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So far, Perseverance has used five of its 43 sample tubes, four for rock samples and one for a sample of the Martian atmosphere. Now, NASA’s team is working on the next, complicated step in Perseverance’s mission: bringing those rock samples to Earth.
This part of the mission is expected to take a decade of work, multiple NASA centers and NASA’s European partners at the European Space Agency (ESA).
NASA’s plan is to send another lander to mars. This next lander will be equipped with a rover that will travel to Perseverance and collect its samples, along with a rocket that will take the samples to an ESA spacecraft orbiting Mars.
In the orbiter, the capsule will be prepped for its final trip to Earth. The orbiter will need to seal the sample, sterilize the seal and place the sample into an Earth entry capsule. From there, it’ll be sent to Earth.
NASA’s JPL team has had nine successful Mars landings, but there are a few firsts involved in this ambitious mission. For the lander to be able to carry and launch a rocket on Mars, it will need to be sturdy. Right now, it weighs about 5,291 lbs, making it the largest and heaviest spacecraft of its kind to go to Mars.
Additionally, the rocket launching from the lander, called the Mars Ascent Vehicle, will be the first rocket ever fired off of another planet.
NASA’s Sample Retriever Lander weighs almost twice as much as the Perseverance rover, which was lowered to the surface of Mars using cables from a rocket-powered jet pack.
Retrorockets will slow its descent, but the lander won’t have a jetpack to help decrease the impact of touchdown, so it’ll all have to be absorbed by the legs of the lander.
A team in a warehouse-like space at JPL, led by Pavlina Karafillis, has been trying to predict how the lander will act on Mars. To do so, they’ve been repeatedly dropping a prototype lander, using high-speed cameras to observe the ways the legs of the prototype slam onto the base.
On each leg of the prototype is a QR-like code that helps the camera to track the lander’s movements. The prototype is only a third of the weight of the lander that will go to Mars, which will help the scientists learn how the lander will move in Mars’ low gravity. The scientists will drop a full-scale lander as well.
“The last step of the journey is really important,” Karafillis said. “There’s all kinds of landing conditions you have to take into account, like rocks, or really soft sand, or coming in at an angle. This is why we have to do all this testing.”
After landing, the scientists need to consider how to launch a two-stage rocket from the lander. The rocket onboard the lander will be nine feet long. Its weight, combined with the exhaust, could make the lander slip or tilt out of place.
To prevent this from happening, the scientists have created a system where the rocket is tossed into the air before it ignites. The process is called vertically ejected controlled tip-off release (VECTOR).
The VECTOR system also adds a slight rotation to the rocket during launch. This pitches the rocket up and away from the red planet’s surface, meaning the lander could be oriented incorrectly or on a slope, and the rocket could still successfully launch.
The rocket will be tossed into the air at a rate of 16 ft per second. During testing, an 881 lb test rocket was tossed 11 ft to the air using a cradle equipped with gas-powered pistons. Cables suspended from a 44 ft tower offloaded over half of the test rocket’s weight to simulate Martian gravity.
“It’s kind of like being on a really fast roller coaster when someone hits the breaks,” said Chris Chatellier, the system’s lead engineer at JPL. “There are a lot of safety aspects to consider. Testing happens in a very controlled sequence of events with everyone outside of the building.”
Chatellier’s team has already done 23 tests this year, and have made adjustments to the rocket’s mass and center of gravity along the way. The plan is to test a heavier rocket shooting higher into the air next year.