Thursday, September 16News That Matters

NASA Mars Helicopter’s Flight: Livestream, Date and Time

Early on Monday, a robotic helicopter that NASA sent to Mars was scheduled to try to rise a few feet in the air, hover and come back down. With that simple feat, it would become the first machine to fly through the wispy air of the red planet. NASA officials have been likening it to the Wright brothers flight in 1903 at Kitty Hawk, N.C. Never before has something like an airplane or a helicopter taken off on another world.

The Mars helicopter, named Ingenuity, traveled from Earth tucked under NASA’s Perseverance rover, which landed in February on the mission to search for signs of ancient life near a dried-up river delta. A couple of weeks ago, Perseverance dropped Ingenuity on a flat Martian plain ahead of the flight tests.

Ingenuity is small. Its main body is about the size of a softball with four spindly legs sticking out. On top are two sets of blades, each about four feet from tip to tip. They will spin in opposite directions at about 2,500 rotations per minute, the rapid speeds needed to generate enough lift for Ingenuity to get off the ground.

For people on Earth, that translated to about 3:30 a.m. Eastern time on Monday. But no one on Earth could know for hours whether the flight has succeeded or failed, or if anything has happened at all. Neither Ingenuity nor Perseverance was in contact with NASA at that time.

Instead, the two spacecraft conducted the flight autonomously, executing commands that were sent to them on Sunday. Perseverance then sent data back to Earth via a spacecraft orbiting Mars.

NASA TV will begin broadcast from the control room at NASA’s Jet Propulsion Laboratory beginning at 6:15 a.m. Eastern time as the data starts arriving on Earth. You can watch it on NASA’s website.

Additional information will be provided at a news conference at 2 p.m. Eastern time on Monday.

What happened during the test flight?

The first flight, if it occurred, was to be a modest up-and-down trip, rising up to an altitude of just 10 feet. There, it would have hovered for up to 30 seconds and then descended to a landing. Its onboard camera recorded images, helping the navigation system keep the helicopter steady. On the ground more than 200 feet away, the Perseverance’s cameras also recorded the flight.

If the test flight succeeds, up to four more could be attempted. The first three are designed to test basic abilities of the helicopter. The third flight could fly a distance 160 feet and then return.

The final two flights could travel farther, but NASA officials did not want to speculate how much.

NASA wants to wrap up the tests within 30 Martian days of when Ingenuity was dropped off, so that Perseverance can commence the main portion of its $2.7 billion mission. It will leave the helicopter behind and head toward a river delta along the rim of Jezero crater where sediments, and perhaps chemical hints of ancient life, are preserved.

Ingenuity was an $85 million nice-to-have, add-on project but not a core requirement for the success of Perseverance.

Why is flying a helicopter on Mars so difficult?

There is not much air to push against to generate lift.

At the surface of Mars, the atmosphere is just 1/100th as dense as Earth’s. The lesser gravity — one-third of what you feel here — helps with getting airborne. But taking off from the surface of Mars is comparable to flying at an altitude of 100,000 feet on Earth. No helicopter on our planet has flown that high, and it’s more than two times the typical flying altitude of jetliners.

Why is NASA flying a helicopter on Mars?

Until 1997, all of the spacecraft sent to the surface of Mars had been stationary landers. But that year, the Pathfinder mission included something revolutionary for NASA: a wheeled robot. That rover, Sojourner, was roughly the size of a short filing cabinet, and planetary scientists quickly realized the benefits of being able to move around the Martian landscape. Four more NASA rovers, including Perseverance, have since followed to the red planet.

Ingenuity is in essence the aerial counterpart of Sojourner, a demonstration of a novel technology that may be used more extensively on later missions. And demonstrating that the helicopter can fly on Mars may help inform flight attempts on other worlds in our solar system, such as Titan, the moon of Saturn where NASA plans to send a nuclear-powered quadcopter.

Why was the earlier flight postponed?

NASA planned the first flight of Ingenuity on April 11. But on April 9, there was a problem during a test in which the rotors had spun up to flight speeds without the helicopter taking off. Telemetry indicated that some of the steps during the test took longer than expected, and a timer that keeps watch to make sure nothing goes wrong expired. Ingenuity’s computer then stopped the test before it entered what NASA calls “flight mode.”

The helicopter was safe and undamaged, NASA said, but the engineers needed to understand what happened and devise a solution to the problem.

Initially, NASA said that it would need to upgrade Ingenuity’s flight software and that it would not even announce a new date until this week. Although the changes were simple, engineers worried that a coding error could accidentally “brick” the computer, leaving it unresponsive and impossible to fix. Installing and testing the upgraded software also would have taken several days.

In a blog post on Saturday, MiMi Aung, Ingenuity’s project manager, said that the upgrade now appeared not to be necessary. The engineers came up with a simpler, quicker fix — adjusting the commands from Earth to tweak the timing of the transition to flight mode while leaving the helicopter’s software untouched.

This was not a perfect fix — in tests on Earth, it failed about 15 percent of the time — but this solution worked on Friday when Ingenuity was able to complete the full-speed spin test that had been cut short a week earlier.

That paved the way for attempting the first flight sooner, on Monday.

“We also know that if the first attempt does not work on Monday, we can try these commands again,” Ms. Aung wrote, “with good probability that subsequent tries in the days following would work even if the first doesn’t.”

If the current approach did not succeed, the engineers have sent the modified Ingenuity flight software to Perseverance. If needed, the rover could install those changes to the helicopter’s computer.