To infinity and beyond, with a swarm of tiny computers costing under $1K each

Boffins believe the future of space exploration may belong to small, affordable probes sailing away under the Sun's power.

In a pre-print paper titled, "BLISS: Interplanetary Exploration with Swarms of Low-Cost Spacecraft," authors Alexander Alvara, Lydia Lee, Emmanuel Sin, Nathan Lambert, Andrew Westphal, and Kristofer Pister outline a project that aims to go where no one has gone before with a fleet of cheap, tiny Linux-powered spacecraft.

"The BLISS project is intended to demonstrate that cellphone technologies and other miniaturization via technological advancements enable unprecedented capabilities in space," the authors, affiliated with the University of California, Berkeley, state in their paper.

BLISS spacecraft, each with a mass of about 10 grams, are smaller than a 10 cm³ 1.33 kg (3 lb) CubeSat. The BLISS design depicts a circuit board joined with a solar panel to form a T-shape, towed by a significantly larger solar sail with an additional "roll sail" to provide rotate the craft.

These spacecraft, projected to cost less than $1,000 each, consist of: a 1 m² square mylar sail; micro-electro-mechanical system (MEMS) motors for sail control; an inertial measurement unit (IMU) for rotation sensing; a laser transmitter and a single photon avalanche diode (SPAD) optical receiver; a highly-oriented pyrolytic graphite (HOPG) radiator fin for thermal control; a lithium-polymer battery; an iPhone camera; a VoCore2 PC running Linux and custom software; and Alta solar cells.

Larger solar sail-powered spacecraft are difficult to build, costly, and tend to entail missions on the order of a dozen years due to the transit times involved, the authors argue. Even CubeSats, they say, require hundreds of square metres of sail area to provide useful propulsion.

For a 10 gram spacecraft, a 1 m² solar sail presents the most practical propulsion option, and the BLISS design, they claim, would work well at scale. A fleet of a thousand would weigh only 10 kilograms and the stack of sails to power them forwards would be only a few millimeters thick.

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The Berkeley boffins suggest a suitable initial mission would be imaging somewhere between ten and a few hundred near-Earth objects (NEOs).

"There are roughly 20,000 known NEOs, roughly 1,000 of which are believed to be asteroids greater than 1 km in diameter," they note. "Only 10 of these NEOs have been visited by spacecraft."

Modeling a trip to Bennu – a near-Earth asteroid visited in 2020 by NASA's Osiris-REx spacecraft – the space scientists estimate BLISS ships could complete a round-trip mission in just over 5.1 years (1,866 days).

The Osiris-REx mission took just over seven years (2,572 days) and samples are due back on Earth on this September. The mission will have cost an estimated $1.2bn when completed.

After completing a NEO visit test run, the BLISS team proposes collecting material from thousands of Jupiter-family comets using the spacecraft. They observe that the most recent US Planetary Decadal Survey identified fetching comet samples as a high priority mission, but could not be completed until the mid-2040s using an approach proposed in the New Frontiers competition. With a swarm of 10 gram BLISS craft, they insist the mission could be completed within the next decade.

As for radiation shielding, BLISS aims to hope for the best. "The BLISS mass budget does not allow for sufficient shielding to have a significant impact on the dose hitting the electronics," the authors state. "Still, carefully-designed electronics should be able to survive a multi-year mission with sufficient probability."

And if not, perhaps it's worth sacrificing a few inexpensive Linux machines for the sake of science. ®