Ingenuity gets a software fix; first flight now expected next week

Mars Helicopter Ingenuity is expected to take its first flight sometime next week after another delay blamed on a subtle timing problem in software that had earlier shut down a full-speed rotor spin test.

NASA/JPL engineers did not discover the timing issue during extensive tests on Earth but have developed a software workaround that is being tested over the next few days.

“This was about a very, very subtle timing challenge,” said MiMi Aung, Ingenuity project manager in an unusual Twitter video session responding to questions from the public.

 “It’s a very, very tiny mismatch that varies very, very slightly and so that’s why have just encountered it,” she added. “We have tested this exact environment on Earth and in that time it did not occur. It is a very subtle issue.”

Aung was joined by Thomas Zurbuchen, associate NASA administrator, both of them wearing lab coats and masks in a JPL lab setting. “These things really do happen,” he said. “It just happens in space.”

No exact date for a first launch next week was set during the Twitter appearance, but Zurbuchen said, “We should be getting back to flight sometime next week. That’s what we think right now.”

Of critical importance is whether the delays will shorten the 30-day window that the Ingenuity team has to conduct five flights in the technology demonstration.  Zurbuchen added some reassurance by saying, “We’re working  for more flights [beyond the first one] that make sure we learn. Our goal is to do all those flights in a month or so…The purpose is to show we can fly in the Martian atmosphere.”

Aung added, “We are going to squeeze results out of this month…This is a flight experiment of the first kind. Every minute on Mars is considered precious. It does take away from the time we want to be experimenting on Mars.” The principle objective of the mission is science for Perseverance rover to dig soil samples primarilyl to determine whether there is evidence of ancient microbial life on the Red Planet.

“We want to get there as fast as we can, but we want to do it very carefully, but as fast as we can and that’s the fine line we have been walking,” she added.

Mars has 1% of Earth’s atmosphere, meaning the helicopter blades need to spin many times faster than drones on Earth, about 2400 rpm to generate enough lift for the 4-pound Ingenuity.

The question is when NASA counts the start date of the month of tests, since April 5 was first named as a potential first flight. That was delayed to April 8, and then to April 11.  On Monday, NASA said in a blog that it would set a flight date next week. Zurbuchen seemed to say on Wednesday that the 30-day clock for all five flights will start with the first flight.

The high-speed test of the helicopters rotors was conducted April 9, last Friday, but suddenly stopped, according to data received later that day. A team came up with a command sequence software modification that involved a reinstallation of Ingenuity’s flight control software.  The update will modify the process to boot up the two flight controllers and allow the hardware and software to safely transition to a flight state.

 Aung called the shutdown of the high-speed rotor test “a surprise.”

She explained the shutdown this way:

“The issue is when the helicopter mode goes from pre-flight mode to flight mode it checks to make sure the helicopter flight computer is healthy. So there is the watchdog that looks at the computers…and saying they’re good. There was a subtle timing [issue]. The flight computers were working, watchdog was working properly, but it was a slight timing [issue] with the stroke from the computers arriving to the watchdog that led the watchdog to say the computers aren’t healthy, even though they were.

“So we have a workaround so that the timing is corrected. That’s the scheme that we are testing right now. We have analyzed it and tested it the lab and we will be testing it incrementally on Ingenuity. We know exactly what went wrong.”

Aung and Zurbuchen answered 13 different questions in video responses on Twitter, each lasting about a minute.

RELATED: Ingenuity’s first flight attempt on Mars is delayed again