The Technology of Curiosity
Saturday, September 01 2012 On April 14, 2004, NASA announced an
opportunity for researchers to propose science investigations for
the Mars Science Laboratory (MSL) mission. Eight months later, the
agency announced selection of eight investigations. In addition,
Spain and Russia would each provide an investigation through
international agreements. The instruments for these ten
investigations make up the science payload on the Curiosity
rover.
Curiosity examines a rock on Mars with a set of tools at the end
of its arm, which extends about 7 feet. Two instruments on the arm
can study rocks up close. A drill can collect sample material from
inside of rocks, and a scoop can pick up samples of soil. The arm
can sieve the samples and deliver fine powder to instruments inside
the rover for thorough analysis. (NASA/JPL-Caltech)
The ten instruments on Curiosity have a combined mass of 165
pounds. Curiosity carries the instruments plus multiple systems
that enable the science payload to do its job and send home the
results. Key systems include six-wheeled mobility, sample
acquisition and handling with a robotic arm, navigation using
stereo imaging, a radioisotope power source, avionics, software,
telecommunications, and thermal control.
Curiosity is 10 feet long (not counting its arm), 9 feet wide,
and 7 feet high at the top of its mast, with a mass of 1,982
pounds, including the science instruments. Curiositys mechanical
structure provides the basis for integrating all of the other rover
subsystems and payload instruments.
Mobility
Curiositys mobility subsystem is a scaled-up version of what was
used on the three earlier Mars rovers: Sojourner, Spirit, and
Opportunity. Six wheels all have driver motors, and the four corner
wheels all have steering motors. Each front and rear wheel can be
independently steered, allowing the vehicle to turn in place, as
well as to drive in arcs. The suspension is a rocker-bogie system,
enabling Curiosity to keep all its wheels in contact with the
ground, even on uneven terrain. Curiositys wheels are aluminum and
20" in diameter. They have cleats for traction and structural
support. Curving titanium spokes give springy support.
The rover has a top speed on flat, hard ground of about 1.5
inches per second. However, under autonomous control with hazard
avoidance, the vehicle achieves an average speed of less than half
that.
Arm and Turret
The Robot Arm (RA) is a five-degrees-of-freedom manipulator used
to place and hold the turret-mounted devices and instruments on
rock and soil targets, as well as manipulate the turretmounted
sample processing hardware.
The science instruments on the arms turret are the Mars Hand
Lens Imager (MAHLI) and the Alpha Particle X-ray Spectrometer
(APXS). The other tools on the turret are components of the rovers
Sample Acquisition/Sample Processing and Handling (SA/SPaH)
subsystem: the Powder Acquisition Drill System (PADS), the Dust
Removal Tool (DRT), and the Collection and Handling for In-situ
Martian Rock Analysis (CHIMRA) device.
This drawing of Curiosity indicates the location of science
instruments and some other tools. (NASA/JPL-Caltech)
The SA/SPaH subsystem is responsible for the acquisition of rock
and soil samples from the Martian surface, and the processing of
these samples into fine particles that are then distributed to the
analytical science instruments SAM and CheMin. The SA/SPaH
subsystem is also responsible for the placement of the two contact
instruments, APXS and MAHLI, on rock and soil targets. SA/SPaH also
includes drill bit boxes, the Organic Check Material (OCM), and an
observation tray, which are all mounted on the front of the rover,
and inlet cover mechanisms that are placed over the SAM and CheMin
solid sample inlet tubes on the rover top deck.
The Powder Acquisition Drill System is a rotary percussive drill
to acquire samples of rock material for analysis. It can collect a
sample from up to 2" beneath a rocks surface. The drill penetrates
the rock and powders the sample to the appropriate grain size for
use in SAM and CheMin. If the drill bit becomes stuck in a rock,
the drill can disengage from that bit and replace it with a spare.
The Dust Removal Tool is a metal-bristle brushing device used to
remove the dust layer from a rock surface or to clean the rovers
observation tray.
