MEDLI Takes the Plunge at Mars: New Data Obtained
When the Mars Science Laboratory’s Curiosity rover made its blazing plummet through the Martian atmosphere in early August, prior to landing it was cocooned within an “aeroshell” – the biggest beat-the-heat hardware ever sent to the red planet.
Thanks to a “behind the scene” set of sensitive devices mounted onto the Mars Science Laboratory (MSL) heat shield, crucial data has been collected of benefit to future robotic and human exploration of that enigmatic world.
During the spacecraft’s dive toward the planet, the MSL Entry, Descent and Landing Instrument – or MEDLI for short – appraised how well the heat shield performed in thwarting the brutal welcoming it received.
Under the Space Technology Program, MEDLI is one of NASA’s Technology Demonstration Missions. These are a series of advanced technology projects intended to move technologies from the lab to flight-ready status, thereby furthering bold missions of exploration and scientific discovery.
The MEDLI instrument array was designed and developed by NASA Langley Research Center, in Hampton, Va., working in partnership with NASA Ames Research Center at Moffett Field, Calif. and NASA's Jet Propulsion Laboratory in Pasadena, Calif.
The MEDLI consists of seven MEDLI Integrated Sensor Plugs, seven Mars Entry Atmospheric Data System pressure sensors, as well as a Sensor Support Electronics box that’s mounted inside the heat shield to provide power, signal conditioning and conversion.
But here’s the scary part.
Using MEDLI sensors meant drilling holes into an entirely good heat shield. A series of high-energy arc jet tests in various ground labs ensured that the implanted sensors wouldn’t compromise the integrity of the heat shield.
“Everything went well with MEDLI,” says Alan Little, MEDLI Project Manager at NASA’s Langley Research Center. “The data quality exceeded our expectations.”
Before the instrumented shield was jettisoned high above the landscape of Mars, MEDLI sensors gauged the savage heat pulse, pressure and other conditions during MSL’s atmospheric entry and descent.
Real engineering data is now in hand on aeroheating by using the MEDLI sensor plugs and pressure ports embedded into holes bored into the spacecraft’s aeroshell.
The Bigger Picture
“A challenge we have faced for years is that we have very little, almost no data, from previous entries at Mars,” points out Michael Gazarik, director of NASA's Space Technology Program. While computer-generated modeling can infer how well heat shields might
work, “we don’t have real data on if our models are correct or not.”
Support to fly MEDLI on MSL came from a trio of NASA directorates, Gazarik says. “They knew how valuable this data would be. They understood the bigger picture.”
Data gleaned from the instruments, Gazarik adds, can help reduce uncertainty in just how much margin is needed in fabricating future heat shields.
MEDLI information can be used for a wide variety of missions. “We spent a large part of our effort to also develop the tools to understand the data that came back,” Little notes.
On the whole, the MSL team accepted the risk of having MEDLI onboard, equipment that was not part of the spacecraft’s core scientific payload.
And the payoff is evident.
Little explains that the full data set from MEDLI is now being assessed by an analysis team. “We expect that the MEDLI data will be of great interest to the MSL engineering team,” he reports.
MEDLI findings will help engineer safer, more capable entry systems for future Mars missions, Little concludes, whether used for robotic vehicles like Curiosity or to support human expeditions to the distant dunes of the Red Planet.