Mars Exploration Rovers

Question:
I recently watched the PBS special on the current Mars project and it seemed to me that, aside from instrumentation on the rovers, there wasn't very much new technology, only upgrades to existing technology (a larger parachute, more robust airbags). What is in the works for upcoming missions that would be a significant step or leap forward?

Answer:
Actually, there are increases in technology -- these include the PANCAM (Panoramic Camera), a robust (and calibrated) APXS [Alpha Particle X-ray Spectrometer], a Mossbauer spectrometer, a microscopic imager -- and, we are *roving* on Mars over significant distances. The Viking landers did not move from their landing sites. Pathfinder lander was a technology demonstration. Its Sojourner rover traversed the distance in your living room. MER will traverse for at least a 1 kilometer along the surface over its 90-Sol lifespan. However, if the rovers remain healthy .... both may last 180 Sols or more!

The difference with MER is that we can now go over that next horizon, check out that new rock 'over there', examine a little sand dune. We did not do this in previous missions.

As far as what is coming down pike (future missions), next year the Mars Reconnaissance Orbiter will be launched and provide even higher resolution images of the Martian surface. Following MRO, in 2007, the Phoenix lander will be sent to the north polar region of Mars. In 2009, the Mars Science Laboratory -- a LARGE rover -- will launch to Mars and explore the surface for one Martian year (~2 Earth years).

These may not represent the 'significant leap' forward to which your questions alludes. Rather, these are incremental deliberate steps forward. Based on what is learned from the MER and missions soon-to-be launched, the science instruments on the later missions will be able answer more sophisticated questions.

Expert:
Rob Landis
Systems Engineer
NASA Jet Propulsion Laboratory

Question:
Does the deploying of the experience of "SPIRIT" help and/or change the program of "OPPORTUNITY" on Jan.24th?

Answer:
The experience we had during Impact to Egress (ITE) with Spirit may be useful during the ITE period for Opportunity, especially if Opportunity comes to rest with the base petal of its lander down (on the ground) as was the case with Spirit. On the other hand, if Opportunity's lander comes to rest on one of its side petals, the experience may be very different.

There are many possible scenarios (large rocks under the lander or petal, lander on a relatively steep incline, different airbag issues, etc), but the lander has been designed to deliver Opportunity to the surface safely in practically any scenario. In addition, our ITE engineers have tested many ways and may times with rover and lander replicas here at JPL. So they have several solutions that can be used.

The experience with Sprit could help/change the solution for Opportunity only if Opportunity's lander is on a relatively level surface and resting on its base petal. If not, then the experiences gained during many tests on Earth will come into play to achieve a successful Egress for Opportunity.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
How do you operate the rover on Mars? What type of instruments or landing equipment you have you put on the rover that makes it move so easily on Mars?

Answer:
Spirit and Opportunity have 6 wheels. All six can drive the rover forward and backward, and the four corner wheels allow for steering. The wheels are mounted on mechanisms that articulate (parts connected to each wheel move differently relative to each other) so that the rovers can drive over rocks about the size of a wheel. When driving over rocks, the body of the rovers stays almost level so that it does not lean from side to side or forward and backward very much. The rovers use a specially designed mobility system invented at JPL called the Rocker-Bogie suspension.

This mobility system is what allows the rovers to move easily on Mars' surface. However, the rovers cannot drive over all obstacles. There are many large rocks and steep slopes or hills that they cannot drive on. To avoid trying to drive in unsafe areas, the rovers use autonomous navigation software and sensors that allow then to see unsafe obstacles and find paths around them.

We operate the rovers by sending a set of commands, using radio communications, for them to execute each day for driving and using their instruments to collect scientific data. They have their own computer and software that allows them to understand the commands and execute the commands on their own (autonomously). When they are done, they communicate with us and send us data using radio signals.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
Congrats to all those involved in this Mars mission.

Would like to know how long Spirit is going to stay there in Mars and what will happen later.

How long it is designed to function in Mars. Are all the batteries are rechargeable with the help of the solar panels ?

Thanks,
Ashwin

Answer:
Thank you.

Spirit and Opportunity will carry out their missions for at least 90 sols (Martian days). Their missions will end when they can no longer operate reliably. This could occur due to accumulation of too much dust on the solar panels (limiting the ability to generate sufficient power to operate and/or recharge batteries), expiration of the useful lifetime of motors, or a combination of these and other possibilities. The batteries are rechargeable via the solar panels but have a limited number of recharge cycles. Similarly, motors have a limited number of revolutions before they may cease to work. This is often the case for hardware that is specially designed to operate in extreme (temperature, radiation, etc) environments of space.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
What will be the ultimate limiting factor that will end the rover missions? Will the electronics get to cold and stop functioning? Or will the solar panels be unable to provide enough power to run the rovers and they will fall silent? I have read the rovers are designed to travel about a kilometer. How many days and how far from Columbia station do you anticipate to be when Spirit stops functioning? Congratulations on a great mission and thank you for letting us live vicariously by looking over your shoulders via the Internet!

Roger de Man

Answer:
The ultimate limiting factor would perhaps be an inability to operate reliably over time. This could be caused by a number or combination of individual factors. Some of the most likely include accumulation of too much dust on the solar panels (limiting power generation sufficient to operate or recharge batteries) and motor lifetime expiration (motors designed for space environments often have a limited number of revolutions before ceasing to work). In addition, as the mission progresses, Mars will move further away from the sun causing a natural reduction in available power generation ability.

We expect the rovers to operate reliably for at least 90 sols (Martian days). They may operate for much longer... It depends on the conditions at their respective landing sites and how we choose to operate them throughout the mission. As for distance that Spirit will travel from Columbia Memorial Station, that too is hard to predict. Each rover has a mission goal to travel at least 300 meters. They are capable of traveling much further. The actual distances will depend on how far the NEED to drive in order to collect good science data. The rovers will go where the scientists believe the best scientific data can be acquired. Beyond the respective goals of 300 meters, their total distances will depend on where the scientists need them to explore.

Thanks for your congratulations and you very good questions.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
Is the rover going to retrace its landing bounces to learn more about how to land on Mars? Shouldn't the parachute and other discarded pieces be close at hand, yet I don't see them.

Answer:
Probably not. If there is something potentially scientific to learn from examination of its bounce marks, scientists may elect to do this. But my guess is that such examinations would only be attempted at the nearest bounce marks, if at all.

