1) How can I make my own martian soil?
Martian soil varies from place to place across the planet, so there's no single recipe that is universal. In fact, we've seen that the martian soil can vary from place to place just within the 20-meter-wide crater where the rover Opportunity landed! On one interior slope of the crater, the mineral hematite is abundant, but elsewhere within the crater, hematite is much less common in the soil. The fraction of finer and coarser particles varies from place to place within the crater, too. Most other places on Mars (apart from the poles) have more dust than the soils found at the Opportunity landing site. Spirit, for instance, landed in a much dustier place. Rover tracks from Spirit disturb this very thin dusty layer, revealing the darker soil just beneath. Although there is no single recipe for making Mars-like soil, here are a few general guidelines:
- Use a wide range of particle sizes, from dust, to silt, to sand, and even a few pebbles.
- Try not to include any organic matter in your "Mars simulant" -- no leaf or twig fragments
- Dry the soil (in the sun, after spreading it out on a mat, or in an oven, with adult supervision depending on age)
- If you want to get really fancy, a generalized composition would be palagonite, a family of materials derived from weathering of basalt, originally a dark volcanic rock.
Making a Mars soil simulant is a messy job, so be careful.
2) Why is the landing of the rovers on Mars so important to us?
Probably you've heard many answers already for this question, involving the importance of exploration, how learning about Mars helps us understand Earth, and so forth. Here are two personal answers from me that you might not have heard somewhere else:
(1) Exploration of the solar system is expensive and most countries cannot afford the enterprise, yet exploration advances the store of knowledge for future generations of our entire civilization (all the data we collect are available to everyone in every nation, permanently). As the world's richest, most powerful country, it is a particularly American responsibility to engage in exploration on behalf of the world and the future of our entire civilization.
(2) When I was a very small child many years ago, the Moon landings were achieved, and books I read then promised optimistically that when I grew up, technological advances would continue and there would be Moon bases, and humans going to Mars. Well, none of these things has happened. Life is short, yet I want to see the great things of the future, and I'm impatient that I ever will. Putting off exploration until every last problem on Earth is solved is unrealistic; I want some of that future now. I do not want my children reading the same books I did and have this civilization's great future just as remote as it is to me now. Roving on Mars is a sign of real progress. We're daring, accomplishing, and learning things we just couldn't any other way. And we're doing it right now, in *our* lifetimes.
3) Are the Mars rovers looking really hard for both microscopic and obvious fossils in the Mars rocks?
We're looking hard at everything, scrutinizing the surface with cameras and spectrometers. If there are fossils in these data, we'd be eager to recognize them. Our approach is that Mars is an alien planet that we know little about, and we need to look at all of our images and other data very carefully, ready to recognize anything of interest. We don't devote specific images or other resources to looking for fossils, because the images and other data we obtain are good for recognizing many different things (including fossils).
4) How does the Mars rover function? Do you tell it what to do or did you program it? How does the rover avoid getting stuck?
Each morning we send up a "to-do" list of activities for the rover for that martian day. In the afternoon we contact the rover again to see how the sol's (sol = martian day) activities went. A good day on Mars is when the rover checks in late in the afternoon with all activities completed. Because the distance between Earth and Mars is so great, it is impractical to control the rover more closely (say, like a toy remote-control car is continuously controlled). For this reason, it's important that the daily list of rover activities be assembled carefully. The activity list (which may include picture-taking, arm-movements, and/or driving) has to be as full as possible with the highest quality science, yet not so full that the rover gets confused and "errors-out" early, canceling observations. The rover avoids getting stuck two ways:
(1) the suspension and wheel system is very agile, allowing the rover to drive over many obstacles; and
(2) the rover can detect obstacles too big to drive over, and drive around them, instead. Even if all six wheels get buried, tests show that the rover can turn and drive away. It's less likely to get stuck anywhere than a typical car.
5) If a person is standing on Mars and looking toward Earth, what color would Earth be?
Bluish-white.
6) How will humans living on Mars affect the martian atmosphere?