A clamshell-shaped scoop collects soil samples from the Martian
surface. The other turret-mounted portion of this device has
chambers used for sorting, sieving, and portioning the samples
collected by the drill and the scoop. An observation tray on the
rover allows the MAHLI and the APXS a place to examine collected
and processed samples of soil and powdered rock.
Power
Rover power is provided by a multi-mission radioisotope
thermoelectric generator (MMRTG) supplied by the U.S. Department of
Energy. This generator is essentially a nuclear battery that
reliably converts heat into electricity. It consists of two major
elements: a heat source that contains plutonium-238 dioxide, and a
set of solid-state thermocouples that convert the plutoniums heat
energy to electricity. It contains 10.6 pounds of plutonium dioxide
as the source of the steady supply of heat used to produce the
onboard electricity, and to warm the rovers systems during the
Martian nights.
Computing
Curiositys mast features seven cameras: the Remote Micro Imager,
part of the ChemCam suite; four black-and-white Navigation Cameras
(two on the left and two on the right); and two color Mast Cameras
(Mastcams). (NASA/JPL-Caltech)
Curiosity has redundant main computers, or rover compute
elements. Of this A and B pair, it uses one at a time, with the
spare held in cold backup. So, at a given time, the rover is
operating from either its A side or its B side. Each computer
contains a radiation-hardened central processor with PowerPC 750
architecture, a BAE RAD 750 processor operating at up to 200 MHz
speed. Each of Curiositys redundant computers has 2 gigabytes of
flash memory, 256 megabytes of DRAM, and 256 kilobytes of EEPROM.
The MSL flight software monitors the status and health of the
spacecraft during all phases of the mission, checks for the
presence of commands to execute, performs communication functions,
and controls spacecraft activities.
Navigation
Two sets of engineering cameras on the rover Navigation cameras
(Navcams) up high, and Hazard-avoidance cameras (Hazcams) down low
inform operational decisions both by Curiositys onboard autonomy
software and by the rover team on Earth. Information from these
cameras is used for autonomous navigation, engineers calculations
for maneuvering the robotic arm, and scientists decisions about
pointing the remote-sensing science instruments.
Each of the Navcams captures a square field of view 45 degrees
wide and tall, comparable to the field of view of a
37-millimeter-focal-length lens on a 35- millimeter,
single-lens-reflex camera. Curiosity has four pairs of Hazcams: two
redundant pairs on the front of the chassis, and two at the rear.
The rover can drive backwards as well as forward, so both the front
and rear Hazcams can be used for detecting potential obstacles in
the rovers driving direction. The Hazcams have one-time-removable
lens covers to shield them from potential dust raised during the
rovers landing.
Mast Camera (Mastcam)
This artists concept depicts Curiosity as it uses its ChemCam to
investigate the composition of a rock surface. ChemCam fires laser
pulses at a target and views the resulting spark with a telescope
and spectrometers to identify chemical elements. The laser is in an
invisible infrared wavelength, but is shown here as visible red
light for purposes of illustration. (NASA/JPL-Caltech)
Two two-megapixel color cameras on Curiositys mast are the left
and right eyes of the Mastcam. These cameras have complementary
capabilities for showing the rovers surroundings in exquisite
detail and in motion. The right-eye Mastcam looks through a
telephoto lens with about three-fold better resolution than any
previous landscape-viewing camera on the surface of Mars. The
left-eye Mastcam provides broader context through a medium-angle
lens. Each can acquire and store thousands of full-color images.
Each is also capable of recording high-definition video.
The telephoto Mastcam is called Mastcam 100 for its
100-millimeter focal-length lens. The camera provides enough
resolution to distinguish a basketball from a football at a
distance of seven football fields. Its left-eye partner, called
Mastcam 34 for its 34-millimeter lens, catches a scene three times
wider on an identical detector.
Chemistry and Camera (ChemCam)
The ChemCam instrument consists of two remote sensing
instruments: the first planetary science Laser-Induced Breakdown
Spectrometer (LIBS), and a Remote Micro- Imager (RMI). The LIBS
provides elemental compositions, while the RMI places the LIBS
analyses in their geomorphologic context.