Other parts of the Entry, Descent, and Landing (EDL) hardware would be elsewhere on the surface but it is not necessarily the case that they would be close at hand. Perhaps we will have a better clue after the EDL events have been fully analyzed, but at present, it appears that Spirit may have bounced a distance of a few hundred meters before coming to rest at Columbia Memorial Station (the new name of its landing site). By comparison, the same type of landing approach was used by the Mars Pathfinder spacecraft in 1997; that lander bounced a distance of about 1.2 kilometers before coming to rest. So in different scenarios, EDL hardware that fell to the surface may or may not be nearby.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
How big does a rock need to be in order for the RAT to be used on it?

Answer:
The RAT may be used on rocks that have a relatively flat surface with an area of at least 10 centimeters in diameter on which to place the RAT. However, there are many factors that the engineers from Honeybee Robotics (makers of the Rock Abrasion Tool) need to consider in order to determine the "RATability" of a rock. In addition to the size of the spot on the rock to be RAT'ed, engineers must consider the overall size and width of the rock, how well it is seated on the ground, the roughness and expected hardness of the surface, and a host of other factors.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
How do NASA engineers keep dust from building up on the lander/rover? Eric

Answer:
Spirit and Opportunity are not designed to control dust build-up on their solar panels. They are designed, however, to operate reliably for the duration of their missions (at least 90 Martian days) despite expected levels of dust build-up on the solar panels. There are methods that NASA engineers are developing for future missions. For more information see http://powerweb.grc.nasa.gov/pvsee/publications/mars/removal.html.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
Does the Rover have some sort of Compass to tell the direction, moreover does the compass point to a Magnetic North on Mars?

Answer:
Thank you for your very good question. The rover does not use a magnetic compass. The magnetic field of Mars is not strong enough to make this a viable approach. Instead, the rover uses a camera (in the mast on top of the rover) to find the sun. Given the location of the sun, time of day, etc, the rover uses software to compute its heading relative to true north. So its camera, acting as a sun sensor, serves as a compass (just not a magnetic one).

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
Will it be possible for Spirit to take any night pictures-maybe of Mar's moons?

Answer:
While it is possible for Spirit and Opportunity to image the late evening sky, night-time operations will be typically restricted to certain activities such as collection of certain science instrument data that requires hours to complete. The rovers operate primarily using solar energy and so most operations occur during daylight hours. While the solar panels energize the batteries, the batteries are used to power night-time operations. So night-time operations are expected to be limited.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
Will Spirit be observing Opportunity's entry and descent to Mars?

Answer:
Opportunity is landing on the opposite side of Mars from Spirit. Therefore it will be impossible for Spirit to see Opportunity's entry, descent and landing.

One of the reasons for having landing sites on opposite sides of the planet is that this allows for two operations staff here at JPL to work with each planet. If they were close together, than there would be a sharing of the Deep Space Network resources between the two rovers leading to less scientific return back on Earth.

Both spacecraft do communicate with one of the orbiting spacecraft during entry, landing and descent (either Mars Odyssey or Mars Global Surveyor). This communication is primarily event-driven as to what events have happened during entry.

Expert:
Terry Wysocky
System Engineer Senior
NASA Jet Propulsion Laboratory

Question:
I wonder what MER-1 will go to do in next days on rocks?

Answer:
I believe you are referring to Spirit which is MER-2 . Opportunity is landing in one week and has the designation of MER-1 (as it was the first one built, but second launched).

Two sols ago, Spirit egressed off the lander. It spent one sol doing instrument check-out. Yesterday, we commanded the Mossbauer instrument into the Martian soil to make measurements over night. We expect to see the Rover to move around the rover to look at some of the soil the next few sols. Scientists are naming and designating rocks they which to examine with the instruments.

Maybe within a week, Spirit will start moving towards the crater which I suspect will take several days as the Rover Planners will be very cautious on the drive. I expect the scientists will choose a few rocks to easing along the way.

After spending time at of the crater, the current plan is to head towards what scientists have called the East Hills. They are about 3-5 km away, and will be an exciting test for the rover.

Expert:
Terry Wysocky
System Engineer Senior
NASA Jet Propulsion Laboratory

Question:
From Paul: Will the rovers obtain a view of the moons of Mars during there stay? Such as a night view? Has that type of photo ever been done before?

Answer:
While the rovers can image the late evening sky, most night-time operations will likely be limited to certain types of science instrument data collection that takes hours to complete. The rover are powered mainly by solar energy and use most of their energy during daylight hours. While batteries are charged using the solar panel, the battery energy powers the limited night-time operations of science instruments.

There may be times during the mission where late evening images are acquired of the sky. This certainly was the case during NASA's previous Mars rover mission (Mars Pathfinder) in 1997. Mars sunset images from that mission can be seen at http://marsprogram.jpl.nasa.gov/MPF/ops/clouds_sunset.html.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
It's been said that the most dangerous distance for the rover to travel is the first few feet down the lander ramp to the surface of Mars.

When the rover is operating on Mars, what is the steepest slope the MER is going to be "allowed" to traverse?

Answer:
The MER rovers are designed to be stable on slopes up to 45 degrees. However, to remain conservative with respect to safety, the rovers will not be allowed (by mission operators or onboard software) to traverse slopes greater than 30 degrees.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
If dust collects on the solar panels, are there any methods for the rovers to remove the dust? For example semi-retracting the solar panels so the dust would fall off.

Have fun on the surface,
Mike
Ottawa Ont. Canada

Answer:
Dust will very likely collect and build up slowly atop the solar panels throughout the coarse of the mission. The rovers are designed to operate for at least 90 sols (Martian days) despite this inevitability. However, Spirit and Opportunity do not have solar panel dust mitigation features or functionalities as part of their design.

Possible solutions are under development for future missions such as methods based on electrostatics. For more information, see http://powerweb.grc.nasa.gov/pvsee/publications/mars/removal.html.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
Is Spirit and/or the Rover equipped with on-board weather station? I'd like to know what the temperatures, winds, etc. are like when Rover is out exploring! A related question is this: we always hear of the tremendous dust storms on Mars, but with the air pressure so incredibly low, how can the winds have any real force, even though they are high velocity?

Answer:
The rovers are equipped with many instruments to measure the temperature of the rover, it's instruments, and motors. This is to insure that we operate at safe temperatures. These devices in general also have commandable heaters to warm them up before use. The temperature on Mars may go as low as -70 deg C during the Martian night, and about 0 deg C at Mars noon.

We monitor temperature for safe operation. For example, the Warm Electronics Box which contains most of the electronic circuitry including processor will need to operate below +55 deg C below it autonomously shuts down. On the last sol, the prediction was +50 deg C during rover operations (due to the heat from electronics, etc).

