laboratory, the instrument suite provided important engineering data for the design of entry systems for future planetary missions.
Its innovative Mars Entry Atmospheric Data System (MEADS) pressure sensors gathered information about the aerothermal and aerodynamic characteristics of the entry vehicle as it descended and studied the Martian atmosphere itself. The MEDLI Integrated Sensor Plugs (MISP), comprised of thermocouples and recession sensors, analyzed the performance of the Mars Science Laboratory's thermal protection system.
Close analysis of this mission is vital to future NASA exploration of the red planet. The Mars Science Laboratory spacecraft entered the Martian atmosphere traveling more than 3.5 miles per second -- the second fastest NASA entry to Mars to date, after the Pathfinder mission in 1997. The MSL vehicle's aeroshell was much larger than Pathfinder’s, the craft itself was much heavier and its entry included the first-ever guided lifting trajectory attempted there -- all conditions that resulted in the highest heat flux and shear stress ever faced by a vehicle's heatshield at Mars.
Because the Martian atmosphere is primarily composed of carbon dioxide, design and testing of the entry system to withstand such environments relied primarily on simulation tools. It is very difficult to conduct experiments on Earth that simulate all aspects of a Mars entry. As a consequence, the spacecraft had to be designed with large safety margins -- which came at the cost of payload mass. The successful MEDLI experiment will help NASA dramatically reduce these margins on future missions, enabling more robust robotic studies and, in time, human journeys of discovery on Mars.
The MSL Entry, Descent, & Landing Instrument suite was designed and developed by NASA's Langley Research Center in Hampton, Va., in partnership with NASA's Ames Research Center in Moffett Field, Calif.
MEDLI launched to space in late 2011 as part of the Mars Science Laboratory's onboard payload. Researchers made their initial analyses of results in 2013. Study is ongoing.