Ultra-fast asteroid rotation threatens space-mining missions

Using an instrument called HiPERCAM, is attached to the Gran Telescopio Canarias in La Palma, Spain, a team of researchers recently found that the near-Earth asteroid 2022 OB₅ is rotating once every 1.542 minutes, classifying the space rock as an "ultra-fast rotator."

In a paper published in Icarus, the scientists claim their findings reflect a wider trend, making 2022 OB₅ one of many fast-spinning asteroids.

“One of the key results of our work is that very fast rotation appears to be common among the smallest and most easily accessible near-Earth asteroids,” Miguel R. Alarcon, the study lead, explained in an interview with New Atlas.

This could be bad news for space mining startups. Once hailed as the modern prospectors of a new gold rush, these companies have faced repeated setbacks in recent years. The new findings present yet another hurdle.

Targeting asteroid 2022 OB5

For years, space mining startups have promised to tap into vast off-world resources that dwarf the limited supplies we have here on Earth.

Some have served as a cautionary tale. High-profile firms like Deep Space Industries and Planetary Resources shifted strategies and went bankrupt, respectively, despite claims they would mine asteroids by 2020.

Another startup, Astroforge, is boldly pushing forward with its space mining plans. The company, which was not involved in the new study, is targeting 2022 OB₅. A flyby mission intended to perform a close-up analysis of the space rock unfortunately ended in failure last year. The company lost contact with its Odin spacecraft shortly after launch.

According to Astroforge, two key factors made 2022 OB₅ an ideal target: it appears to be metallic, and it has a low delta-v – in layman’s terms, low delta-v means an object is accessible via a relatively simple, low-fuel-cost maneuver. The startup claims that mining one metal-rich asteroid would be enough to supply Earth with precious metals for 200 years.

A space-mining target’s extreme rotation

Now, the new observations may complicate plans to fly to the same target, or land on any similar space rocks.

According to Alarcon, a former PhD fellow at the Instituto de Astrofísica de Canarias (IAC), he and his team chose to study 2022 OB₅ primarily to test the capabilities of HiPERCAM.

“The fact that it had also been selected by AstroForge, together with the possibility that it could be metallic, made it more interesting, but that was not really the main motivation,” he explained.

HiPERCAM’s high-speed optical camera captures images at over 1,000 frames per second, collecting this data simultaneously in five different colors, covering the entire optical spectrum.

Asteroids are relatively small, faint objects in the night sky that typically provide a very short observation window. So HiPERCAM’s multi-task approach was key.

According to Alarcon, HiPERCAM, which leverages the light-gathering power of the 10.4-meter (31.4-ft) Gran Telescopio Canarias (GTC), allowed the team to “measure both the rotation and the surface properties at the same time.”

“There is often not enough time,” he said. “With HiPERCAM, both can be measured simultaneously, which is a major advantage.”

The team found that 2022 OB₅ lies within the "X-complex" taxonomy group. This lends weight to the idea that the space rock is metallic, without confirming it outright.

Importantly, they also discovered that the centrifugal acceleration at 2022 OB₅’s equator is nearly 100 times that of the gravity that would otherwise keep a lander on its surface.

A tough break for space-mining startups?

Though Alarcon and his team didn’t specifically set out to assess the viability of 2022 OB₅ for space mining, he is aware that the findings are highly relevant to the field.

2022 OB₅ and similar objects are “attractive mission targets because they require relatively little energy to reach,” the scientist told us. “But their physical properties may make surface operations extremely difficult with current technology. Orbital accessibility alone is not enough: physical characterization, especially determining the rotation state, is essential before considering any realistic mining or sampling mission."

In the case of 2022 OB₅, the high centrifugal acceleration could present a real problem, meaning spacecraft could be “unable to stay attached to the surface,” Alarcon said.

“The asteroid rotates once every 92 seconds, which is extraordinarily fast,” he continued. “At that speed, the outward centrifugal acceleration is much stronger than the asteroid’s own gravity. A spacecraft trying to land or anchor itself would have an extremely difficult time remaining attached and could easily rebound or be thrown back into space unless it used a very sophisticated anchoring system."

We reached out to Astroforge for comment. In response, CEO and co-founder Matt Gialich claimed the company has such a system.

“Getting a surface speed is really difficult, mainly because of the variation in diameter,” Gialich said. “Regardless of that, our attachment methodology, using magnetism, allows us to anchor to asteroids with a force much higher than the centrifugal force pushing us off.”

After last year’s serious setback, Astroforge is pushing ahead with plans to land a spacecraft on an asteroid later this year. A lot will be riding on the upcoming mission, called DeepSpace-2. Whether that mission will still target a landing on 2022 OB₅ is unclear.

“2022 OB5 is small, and we have orders of magnitude more targets to go after that we're currently characterizing with Earth-based telescopes,” Gialich told us.

The research appears in the journal Icarus.