>Balance mass should perform some type of scientific or technological function<p>So that's 661 lbs. I wonder how far we are from a solar powered 3D printer. Can we build a self-replicating robot of any kind that would work on Mars? What practical raw materials could a machine tap, if any? Imagine this platform being used to test off-planet manufacturing. Even on a small scale it would be pretty impressive.<p>Didn't the Mars society have a proposal for a low cost Mars mission with automated missions flown before-hand performing some kind of fuel extraction from Mars (hydrogen?) So that when humans landed, they'd tap these reservoirs of fuel instead of paying all this money to fly fuel with them. Even a small scale test of that would be a game-changer.<p>If that's too lofty, get 50 colleges to make mini robots/sensor/whatever with a 6lbs limit, kind of like we do with CubeSats today. That leaves NASA ~350lbs for a lander to safely drop these things. Having just one single winner seems a little short-sighted. I'd rather see lots of people given the chance to drop something on Mars than just one group.
<i>> Payloads replacing Balance mass should perform some type of scientific or technological function adding to our knowledge base while closely matching the volume and weight characteristics of the original Balance mass.</i><p>Um, the one being replaced was solid tungsten, which is almost twice as dense as lead. How is anything going to come close to matching that?
My first thought for something actually doable would be a group of compressed gas cannisters with highly reflective balloons attached to them. Very simple mechanics, all you need is a strong valve on a timer, so it can be made to survive the impact with the ground.<p>Once they're inflated, they would rise to relatively high up, so they can be carried off by winds. Because of the high reflectivity, we would be able to track them from orbiting imaging satellites and probably even from earth, teaching us more about wind speeds and flows on Mars.<p>One thing I'm not sure about is if this could meet the weight/space requirements.
ExoLance project is supposed to use that dead mass to shoot darts under the Mars surface to look for signs of life:<p><a href="https://www.indiegogo.com/projects/exolance" rel="nofollow">https://www.indiegogo.com/projects/exolance</a>
is there any logic to bringing some fissile material to mars for use as a future fuel source? My gut instinct says no, but its among the only things I can think of that would be heavy enough. Uranium and Plutonium are pretty heavy.<p>The only other things I could think of would be common catalyst materials like platinum. Something that could be collected and used later by some future mission. Lead might be useful, as a battery component, but forming it would be problematic.<p>If it remains tungsten, and the impact is going to be at very very high speeds, do any of the other mars rovers have instruments capable of detecting the seismic waves produced? Could that provide us any details of the makeup of the crust? A 150kg tungsten mass would likely make quite a crater traveling at 9000MPH.