NASA's Curiosity rover used its robotic arm to snap a selfie on Mars last week.
A few days later, the agency's Ingenuity helicopter finally stretched out all four legs.
Photos of both events showcase NASA's growing presence on the red planet.
There's a flurry of activity on Mars.
Last week, NASA's Curiosity rover used its robotic arm to snap an impressive selfie in front of Mont Mercou, a 20-foot-tall rock formation. The photo, released Tuesday, offers a glimpse of the vast Martian landscape. About 2,300 miles away on the same planet, NASA's Ingenuity helicopter finally stretched out all four of its landing legs - and cameras captured that scene, too.
Ingenuity's mission is to attempt the first controlled aircraft flight on another planet. The helicopter traveled to Mars in the belly of the Perseverance rover, which touched down in February. The rotocraft is now in position to land on the Martian surface, NASA revealed Tuesday - a feat scientists have awaited for months.
Ingenuity will likely fly within weeks, and could be deployed as early as April 8. But its flight - which is meant as a technology demonstration that could pioneer a new method of planetary exploration - will be perilous. The helicopter must lift off in Mars' thin atmosphere and survive frigid night temperatures for 30 Martian days (roughly one Earth month).
"As with everything with the helicopter, this type of deployment has never been done before," Farah Alibay, a systems engineer at the NASA Jet Propulsion Laboratory, said in a statement. "Once we start the deployment, there is no turning back."
Ingenuity is hovering 5 inches above the Martian surface
Earlier this month, Perseverance dropped the guitar-shaped shield that protected Ingenuity, exposing the helicopter to Martian air for the first time. From there, it had to be rotated out of its horizontal position beneath the rover using an electric motor. Ingenuity's legs also had to be unfolded two at a time.
NASA has called the process "reverse origami."
Now, Ingenuity is almost ready to drop the 5 inches to the ground and make its first contact with the Martian surface.
That final drop requires the cord between the helicopter and Perseverance to be severed; right now, they're connected by a single bolt and a couple dozen tiny electrical connectors.
"The most stressful day, at least for me, is going to be that last day, when we finally separate the helicopter and drop Ingenuity on the ground," Alibay said at a recent press briefing.
Once Ingenuity falls, Perseverance must drive away quickly to expose the helicopter's solar panels so the drone can begin charging. After its first charging session, Ingenuity will spend about a week testing its sensors and motors before it's ready to fly.
The helicopter will attempt up to five flights in total.
Its first flight will test whether Ingenuity can successfully get a few feet off the ground, hover for about 30 seconds, then touch back down. Each subsequent test will get more difficult than the last, culminating in a final flight that could carry the helicopter over 980 feet (300 meters) of Martian terrain.
Curiosity is snapping photos while climbing a 3-mile mountain
Unlike Perseverance, NASA's Curiosity rover isn't a newcomer to the Martian landscape. The car-sized rover landed on the red planet in 2012.
Since 2014, Curiosity has been climbing the 3-mile-high Mount Sharp, which is located in a large impact basin known as Gale Crater. Along the way, the rover has spotted strange rock formations and evidence of ancient, long-lived lakes.
In early March, Curiosity began approaching Mont Mercou, a rock outcrop named after a mountain in France.
The rover's camera snapped two panoramas on March 4 while stationed about 130 feet from the cliff face. The photos offer a three-dimensional view of the outcrop's sedimentary layers. The colors in the images represent how the rocks would appear during daytime on Earth.
On March 16, a camera on the rover's mast captured 11 more images of Mont Mercou. These were stitched together with another 60 images taken by Curiosity's robotic arm on Friday.
The resulting "selfie" shows the rover's full body next to the rock formation.
It also shows Curiosity departing a clay-rich region on Mount Sharp for a sulfate-rich region higher up the mountain. Scientists believe this change in landscape could help explain how Mars became a desert planet. The presence of clay signals a watery environment, whereas sulfates usually form as water evaporates.
To the left of the rover, you can spot a fresh drill hole where Curiosity collected its 30th rock sample from Mars.
By now, Curiosity has been scouring the red planet for signs of microbial life for more than 3,000 Martian days - nearly nine years on Earth.
Once the Ingenuity helicopter finishes its flights, however, Curiosity will no longer be alone in its mission. Perseverance is also designed to hunt for microbes - this time in ancient lake bed called Jezero Crater.
Morgan McFall-Johnsen contributed reporting.
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