Though the aliens in 2010 told humanity to stay away from Jupiter's moon Europa, that hasn't stopped aerospace engineer Joseph Shoer from designing a probe that could look beneath the moon's icy surface and peek into the oceans below.
Shoer proposes a way to search beneath the kilometers-thick ice of Europa by sending light probes into vast rifts on Europa's surface (you can see one above). Experts believe that these rifts may open and close with Europa's tides. Shoer writes:
The Ice Fracture Explorer, or IFE, would be a combination lander/penetrator vehicle that I imagine to be a little smaller than the size of one of the MER rovers. Ideally, several IFEs would accompany an orbiter to Europa. The orbiter component of the mission would contain instruments designed to give the planetary scientists on the mission enough information to select a few double-ridged cracks that are actively being worked open and shut by tides. The flight controllers would then dispatch an IFE to each of those cracks . . .
The IFE will wait until the crack is closed, and then separate form the landing legs and inflate some gas-bladder cushions, causing the vehicle to roll down towards the center of the double ridge. Using its thrusters for attitude adjustment, the IFE will right itself, centered over the crack . . . Next, the IFE would fire projectiles into the crushed-ice ridges on either side of the vehicle. These projectiles could be barbed, contain chemical flash heaters, or anything else design to make them really stick into the ice, because they would be the anchors for twin tether lines that unreel from the spacecraft. The IFE would also deploy a high-gain antenna for communicating with the orbiter overhead, since the mission will have to happen very quickly from this point on. . . .
As Jupiter rises overhead, its tides will pull apart the two sides of the ice fracture. The IFE will be suspended in the middle as the crack opens, with nothing below it until the ocean 1-10 km down! At this point, the IFE will drop its deflated cushions and begin to deploy a smaller penetrator vehicle from its underside. The penetrator is a small, two-stage vehicle with two instrument packages, a hard-shell body, and a data line connecting it to the IFE's main bus. . .
Eventually, the penetrator would hit the ocean surface. The water would have iced over, but the weighted penetrator with its reinforced lower body would smash through the ice and reach the liquid water below. At that point, a buoyant surface instrument package would separate from the lower penetrator, which would continue down into the water. The surface instruments would try to identify any interesting chemistry or biology occurring at the water surface, where photosynthesis might take place. The lower body of the penetrator would simply try to go as far down as it can, illuminating the depths and taking pictures.
There's a lot more to Shoer's idea, so you'll want to read more about it on his blog.