One of the key systems of the upcoming landing of the Mars Science Lab is a new pulse-Doppler radar. The Terminal Descent Sensor provides velocimetric and altitude data.
Its rigorous test program included two series of flight tests at NASA’s Dryden Flight Research Center, Edwards, Calif.
JPL field test lead Jim Montgomery presented a colloquium on the tests to the Dryden community July 25.
The test program uses a “test it as it flies” philosophy. It thus included the low altitude, low velocity regime up to the anticipated approach angles and speeds of the descent.
The first Dryden involvement was the use of a helicopter-suspended test model over Rogers Dry Lake. Altitude data was compared to GPS ground truth values. The flat terrain of Rogers made it possible to eliminate any errors involved with terrain variations. This made data analysis more direct. The first TDS tests were in July 2006, and showed issues were resolved as development continued. The Rogers Dry Lake helicopter tests were done in May, 2010
A joint Dryden-JPL team worked very hard to find the way to reproduce the landing angles and velocities anticipated. The Dryden F/A-18 pilots found the required involved flight paths. These involved a vertical dive of the inverted aircraft. The engineering model of the Terminal Descent Sensor was housed under the F/A-18 in a Quick Test Experimental Pod.
From May to June, 2011 there were 21 hours of test flights. Data taken for 44 minutes during these tests matched the Mars Science Lab carrier stage flight profile. At this stage of the mission, the carrier is free swinging, suspended from its parachute. The data collected was sufficient to fine-tune the software, to ensure it was calibrated as accurately as possible prior to Curiosity’s landing.
Montgomery expressed his appreciation. “You should be proud of your professionalism,” he told Dryden employees.
There were more than 70 people involved in conducting the tests.