ChemCam uses a rock-zapping laser and a telescope mounted atop
Curiositys mast. It also includes spectrometers and electronics
inside the rover. The laser can hit rock or soil targets up to
about 23 feet away with enough energy to excite a pinhead-size spot
into a glowing, ionized gas called plasma. The instrument observes
that spark with the telescope and analyzes the spectrum of light to
identify the chemical elements in the target. The telescope doubles
as the optics for the camera of ChemCam, which records monochrome
images. The telescopic camera, called the remote micro-imager, will
show context of the spots hit with the laser. It can also be used
independently of the laser for observations of targets at any
distance.
The spot hit by ChemCams infrared laser gets more than a million
watts of power focused on it for five one-billionths of a second.
Light from the resulting flash comes back to ChemCam through the
telescope, then through about 20 feet of optical fiber down the
mast to three spectrometers inside the rover. The spectrometers
record intensity at 6,144 different wavelengths of ultraviolet,
visible, and infrared light.
Alpha Particle X-Ray Spectrometer (APXS)The APXS on Curiositys
robotic arm will identify chemical elements in rocks and soils. A
pinch of radioactive material emits radiation that queries the
target and an X-ray detector reads the answer. The instrument
consists of a main electronics unit in the rovers body and a sensor
head mounted on the robotic arm. Measurements are taken by
deploying the sensor head towards a desired sample, placing the
sensor head in contact or hovering, and measuring the emitted X-ray
spectrum for 15 minutes to 3 hours without the need of further
interaction by the rover.
Mars Hand Lens Imager (MAHLI)
MAHLI is a focusable color camera on Curiositys turret.
Researchers will use it for magnified, close-up views of rocks and
soils, and also for wider scenes of the ground, the landscape, or
even the rover. Essentially, it is a handheld camera with a macro
lens and autofocus.
The investigation takes its name from the type of hand lens
magnifying tool that every field geologist carries for seeing
details in rocks. MAHLI has two sets of white light-emitting diodes
to enable imaging at night or in deep shadow. Two other LEDs on the
instrument glow at the ultraviolet wavelength of 365 nanometers.
These will make it possible to check for materials that fluoresce
under this illumination.
This camera uses a red-green-blue filter grid like the one on
commercial digital cameras for obtaining a full-color image with a
single exposure. It stores images in an 8-Gb flash memory, and it
can perform an onboard focus merge of eight images to reduce from
eight to two the number of images returned to Earth in
downlink-limited situations.
Chemistry and Mineralogy (CheMin)
CheMin is one of two investigations that will analyze powdered
rock and soil samples delivered by Curiositys robotic arm. It will
identify and quantify the minerals in the samples. CheMin uses
X-ray diffraction, a first for a mission to Mars. It supplements
the diffraction measurements with X-ray fluorescence capability to
determine further details of composition by identifying ratios of
specific elements present. X-ray diffraction works by directing an
X-ray beam at a sample and recording how X-rays are scattered by
the sample at the atomic level.
A sample processing tool on the robotic arm puts the powdered
rock or soil through a sieve designed to remove any particles
larger than 0.006 before delivering the material into the CheMin
inlet funnel. Each sample analysis will use about as much material
as in a baby aspirin.
Sample Analysis at Mars (SAM)
SAM is designed to explore molecular and elemental chemistry
relevant to life. SAM addresses carbon chemistry through a search
for organic compounds, the chemical state of light elements other
than carbon, and isotopic tracers of planetary change. SAM is a
suite of three instruments: a Quadrupole Mass Spectrometer (QMS), a
Gas Chromatograph (GC), and a Tunable Laser Spectrometer (TLS). The
QMS and the GC can operate together in a GCMS mode for separation
(GC) and definitive identification (QMS) of organic compounds.
SAMs analytical tools fit into a microwave-oven-size box inside
the front of the rover. While it is the biggest of the ten
instruments on Curiosity, this tightly packed box holds
instrumentation that would take up a good portion of a laboratory
on Earth.
