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Launch Director's Duties / Mars Rover
Stephanie
from Edmonton,Canada
Since the only cameras are on the rover itself, will you
have any way of showing what the rover looks like roaming
on Mars? (i.e., will you be using digital animation to
give the public a feel for what the rovers look like on
the surface?) |
| Squyres:
Well, there are a couple ways we can do that. One thing,
of course, is that the rover can actually take pictures
of itself. Those cameras are mounted high on the mast
and if they look down or around they can get a very good
view of the solar arrays. We've also got some nice
cameras out in front that will actually show the arm nicely
as it deploys. So we will actually be able to do a fairly
good job of photographing the rover ourselves. We probably
will try to do some digital animations as well. We have
made some animations already of what we think the rover
is going to look like as it drives around Mars, and I
anticipate once we get real Mars data we will continue
with that. |
Stephanie
from Edmonton,Canada
When Opportunity lands at Meridiani Planum, what will
you do if it lands far away from the hematite? If you
find olivine at either of the two rover sites, would that
change the scientists' theories about the sites? |
| Sqyures:
Well, with respect to what we would do if we found we
weren't near hematite, that's the reason why
we have wheels. There is definitely a possibility that
there will be no hematite bearing rocks that are within
easy and immediate reach, but we have got a lot of ability
to drive this rover. We can drive for hundreds of meters
across the surface if we need to, and so we can look off
into the distance using our instruments, find where we
think hematite bearing minerals are and then actually
drive over to them. With respect to olivine, actually
I don't think that will change things too much.
Olivine is a mineral that is found in a lot of very common
rocks. Basalt, which is a common igneous rock, has olivine
in it. And we expect a lot of that stuff to be there.
The question is not what are the main rocks, the volcanic
rocks and so forth; the question is what are the trace
minerals, the minerals that are present in lower abundances,
and how much of those there are, because those are the
ones that are more likely to tell us about water. |
Stephanie
from Edmonton,Canada
What is the difference between Terra Meridiani and Meridiani
Planum? What is the correct name of the landing site? |
| Squyres:
The correct name of the landing site is Meridiani Planum.
Terra Meridiani is an old name; it's one that's
been around since very early in the days of Mars exploration
and it refers to the whole broad Meridiani region. Meridiani
got its name from the fact that the zero degree line of
longitude, the meridian on Mars, runs right through that
location. So that big area near the equator is called
Terra Meridiani - the specific plateau or plane,
which Latin for plane is planum, that we're landing
on - is called Meridiani Planum. So that is the
right name for the landing site. |
Stephanie
from Edmonton,Canada
During the launch of MER-A, at about T+15 through to T+30
seconds, there appeared to be a splattering of a liquid
onto the onboard camera. Was that bychance the rocket
going through the clouds? |
| Baez: No, Stephanie.
What we have is, if you notice the Delta II rocket before
we tank it, it is actually a nice teal blue color. When
we tank it, it turns a nice white frosty color, and there's
a reason for that. We load the first stage up with liquid
oxygen, which is at minus 300 degrees Fahrenheit, and
we form a frost coating over the first stage, or ice actually.