Daily global weather maps can be provided by Mar Global Surveyor, in orbit about Mars sine the lat 1990's.

From a recent report from the MGS scientists, it was reported that "Dust plays the same role in Martian weather that water plays on Earth. Dust heats the atmosphere by absorbing sunlight and starts small storms that every few years merge into major weather events. Some years are dusty and some are not. We blame our wet and dry years on El Niño, but no such scapegoat exists for Mars. That is the mystery. Without oceans or another large heat reservoir that sloshes back and forth, every year on Mars should be the same as every other.

As during the Viking era, most of the dust storms occurred when Mars was closest to the Sun, which happens during the northern fall season. (We are presently approaching the late summer for Spirit). The largest storms started in the north and spread across the equator at speeds up to about 32 kilometers per hour (20 mph). During the Viking years the large dust storms started in the south, where it was springtime. Also, more storms started near the edge of the polar caps than during the Viking era.

You might want to view the Mars Global Surveyor web site at JPL for more information and pictures of dust storms on Mars.

Expert:
Terry Wysocky
System Engineer Senior
NASA Jet Propulsion Laboratory

Question:
Does the deploying of the experience of "SPIRIT" help and/or change the program of "OPPORTUNITY" on Jan.24th?

Answer:
We learn things from each Mars mission that help with future missions. The experience of SPIRIT will especially help OPPORTUNITY since these two missions are similar. We learned some new things with SPIRIT so far about retracting the air bags and about the composition of the soil.

Expert:
Janice Bishop
SETI Institute P.I.
NASA Ames Research Center

Question:
Does the deploying of the experience of "SPIRIT" help and/or change the program of "OPPORTUNITY" on Jan.24th ?

Junichi MAKI from Japan

Answer:
Spirit's successful landing does help in one big way. The rover team knows that the system does work. Your question is a good one, as the science team has asked the same question. Do we need to do the all the steps in the deployment of the rover to the surface (off the lander), or can we now skip some steps on the Opportunity rover. The answer, which is really the right one when you think about it, is that the procedures will stay the same. Even though these are "twin" rovers, the rovers are landing at different landing sites, experiencing different landings with different conditions (winds, etc), bouncing in on different terrains, and will have to go through complete systems checkouts prior to rolling off to the surface.

Expert:
Sheri Klug
Mars Space Flight Facility
Arizona State University
Tempe, Arizona

Question:
What happens to the rover when the mission is over? Does it come back to Earth? Do we somehow clean up after ourselves?

Answer:
We will continue to operate the rovers on Mars until they are no longer functional. We don't have the technology on this mission to send them back to Earth. They will remain on Mars until some future generation finds them.

Expert:
Diane Bollen
Education and Outreach Coordinator
Cornell University

Question:
What do you suppose is the evidence of life on Mars, in case the Microscope of "SPIRIT" is not able to recognize the really small Bacteria-like life?
Junichi MAKI from Japan

Answer:
SPIRIT has a camera and a number of other instruments, but does not have a microscope. The goals for SPIRIT and OPPORTUNITY are not detection of life on Mars, but characterization of the minerals in the rocks and soils that tell us information about the extent and duration of water on Mars. As water is thought to be important for life, we could gain indirect information that will help design future mission to Mars that more directly focus on the question of life.

Expert:
Janice Bishop
SETI Institute P.I.
NASA Ames Research Center

Question:
Will there be any video taken by the rover and sent back? If there is, when will that be available to the public?

Answer:
This mission is different from the Mar Pathfinder mission in 1997. That mission had a camera on the lander to take pictures of the Sojourner rover. On the Mars Exploration Rover mission, the rovers are the only ones to have cameras (9 in all). The lander has no camera, so we will never see a picture of the whole rover. In the images so far, you can see some parts of the rover (like parts of the solar panel). Also, the main plan of this mission was for the rover to leave the lander, so a camera on the rover would only have been good for a very short time. It would have taken up mass that could have been used for an instrument on the rover but would not have returned information except for a very short time.

Expert:
Sheri Klug
Mars Space Flight Facility
Arizona State University
Tempe, Arizona

Question:
Hi, I am Joshua Lam from Holland. Congratulations and I am looking forward for your second landing on Mars next week. My question: by dropping the Rover with the airbags, I understand that the rover will bounce a couple of times on the surface of Mars before it stands still. How is it possible that the Rover is standing at the right way as the panels unfolds? And why doesn't it happen to the Rover to turn upside down as the force hitting the surface is about 40G?

Much luck and success for the next advantages to Mars!

Answer:
Hi Joshua, Actually the spacecraft inside the airbags bounces many times, I believe the count on Spirit was 28 times before coming to rest. If the spacecraft is not on its base petal when it stops bouncing and rolling, it will right itself as the petals open. If you look at the animated video on www.athena.cornell.edu, you will be able to see this.

Expert:
Diane Bollen
Education and Outreach Coordinator
Cornell University

Question:
In that the unit bounces a lot, how do you make sure it settles down the way it should, and not be upside down or sideways when it stops bouncing?

Answer:
The lander was designed to be able to right itself, no matter what petal it landed on. If you watch the animated video on www.athena.cornell.edu, you can see this in action.

Expert:
Diane Bollen
Education and Outreach Coordinator
Cornell University

Question:
Will the soil PH be checked? Is there any equipment on the rover designed to check for metallics in the soil?

Answer:
pH is not being measured by the MERs; however, there is an instrument that measures the chemical elements in the rocks and soil (including metals), and an instrument called a Mossbauer spectrometer that can detect the state that the metal iron is in. This means whether the iron is in metallic form or an oxidized form such as rust.

Expert:
Janice Bishop
SETI Institute P.I.
NASA Ames Research Center

Question:
Why parachute, retrorockets and 360 air bags? Why not just a bigger parachute and a cushion on the bottom? Does thin atmosphere preclude this?

Also, what rights the lander if its last bounce leaves it upside down? And, are the airbags winched in after deflation? What separates them so they are no longer a cocoon?

Puzzled

Answer:
The entry, descent, and landing system for this mission was designed after the successful Mars Pathfinder mission in 1997. The atmosphere and gravity of Mars definitely determines what types of landing systems will work. The lander is designed to right itself as it opens, no matter which petal is down when it stops rolling. There are motors on the lander that retract the deflated airbags.