SAMs sample manipulation system maneuvers 74 sample cups, each
about one-sixth of a teaspoon in volume. The chemical separation
and processing laboratory includes pumps, tubing, carrier- gas
reservoirs, pressure monitors, ovens, temperature monitors, and
other components.
Rover Environmental Monitoring Station (REMS) REMS records six
atmospheric parameters: wind speed/direction, pressure, relative
humidity, air temperature, ground temperature, and ultraviolet
radiation. All sensors are located around three elements: two booms
attached to the rover Remote Sensing Mast (RSM), the Ultraviolet
Sensor (UVS) assembly located on the rover top deck, and the
Instrument Control Unit (ICU) inside the rover body.
Radiation Assessment Detector (RAD)
RAD will monitor high-energy atomic and subatomic particles
reaching Mars from the Sun, distant supernovas, and other sources.
These particles constitute naturally occurring radiation that could
be harmful to any microbes near the surface of Mars or to
astronauts on a future Mars mission. RAD is an energetic particle
analyzer designed to characterize the full spectrum of energetic
particle radiation at the surface of Mars. RADs measurements will
help fulfill MSLs key goals of assessing whether Curiositys landing
region has had conditions favorable for life and for preserving
evidence about life.
Dynamic Albedo of Neutrons (DAN)
DAN is an active/passive neutron spectrometer that measures the
abundance and depth distribution of H- and OHbearing materials in a
shallow layer of Mars subsurface along the path of the rover. DAN
can detect water bound into shallow underground minerals along
Curiositys path. It shoots neutrons into the ground and measures
how they are scattered, giving it a high sensitivity for finding
any hydrogen to a depth of about 20" directly beneath the
rover.
Mars Descent Imager (MARDI)
During the final few minutes of Curiositys flight to the surface
of Mars, the Mars Descent Imager (MARDI) recorded a full-color
video of the ground below. MARDI is a fixed-focus color camera
mounted to the fore port side of the rover, even with the bottom of
the rover chassis. The camera took images at 5 frames per second
throughout the period of time between heat shield separation and
touchdown. Throughout Curiositys mission on Mars, MARDI will offer
the capability to obtain images of ground beneath the rover for
tracking of its movements or for geologic mapping.
Learn more about Curiositys science instruments at
http://mars.jpl.nasa.gov/msl/mission/science. View the latest
videos of the Mars Science Laboratory and Curiosity rover on Tech
Briefs TV at www.techbriefs.com/tv/mars. Get the latest news on the
MSL mission at www.nasa.gov/mission_pages/msl/.
http://www.techbriefs.com/component/content/article/14715NASA
Begins a New Journey of Exploration
Saturday, September 01 2012 Tonight, on the planet Mars, the
United States of America made history. The successful landing of
Curiosity the most sophisticated roving laboratory ever to land on
another planet marks an unprecedented feat of technology that will
stand as a point of national pride far into the future. It proves
that even the longest of odds are no match for our unique blend of
ingenuity and determination. Tonights success reminds us that our
preeminence not just in space, but here on Earth depends on
continuing to invest wisely in the innovation, technology, and
basic research that has always made our economy the envy of the
world. I congratulate and thank all the men and women of NASA who
made this remarkable accomplishment a reality and I eagerly await
what Curiosity has yet to discover.
- President Barack Obama, August 6, 2012 At 1:32 a.m. EDT on
August 6, NASAs Mars Science Laboratory (MSL) touched down on the
Red Planet, beginning a two-year mission of exploration and
discovery. The Curiosity rover is a mobile laboratory equipped with
10 science investigations and a robotic arm that can drill into
rocks, scoop up soil, and deliver samples to internal analytical
instruments. (For detailed information on Curiositys instruments,
see the feature beginning on page 28.)
The spacecrafts descent stage, while controlling its own rate of
descent with four of its eight throttle-controllable rocket
engines, begins lowering Curiosity on a bridle. The rover is
connected to the descent stage by three nylon tethers and by an
umbilical, providing a power and communication connection. The
bridle extends to full length, about 25 feet, as the descent stage
continues descending. Seconds later, when touchdown is detected,
the bridle is cut at the rover end, and the descent stage flies off
to stay clear of the landing site. (NASA/JPL-Caltech)
Following a harrowing seven minutes of terror in which Curiosity
had to survive a dive that took it from 13,200 miles per hour to
zero, the rover touched down and immediately began sending back
images from its landing spot in Gale Crater.
