Mars Helicopter Ingenuity Is Preparing For Its Longest Flight Yet

NASA's Ingenuity Mars helicopter made its 24th flight recently, on Sunday April 3, but now it's getting ready for a distance run with its 25th flight, which will be its longest flight to date (via JPL). Originally designed for just five flights, the helicopter has been so successful that it's now been tasked with helping out the Perseverance rover by scouting out driving routes and looking for targets of scientific interest (via JPL). 

Perseverance is heading for an area of the Jezero crater that is the site of an ancient river delta, where water was abundant billions of years ago and where microscopic life could once have formed. The rover will search the area for evidence of this ancient life, but to help it out, the helicopter needs to travel from its current location, the Séítah region, to the delta. To do that, the helicopter first needed to take its short 24th flight before getting ready for its long flight 25.

How engineers decide on Ingenuity's flight plan

When it comes to deciding when and where the Ingenuity helicopter will fly, it's not a simple matter of plugging in a destination and hitting a button. The team's biggest concern is to preserve the helicopter for as long as possible, so they aim to make its flights as safe as they can. In a recent blog post, Ben Morrell of NASA's Jet Propulsion Laboratory — one of the engineers responsible for making Ingenuity's flight plans — described how the team came to its decision about Ingenuity's 24th and 25th flight.

The team were considering three options for the flight, Morrell writes: one single long flight, two shorter flights, or one tiny hop followed by a longer flight. In making this decision, the team had to contend with Mars' changing seasons, which are making its already thin atmosphere even thinner. That provides a challenge for a helicopter that keeps itself aloft by moving air with its blades, so to adapt to the atmospheric conditions it has to spin its rotors even faster than before. But this higher rotor speed means components heat up faster, so the team has kept Ingenuity's flights short, to 130 seconds or less to avoid overheating. Now, though, the Martian summer is coming to an end, which means the air density is rising again; that means the rotor speed can be reduced, allowing for longer flights.

Picking a plan

When planning flight 24 the team also had to consider which landing spots were available (via NASA); they needed a large flat area to land the helicopter safely. The team also wanted to make sure to keep Ingenuity on pace with the Perseverance rover — which is currently traveling toward the delta at relatively high speeds — so that the helicopter would arrive at the delta before the rover does. Arriving before Perseverance allows Ingenuity to communicate with the rover and helps avoid a disastrous collision between the two.

In the end, the team decided that the safest option would be a very short hop for Flight 24, followed by a longer Flight 25. Flight 24 covered just 47 meters, with under 70 seconds spent in the air, but it set the helicopter up for its next big flight. Flight 25 will be the helicopter's longest flight yet, covering a massive 704 meters (which is 80 meters longer that its previous longest flight) and should last more than 160 seconds. NASA has not yet announced when flight 25 will be performed, but Morrell writes that the plan has already been uplinked to the helicopter so we can expect it to happen soon.