Expert:
Diane Bollen
Education and Outreach Coordinator
Cornell University

Question:
Given unlimited operating time, how far could the Mars Rover travel? How far can this vehicle be pushed? Are there plans to run it until it stops? I say, complete the tasks you set before yourself and then head for the horizon.

Answer:
The rover was originally tasked to travel about 1-2 kilometers. On a good driving day, the rover could travel about the distance of a football field at the speed of a giant tortoise (the kind you see at the zoo). There is a couple of factors that will impact how far the rover travels, overall. First, the scientists have planned certain experiments and observations that are necessary to get the important scientific results that they can use to better understand Mars. Secondly, the temperatures are starting to get colder, as the season is changing on Mars from summer to fall. If the scientists get their "mission success" results sooner than later, they can then drive farther and do extended science at sites farther away. With temperatures dropping and the solar panels getting dustier from the atmospheric dust settling on them (causing the solar panels not to be able to get as much energy from the Sun), the critical science must be obtained first.

Expert:
Sheri Klug
Mars Space Flight Facility
Arizona State University
Tempe, Arizona

Question:
Could we use either MER A or B to find Beagle 2 to see why its not transmitting

Answer:
Even though Mars is only 1/2 the size of Earth, Mars is still a big place. The Beagle 2 was landing on a large plain in the northern hemisphere of Mars called Isidis. Both of the MER rovers are landing thousands of kilometers away from where Beagle 2 would have landed. The rovers will not be traveling that far. Besides, both of the rovers have their own scientific work to do at their landing sites.

Expert:
Sheri Klug
Mars Space Flight Facility
Arizona State University
Tempe, Arizona

Question:
Why are the rovers missions only planed for 90 days? Why wouldn't they be used for a longer period of time?

Andy
Cleburne, TX.
Age: 29

Answer:
When you build a piece of space hardware you have to set target for how long you want it to keep working so you know how strong and durable to make the hardware. If you set it too long parts get heavier and more expensive, etc. You also need to set a target of how long the operations team is going to be up and running. We expect the rovers will last much longer than 90 days, but that's our target duration for the design and planning.

Expert:
Steve Collins
Attitude Control
Mars Exploration Rovers
NASA Jet Propulsion Laboratory

Question:
Is there a website showing the detailed agenda for Spirit? When various tasks will be performed? Live video from the control room as Spirit explores?

Answer:
The official website is http://marsrovers.jpl.nasa.gov/home/index.html.

A detailed agenda is hard to maintain since all activities are based on what scientists learn from prior activities and what new and interesting things are revealed in prior days. It's a day by day exploration adventure. However, there is an effort to develop a long term plan and right now it's focused on visiting a crater a few hundred meters away from Spirit's landing site, and then traveling toward what scientists have termed the "East Hills Complex".

Live video from the control, when active, can best be seen by watching NASA TV at http://www1.nasa.gov/multimedia/nasatv/.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
Why does Spirit have a limited life-span ? One would think it would operate indefinitely with the solar cells for power. Why can't it operate for years?

Answer:
Spirit and Opportunity have a limited life-span for a number of reasons. Regarding solar panels, they are not designed to keep dust from accumulating on top of the solar cells. Over time, enough dust could build up to significantly reduce the amount of power that the solar panel can generate. The rovers are designed to operate reliably for at least 90 sols (Martian days).

There are other factors such as limited life time of motors, for example, which are often limited in the number of revolutions they can perform before ceasing to work. This is particularly true for space hardware components that are specially designed to operate in the harsh and extreme environments (temperatures, radiation, etc) of space.

In addition, as the mission progresses, Mars will move further away from the sun and therefore will provide less and less solar energy for the rovers to operate. These and a number of other factors all contribute to the limited life-span of Spirit and Opportunity.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
How do NASA engineers keep dust from building up on the lander/rover?

Answer:
What an excellent question! Actually, we haven't really solved that problem yet, though many solutions have been proposed. Among the more exotic include a windshield wiper, electromagnets to repel the charged dust particles, blowers, etc. The MER rovers do not have any dust mitigation devices, so we're at the mercy of the Martian atmosphere. That's one reason the mission may only last the planned 90 Sols (92 Earth days), because accumulating dust on the solar panels decreases the available electric power for the rover. The Sojourner rover, in fact, lost about 1% of its available electric power each Sol during its months-long mission.

Thanks for an excellent question!

Expert:
Todd Barber
Propulsion Engineer
Mars Exploration Rovers
NASA Jet Propulsion Laboratory

Question:
What are the major factors that will limit the life of the rovers, and how likely are they to exceed those limits just as the Galileo probe and many other missions have done?

Answer:
One of the major factors that could limit the life of the rovers is dust accumulation on the solar panels -- their primary source of energy. The rovers are deigned to operate reliably for at least 90 Martian days (sols) even with dust accumulation. The likelihood of them lasting longer depends on the dust activity at their landing sites. It is likely that they will last longer thatn the minimum mission lifetime.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
What kind of wind will Spirit have to endure?

Answer:
On the surface, Spirit will be just find. It is designed for a 90 day mission. During landing, we found low winds of around 20 kts which were not expected. These were countered by our small attitude control rockets, which were designed for this purpose, and increase the probability of a successful landing.

From the Viking era, the largest dust storms measured were about 30 miles/hour.

Expert:
Terry Wysocky
System Engineer Senior
NASA Jet Propulsion Laboratory

Question:
Will spirit be able to capture sunrise and sunsets? I find Mars very interesting...and would love to see a Martian sunset or sunrise thank you..Sid Ft. Lauderdale, Florida

Answer:
Yes, of course! There is also an interesting press release, sol2 or sol3 showing the Sun captured by Spirit's cameras. Check mars.jpl.nasa.gov

Expert:
Paulo Souza
PDL Mossbauer
NASA Jet Propulsion Laboratory

Question:
How long does it take a signal to travel from here to Mars ?

Answer:
The signal at landing in Gusev Crater was taking 9.46 minutes (that is traveling at the speed of light - 186,000 miles per second). Mars has since been moving away from Earth and the signal time is (at this time) nearing 11 minutes.

Expert:
Sheri Klug
Mars Space Flight Facility
Arizona State University
Tempe, Arizona

Question:
Is there a chance Opportunity will not survive its landing on Mars?

From Tyler

Answer:
Hi Tyler, We certainly hope that Opportunity's landing is every bit as smooth as Spirit's landing was. The entry, descent, and landing systems on both spacecraft were identical. There is always the remote possibility some anomolity will happen, but we have every reason to believe Opportunity will be successful.