I can only speculate about this. Humans breathe out carbon dioxide as a waste product, but the martian atmosphere is already primarily carbon dioxide, so our respiration should make little difference. Nuclear power or solar power of some kind probably will provide energy to the first human settlement on Mars, and these do not impact that atmosphere the way combustion (e.g., a coal- or oil-fired plant on Earth) would. However, the atmosphere of Mars is very thin, so even subtle effects of human habitation might cause changes that could be detected.
7) Will the two rovers ever meet on Mars?
No, they are too far apart (half-way around Mars from each other) and their ranges are too limited (a few kilometers at most).
8) Where do you see this mission leading us 10 or 20 years from now?
Rovers are tough to build right, but when that happens the scientific potential is far, far greater than landers. Ten or twenty years from now I expect we will be using bigger, more advanced, more autonomous rovers to do great science on Mars.
9) Who designed the rovers? Who built them?
A team of engineers and partners in private companies designed and built the rovers, and scientists helped, too, to make sure the science capabilities were excellent. Most of this work was done at the Jet Propulsion Laboratory (JPL) in Pasadena, California.
10) What are the major difficulties the Mars Rovers went through?
There were many difficulties to be overcome when the rovers were designed and built, and more difficulties during launch, and from that point the rovers had to perform in the alien, inhospitable environments of space (during months-long cruise from Earth to Mars) and Mars (during their missions on the surface). Here's a short list of some of the largest difficulties (other scientists or engineers might come up with a different "top ten"):
- Extremely tight schedule to solve all the problems below:
- Fitting a 174 kg rover (with enough solar panel area to power it on Mars) into a small enough volume to fit inside the airbags. If less solar panel/power, then much shorter mission.
- Making the airbags tough enough to survive landing, even if there were some winds blowing the rover+parachute sideways
- Designing system with descent camera and auxiliary rockets to detect strong winds and counteract these at the last minute to assure a safe landing
- Designing and building all the instruments to make sensitive enough measurements yet still be light enough to fly on the rovers
- Designing and building the "PMA" or mast for the Pancam/Navcam/MiniTES instruments. The mast serves as a swiveling mount for the cameras, as well as a periscope-like optical system for MiniTES.
- Developing software to do so many things on the rovers, like driving, imaging with 10 different cameras, moving all the arm joints, transmitting and receiving data from Earth.
- Designing and building the IDD or instrument arm, a very complex piece of hardware that has proven to be very reliable and capable.
- Developing a whole system of tactical planning that allows us to rapidly assess a rover's most recent activity (latest position, pictures, etc.) and create a command list in time for the next "sol's" (martian day's) activities, all while the rover is sleeping overnight. This required lots of specialized software and training of many, many personnel.
- Long hours away from family members.
11) Did Mars have vast oceans billions of years ago?
We don't know, but evidence gathered by Opportunity suggests water was available at the surface at that location in the distant past. We don't know the extent of the water, though (pond, lake, or ocean).
12) Why did NASA send TWO robots to Mars?
First, once you've gone to the trouble of designing and developing one rover, building a second one is much less expensive, so you get two rovers for less than double the price. Second, landing into unknown environments is risky, so having two rovers kept us from putting "all eggs in one basket."
13) How much longer are the rovers going to work?
We're not sure. We tested the components to assure they'd work for at least 90 martian days--that was the requirement. It would have cost extra money to test enough to learn how much longer the rovers might work after 90 martian days. The rovers have conservative designs because much about the martian surface environment is unknown, so the designers were as careful as they could be. This philosophy will help the rovers last longer. We are hoping they will both work through the end of September.
14) Are the rovers going to study the soil at the heatsheild impact sites?
Probably not. It would be a nice thing to do, but more important science objectives and destinations take the rovers away from their heatshield impact points. To get to the heatshields, we'd have to make large detours from the current plans. There is a small possibility this might still happen on Opportunity, but Spirit is definitely heading toward the Columbia Hills, away from it's heatshield impact point.
