Tuesday, October 20, 2020
Oct. 20, 2020

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Moses Lake explosive critical to success of Mars rover mission

Chute deployment key to landing relies on system working


MOSES LAKE — With the successful launch early Thursday of NASA’s Perseverance spacecraft, a little bit of Moses Lake is now headed to Mars.

But it’s a very important bit, several grams of explosive used to deploy the parachute, without which the roughly 1-ton rover — and the tiny helicopter it is carrying — will not be able to land successfully.

“This system is one of the few on the spacecraft that is what is called a single-point failure,” said Paul Lichon, general manager with General Dynamics Ordinance and Tactical Systems in Seattle. “If ours does not work, you have a billion-dollar mission that is going to fail.”

One of the divisions of the massive Reston, Va.-based defense contractor General Dynamics, which builds everything from communications equipment to missile warheads to nuclear submarines, GD’s Ordinance and Tactical Systems has an outpost at the Port of Moses Lake, where it builds and tests precision munitions designed and engineered at the division’s main offices in Seattle.

The role for the Mars mission is critical. After crossing more than 400 million miles, Perseverance will hit the Martian atmosphere at a speed of roughly 13,000 mph. The thin Martian air will slow the spacecraft down to around 940 mph when the parachute is supposed to deploy, slowing the descending spacecraft to around 200 mph so the lander can use its retrorockets to slow down even further and lower the rover to the surface on a cable.

The $2.4 billion mission will explore what scientists believe is an old flood plain on the Martian surface, as well as take soil samples for a future mission to recover.

The explosive the company has engineered and provided has a simple but important job — it needs to shoot out the landing parachute, which cannot unfurl by itself in Mars’ thin atmosphere, Lichon said.

Mars’ atmosphere, which is mostly carbon dioxide, is only 1 percent as dense as Earth’s. So the parachute is loaded in a tube the way a firework is in a mortar and has to be “pushed out” of the spacecraft at very high speed in just the right way, Lichon added.

It’s not all that different from deploying an air bag, Lichon said, noting that General Dynamics devised the technology used across the street by Joyson Safety Systems to make air bags.

“Typically, on Earth, you put something out as you’re traveling fast and it pulls it out, the air resistance does that,” he said. “On Mars you don’t have as much, so therefore you have to shoot the parachute out and put it into position that it will open up versus hoping that the air drags it out and it opens it up.”

The explosive itself is simply gunpowder, and “not really all that special,” Lichon said. But the entire system is designed and assembled to take into account all of the conditions the vehicle might find when it enters the Martian atmosphere, such as temperature and the speed of the vehicle.

Lichon said the company designed the explosives and launcher in Seattle, and then tests them to make sure that everything works as expected. Complex computer models are also used to estimate the conditions on Mars, since the company cannot create them on Earth, he explained.

“We also do testing in Moses Lake, final testing, where you have the space to test it, shoot it up into the air and show that you’re getting the velocities and the deployment vector expected,” he said.

Skilled explosives handlers will also make the final product here, clean it and pack it for delivery to NASA, Lichon said.

It’s an outgrowth of the company’s defense business, Lichon said, that require the company to build things that don’t simply go boom, but can go boom in the right way at the right time and often launched by vehicles going at very high speed.

“We’ve been working on this type of technology for roughly 20-some years,” he said. “We’ve been on virtually every Mars lander, including a European Mars lander, so we have obviously a fair amount of experience.”

Lichon said despite the years of doing this, it will still be a nail-biter when Perseverance gets ready to land on Mars next February. After all, only half the spacecraft sent to Mars actually make it there successfully.

“I don’t think you can ever not stop worrying about it,” he said. “We have engineers with a lot of experience, and it’s sophisticated work they’ve done over the years.”

But he notes the project would never have gotten done without an entire team of engineers, craftspeople and accountants to make sure that “kaboom” takes place exactly when and how it needs to 40 million miles away.

“In Moses Lake, you have the craftsmen who put this together, that make sure things are built right, carefully assembled, packaged and cleaned and make sure there are no issues,” Lichon said. “It takes a group to make things like this happen.”