Like a plucky character in a children’s book, NASA’s intrepid four-pound helicopter has survived a long, perilous journey to reach the rocky bottom of Mars’ Jezero Crater. There it will attempt what has never been tried before: flying on another planet.
The four-foot robot has already gotten through the rivet-wrecking vibrations of a rocket launch and overnight temperatures on Mars as low as minus 90 degrees Celsius (-130 degrees Fahrenheit). It detached itself from the Perseverance rover, straightened out its legs and raised its solar panel to the sun for the energy it needed to not only keep warm but also lift off from the surface.
The little helicopter with the oversized blades is poised to take flight no earlier than Sunday, April 11.
On that first voyage, Ingenuity aims to climb straight up at the rate of about one metre (three feet) per second, fly to an altitude of about three metres (10 feet) and hover for roughly 20 seconds. It will then descend at the same speed until it touches down.
Overall this first flight is expected to last 90 seconds. In 1903, when Orville and Wilbur Wright achieved the first powered flight on Earth, it lasted 12 seconds.
Dealing with extremes
Making the trip possible are oversized rotor blades made of a specially formulated composite carbon fibre.
The blades are both longer from tip to tip and wider across compared to what would be needed to fly Ingenuity on Earth, said Ben Pipenberg, the engineering lead at the California company AeroVironment, which built the blades, airframe and much of the primary structure of Ingenuity for NASA.
The blades must also spin much faster on Mars than they would have to on Earth to generate enough lift in the very thin Martian atmosphere, Pipenberg told Al Jazeera. “If this was flying just right here on Earth, the rotors would be turning at about 500 rpm (revolutions per minute); and on Mars, they’re turning at about 2,400 rpm.”
The materials used to construct the blades and the rest of Ingenuity must be able to handle not only the Martian cold but also its heat, which can reach 100C (212F).
“In addition to just the temperature, you have a very difficult radiation environment on Mars,” Pipenberg told Al Jazeera. “And so that, again, impacts a lot of the materials that we can use. And just getting to Mars is actually very challenging. The ride on the rocket is actually really violent – that’s the highest forces that the helicopter ever sees are when it’s on the rocket, just after it takes off and is on its way to Mars.”
Ingenuity is carrying a suite of sensors that will help it start right and stay on course even if it runs into trouble with, for example, the Martian winds.
Given that the ground it is sitting on may not be level, Ingenuity is carrying an inclinometer to tell it if it’s resting at an angle.
“[It] lets us know what it takes to get ourselves upright when we’re flying,” said Timothy Canham, NASA’s helicopter operations lead for the Ingenuity helicopter.
To keep Ingenuity on course, there’s an inertial sensor, which is similar to one in a mobile phone and notes when the helicopter changes course, Canham told Al Jazeera.
“We also have a laser altimeter, which bounces off the ground to tell us what our altitude is,” he said. “And finally, we have a downward-pointing camera that takes pictures 30 times a second. And as the helicopter moves, as we fly it in a particular direction, it tracks features from frame by frame in the picture. And from those, from those features, it can tell which direction and what speed it’s going.”
Ingenuity is also carrying a colour camera, one that is quite similar to that in a typical smartphone and aimed at the horizon, said Josh Ravich, the mechanical engineering lead for Ingenuity, who added “That’s there to hopefully take really cool pictures while we’re flying.”
Though there are only two cameras on Ingenuity itself, the Perseverance rover will be shooting photos of the flight from a slight rise a distance away.
Data for future
Beyond the colour camera, there are no sensors on Ingenuity designed to tell scientists about Mars. The helicopter’s only goal is to fly and gather performance data to inform the design of future helicopters and missions.
Ingenuity has 30 sols or Mars days to complete up to five tests. Flight managers will assess the results of each test and then send instructions for the next.
If the first test flight is successful, then a second test could include another 90-second flight where Ingenuity would reach an altitude of up to 5m (16ft), then fly horizontally for a few feet, flying back horizontally and then descending to where it started.
A third flight could see the helicopter flying farther and faster – up to 50m (164ft) from the airfield and then returning. Again the total flight time would be up to 90 seconds.
If the project timeline allows for a fourth and fifth flight, they may be used to explore Ingenuity’s aerial capabilities, said NASA, including flying at a time of day when higher winds are expected and travelling farther downrange with more changes in altitude, heading and airspeed.
NASA wants to know what Ingenuity can do so it can use the information to design future aircraft that could explore difficult-to-reach areas, map the surface or even help astronauts on the surface of the Red Planet.
“All that [data] really brings back to Earth information we need to design a potential future helicopter,” Ravich told Al Jazeera. “Just like if you’re building a car, you go driving around a test track, see how it does. And then that actually lets you build the model that you’re going to sell to the public.”