If you look at the tape when it rolls initially, right
at launch, you will notice a lot of ice coming off. What's
going on in that first couple of seconds is, as we're
rising, some of that frost on the launch tank is melting
off and that is the precipitation you see forming on the
lens of the camera as it came over the fairing on the
first stage camera. |
Richard
from Arcadia FL
Will using the RAT cause any problem with dust on camera
lens or instruments? |
| Squyres:
We're pretty confident that it won't. This
was something that we thought about a lot as we were designing
this payload. In fact, the first version of the RAT actually
had what we called a dust skirt. There was a fabric skirt
all the way around the outside of it, and the idea of
that was to prevent pieces of dust and particles from
getting thrown off by the RAT. What we found out, though,
was that when we actually tested it, what that did was
it kept so much of the dust inside that the dust would
fall back into the hole and we couldn't see what
we were looking at. So what we did was, we did a bunch
of tests where we actually took a rock abrasion tool,
the real instrument itself, put it into a vacuum chamber,
pumped most of the air out of it, and took it down to
the kind of atmospheric pressure we'll have on Mars,
and ran it. What we found was the cuttings, as we call
them, flew in directions that would not impact the camera
and so we really feel pretty safe that we will be able
to use that. So we took the skirt off and we're
going to let the particles fly. |
Peter
from Leipzig
Is this a hope for a future manned crew to Mars? I hope
that and I think it's the next step into space for mankind. |
| Baez: Peter,
absolutely this is a future hope for a manned crew to
Mars, although I don't think it's the next
step. For me to stay in business, we've got to launch
a couple more of these robotic missions, but it sure is
one of the steps in getting there, to make sure that we
are going for the right reasons, and it's one of
the many steps. There are other things we want to do out
there past this geological mission and this is one of
those steps in getting there. |
Rich
from Elk Grove, IL
What steps are in place to handle a rover that does not
respond correctly to the commands it is given? Is there
a possibility of the rover doing its 'own thing'? |
| Squyres:
Well, certainly we do have situations where the rover
does not respond in the way that we expect it to when
we send it a command. The rover is basically run by a
computer. One thing you learn about computers is they
don't always do what you expect them to; they do
exactly what you ask them to, even if what you asked them
to do is wrong. What we have done, though, is we've
put into the rover at very fundamental level in the software,
what we call fault protection. There are circumstances
where we can accidentally ask the rover to do something
that would hurt itself and the rover will reject that
command. The rover is, we found in some instances during
the testing, a bit smarter than we are. So what we have
done is set it up so that if there is an invalid command
that is accidentally sent, despite many checks and balances
that we have along the way, it will be rejected by the
rover and that is something that we have tested very extensively.
So I feel pretty confident that if we tell it to do something
bad it won't do that. As far as doing its own thing,
the software really isn't set up to allow it to
do that, fortunately, so that is not something we worry
about. Host: I have heard you mention in another presentation
I saw that it basically tells you, ok; I'm here,
now what?
Right, and in fact, it also has built into it the ability
to know when it gets into trouble. The rover, you don't
want it to tip over for example, so one of things it's
got is its got the ability to tell which way is up and
which way is down. If the rover ever got tilted more
than about 45 to 50 degrees it actually could flip over
which obviously would be a bad thing. So what we've
done is we've built into the capability that if
it gets to a rock and it ever senses that it's
tipped as much as 30 degrees, which is still far short
of the danger zone, at 30 degrees it will just freeze.
It will just absolutely stop, take a set of pictures,
and send the pictures back and say help me, I'm
in trouble and what do I do. So it knows when to quit.
|
David
from Winter Springs
What is your spaceship's name going to be? |
| Baez: The
spaceship's name is going to be Opportunity, and
this was one of the names that a little girl came up with.
The first one being Spirit, the second one being Opportunity. |
Russ
from Yuba City, Cali
Will JPL/NASA labs be monitoring both rovers at the same
time? Will the public be able to see both rovers working
at the same time? Split screen stuff? |
| Squyres:
Well, we will certainly monitor both rovers at every chance
that we get. But the thing you have to realize is that
the two landing sites that we have chosen are on opposite
sides of Mars from one another, they are 180 degrees apart
on the planet. And so when one of them is visible from
the earth, the other one is out of sight on the other
side of the planet. When one of them is in sunshine and
the rover is active, the other one is in darkness and
the rover is asleep. So even though they will both be
on Mars simultaneously, they're never both active
at the same time, just because they are on different parts
of the planet. |
Peter
from from Basel SWISS
When Spirit and Opportunity land on Mars, how long will
we need to wait for the first photo? |
| Squyres:
It takes a little while, because when the rover first
touches down, there are a bunch of things that have to
happen. The lander has to open up, the petals have to
open out on the solar array, and it takes a period of
time before the spacecraft is really to the point where
it's able to start even doing any picture taking.