Expert:
Diane Bollen
Education and Outreach Coordinator
Cornell University

Question:
My question is why wasn't one of the landing sights on the north or south polar cap regions of Mars? If water is what we are looking for, isn't there a lot of ice there? Wouldn't this ice have a good chance of having the presence of water?

Answer:
The airbag landing approach is most successful on landing sites which are less rocky. The airbags used several layers to protect them, but even them it is not uncommon for tearing on the outer layers.

We believe the polar landing regions require a different lander to increase the success of a landing there. There are currently in design, and your right, we do want to look closely at the polar caps.

Expert:
Terry Wysocky
System Engineer Senior
NASA Jet Propulsion Laboratory

Question:
If the rover finds evidence of biological traces, will it be able to re-direct its focus and concentrate on the find? Is it capable to adapt to a "new" mission?

Answer:
The rovers are designed to primarily for geological science and don't really have "biological" instruments onboard, but they are very flexible science platforms and can be re-directed to any task that the science team finds scientifically interesting. If, for example, they found something that looked like lichen growing on a rock, I'm sure we would use every capability of the rover to investigate.

Expert:
Steve Collins
Attitude Control
Mars Exploration Rovers
NASA Jet Propulsion Laboratory

Question:
After the mission is over, can you send Spirit to look for Beagle 2?

Answer:
Afraid not. The present plan from the scientists is to head east. Beagle 2 is about one-fourth around the planet of Mars in a westerly direction. Spirit is not designed to cover such a distance and any obstacles that may be between it.

Expert:
Terry Wysocky
System Engineer Senior
NASA Jet Propulsion Laboratory

Question:
How long will the Spirit stay on Mars? When will it land back on the earth?

Answer:
Spirit will stay on Mars forever. NASA does not bring back these rovers to Earth. Someday, when astronauts visit Mars, they will visit these rovers and perhaps bring some parts back to be put in our museums.

Expert:
Sheri Klug
Mars Space Flight Facility
Arizona State University
Tempe, Arizona

Question:
What is that round rock in front of the landers arm? it looks like it has a hole in the center of it. it does not look like any other rock in the area.

Answer:
It seems to be a hole there. It is common in volcanic rocks (vassels).

Expert:
Paulo Souza
PDL Mossbauer
NASA Jet Propulsion Laboratory

Question:
We can see round rocks in gusev crater, how could they have formed without water being present?

Answer:
It turns out that you don't have to have flowing liquid water to form round rocks. There is a geologic process called "spheroidal weathering" that operates on certain kinds of rock. If you take a rock cube and expose it to weather (even just traces of water vapor like those found in the martian atmosphere), the sharp corners and edges tend to get crumbly and flake off faster than the faces. This makes the rocks get more and more round with time.

Expert:
Steve Collins
Attitude Control
Mars Exploration Rovers
NASA Jet Propulsion Laboratory

Question:
How does the Spirit land on Mars? Is it flat flying through space, or is it all folded up like in a ball? Does it just land straight from the air, or does it have to roll around on the planet.

Answer:
The rover is "folded" up inside the lander as it travels from Earth to Mars. The lander has four triangular petals. The rover is attached to the base petal and the other three petals are hinged to this and folded up to form a tetrahedran. The lander is then placed inside the heat shield and back shell, part of the criuse stage. Once it reaches Mars, the cruise stage separates, parachutes deploy and slow the descent. The lander is lowered on a bridle and airbags are inflated. Retro rockets slow the space craft a bit more and the lander is released. It bounces on its airbags, and rolls until it comes to a stop.

Expert:
Diane Bollen
Education and Outreach Coordinator
Cornell University

Question:
Will the Micro-imager on board the "Spirit" rover be able to image any possible fossil remnants that may be present in the Gusev dry lake bed?

R. Mark Elowitz, Albuquerque, New Mexico

Answer:
This depends on the size of the fossils. If fossils the size of sea shells are present, then the imager would be able to see them; however, if only microorganisms are present, then these would be too small. The imager was not designed to detect life or fossils, but to characterize the texture and grains of the rocks.

Expert:
Janice Bishop
SETI Institute P.I.
NASA Ames Research Center

Question:
If I understand correctly, Spirit has the capability of digging holes under the soil so we can take pictures and send them back. How far down can the wheel(s) on Spirit dig down?

Answer:
Spirit and Opportunity cannot exactly dig holes as you described. They have a tool on a robotic arm called the Rock Abrasion Tool (RAT). The RAT can abrade a shallow hole of about 5 millimeters deep into a rock. In addition, a rover wheel can be used to trench (similar to digging) a wheel-sized hole in the soil about 10 cemtimeters deep. In each case, pictures of the hole and spectra of the exposed rock or soil can be acquired by the rovers' cameras and science instruments.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
Are the Mars 'dust devils' any threat to the rovers?

Answer:
Thanks for your very interesting question! As it turns out, the Martian atmosphere is so rarified that dust devils are no trouble for our landed missions. In fact, the Mars Pathfinder mission measured the effects of a dust devil passing directly through! The wind speeds can get pretty large on Mars, but with such a thin atmosphere, there is very little force to the wind to cause any damage.

Thanks for an awesome question!

Expert:
Todd Barber
Propulsion Engineer
Mars Exploration Rovers
NASA Jet Propulsion Laboratory

Question:
How do you control the Spirit from the Earth? Is it anything like controlling a remote controll car?

Answer:
Hi! Thanks for your excellent question. We control Spirit quite differently than a remote controlled car, largely due to the communication delay. The round-trip radio communication time to Mars, even with radio signals moving at the speed of light (186,000 miles per second!), is between 6 and 40 minutes! Imagine playing a driving video game where it was 6-40 minutes before you knew the results of your actions!

Clearly, a different strategy is needed for Mars. Generally, the scientists will look at the results from a given Martian day. They will make their plans for the next day, based on their results, and then tell the engineers. During the Martian night, the engineers will build the sequences to accomplish the science objectives of the next day.

Within this framework, Spirit is pretty clever, too! It knows to steer around large rocks, not drive off a cliff, etc. It uses its own cameras and fancy software as a form of artificial intelligence.

Thanks for your great question!

Expert:
Todd Barber
Propulsion Engineer
Mars Exploration Rovers
NASA Jet Propulsion Laboratory

Question:
It was mentioned by Steve that the rover was designed for a maximum distance of 600 meters of traveling from the base. My question is how was this figure attained and why since it is operating independently from the base.
Thanks

Answer:
The distance mentioned by Steve is actaully a mission goal for traverse distance. The rovers may actually travel farther and are certainly capable of doing so. It all depends on how each mission unfolds. The rovers will trvael where the scientists need them to go based on observations made on a daily basis. But there will be a concerted effort the achieve the traverse distance goal in the very least.

