Well here is the thing about Europa. I support a mission, but it is so far beyond our comprehension that many of the efforts in the scientific community right now are laughable at best. Consider:
As a satellite of Jupiter, Europa is roughly 740,573,600 km at perihelion, or at its closest point. The time it would take for a signal to any probe sent to land on Europa is over 32 minutes
one way. As we have seen with the Mars landers, a certain amount of pre-programming can be done to facilitate the landing procedures. That will get a lander down, but that doesn't mean in safety. Unlike Mars, where we have the luxury of sometimes flat, dust filled terrain, Europa has a solid sheet of ice covering it, which can and will complicate any landing procdedures. In addition, the cracks formed on the surface can be around 12 miles wide. To put this in perspective, the widest point on the grand canyon is 18 miles. The average adult running at full speed could cover the distance in
48 minutes (assuming a mile in 4 minutes). The enviorment itself is rather hostile. The surface temperature averages around 110K (or -160 to -260 F) at the equator, where such a mission would have to be directed. We do not have enough data to draw conclusions about the thickness of the ice or what we would find beneath. In addition, any space craft would have to contend with the incredible malevolence that is Jupiter itself. The gravitational pull is well over twice as great as it is here on earth. In addition, the radiation generated will eventually take its toll on any vehicle that operates within the system (look at the effects that the radiation had on Galileo).
Next, lets examine the problem of actually cutting through the ice to deposit a remotely operated vehicle within the suspected liquid ocean beneath. This will have to be a lot of speculation, because as of this moment the thickness of the oce sheet is unknown, as well at its composition. The fact that a mission of this type has never been undertaken leaves us without a lot of information that we could begin to draw procedures from. Lets draw some comparisons on earth. The average thickness of the ice sheet in Antartica is about 7000m. This must also be considered with the rock formation that has helped. The thickness at the North Pole is about 6500M on average. Because the assumption is that Europa is a water world, we'll work with the 6500M figure. We have to assume that the thickness will be greater, so lets build some allowances into the math, starting with 6500m as our low number, and computing a figure double that for our maximum thickness. So from 6500 to 13000m at the equator based on this haphazard model. So whatever we send will have to cut through all of that ice, which will have a hardness of anywhere between 1.5 and 6 on the Mohs scale.....or even beyond, since these two numbers come from natural ice formations on earth, with 6 being achieved when teperatures reach -70C. So we can probably expect that the ice will be a great deal harder there. For some perspective:
http://query.nytimes.com/gst/fullpage.html...754C0A9659C8B63It took this team 7 years to cut through 2 miles of ice. Which is actually below the minimum thickness in our range by about 813 yards. Short of deploying something truly novel and high tech, we have to assume that drilling will take the better part of a decade. Even if we follow the concept of deploying an assemply that uses a nuclear reactor to melt through, we are probably talking about a similar time frame. I feel that the nuclear option has to be left out because of the risk of introducing a dangeroud element onto an alien planet. Then we have to consider a factor of refreezingaround the drill assembly, and the possible damage that would cause to the vehicle. Ice can destroy even the most durable of platforms, as is proven even today in the ice channels of the ocean going fleets. We also have to consider what the ice will do to signal reception. Then if the ice composition will have a corrosive effect on the vehicle itself. Will the introduction of absolute zero temperatures into sections of the crust create unforseen circumstances?
Once we have bored through the ice somehow, we have to design a vehicle that will then go into the water and proceed to investigate for signs of life. Even this step is faced with a myriad of issues. First and foremost is contamination of a possibly foreign enviroment with an otherworldly artifact. Then we have to go back to the composition question. Will the liquid adversely affect the vehicle? Will the vehicle be able to operate as envisioned in the enviroment? Does the characteristics of the liquid mirror our own oceans, or would they share more in common with the lakes on Titan of methane, which is less dense and therefore less viscous that our own oceans. Then we have to deal with the highly likely possibility of currents within the ocean. Since we have a tidal effect with Jupiter, and the possibility of geo-thermal activity as a result, we have to assume that the heat generated is likewise affecting these liquid oceans in much the same way as thermal warming and cooling affects the currents on our own. We are not entering a stagnant enviroment, but one that has just as dynamic an enviroment as we have on earth. Currents mean an unpredictable enviroment. It is highly unlikely that any amount of computer programs can be written to guide an unmanned vehicle through such a dynamic enviroment....DARPA still hasn't been able to find a team to build a robot car to drive along a road under real world conditions. How could we control such a vehicle in such a dynamic enviroment when it takes 32 minutes for a signal to reach it. The delay alone makes it impossible. How will a signal be transmitted in such a dynamic enviroment? How will we get those pretty pictures of alien thermal vents that the artists illustrations dictate we will find? Thermal vents of that sort will be on the ocean floor, and goodness knows how deep that is on a Europan ocean, or the pressures that will be exerted on a vehicle heading into those depths. The temperatures around such vents can be several thousand degrees hotter than the surrounding area, capable of damaging or destroying a vehicle.
In the next post I'll touch on possible solutions to the problem.