Inside NASA’s bid to make spacecraft as small as possible

The NASA probe’s retrorockets pressed desperately against the apricot afternoon skies of Mars. It was November 26, 2018, by Earth’s calendar. As the InSight lander worked its way down, slowing from 12,000 miles per hour to a graceful landing, overhead a pair of robots coursing through space monitored its progress. Though InSight was the size of a grand piano and the twin Mars Cube One spacecraft the size of cereal boxes, the lander was, in some sense, the easier challenge. Since the 1970s, we’ve sent a lot of big things to Mars. Until that moment, we had never sent something so small.

Engineers designed the tiny travel companions to act as radio relays, sending InSight’s telemetry back to Earth. Technically their job was a nice-to-have: InSight was landing autonomously, and it would communicate with Earth via the Mars Reconnaissance Orbiter after touching down.

But just making it this far heralded a new age in space exploration. And engineers were only more pleased when the Deep Space Network, a global array of radio antennas, picked up the tiny explorers’ real-time signals from Mars. InSight was healthy, said MarCO. Its parachute had deployed, the cubes added. The lander had separated from the back-shell and chute; it was on rockets now. One minute later, it was done. InSight, the small spacecraft reported, had survived.

In this diminutive mission, NASA as an agency, and the community of planetary science researchers, caught a glimpse of a future long sought: a pathway to much more affordable space exploration. Each MarCO was the smallest, cheapest spacecraft ever to fly beyond the Earth-moon system. The pair cost less than $20 million to construct, launch, and operate. If engineers could build more such spacecraft—and make them even more capable in the process—they’d be an attractive alternative to multibillion-dollar flagships that launched only every 20 years or so, or even near-billion-dollar probes like InSight.

The media ran with the vision. The Wall Street Journal championed MarCO as the vanguard of a new era of “swarms of tiny probes prowling the solar system.” The New York Times reported the potential for “whole fleets of MarCO-like satellites” exploring deep space.

Engineer Joel Steinkraus uses sunlight to test the solar arrays on one of the Mars Cube One (MarCO) spacecraft.NASA/JPL-CALTECH

NASA had been quietly building toward the notion of small solar system explorers. In addition to greenlighting MarCO, it had launched a program to develop other small planetary probes. As MarCO sped toward Mars, making trajectory maneuvers and phoning home like any large spacecraft,Thomas Zurbuchen, then associate administrator for NASA’s science mission directorate, declared that every rocket launched by NASA’s science program would include a payload adapter for small spacecraft to hitch a lift. “We’re not going to ask whether we need it,” he said. “You have to convince us that we don’t need it.”

There was a catch, though—one that NASA soon had to grapple with. Miniaturization can only go so far before it comes to a crashing halt against some very fundamental laws of physics.

Have you ever heard of a wicked problem?” Alfred Nash asks me.

Five years after the InSight landing, we are in his office on the third floor of the formulation building at the Jet Propulsion Laboratory, NASA’s sprawling research and development facility in Pasadena, California. The room is sparsely decorated. He recently changed offices, and many of his things are still in boxes stacked off to the side.

In 1973, he explains, two professors at UC Berkeley published a paper asserting that there are two kinds of problems. One type—the “tame” kind—can be solved with science and brute-force engineering. But there is another sort that is resistant to being solved with math and physics. In these complex problems, a group of stakeholders with differing value propositions want distinct and oftentimes contradictory outcomes. These are the “wicked” problems.

Nash says that when people think of formulating a space mission—turning a probe from scribbles on a notepad into hardware on a lathe—they imagine only the

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By: David W. Brown
Title: Inside NASA’s bid to make spacecraft as small as possible
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Published Date: Tue, 24 Oct 2023 09:00:00 +0000

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