Moon Express / NASA Mighty Eagle Flight Test 11/14
For the past several months, Moon Express has been validating and testing its lander guidance, navigation and control (GNC) software in collaboration with the NASA Marshall Space Flight Center and its “Mighty Eagle” team through a Reimbursable Space Agreement. On September 20th we flew our GNC software aboard the Mighty Eagle in an “open loop” flight test mode that allowed us to compare and validate the logic flow and command outputs of the Moon Express software to NASA’s “in-charge” flight software. In open loop mode we “fooled” our software into thinking it was flying the vehicle, and we were later able to validate with NASA that the software behaved as expected and was outputting the correct commands that “would have” provided proper flight guidance instructions to the Mighty Eagle.
The September 20th open loop flight test was an important milestone in our goal to implement a closed loop test in which our GNC software has flight control input to the vehicle.
On Friday November 8th we passed our Flight Readiness Review (FRR) with NASA, providing us the green light to proceed to the next planned step of our test series – a tethered closed loop test, similar to the initial tethered test that NASA performed with its own software at the beginning of this test series.
In order to pass the FRR, our September 20th open loop GNC test results were fully analyzed and compared to Mighty Eagle flight computer data, validating that we would have operated the vehicle well had we actually been in the “driver’s seat”. Our GNC team has also been running hundreds of simulations within the NASA Mighty Eagle flight simulator with positive results. This gave NASA and Moon Express the confidence we needed to place the Moon Express software in the control loop of the vehicle. Since we’re doing this for the first time, we naturally want to be cautious and limit the flight with a tether, just as NASA did during its own initial tests. Contingent on a successful test tomorrow, and NASA’s consent, we will consider moving on to a closed loop free flight untethered test with the Mighty Eagle.
Currently we are go for our first closed loop test on the Mighty Eagle tomorrow afternoon, November 14th. Our GNC and propulsion team will work alongside the Mighty Eagle team to perform this test, which will be conducted outdoors in tethered mode at the Mighty Eagle test range at the NASA Marshall Space Flight Center. The tether technique that will be used is a “leash” attached to the ground, not a hanging tether such as is utilized in the recent “Morpheus” tethered test at NASA Johnson Space Center. There are pros and cons to each tether technique, but a ground tether is our preference and we’re happy that NASA Marshall utilizes it in their Mighty Eagle test program.
The image below shows the Mighty Eagle during its tethered flight on August 30, 2013. This was the initial flight test in the current test series, used to validate many new enhancements to the NASA GNC software. While testing a number of NASA software and hardware systems, the test series includes a sequence of progressive validations and testing of our Moon Express GNC flight software.
While we share high confidence with the NASA team that tomorrow’s closed loop tethered test will go well, GNC flight software is highly complex and these tests are designed to illuminate glitches and help us improve our software. Developing, simulating, testing and iterating is an ongoing improvement process with flight software that will continue as we work our way toward spaceflight.
Working with NASA Marshall and the Mighty Eagle Team continues to be a great experience and we’re very pleased with the level of support and encouragement we’ve received.
We will not be able to provide a live feed of the test, but we will keep you posted as much as we can as we progress through tomorrow’s flight test.
Wish us luck!