NASA’s Perseverance rover released the Ingenuity helicopter onto the surface of Mars Saturday, leaving behind the experimental flying drone to survive on its own power until attempting a historic hop in the Red Planet’s thin carbon dioxide atmosphere.
The milestone kicks off a week of checkouts and testing before NASA commits to the $80 million Ingenuity helicopter’s first test flight, currently targeted for April 11.
NASA officials confirmed rover deposited the 4-pound (1.8-kilogram) helicopter on the ground Saturday. Imagery from one of the Perseverance rover’s hazar cameras showed Ingenuity standing upright on the planet’s surface.
The six-wheeled rover needed to drive away from the helicopter within 25 hours to ensure sunlight could begin charging the rotorcraft’s six lithium-ion batteries. Based on the hazard camera view from Perseverance, the Ingenuity helicopter appeared to be basking in sunlight after its deployment, with the afternoon sun casting a shadow on Mars’s rust-colored soil.
#MarsHelicopter touchdown confirmed! Its 293 million mile (471 million km) journey aboard @NASAPersevere ended with the final drop of 4 inches (10 cm) from the rover’s belly to the surface of Mars today. Next milestone? Survive the night. https://t.co/TNCdXWcKWE pic.twitter.com/XaBiSNebua
— NASA JPL (@NASAJPL) April 4, 2021
The Ingenuity helicopter has been attached to the belly of the Perseverance rover for nearly one year. Technicians working inside a clean room at NASA’s Kennedy Space Center attached the rotorcraft to the rover April 6, 2020, a few months before the mission blasted off from Cape Canaveral aboard a United Launch Alliance Atlas 5 rocket July 30.
A debris shield protected the helicopter during the rover’s landing on Mars on Feb. 18. Last month, engineers at NASA’s Jet Propulsion Laboratory in Pasadena, California, uplinked commands to jettison the debris shield in preparation for the helicopter’s release.
Over the last week, ground teams stepped through a choreographed sequence of commands to first release a lock that held the helicopter firmly against the belly of the rover in a horizontal position. Then the helicopter rotated to a roughly 45-degree angle, and two of the craft’s four carbon composite legs extended.
Last week, the helicopter moved into a vertical orientation and the other two landing legs unfurled. That left just a tiny bolt and some electrical connectors linking the rover with the helicopter.
Those electrical wires allowed the rover’s nuclear battery to charge up the helicopter’s batteries to full capacity.
“That’s a good thing, because Ingenuity has to run its own heater from its own battery after the drop. No more free power from the rover!” wrote Bob Balaram, the helicopter’s chief engineer at JPL, in a blog post Friday.
Before the helicopter dropped off the belly of the rover, Perseverance powered a heater that kept the rotorcraft’s internal electronics at about 45 degrees Fahrenheit (7 degrees Celsius). Temperatures at Perseverance landing site inside Jezero Crater can drop as low as minus 130 degrees Fahrenheit (minus 90 degrees Celsius).
Ingenuity is now on its own, and it doesn’t have the same robust plutonium power source as Perseverance. The helicopter’s tiny batteries will power a heater set to keep the craft’s internal electronics at about 5 degrees Fahrenheit (minus 15 degrees Celsius), according to Balaram.
“Then it’s off to survive the first night on its own!” Balaram wrote. “The Ingenuity team will be anxiously waiting to hear from the helicopter the next day. Did it make it through the night? Is the solar panel working as expected?
“The team will check the temperatures and the battery recharge performance over the next couple of days,” Balaram wrote. “If it all looks good, then it’s onto the next steps: unlocking the rotor blades, and testing out all the motors and sensors.”
NASA said Wednesday that Ingenuity’s first flight is now targeted for no earlier than April 11, with data confirming the outcome of the hop expected back on Earth the next day.
Perseverance will head for an observation location at least 200 feet, or 60 meters, away from Ingenuity’s flight zone, which itself is about the length of a football field. The flight zone includes an airfield, a 33-by-33-foot (10-by-10-meter) area where the helicopter will take off and land.
Engineers used imagery from Perseverance’s cameras to select the site for the airfield, an area free of large boulders and steep slopes.
The Ingenuity helicopter is a technology demonstration, and the autonomous test flights will come with risks. NASA wants to ensure the Perseverance rover is a safe distance away from the rotorcraft when it takes off.
Ingenuity’s counter-rotating carbon-fiber rotor blades span about 4 feet (1.2 meters) tip-to-tip, and the blades will spin up to 2,537 rpm — more than 40 times per second — while the helicopter remains on the ground, a final test before engineers commit the aircraft to flight.
Engineers plan up to five test flights, starting with an ascent to an altitude of about 10 feet (3 meters), where the craft will hover for about 30 seconds before making a turn and landing back where it took off. Further test flights will reach a maximum altitude of about 16 feet (5 meters), and introduce forward motion to carry the helicopter down the flight zone and back to its takeoff location.
Using a wireless transmitter and receiver, the Perseverance rover will relay commands and data between ground controllers on Earth and the Ingenuity helicopter.
NASA has set aside one month for the Ingenuity helicopter’s demonstration flights, and that clock started when Perseverance released the rotorcraft onto the surface of Mars. The airborne drone will attempt to fly in an atmosphere just 1% the thickness of Earth’s. To do that, the helicopter’s rotors will spin five-to-ten times faster than a typical helicopter flying in Earth’s atmosphere.
Ingenuity does not carry any scientific instruments. It has black-and-white and color cameras to assist in autonomous navigation and gather aerial imagery of the Perseverance rover’s landing site at Jezero Crater, which harbored a lake of liquid water more than 3 billion years ago.
The helicopter will be operating on its own on each of its flights. The one-way travel time for radio signals between Earth and Mars is currently more than 14 minutes.
If the experiment works, Ingenuity could pave the way for future aerial explorers to fly around other planets. NASA is already developing a rotorcraft to fly around Saturn’s moon Titan, which has an atmosphere denser than Earth’s.
After the 31-day helicopter test campaign, the Perseverance rover will continue on in pursuit of its primary goal to identify, collect, and seal rock samples for return to Earth by a future mission.
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