Said MSL project scientist John Grotzinger, Curiosity is not a
life-detection mission. Were not actually looking for life. We dont
have the ability to detect life if it was there. What we are
looking for are the ingredients of life.
MSL will study whether the Gale Crater area has evidence of past
and present habitable environments. These studies will be part of a
broader examination of past and present processes in the Martian
atmosphere and on its surface.
Curiosity will rely on new technological innovations. For its
landing, the spacecraft descended on a parachute and then, during
the final seconds prior to landing, lowered the upright rover on a
tether to the surface, much like a sky crane. Now on the surface,
the rover will be able to roll over obstacles up to 29 inches high,
and travel up to 295 feet per hour. On average, the rover is
expected to travel about 98 feet per hour, based on power levels,
slippage, steepness of the terrain, visibility, and other
variables.
This full-resolution image shows part of the deck of Curiosity
taken from one of the rovers Navigation cameras looking toward the
back left of the rover. On the left, part of the rovers power
supply is visible. To the right of the power supply is the pointy
low-gain antenna and side of the paddle-shaped high-gain antenna
for communications directly to Earth. (NASA/JPL-Caltech)
To make best use of the rovers science capabilities, a team of
scientists and engineers will make daily decisions about the rovers
activities for the following day. MSL is intended to be a
discovery-driven mission, with the science operations team
retaining flexibility in how and when the various capabilities of
the rover and payload are used to accomplish the overall scientific
objectives.
Curiosity landed in a region where a key item on the checklist
of lifes requirements has already been determined: It was wet.
Observations from Mars orbit during five years of assessing
candidate landing sites have made these areas some of the most
intensely studied places on Mars.
While the possibility that life might have existed on Mars
provokes great interest, a finding that conditions did not favor
life would also pay off with valuable insight about differences and
similarities between early Mars and early Earth.
Learn more about Curiositys mission at
http://mars.jpl.nasa.gov/msl.
http://www.techbriefs.com/component/content/article/14713Talking
Mars
Saturday, September 01 2012 Page 1 of 3
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NASA Tech Briefs recently spoke with Doug McCuistion, Director
of the Mars Exploration Program, and Michael Meyer, lead scientist
for the Mars Exploration Program and Program Scientist for the Mars
Science Laboratory (MSL). We talked about what NASA hopes to find,
the technologies used onboard, and how the two-year mission is
expected to progress. NASA Tech Briefs: What are the science
objectives for the Mars Science Laboratory?
Michael Meyer: The overarching goal of the Mars Science
Laboratory and rover Curiosity is to understand whether Mars has
ever been, or is capable today, of supporting microbial life. So
thats another way of saying we want to determine the habitability
of Mars. There are other things that can be discovered by Curiosity
as it roves about, but thats the overall goal and how it was
designed.
NTB: Why was Gale Crater selected as the landing site?
Michael Meyer, lead scientist for the Mars Ex - ploration
Program and Program Scientist for MSL.
Meyer: Over the past five years, the science team got together,
people proposed what they considered were very interesting landing
sites, and then there were discussions about how interesting it is
to everybody else. As we narrowed it down, we also got into how
safe it is, does the landing ellipse fit inside a good place, and
are there rocks.
The science community had to be self-policing about what it
could actually do and what it could reasonably speculate. This is
one of the things we really benefit from the amount of information
we got from having a Mars program. We ended up picking Gale Crater
because it has Mount Sharp in the middle this huge mound that
should have an extensive history of Mars starting from more than
three billion years ago to whatever Mars is like at present.
NTB: This is the first time since the Viking landings in 1976
that NASA has used throttleable engines for landing a Mars
spacecraft. Why was this method chosen for MSL?
