The Mars Helicopter, visible in lower center of the image, was attached to the belly of NASA's Perseverance rover at Kennedy Space Center on April 6, 2020. The helicopter will be deployed onto the Martian surface about two-and-a-half months after Perseverance lands.

The newest Mars rover's pioneering passenger has come aboard.

Technicians attached the first-of-its-kind Mars Helicopter to the belly of NASA's Perseverance rover on Monday (April 6) at the agency's Kennedy Space Center in Florida, where the robot is being prepped for its upcoming launch. That liftoff will take place during a three-week window that opens on July 17.

Prep work on the rover is officially in high gear. For example, over a four-day span in late March, mission team members finished installing Perseverance's parachute system and also put on the robot's six wheels .

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The Mars Helicopter and its Mars Helicopter Delivery System were attached to the Perseverance Mars rover at Kennedy Space Center on April 6, 2020. The helicopter will be deployed about two-and-a-half months after Perseverance lands. (Image credit: NASA/JPL-Caltech)

Perseverance's descent stage was also fueled up last weekend, just before the helicopter integration, NASA officials said.

The descent stage is the rocket-powered sky crane that will lower Perseverance onto the Martian dirt via cables in February 2021. Gassing up the crane was no trivial task; the craft's four tanks hold a total of 884 lbs. (401 kilograms) of hydrazine propellant, agency officials said.

"The last hundred days before any Mars launch is chock-full of significant milestones," David Gruel, the Mars 2020 assembly, test and launch operations manager at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, said in a statement . (JPL built Perseverance and is the lead center for the rover's mission, which is called Mars 2020 .)

"Fueling the descent stage is a big step," Gruel added. "While we will continue to test and evaluate its performance as we move forward with launch preparations, it is now ready to fulfill its mission of placing Perseverance on the surface on Mars."

That placement will occur inside Jezero Crater, a 28-mile-wide (45 kilometers) hole in the ground that hosted a lake and a river delta in the Red Planet's ancient past. Perseverance will hunt for signs of long-dead Martian life, characterize the region's geology and perform a number of other tasks, chief among them collecting and caching samples for a future return to Earth .

The Mars 2020 mission will also demonstrate several new technologies, including an instrument that will generate oxygen from the carbon-dioxide-dominated Martian atmosphere and the 4-lb. (1.8 kg) Mars Helicopter, which will be the first rotorcraft ever to ply the skies of a world beyond Earth.

If all goes according to plan, the helicopter will be deployed in May 2021, 2.5 months after Perseverance's touchdown. The little solar-powered chopper will then conduct a series of short flights during a test campaign that will last up to 30 days.

The Mars Helicopter won't gather any scientific data during these excursions; it carries no instruments. But a successful test campaign could pave the way for extensive aerial exploration of the Red Planet in the not-too-distant future, mission team members have said.