A group of scientists has come up with a proposal to crash a probe into one of the icy moons of the Solar System, as a means to finding out more about their surfaces.
Led by Peter Wurz from the University of Bern in Switzerland, their idea is available to read in a pre-print paper on arXiv.
They suggest that an impact probe, similar to those used on some past missions, could help us learn a lot more about moons like Europa, which is thought to have an icy shell hiding a liquid water ocean below.
“The descent probe has the potential to provide a high science return to a mission at a low extra level of complexity, engineering effort, and risk,” the authors write.
Sent in tandem with an orbiter or other spacecraft, such as NASA's upcoming Europa Clipper on which a lander has been considered, they say their small probe called the Europa Descent Probe (EDP) could be deployed by the mother spacecraft on arrival, hitting the target world and exposing material underneath.
“A lander is much more complex, thus riskier, much heavier, and much more expensive than a descent probe,” Wurz told IFLScience. "A lander is typically a mission by itself and is the ultimate goal in planetary exploration. A descent probe would be much cheaper and would be an addition to flyby mission.”
The probe, costing about $116 million, would be less than 100 kilograms (220 pounds) in mass, and it would travel towards the surface at a high speed of 4 kilometers (2.5 miles) per second after being released by the spacecraft. It would be cube-shaped, with four thrusters directing it towards its target impact site.
The researchers say it could be possible to use this probe to take images and measurements up to 1 kilometer (0.6 miles) from the surface of another body. This would include detecting the presence of a thin atmosphere (exosphere) and measuring the local magnetic field strength.
While it could be used for a number of worlds, the team particularly looked at Europa. Here, they say the probe could study the water plumes at the south pole in even more detail than before.
After the EDP had slammed into the surface, its orbiting mother spacecraft could study the produced crater, getting a look at what the surface and sub-surface is made of.
There are of course planetary protection rules to be wary of, namely that we cannot contaminate other worlds with Earth-based microbes. The spacecraft would therefore need to be cleaned to an extremely high level, something the team says is possible.
We’ve used descent probes like this several times before, including Philae on the Rosetta mission, Huygens on the Cassini mission, and NASA’s Deep Impact mission to comet Tempel 1.
Wurz said their proposal had been presented to ESA and NASA but had not yet been selected. “Perhaps it will be selected, perhaps for another moon,” he said.
“There are many objects in the Solar System where the science return of a mission could be significantly improved by the addition of a descent probe,” he continued, noting that Neptune and its large moon Triton was an intriguing destination.