Doug McCuistion: The engines are a new design based on a
heritage unit. Because of the throttleable nature and the amount of
thrust we can get from these, they make a great engine for orbiters
for certain Mars orbit insertions as well. So, well use these
again, maybe next time on an orbiter.
Doug McCuistion, Dir ec tor of the Mars Exp loration
Program.
There were a lot of things chosen because of the additional mass
of MSL. Airbags max out around 200 kg, so the airbag technology
couldnt handle a rover of this mass. So we had to come up with a
new technique. The concept was a larger parachute to get more drag,
and obviously a larger entry shell that reduces our speed and also
is volumetrically necessary. But once we got done with the
parachute, the replacement for the airbags had to be something that
could handle a 1,000-kg rover underneath it, to be able to take out
both horizontal and vertical velocities. So instead of putting the
engines underneath it like Viking, we decided to put the engines on
top.
NTB: Curiosity is NASAs largest and most complex rover. Other
than size, how does it differ from Opportunity and Spirit?
McCuistion: Its very different probably the two biggest
differences are the payload capability and the power source.
Essentially, the plutonium 238-powered radioisotope thermal
generator is a constant power source, regardless of time of day.
Were not dependent upon solar energy any longer. Weve got a
constant feed of power, with a constant output of about 110 Watts.
That gives us a great capability to charge batteries overnight, to
be able to rove farther, and to be able to last longer on the
surface by design. Thats a fantastic capability because of the
power source. For the instruments, weve gone from less than 6 kg of
instruments to over 80 kg of instruments, comparing the MER (Mars
Exploration Rover) rovers to the MSL rover.
Meyer: The key difference is that Curiosity is a roving
analytical laboratory. There are two instruments in the interior of
the rover that are major instruments. For Spirit and Opportunity,
all of the instrumentation was remote and contact instruments,
while Curiosity has two analytical instruments inside.
On the interior, we have an instrument called CheMin (Chemistry
and Mineralogy), which is an x-ray diffraction/x-ray fluorescence
instrument that measures the distance between atoms. This is the
same kind of instrument youd have in a laboratory. Mineralogy is
important because it tells you the environment in which the rock
was formed. The other instrument is SAM (Sample Analysis at Mars),
and thats a gas chromatograph mass spectrometer. This gives you
composition it tells you what things are made out of. Its not the
elements, but also the smaller compounds. It also can do isotopes.
In addition, SAM has whats called a tunable laser system (TLS),
which is a spectrometer that can measure certain things to an
extreme degree. It can measure carbon dioxide, water, and also
methane, which is probably the one were most excited about.
The other instrument thats unique is the ChemCam (Chemistry and
Camera suite), which is a laser-induced breakdown spectrometer. It
fires a laser, creates a plasma, and then uses a spectrometer to
look at the plasma and tell what the composition is. Its a remote
sensing instrument, so you dont have to place the instrument
against whatever youre interested in. You can do it within 7 meters
of the rover.
NTB: Are there other minerals youre looking for besides carbon
and methane?
McCuistion: This mission is highly unusual in that weve already
targeted minerals that we see from orbit. We see sulfates and we
see clays, both of which are minerals that form in water, and they
also represent slightly different environments. Clays form in a
neutral environment with a pH around 7, while sulfates tend to form
in more acidic environments and you also find them, at least on
Earth, in environments where the water is drying out. Those are
good indicators that were going to go to a place where we have
mineral deposits that were laid down when Mars was warmer and
wetter, and mineral deposits that were laid down when Mars was
drying out. As you go further up Mount Sharp, well find things that
are indicative of modern Mars, which is cold and dry.
NTB: What are the first steps in Curiositys commissioning
phase?
McCuistion: After it does its health check and everythings
working, it recalibrates its thermal model to make sure it has the
right energy budget for managing things. Its then going to move
into a mode of first-time events. The team will move it a little
bit and then say, OK, we told it to move a foot did it move a foot?
But these things come much later. Things wont happen right away
this is all within the first 30 days. For each instrument, the team
will turn it on and see if its working, and put it through its own
personal health check. Theyll make a measurement, see what the
measurement says, and if it corresponds to whats expected.
