Successful first test of high speed Moon penetrator
BY DR EMILY BALDWIN
ASTRONOMY NOW
Posted: June 11 2008

High speed penetrators that could one day be used to breach the surface of planets, moons and asteroids have successfully passed their first test in the UK, accelerating to over 1000 kilometres per hour and 20,000 gee at the point of impact.

Video of penetrator test

Video of penetrator test firing as seen from different angles at the test site. Credit: MSSL/UCL. Experiment conducted at the QinetiQ facility at Pendine.

Penetrators are a bit like missiles, but instead of exploding upon impact they are designed to survive, protecting vital electronics, sensors and data-collecting systems that are cocooned inside, which record the impact and subsequently perform in situ experiments at their landing sites.

A team lead by Professor Alan Smith at University College London ran three test firings of small, suitcase-sized dart-like penetrators at QinetiQ’s long test track in Pendine, South Wales, into a simulated Moon target: sand, a rough approximation to the soil-like “regolith” that covers the lunar surface to a depth of a few metres.

“Sand is a good first approximation,” says Smith. “We made some very careful measurements of it which we’ll input into our computer models. With a validated model we’ll then use lunar regolith values, as well as they are known, and look at the differences and consequences to our design.”

The projectiles were secured to a rocket sledge and fired along a rail track. The onboard electronics remained operational throughout, even though one of the impacts was particularly demanding, striking the target at an angle greater than that expected for a real planetary mission.

“As far as we can tell the trial has been enormously successful, with all aspects of the electronics working correctly during and after the impact,” says Smith. “I congratulate the team on this really impressive achievement – to get everything right first time is wonderful, and a tribute to British technology and innovation.”

Top: the penetrator is attached onto the rocketsled and fired along a rail track. Bottom left: the penetrator before impact. Bottom right: the penetrator after impact. Much of the paintwork has been "sand-blasted" away, but the electonics contained inside remained operational. Images: MSSL/UCL. Experiment conducted at the QinetiQ facility at Pendine.

Sequence of events showing the pre-impact target (top left), and progressive stages as the penetrator approaches the target (top right), makes first contact (bottom left) and finally is embedded in the sand (bottom right). Images: MSSL/UCL. Experiment conducted at the QinetiQ facility at Pendine.

It is hoped that the penetrators will get a ticket to ride on the UK’s proposed MoonLITE mission (where the acronym LITE stands for Lightweight Interior and Telecoms Experiment), which will comprise a satellite that would travel to the Moon, enter orbit and deploy four penetrators at different points around the Moon. The penetrators, which will contain a drill mechanism, sensors, accelerometers, a seismometer and mass spectrometer, will become embedded into the Moon’s surface while the satellite orbiter acts as a telecommunications relay station between the surface penetrators and Earth during its proposed one year lifetime. If successful, the mission will deliver important new science about the Moon’s interior and history while also testing the space communications network needed by future robotic and human explorers.

MoonLITE is currently undergoing peer review but it is hoped that studies will continue well into next year, with an ultimate launch date no earlier than 2013. “In the next trials, next spring, we plan a more sophisticated payload with a transmitter, and all the penetrator compartments will be operational," says Smith, “and the target will be more Moon-like (although still sand).”

A schematic of the penetrator interior. It is divided up into compartments which will contain different instruments reponsible for a variety of experiments once on the lunar surface. Image: MSSL/UCL/QinetiQ.

The feasibility studies are being supported by STFC on UCL’s Mullard Space Science Laboratory’s Rolling Grant. The mission already has academic and technical input from a variety of British universities and industries, including UCL, Birkbeck College, Imperial College, Leicester University, Open University and Surrey University, and Astrium, QinetiQ and Surrey Satellite Technology Ltd, which collectively make up the UK Penetrator Consortium. It was also hinted earlier in the year that NASA may offer some support.

Although these latest tests were performed as part of a feasibility study to send penetrators to the Moon, it is also part of a wider series of technical developments that could eventually see penetrators going to Europa, Ganymede, Enceladous and Titan, opening up an innovative way of conducting research on other planetary bodies.