The NASA Mars Pathfinder mission of 1997 included a rover named Sojourner that depended on its lander (base) which had a number of science experiements and cameras on it. Sojourner relied on the lander for communicating with Earth and as a result, Sojourner could only explore in the relative immediate vicinity of the lander due to limited communications range. The MER rovers include the science instruments, cameras, and communications equipment all onboard and do not depend on the lander. This way they can travel much further distances and achieve broader coverage since they are self-contained.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
Can you describe the Spirits current activity,what it does, what functions it performs, and can u list any sensors it uses? Thank you!

Answer:
Yesterday we used the rover's robot arm to place a science instrument on the Martian soil. It is sitting there right now, collecting data. It will tell us information about the chemicals and minerals in the soil that will help us understand more about Martian geology.

Tonight, we'll do a "tool swap", flipping over the rover's "wrist" to place another instrument down on the soil. In addition to these chemical instruments, we have cameras that can take pictures in lots of different colors and an "infrared spectrometer" that takes color "heat pictures" of martian rocks. In these "heat pictures" (infrared spectra) different minerals show up as unique different colors. You can basically drive around tell what minerals the rocks are made of by looking at these pictures. There is a grinding tool called "The RAT" that can grind the crust off the surface of rocks so we can look at the inside, and a microscope so we look at rocks and dirt up close.

Question:
Where will the first man on Mars live in when he is on Mars?

Answer:
The answer to your question is not known precisely yet. However, many think the the most logical place would be an outpost with special habitats (buildings designed with life support systems for humans), perhaps underground. Some believe that robots could be used to build such habitats for astronauts before the ever arrive on Mars.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
Dear Sir / Madam,

How Marsrover fire rockets to tune and hit the bull eyes ? I don't understand in the mission status.

"The spacecraft is spinning at two rotations per minute. The maneuver began with a 20-second burn in the direction of the axis of rotation, then included two 5-second pulses perpendicular to that axis."

Best Regards Patrick Lam from Hong Kong

Answer:
There are many parameters that go into the calculations on hitting the "bulls eye" There is a wonderful article at http://marsrovers.jpl.nasa.gov/spotlight/navTarget01.html that describes exactly how this was done.

Expert:
Diane Bollen
Education and Outreach Coordinator
Cornell University

Question:
Is it possible to paint the sections of the airbags different colors to enable them to know what position it has come to rest? Thank You, Rick Duenas San Francisco

Answer:
Although it would be possible to make the airbags different colors, we would have no way to see the colors. We rely on tones sent back to Earth from the space craft to know what condition it is in after it lands.

Expert:
Diane Bollen
Education and Outreach Coordinator
Cornell University

Question:
Looking at orbital views of Gusev crater from MGS show the eastern hills to look like their remnants of uneroded sediments that were deposited over billions of years..am I right in sayingthat these hills could be THE place where to look for layers formed when the site was submerged under water?Also these layers should be relatively preserved to what we're actually seeing right now because the landscape where Spirit is right now has been modified by cratering and dust depositions by winds.Is my line of thought correct?

Answer:
Some scientists have said the same things you mentioned, which is why this is in the plans for the Spirit to get there after visiting the nearby crater. The layers is one area of high interest among scientist.

Expert:
Terry Wysocky
System Engineer Senior
NASA Jet Propulsion Laboratory

Question:
Why such a limited lifetime? I certainly haven't done all the math, but it seems to me that using solar panels and lithium polymer battery technology, the mission lifetime could be greatly extended.

Answer:
The estimated lifetime of the rovers is the engineers best guess given what we know about the technology of the rover systms, the environment of Mars, and Mars orbit around the Sun. As the solar panels collect dust from the martian atmosphere, the ability to generate power will diminish over time.

Expert:
Diane Bollen
Education and Outreach Coordinator
Cornell University

Question:
Do you have a built-in system for Spirit to blow off dust if it becomes a impeding factor for the cameras to operate? Thank you very much and your collective works are awe-inspiring, Congratulations.

Answer:
We don't have a specific method for removing dust from the rovers. We do however have specific operation guidelines for using the instruments that are designed to keep them as clean as possible. Also, the microscopic imager has a dust cover, to protect it from dust generated by the RAT or the wheels.

Expert:
Diane Bollen
Education and Outreach Coordinator
Cornell University

Question:
I was looking at the tech specs on the Sprit, but saw nothing about its top speed, range nor other physical characteristic.

George

Answer:
Hi George,
Each rover is designed to travel up to 100m per Sol. It will likely not go that far each day, becasue we will stop to do science. Its top speed is 5 cm/sec, with hazard avoidance on, it will travel more slowly. For more information, go to http://marsrovers.jpl.nasa.gov/home/index.html or www.athena.cornell.edu.

Expert:
Diane Bollen
Education and Outreach Coordinator
Cornell University

Question:
How long does it take the radio signal to get from Earth to Mars

Answer:
The one-way light time is currently about 12 mintues. As the mission progresses that time will lengthen to almost 20 minutes.

Expert:
Diane Bollen
Education and Outreach Coordinator
Cornell University

Question:
Are the scientists arguing about where they want to explore and if they are will it slow the mission down?

Answer:
There is a special way that the scientists have set up this mission to allow every team member's ideas and opinions to be heard and discussed without slowing down the mission. Every sol ( a martian day lenght - 24hrs, 40 minutes), a series of meetings take place. All the scientists attend these meetings. The first is a science context meeting, where general ideas about the landing site and overall science is discussed...what do we know about this site? What do we want to know? Next is the science downlink meeting. What information did the rover send back on the experiements it did the sol before? The information is then discussed at that meeting. Next is the Science Operation Working Group meeting where all the next day's activities are decided by what they discussed and learned in the previous meetings that sol (all the science team is living on Mars time, not Earth time so they can be awake when the rover is awake). Then, if there is anything left to discuss, there is an end of the day science meeting. This is a very efficient way to make intelligent decisions with all the Mars experts having their input and not slowing down the process at all. This happens every day and soon will happen twice, as the teams will be splitting between two landing sites.