Pathfinder, Phoenix, and MER landed on the surface and they were
expected to live 90 to 120 days. So it was, We better get on with
it, because we dont have much time. MSL is designed as a two-year
mission. Its a long-life mission and its going to take a couple of
months to really get this thing fully commissioned before its fully
operational.
NTB: What is Curiositys expected range of travel?
McCuistion: Spirit and Opportunity have proven to us that any
predictions are completely useless. From an engineering
perspective, its how long the mechanical systems last. Thats really
the limiting factor. The power source will give us many, many years
on the surface of nice, clean, consistent power. The rover is
designed to be able to travel 20 kilometers. The reason for that is
its designed to be able to get out of its landing ellipse. What
that does is enable the mission to have a goal to go see something
it cant land on. And in fact, thats Mount Sharp. It has to be able
to travel a good distance to be able to get there.
NTB: Are the decisions of the science team as far as where
Curiosity will go each day determined according to what findings
were made the previous day?
McCuistion: Yes, this is actually unique and exciting at the
same time. There is a Science Operations Working Group and
essentially, every day, they find out what the rover did yesterday
did it do what it was supposed to do, and did it find something
particularly exciting. They analyze the data and have a debate
about what to do tomorrow. So filtering into the tactical decision
about what to do each day will be are we still headed in the right
direction to meet our strategic objective?
NTB: Curiosity has a payload of 10 instruments. Can you briefly
describe some of them?
Meyer: Well characterize the modern environment of Mars very
well. We have whats basically a weather station contributed by the
Spanish. Well also be measuring neutrons and return of neutrons
from a neutron generator (Dynamic Albedo of Neutrons, DAN) that
tells us how much water there is in about the upper meter of the
regolith, and thats contributed by the Russians. We have an alpha
particle x-ray spectrometer (APXS) that is similar to whats on the
Mars Exploration Rovers that gives us elemental composition from
contact. Its provided by the Canadians.
The Mars Hand Lens Imager, MAHLI, is different in that it has
its own light source, so it has a better magnification field to see
things down to about 14 microns. It can see at night so if there
are any fluorescent minerals, it will be able to detect those.
The MastCam is interesting in that not only is it stereo, but
also it has a filter wheel so it gives you different colors. Well
finally resolve the debate about if youre on Mars, what color would
the sky be? It has a huge amount of memory. It can take a
high-resolution picture of everything and then send back
thumbnails. The science team can say, We really like this rock, and
instead of having to ask the camera to go look at that rock and
take a picture, you just ask the system to send you back the
highresolution picture of it. The pictures already taken its
whether or not you request the data.
Curiosity also has a drill for sampling (PADS, Powder
Acquisition Drill Sys tem). Well be able to get below the veneer
thats on rocks and sample the interior of the rock. That will be
particularly useful for the analytical laboratory thats in the
rover. It will be able to take those, determine mineralogy, and
also composition. Because we havent done that before, it may
provide some real surprises.
NTB: Are there potential commercial applications for these types
of instruments?
McCuistion: We already have one example, which is the CheMin. It
already has a commercial version called Xterra. Its a suitcase you
can carry into the field to measure metals. I would expect that,
for instance, ChemCam (the laser-induced breakdown spectrometer)
might be very useful. Some people might be worried about carrying
around a laser in a suitcase, but I can imagine that being a useful
tool here on Earth.
Other things like SAM there may be some commercial spinoffs just
because of the efforts its gone through for miniaturization. It is
taking a laboratory instrument that everybodys happy with, and
shrinking it down so that it fits in a box.
One of the things thats unique about Curiosity is it will be
able to measure organic compounds. One of the big surprises from
Viking was not finding any organic compounds. You expect to find at
least some because you get them from meteorites, if nothing else.
So thats going to be a big issue for Curiosity.
NTB: The Navcams and Hazcams enable Curiosity to navigate and
see where its going. What other types of hazard avoidance measures
are in place?