So it's going to be at least, I think, 24 hours
or so after we touch down before we are actually going
to see pictures. |
mirtha
from manahawkin
Do you think there are people up there? |
| Baez: Mirtha
from Manahawkin, no, I don't think that there are
people up there. What we are looking for is really, are
there signs of water, and what has the water done to that
planet, and in what quantities and so forth. And maybe
looking back in retrospect, is there something we can
do to support our planet a little bit longer. What went
wrong on Mars? There's evidence of water there and
it happened a long, long time ago. There's an atmosphere
there, it's a colder climate, but has similar days
to us and it has an atmosphere. So what we are looking
for is how long was the water there, how much of it was
there, and maybe take some of that information and apply
it here and hopefully the earth will sustain much more
than Mars did. |
george
from concord
How long till the units arrive on Mars? And how long can
the robots run on Mars? How long did the last robot stay
active? |
Squyres:
Okay, it's going to take us about seven months
to get to Mars. One rover is on the way right now and
the second one is about to be launched. They will arrive
at Mars the 4th and 25th of January of next year. As
for how long they are going to last, it's a good
question. The design lifetime, as we call it, is 90
Martian days or 90 sols, which is about three months.
That doesn't mean that the wheels are going to
fall off when the sun comes up on the morning of the
91st sol. What it means is, basically, that's
when the warranty expires. We have designed these vehicles
to last at least that long. How long they will actually
survive depends on a bunch of factors. It depends on
the Martian weather. It depends on how much dust falls
on the solar arrays, that's one of the things
that will limit the lifetime of the vehicle. But we
think it will be at least three months and maybe a good
deal more.
Host: Now when you mention warranty is that similar
to, or are you talking about the battery?
I'm talking about every aspect of the vehicle.
If you look at this rover, it's an incredibly
complicated machine. It's got a lot of moving
parts, it's got a computer, I'ts got batteries,
it's got solar cells, it's got these wheels.
Every one of those things can eventually wear out as
a consequence of lots of use. And so you've got
to make sure that every part of it is going to be able
to withstand at least 90 days of operations.
|
Jennifer
from Edmonton,Canada
Are there any specific geological interests about the
landing sites chosen for the MER rovers? Is there anything
that would make you suspect that these landing sites would
contain more relative information than another site? |
| Squyres:
Absolutely, we started off with 185 different possible
landing sites for this mission, a whole bunch of them.
All of those were landing sites that this vehicle was,
in principle, capable of getting to. Even when we looked
at them carefully and started throwing away the ones that
for whatever reason looked too unsafe, like the vehicle
couldn't go there, we still had many sites available
to us that were safe enough and so we could pick the ones
that had the best science. So what we have done is try
to pick two sites that are not only safe enough to land
at but also have a lot of scientific interest. Mars varies
a lot from place to place and we have tried to pick two
places that have a very good chance that there were once
warmer and wetter conditions there. |
Jennifer
from Edmonton,Canada
How is the process by which the MER Rovers will be traveling
to Mars (trajectory speed, etc.) unique between the two
rovers? How is it different from the Mars Pathfinder rover? |
| Baez: Jennifer,
there is not much difference between Pathfinder and the
MER-A and the MER-B missions. But I will tell you the
slight differences are the timing of events. As I told
you earlier, we're using the Delta II Heavy vehicle
for the MER-B mission. The later we wait, the more energy
it takes to get into an Earth escape and a Mars impact
type trajectory. So we are going a little bit later than
MER-A, therefore it takes a little bit more energy. If
I looked at the relative speeds between MER-A and MER-B,
MER-A when we left it - or when we separated it
from its third stage - was traveling at approximately
23,042 miles an hour. MER-B should be separated at 23,135
miles an hour, a difference of about 90 miles an hour.
