Faster Than Any Other Speeding Bullet

September 2011

Professor Andrew Higgins (right) with team members Daniel Szirti (since graduated and now working with Rolls-Royce) and (centre) current PhD student Jason Loiseau. (Photo: Owen Egan)

The amount of space debris orbiting the Earth increases every year. While larger chunks can be detected by radar and avoided, smaller pieces, around 10 cm or less, elude tracking. Travelling at speeds of up to 8 km/sec, debris like this striking a space station or a satellite would cause immense damage.

For some time researchers have been using specialized light-gas guns to fire particles at speeds approaching that of orbiting debris, attaining speeds of almost 8 km second (a good rifle, by comparison, fires bullets at about 1 km/sec). But when Russian and American satellites collided in 2009, the relative speed of the impact was about 11 km/sec; such strikes could occur at relative speeds of up to 15 km/sec.

“There is a lot of concern about these impacts,” says McGill Mechanical Engineering Professor Andrew Higgins. “But the physics isn’t understood because we don’t yet know how to recreate collisions at that speed in the laboratory.”

That’s where the McGill research comes in. Professor Higgins and his team have been developing a novel implosion-driven hypervelocity launcher. When explosives surrounding the launcher-barrel are detonated, they pinch the barrel at extremely high pressure to drive the projectile forward.

Unique capability

“In effect, the gun squeezes behind the projectile, pushing it down the barrel, much like squeezing toothpaste from a tube,” Professor Higgins says.

The launcher has succeeded in firing dime-sized projectiles at 7.9 km/sec, matching the best efforts of the traditional “light-gas gun” approach, but Professor Higgins is hoping more research can increase the velocity further. “Then we’ll have a truly unique testing capability.”

The Canadian Space Agency has been a long-term collaborator, and this past summer Professor Higgins did testing for MPB Communications, which is developing sensors that can be integrated into spacecraft materials to record and assess damage from debris impact.

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