McCuistion: MSL has gained a lot from the Spirit and Opportunity
rovers, and thats in regard to autonomous software. It has a lot of
software onboard that can actually navigate and recognize hazards
autonomously and either navigate around them or decide its too
complicated to do that, and just wait for Earth to help it. The
rover driver and navigation teams use the cameras on a regular
basis to understand the rovers surroundings and identify safe paths
of traverse. The most important portion of that capability is the
autonomous software aboard that helps us with navigation.
The rover also has accelerometers and inclinometers in the
system, so it understands what its own tilt and roll angles are.
So, as it climbs Mount Sharp, if it reaches limits of tilt and
roll, the inclinometers tell the system its at its limits so it
does not roll. The whole rocker-bogie system has a design that goes
all the way back to the Sojourner rover, and is an extremely
capable and flexible system.
Meyer: Just to add to what Doug said about software navigation,
right now, you can take your images from a Mastcam or Navcam and
plot out, safely, about 30 meters. And then after that, your
imagery is too planar and you cant really decide what would be the
best path to go. So the rover itself has to decide that. One of the
things that has been developed from MER is navigation software that
is able to take images as the rover goes along and say, OK, thats a
big rock turn to the left. Thats why the Mars Exploration Rovers
have been able to go up to 100 meters. Curiosity will benefit from
that.
McCuistion: Thats the advantage of the longevity of Spirit and
Opportunity. I think people dont realize the advancements in
surface navigation that are only possible because Spirit and
Opportunity survived for so long; that we could build new software
tools, new concepts, new techniques, and then test them, upload
them, and use them. Its been spectacular, not just scientifically,
but from an engineering perspective, what Spirit and Opportunity
were able to do and port into MSL.
NTB: The Radiation Assessment Detection (RAD) instrument was
taking measurements during the trip to Mars. What has it found that
you didnt know before?
McCuistion: The RAD is designed for a broad spectrum of
high-energy radiation measurement, and it was turned on about a
week after launch. It was turned off on July 13, getting ready for
entry, descent, and landing. Whats interesting about RAD measuring
in transit is that it sees what might be seen by an astronaut on
his way to Mars. One of the concerns about high-energy radiation is
what gets shielded by the spacecraft, and also what gets generated
by the spacecraft. So, high-energy particles impinging on the
cruise stage actually generate secondary particles that may be just
as harmful, but of a different nature. RADs been able to measure
those.
NTB: What have you already learned from MSL for future Mars
missions?
McCuistion: Scientifically, weve already got a data set from RAD
that weve never had before, which is the true radiation levels,
dosages, etc., that astronauts might see in space in transit to
Mars. From an engineering perspective, weve learned an enormous
amount about how to build a system of this capacity and capability.
The sky crane technique is a great technique for being able to put
larger and larger masses on the surface, and frankly, as a
feed-forward technology capability, you could foresee this putting
all kinds of different scientific systems on the surface and
potentially even re-supply for astronauts on the surface sometime
in the future. We have learned to shrink instruments dramatically,
changing their footprints significantly, which will always pay off
in future scientific missions, whether they are on Mars or some
other location.
Guided entry is another one the ability to shrink the landing
ellipse so significantly that we can get into areas that we couldnt
have imagined ten years ago. That opens up science portals that we
cant even fathom at this point. There are pretty exciting
opportunities.
Meyer: With MARDI, the Mars Descent Imager, one of the big
debates was whether or not, because of thruster plume, youll get
useful images. So who cares, other than the scientists who have to
figure out where youre going? Well, one of the derived benefits of
decent images would be for terrain recognition, which means in the
future you could say, I want to land right over here next to that
rock, and you can have the software look at the images and actually
plan exactly where you want to go. And that will make a big
difference when we do sample return or we send humans to Mars, when
you want them to land next to where we put the foodstuffs.
McCuistion: The other thing is the heat shield material. The
heat shield material is called PICA (Phenolic Impregnated Carbon
Ablator) and we adopted it for use when we saw what kind of mass we
were dealing with and what the heating rates were. PICA was a lot
safer and gave us a lot more margin. This will be the first time
its actually been used. This is a potential heat shield material
for human exploration in the future.
http://www.techbriefs.com/component/content/article/14714