Expert:
Sheri Klug
Mars Space Flight Facility
Arizona State University
Tempe, Arizona

Question:
Is it possible that their may be a quicksand type of soil on Mars and if so would the Rover be able to detect that danger? From Ms.Hoffman, Los Angeles City School Teacher

Answer:
It is possible for Mars to have terrain (such as dust pits) in which the bearing strength (ability to support a load) is insufficient to support the rover. The rover's sensors could not detect such soil or the apparent danger of getting stuck in it. We rely on geologists here on Earth who are part of the mission operations team to identify such areas of potential danger (that is undetectable by the rover itself), and we command the rover in such a way as to avoid traversing into those areas.

Expert:
Eddie Tunstel
Senior Robotics Engineer
MER Mobility/IDD Lead Engineer
NASA Jet Propulsion Laboratory

Question:
How long did it take for the Spirit to get to Mars from the earth?

Answer:
Seven months. We launched on June 10, 2003 and arrived on January 3.

Expert:
Diane Bollen
Education and Outreach Coordinator
Cornell University

Question:
Will we see any live feeds as the rover does manuvers?

Answer:
Since the time it takes for a signal to go from Mars to Earth is around 11 minutes (traveling the speed of light: 186,000 miles per second) there can be no live feed. The distances are just too far.

Expert:
Sheri Klug
Mars Space Flight Facility
Arizona State University
Tempe, Arizona

Question:
If Opportunity does not land on Mars, will your plans change? Shahan, from Kilmer School in Chicago

Answer:
We have every reason to believe that Opportunity will land as planned. In any event, we will continue to collect data with Spirit.

Expert:
Diane Bollen
Education and Outreach Coordinator
Cornell University

Question:
Did we take precautions to disinfect all equipment of the lander so not to contaminate the Mars surface? If yes, how did you do it. Also, do any of the staff think that life of any form is now on Mars?

Answer:
Yes. NASA has a Planetary Protection Office for such purpose. For example, there is a possibiliy of very simple life forms on Jupiter's moon Europa. The Galileo spacecraft ended its mission last year, and was intentionally sent into Jupiter to avoid any future contact with some of the moons.

As for the rovers, they are wiped down (think of alcohol wipes for example) during assembly before entering the clean room to minimize any contamination.

Expert:
Terry Wysocky
System Engineer Senior
NASA Jet Propulsion Laboratory

Question:
Are there any audio devices onboard the rovers if so can you here any sounds from the surface of mars.

Dave Sydney Australia

Answer:
No, we don't have any sound equipment, but it might be a good idea for future missions.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
Is there any plans for helping find the failed Dec.25th(?) landing?

Andy
Cleburne, TX.
Age: 29

Answer:
There are no plans. Beagle landed about one-quarter of the planet from Spirit towards the West. The long-range plans for Spirit is to head towards the Eastern hills.

Expert:
Terry Wysocky
System Engineer Senior
NASA Jet Propulsion Laboratory

Question:
How do you ensure that the rover will land right side up on Mars?

Answer:
The center of gravity of the lander makes the lander have a preference for right side up, but it can open the lander petals in any orientation and come out right side up.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
What did you found about Mars ?

Answer:
We are at the very beginning of our investigation about Mars. One preliminary measurement hints at the mineral Carbonite at the landing site. Carbonite can only be produce when water was present. Stay tuned for more!

Expert:
Terry Wysocky
System Engineer Senior
NASA Jet Propulsion Laboratory

Question:
Do you think it would be better to send two rovers to each sites (in a single delivery ship), so you could cover more areas?

Rao

Answer:
No, the logistics of operating two rovers simultaneously would be extremely difficult. We will have two rovers on opposite sides of the planet so that when one is working during the Mars day, the other is at rest for the night. Getting all the data back would be difficult if they were at the same location.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
About how fast do the MER's travel and how far do scientist expect them to get during the course of the mission? Are additional rovers being planned for Mars that will have even better capabilities?

Answer:
They travel about as fast as a turtle. We expect them to go about 1000 yards in 90 days. Scientists want to spend a lot of time imaging rock formations and not so much time driving. In 2009 we will be launching an even larger rover.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
I have heard that the rovers will only operate for about 3 months, until the solar panels get too covered in dust and the sun is at too low an angle to provide enough power for the rover. If the rover does not suffer damage from the wind or freezing, what are the chances of reviving the rover in a year when the solar conditions are the same as they are now?

Answer:
They won't be able to be revived. The rechargable batteries would be completely dead by then and wouldn't be able to be recharged.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
I'm aware that ESA is "recycling" the design for the Mars Express in their upcoming Venus Express. Is our space program looking at the possibility of reusing successful designs in this manner? Possibly a Lunar Exploration Rover or a Mercury Exploration Rover.

Answer:
Yes, we try to build on history as much as possible, but changes are always inevitable.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
Are there differences in the science goals between the both rovers? What is the microscopic camera for?

Kind regards,

Thomas Suchan
Space Exploration Enthusiast ;-)
Hannover, Germany

Answer:
The goals are essentially the same for both rovers. The microscopic camera can take pictures of the rocks much the way a field geologist uses a magnifying lens to identify the structure and composition of rocks and soil.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
In comparison to a home computer, how much computing power do the rovers have?

Earnie
Hampton, GA

Answer:
Probably about 1/10 the power. Remember, we don't need to deal with Windows and computer viruses!

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
What is expected to be the failure mechanism for the Mars Rovers.( What will likely limit their life/mission on Mars?)

Answer:
Same as your car: A dead battery will end it all.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
Why haven't you made or equiped a rocket on the mars landing rover station that will send back mars earth samples back to earth?

Answer:
We started on this kind of mission several times before but it gets to be too expensive and NASA isn't ready to pay for it yet.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
How long will the two rovers stay on Mars?

Answer:
They are planned to stay there forever, but operate for at least 90 days.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
Can the rover turn over rocks to see if the bottom is different from the top?

Answer:
It might be able to turn over small rocks with one of its wheels. But I don't think they're planning on doing this.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
Are the two rovers (Spirit and Opportunity) going to work with each other or independently of each other? If together, how do the rover communicate?

Answer:
They will be on opposite sides of the planet. So they will work independently.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
A dust storm could deposit dust on the solar cells rendering the rover useless once battery power fails. Why isn't there a procedure for removing dust from the solar cells permitting the rover to be used until some mechanical failure?

Answer:
You are correct that a dust storm could deposit dust on the solar panels. Scientists have and are looking at the global views of Mars to be able to detect any such storms brewing that might impact any of the landing sites. If a storm does indeed blow in, the panels would be affected and the power would be minimized. There is also the effect of atmospheric dust that is already sifting down onto the solar panel on a daily basis. Scientists have planned for this degrading over time of the power from the panels and have planned their sequences for the science accordingly. The solar panels cannot be cleaned easily. Students often ask about windshield wipers. This method would scrape the surface of the solar panel and make them even less efficient.

