Mars And Beyond: Minisatellites Open New Vistas Two briefcase-sized satellites gave the control room of the Jet Propulsion Laboratory in November what scientists had never been able to get before: real-time information about a spacecraft's landing.

What's Next For Tiny Satellites?

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To another story now, two miniature spacecraft pulled off a remarkable feat last month. They provided live play-by-play as NASA's InSight probe made its successful touchdown on Mars. NPR's Joe Palca has the story of the two experimental mini-satellites known collectively as MarCO.

JOE PALCA, BYLINE: When InSight left Earth last May, NASA provided a familiar narration.


UNIDENTIFIED NASA EMPLOYEE: Five, four, three, two...

PALCA: Blastoff. Now, you expect to hear that. What's more unusual is this.


CHRISTINE SZALAI: Altitude 400 meters, 300 meters, 200 meters.

PALCA: That's Christine Szalai, a member of the InSight landing team at the Jet Propulsion Laboratory in Pasadena. She narrated InSight's descent from the control room at JPL.


SZALAI: Thirty meters, 20 meters, 17 meters.

PALCA: And then blastoff - I mean, touchdown.


SZALAI: Touchdown confirmed.


PALCA: Now, most of the time there is very little information coming back to Earth from a space probe as it comes in for a landing, maybe just a simple tone at key moments. And if there are any numbers, they're based on where mission controllers think the spacecraft should be based on a projected timeline. But the numbers Szalai was reading off were coming from InSight's onboard radar, actual data as it was coming in for landing.

Anne Marinan helped provide that data. She's an engineer at JPL who worked on MarCO. And she heard Szalai's narration.

ANNE MARINAN: She was doing it based on data that she was seeing that was transmitted from MarCO.

PALCA: How did that make you feel?

MARINAN: I didn't quite appreciate that that's what she was doing until I saw a rebroadcast. And it kind of hit me that she was able to make those calls based on data that my spacecraft had sent.

PALCA: MarCO is actually two briefcase-sized spacecraft that left Earth with InSight. The pair trailed close behind InSight on the way to Mars. InSight's radio couldn't reach Earth directly as it plummeted to the surface, but it could reach MarCO flying nearby. And MarCO's job was to relay back to mission control what InSight was sending. Marinan says the miniature satellite was an experiment.

MARINAN: MarCO was primarily a technology demonstration. So there were brand-new components and technologies that we flew for the very first time in deep space.

PALCA: A new kind of antenna, a new kind of propulsion. And Marinan says the new technology didn't always work perfectly. The propulsion system gave them headaches. But...

MARINAN: Well, it worked perfectly when it had to.

PALCA: This was Marinan's first assignment at JPL. She only recently earned her Ph.D. So what do you do for an encore when your first mission works so well?

MARINAN: I am actually currently putting together another spacecraft.

PALCA: Another miniature spacecraft, this one more science-y (ph), going to take pictures of a nearby asteroid. Joe Palca, NPR News.


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