AIR & SPACE MAGAZINE

Mars-Bound MarCO Twins Will Go Where No CubeSat Has Ever Gone

A pair of 30-pound satellites point the way to cheaper space exploration.

May 4, 2018

The MarCO CubeSats will separate from InSight's Atlas rocket shortly after launch, then make their own way to Mars.

CubeSats, those pint-size satellites that ride along on most every orbital launch these days, are quietly transforming the space business. So far, though, their impact has been limited to missions in Earth orbit.

That’s about to change. If all goes well, NASA’s latest Mars lander, due to launch on Saturday from Vandenberg Air Force Base in California, will be accompanied by two tiny companions making the trip to the Red Planet. It will be NASA’s first planetary mission launched from the West Coast, and the first time CubeSats have been sent into deep space.

Mars Cubesat One, or MarCO, consists of two briefcase-size robots (MarCO-A and -B) equipped with their own solar arrays, communications, navigation and propulsion. They’ll get a boost out of Earth orbit with the InSight lander on its Atlas V rocket, then separate and fly on their own for the six-month coast to Mars. The 30-pound CubeSats will use a compact, cold-gas propulsion system (think fire extinguisher and office chair) to make course adjustments along the way, hopefully arriving and taking their places just as InSight begins its descent to the Martian surface on November 26.

That mission, short for Interior Exploration using Seismic Investigations, is dedicated to Martian geology. The modest-size lander (no rover on this one) will use a seismometer and a burrowing heat probe to study the interior of Mars, including the movement of its tectonic plates and how heat flows beneath the surface.

After entering Mars’ atmosphere, the lander will deploy a parachute, then fire retrograde rockets to slow it as it approaches the ground. The MarCO twins’ job will be to listen to InSight during its entry and landing, then relay the data back to Earth.The veteran Mars Reconnaissance Orbiter (MRO) will also be listening, so technically the mission doesn’t need MarCO. The idea is to test whether landing telemetry can be relayed by small CubeSats if no other spacecraft are available to do it. In that sense, the MarCOs will act as a kind of backup “black box” in the event something goes wrong. Their data will be sent back to Earth almost immediately, while the MRO transmission will be on delay.

“We have had a number of failures at Mars over the years,” says Andy Klesh, who heads up an interplanetary small spacecraft program at NASA’s Jet Propulsion Laboratory and serves as MarCO’s chief engineer. “Carrying our own relay, providing a real-time link back to Earth, gets that information back for future lessons learned.”

But the primary purpose of the MarCO mission, says Klesh, is to prove that mini-spacecraft technology is up to the challenge of interplanetary travel. CubeSats have never ventured beyond the vicinity of Earth, and Klesh and his team have developed new technologies to make long-distance trips possible. In addition to new radio and propulsion systems, MarCO will deploy a flat antenna called a reflectarray that will allow it to send data at a rate more than 10,000 times faster than previously possible on such a small platform. “MarCO is a technology demonstration mission,” says Klesh. “We just needed the ride [with InSight] to essentially get out to interplanetary speeds.”

Still, with a price tag of only $18.5 million, MarCO could prove its worth as a cheap bit of added functionality for missions like InSight, which cost NASA and its European partners a billion dollars.

If MarCO works as advertised, proving that CubeSats can survive and thrive in deep space, its successors could become true space explorers in their own right. Because they’re relatively expendable, says Klesh, CubeSats could be flown into a comet’s tail, the volcanic plumes of Io, or other places where big, expensive spacecraft can’t.

Some of those projects are already in the works. “Many missions forward are now actually utilizing the technology that we will be demonstrating on [MarCO’s] flight,” says Klesh. For example, next year’s unmanned launch of NASA’s Orion crew vehicle will also carry CubeSats that use elements developed by the MarCO project. Those CubeSats will make the somewhat shorter journey to lunar orbit, but they’ll be doing real scientific observing when they get there.

MarCO has already paved the way. Now it just needs to ace the test.