But these events take place at different times. For the
MER-A mission, we achieved this escape velocity shortly
after the second stage was done with its mission out over
Africa and over into the Indian Ocean. This mission takes
a little bit longer. As it leaves here from the Cape,
we have approximately a 70-minute coast phase, and we
do our escape out over the Pacific Islands of Kwajalein,
the atolls out there in Hawaii, so we're taking
a little bit longer and we're going a little bit
faster to catch up with what MER-A is already doing. |
Jennifer
from Edmonton,Canada
If siginificant geological findings do occur (i.e. evidence
that Mars could have supported life) will another rover
be sent to investigate this and bring back rock samples
for further analysis on Earth? What are the options if
something like this is found? |
| Squyres:
Squyres: Well, that's a great question, and I really
hope that's exactly that happens. Your question
is dead on; what we are trying to do with MER is to determine
whether or not these landing places were places that could
once have supported life. If we find that Gustav Crater
or Meridiani Planum is in fact the place that looks like
it was warm, and wet - inhabitable - what
I would love to see happen is to go back there with another
vehicle, bring some rocks back and get them to the best
laboratories on Earth and really check them out in detail.
Whether or not that's going to happen certainly
depends on what we find. It's a process of continual
exploration and learning. |
Richard
from Melbourne, FL
I have just recently read that the mission is being postponed
for several more days because of an issue with a band
of cork insulation on the Delta launch vehicle. This seems
to be such an odd choice for an insulation material on
the spacecraft. Why is cork being used on the outside
of the launch vehicle in such a humid environment with
such strong sunlight as well? Thank you. |
| Baez: This
is a good question, Richard. I'll tell you, the
simple thing is, we use cork all over this vehicle. It's
a readily available natural material and it is easily
shaped to round surfaces such as the Delta II or the cylindrical.
And it is very forgiving. I talked earlier about the tank
seeing temperatures from ambient - about 90 degrees
- and when we load LOX onboard, it goes to minus
300 degrees. So things made of aluminum and such, which
the tank is made of, shrinks. So what we need is an insulation
barrier of some kind that can also take the shrinking
and expansion and be flexible enough to lift through this.
I think that cork is one of those materials that we fell
in love with early in the space program and are using
it ever since. It's a material that is very natural;
you don't have to wear special equipment to apply
it. It's very easy to cut and shape. And yes, it
does have its drawbacks; one being, yes, it loves to absorb
moisture and it doesn't do very well in sunlight.
But, then again, we don't like to keep our rockets
out in the rain and we don't like to keep it out
in the sunshine. That's why we have a tower around
it. The Delta II that we are going to use for the MER-B
mission just stayed out there a little bit longer than
we intended it to. |
David
from Berkeley
What improvements have been made in the rechargeable batteries
(since Pathfinder) to insure that electrical power lasts
longer? |
| Squyres:
Well, there are two things that are different. One is
that we are using lithium ion battery technology; it's
the best battery technology that's available these
days. It is the same stuff that is used in highly sophisticated
applications, like laptop computers. So we are really
up with the state of the art on the batteries. The other
is that we have much, much more capable, much more powerful
solar arrays to recharge the batteries every night. So
each day, during the daytime we top off the batteries
to a pretty substantial load, and so there is a lot of
power to keep the vehicle alive overnight. |
Klaus
from Aabybro, Denmar
During this long trip to Mars, what is the top speed the
craft will achieve? Thank you for your time! |
| Baez: At
the point that we separate the third stage from the MER-B
spacecraft, we're looking at about 333,932 feet
per second. If I convert that to miles an hour, that's
23,135 miles an hour. There'll be some additions
to that with the trajectory control maneuvers, TCMs, but
those are very small, they're on the order of 4
to 12 feet per second. |
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Last Updated:
July 23, 2003
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