A Combination Drill and Gas Conveyor Could Simplify Asteroid Extraction

Collecting material from an asteroid seems like a simple task. In reality, it isn’t. Low gravity, high rotational speeds, lack of air, and other constraints make collecting material from any asteroid difficult. But that won’t stop engineers from trying. A team from Beijing Spacecrafts and the Guangdong University of Technology recently published a paper that described a novel system for doing so – using an ultrasonic drill and gas “conveyor belt.”

So far, three missions have successfully taken samples from an asteroid: Hayabusa-1 and -2 and OSIRIS-REx. Both Hayabusa missions used a projectile to impact the asteroid and collected the debris from that impact. OSIRIS-REx used a system called the Touch and Go Sample Acquisition Mechanism (TAGSAM), which touched down briefly on Bennu, the mission’s target asteroid, and then pulled away with a sample of its regolith.

Another mission, Rosetta, attempted a more involved sample collection process that involved anchoring to the asteroid itself. However, its lander, Philae, didn’t successfully attach to the asteroid and never managed to return samples to the Rosetta orbiter. Its collection mechanism known as the Sampling and Drilling Device (SD2) was the most similar to conventional sample collection here on Earth, and utilized a drill.

Fraser and Pamela discuss what all goes into a asteroid sample return mission.

That concept of drilling is at the heart of the new proposed system. It utilizes an ultrasonic drill to break up the regolith into small chunks. It’s pretty standard stuff and nothing to write home about, as robots have been doing so on celestial bodies for decades. However, in this case, the drill is surrounded by a system that utilizes gas to push the tiny grains of dust created by the drill up into a sample collection system.

In the paper, the researchers describe it as a “gas conveyor belt,” which pushes the small particles hard enough to allow them to float in the asteroid’s microgravity environment. According to the authors, the proposed system has several advantages. These include low cost, low power consumption, and adaptability to different sample collection site environments.

Another significant advantage is that the probe that utilizes it doesn’t need to be entirely securely anchored to the asteroid. This was the problem for Philae, but the physics of the ultrasonic drill made it possible for the probe to be lightly tethered to the asteroid without having the system for the probe away from the surface.

Visualization of how the gas and drill work together in the system.
Credit – Zhao et al.

In addition to the modeling and theory behind the development of the system, they also built a prototype. They tried it on various regolith simulants in a vacuum and under pressure. Since the experiment was only on a benchtop, they couldn’t test it in the microgravity environment. The ultrasonic drill, which has a “percussive” function similar to a hammer drill used in construction, made neatly drilled holes in a sample rock on the benchtop.

However, some work remains, including more comprehensive system testing, microgravity, and more theoretical modeling of the system’s efficacy. The authors believe this system could be integrated into China’s upcoming asteroid exploration and sample return missions, which they think will happen soon. If they do, they might get a chance to prove this novel piece of technology and move us one step closer to solving the technical challenge of asteroid sample return.

Learn More:
Zhao et al. – Gas-Driven Regolith-Sampling Strategy for Exploring Micro-Gravity Asteroids
UT – Finally, Let’s Look at the Asteroid Treasure Returned to Earth by OSIRIS-REx
UT – Asteroid Ryugu Contained Bonus Comet Particles
UT – OSIRIS-REx’s Final Haul: 121.6 Grams from Asteroid Bennu

Lead Image:
Images of the prototype drilling system in different test configurations.
Credit – Zhao et al.