Expert:
Sheri Klug
Mars Space Flight Facility
Arizona State University
Tempe, Arizona

Question:
I chose this topic as closest to my question, which really is specifically about the analytical approach.

What is the size of the area analyzed by the APXS, and what are the approximate detection limits you seek for the EDS and alpha-particle spectrometers?

Thanks!

Jim

Answer:
You should check out the website at Cornell University to get the details on the instruments you mentioned. you can even write to the scientists who build them.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
Hi, from the information sent by instruments on the mars rovers, to what extent do you think we will be able to understand..at what time in the planets history (and for how long)water may have flowed in the Gusev region and if it did, is it possible that the rovers (certainly 'spirit')may encounter evidence of fossilised life during this very exciting voyage of discovery? from marko :)

Answer:
We use pictures to provide context for the rocks and geologic feaures and a spectrometer to tell us what minerals are present. The minerals form under different conditions, some requiring water for formation. Minerals such as carbonate and clay are thought to require water. Spirit has detected some spectral features that may indicate that carbonate is present. Scientists need to analyze the data further and compare the spectral features with a number of minerals in a spectral library to confirm this result. We will be using the mineral data and the rock context data to try to understand the extent and duration of water on Mars. We are just beginning to receive this new information now and will learn more each day that the mission progresses. If fossils are present in the surface material (or near the surface) examined by the micro-imager and the fossils are large enough, we should see them. Part of the problem is knowing where to look. More interest will be placed on rocks that appear to exhibit sedimentary properties. The micro-imager can see a few times greater than our eyes, but not as small as a microscope in the lab.

Expert:
Janice Bishop
SETI Institute P.I.
NASA Ames Research Center

Question:
With solar panels, why will the rovers "die"? Thanks, Daryl.

Answer:
As the Mars summer fades into fall, the solar panels will get less energy. Eventually, there won't be enough energy to keep the rechargable battery from freezing. When that happens it will be unable to wake itself back up even the following summer.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
I am an old "Space Bunny" from the 50's. We use to keep the un-informed aware of Space and Space travel. My question refers to the naming of the MER's, to give them an identification that we all can associate with. I suggest "Wasp" and "Hornet", which seem appropiate to their shape, and mission.

Answer:
Yes, we felt the same way that they looked like a big fly. NASA held a name the rovers contest last year and had thousands of entries. I'm sure wasp and hornet may have been among them. But it was won by a 10 year old girls essay on why they should be named Spirit and Opportunity.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
Does the rover's camera(s) have sufficient magnification to see micro-fossils such as tiny sea shells?

Answer:
If fossils are present in the surface material (or near the surface) examined by the micro-imager and the fossils are large enough, we should see them. Part of the problem is knowing where to look. More interest will be placed on rocks that appear to exhibit sedimentary properties. The micro-imager can see a few times greater than our eyes, but not as small as a microscope in the lab, so whether or not the micro-imager can see them depends on how big they are.

Expert:
Janice Bishop
SETI Institute P.I.
NASA Ames Research Center

Question:
Hello,

The viking landers used a nuclear thermo-electric power source, which allowed them to run for well over a year in the martian environment.

Why were solar panels used on the exploration rovers? If a nuclear power source were used instead, what would be the likely cause of the end of the mission? I understand the current mission is limited by waning daylight during the "winter" months, dust covering the solar cells, and a limited number of recharge cycles for the battery pack.

Thank you for your time.
Brent Picasso

Answer:
Cost of nuclear power is a major reason why we didn't use them for this mission. Time was another factor. We only had 3 years to design, build and launch the rovers and it takes at least 5 years to develop a vehicle to deal with the complexities of nuclear power. If nuclear power were used for a mission the end would probably be a result of fatigue on the instruments going through such drastic temperature swings every day. In 2009 we are planning to launch a nuclear power rover.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
Since the prior polar probe mission failed, why not send Opportunity to one of the poles?

Answer:
Scientists are more interested in looking for the precursers to life than anything else and they believe that features near the equator might be better candidates for finding such life clues. Power availability for the rovers was another issue.

Expert:
Mike Pauken
Thermal Engineer
NASA Jet Propulsion Laboratory

Question:
I have an interest in what 'it sounds like' on Mars but have heard nothing about audio data being captured nor returned to earth. Is there a microphone on the rover? If not what considerations prevented it? If a rock drops on Mars but there is no one there to hear it... does it make a noise? Bruce, Michigan

Answer:
Scientists and the public alike have been interested in this question. The Planetary Society actually funded a microphone instrument that was part of the Mars 1999 Lander. This spacecraft was scheduled to land near the south pole of Mars, when it was lost. Communication was never established with the lander. The microphone was the first sound experiment ever attempted at Mars and will probably not be the last. As for the sound you would hear on Mars, Mars has about 1/100th the atmosphere as Earth. Sound would be greatly reduced, as there would not be as many air molucules to propigate the sound waves.

Expert:
Sheri Klug
Mars Space Flight Facility
Arizona State University
Tempe, Arizona

Question:
How can I buy one of those NASA Rover izod-type shirts you guys where on the panel? I would love a sweatshirt with the logo of the rover on it.
Thanks,
Roxy

Answer:
Mars Rover polo shirts, jackets, etc. can be found at the JPL store (or I suspect at other Nasa center stores). You can buy some merchandise on line at

http://www.bookstore.caltech.edu/JPLLAB/DEFAULT.ASP

There have been some special designed shirts made by a few which are not available for purchase (such as the one seen at one of the press conferences saying "My other car is on Mars." One would have to find the artwork (if available) and use iron-on transfer.

Several people have asked about the t-shirts you, I and Sofi have, and wanted to know where to get them. I made them myself, so they are not commercially available. But if anyone wants to make their own version, I have put the artwork on DocuShare in collection #237. The artwork for both the front (My other car ... is on Mars!!!) and the back (... and so is her sister!!!) are there. It is already reversed, and ready to go. To make the shirts, people just have to get some iron-on transfer paper (available at Office Depot and other office supply stores), and a high-quality t-shirt. Print the artwork on the transfer paper on an ink-jet printer, iron it on to the t-shirt, and voila! Once custom shirt ready to go.

If anyone asks, just let them know where to get the artwork, and they should be good to go.

Expert:
Terry Wysocky
System Engineer Senior
NASA Jet Propulsion Laboratory