Honeywell’s Miniature Inertial Measurement Unit (MIMU) has been a part of Lockheed Martin’s Mars satellites and landers since 1998, and the device recently played a critical role in the successful deployment of NASA’s InSight Mars lander on the red planet’s surface.
The InSight spacecraft landed in November 2018 on a mission to study the deep interior of the Martian planet. But this is more than a Mars mission — it’s designed to help scientists understand the formation and early evolution of all rocky planets, including Earth, said Dale Howell, InSight’s Guidance, Navigation, and Control Lead at Lockheed Martin.
InSight stands for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport.
“The lander itself is unique because it has a seismometer to detect what are termed ‘Marsquakes’ and a heat probe to get a better understanding of the core,” Howell said.
Inertial Measurement Units are hyper-sensitive motion detectors that help spacecraft, aircraft, submarines, robots, unmanned air vehicles and other machines navigate by keeping close track of their own movements. Because IMUs don’t depend on satellites, radio beams, starlight or other means of navigation, they are ideal for deep space missions.
The Miniature Inertial Measurement Unit is an affordable, lightweight, high-reliability inertial measurement unit that uses proven GG1320 ring laser gyros. It helped control and stabilize the spacecraft during the entry, descent and landing phases.
“Lockheed Martin has a long history with the MIMU and it has proven itself on many missions,” Howell said. “There is no other unit that can deliver the optimal level of performance in the small package that this unit can.”
MIMU technology enables precise positioning for communications, military and civil satellites and interplanetary probes by providing inertial guidance data to the spacecraft so it can maintain orbit and payload orientation.
The Honeywell MIMU is one of the few units that can be packaged in the tight confines of an aeroshell lander, which forms a protective covering during the seven-month voyage to Mars.
“Although the packaging was tight, our familiarity with the unit made it easier to find a suitable place for it,” said Howell.
Despite their confidence in the spacecraft, Howell admitted some nervousness during the so-called “seven minutes of terror” — the period of radio silence as the spacecraft approached the Martian surface at 13,000 miles per hour. Not only did the lander have to descend safely, it had to land within five degrees of its target attitude to be able to carry out its science mission.
After touchdown, Howell recalls an immense sense of relief and pride.
“It’s a fairly small group that has successfully landed on Mars, and it makes you feel pretty good to have joined that group,” he said.