Emily Lakdawalla
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available to support the instruments.
Box 1.2. Primary objective of the MSL mission.
The Mars Science Laboratory Mission will explore and quantitatively assess the
habitability and environmental history of a local region on Mars. The mission has
the primary objective of placing a mobile science laboratory on the surface of Mars
to assess the biological potential of the landing site, characterize the geology of the
landing region, investigate planetary processes that influence habitability, and
characterize the broad spectrum of surface radiation. The MSL project aims to
achieve this objective in a manner that will offer the excitement and wonder of space
exploration to the public.
Box 1.3. Components of the MSL flight system.
• A cruise stage to provide power, navigational capability, and thermal control
to the spacecraft for the trip from Earth to Mars.
• An aeroshell consisting of a heat shield and backshell with a parachute to
protect the rover during its initial entry and descent in the Martian atmo-
sphere. The aeroshell would also have the necessary hardware to provide
communications during cruise, entry, and descent. The aeroshell would be
able to maneuver in the air in order to reduce landing location errors caused
by uncertainty in atmospheric conditions.
• A descent stage that would decelerate with rockets while scanning the land-
ing area with radar, allowing the rover to generate a terrain map and identify
a safe landing site. The descent stage would come to a hovering stop 5 meters
above the landing site, then lower the rover on a tether to rest on its wheels.
Once the rover was at rest, it would cut the tether to the descent stage, and fly
away.
• A rover that would be capable of a mission lasting one Mars year (670 sols),
driving 50 meters per sol at 5–10 centimeters per second on typical sols, with
a total mission traverse capability of at least 6 kilometers. It would carry a
58-kilogram science payload, of which about 3 kg would be on an instrument
arm, 9 kg on the mast, and 38 kg inside the rover. To accommodate this large
payload, the rover’s body would be 1.2 meters long by 0.7 meters wide by
0.35 meters deep.
• Landing accuracy would be within a 5-by-10-kilometer ellipse.
• Two instruments were already included: a meteorology package contributed by
Spain, and an active neutron spectrometer contributed by Russia.
12 Mars Science Laboratory
Figure 1.3. Initial design for MSL from the Proposal Information Package. Note the two arms, two RTGs, huge dish, and tall mast mounted at the center of the front of the rover. The landing sequence is substantially similar to Pathfinder’s (Figure 1.1).
1.3 Becoming Mars Science Laboratory (2003–2004) 13
The design drawn in the 2004 Proposal Information Package was far from final. In
actuality, the spacecraft design was in a state of extreme flux, with the mission being torn between reliability, capability, and expense. 14 The 2004 rover concept differed from the final one in a number of ways. The originally planned mast was quite tall, reaching to 3.5
meters from the ground. It had a huge dish for direct-to-Earth data relay, as Odyssey
wouldn’t have the capacity to relay all of MSL’s hoped-for data volume, even if the orbiter survived until the 2010 landing.
The Sample Acquisition/Sample Processing and Handling (SA/SPaH) system on the
original rover design included two robotic arms, separating the heavy, rattling, dust- raising activities of drilling and retrieving rock cores and the finer tasks of scientific analysis and soil scooping onto separate arms. Both arms could deliver material to a sample processing
system mounted directly to the rover body. The sample processing system would have two
rock crushers to smash and sieve the rock samples into pieces smaller than a millimeter in
diameter. A sample delivery system would move these samples into the analytical labora-
tory instruments, and an ejection system would get rid of detritus. Both arms could acquire samples in icy material, though the rock crusher would not be expected to handle ice. If
the corer failed, the scoop would presumably still be available to gather loose rock samples and deliver them to the crusher.
But the biggest difference between proposed and final rovers was power. As originally
planned, MSL would carry two Radioisotope Thermoelectric Generators to provide ample
power and heat for operation at a wide range of latitudes.
1.3.3 Instrument selection
Teams of scientists and engineers responded to the Announcement of Opportunity by pro-
posing 48 instruments to NASA. NASA turned around the proposals quickly, selecting
eight (Box 1.4). Adding the already-accepted Russian and Spanish instruments brought the MSL mission payload to a total of ten. Some, the remote sensing instruments, would
study the landscape from a distance, mostly from the top of the remote sensing mast.
Others, the in situ instruments, would study rocks and soil from a turret at the end of the robotic arm, or measure the environment that the rover experienced. Finally, there were
two analytical laboratory instruments buried within the body of the rover that would accept samples of rock, soil, and atmospheric gas for detailed study.
This was a huge and exciting instrument package. Some of the instruments looked
familiar. Mastcam, MAHLI, and APXS all had direct parallels on the Mars Exploration
Rovers (Pancam, Microscopic Imager, and APXS), but in each case the proposed MSL
instrument had major improvements. Mastcam promised the possibility of color, stereo,
high-definition video of rover traverses across Mars. APXS would have higher spatial
resolution and speedier data acquisition than ever before.
The novel instruments were just as exciting. ChemCam would provide remote elemen-
tal analysis capability unlike anything seen on a Mars mission before, and would do it with 14 Manning and Simon (2014)
14 Mars Science Laboratory
Box 1.4. Mars Science Laboratory Instruments, as described in the 14 December 2004 press release announcing them.
Remote Sensing Instruments:
Mars Descent Imager (MARDI), located on the body of the rover. Principal inves-
tigator: Michael Malin, Malin Space Science Systems. The Mars Descent Imager will
produce high-resolution color-video imagery of the MSL descent and landing phase,
providing geological context information, as well as allowing for precise landing-site
determination.
Mast Camera (Mastcam), located on the mast. Principal investigator: Michael
Malin, Malin Space Science Systems. Mast Camera will perform multi-spectral,
stereo imaging at lengths ranging from kilometers to centimeters, and can acquire
compressed high- definition video at 10 frames per second without the use of the
rover computer.
ChemCam: Laser Induced Remote Sensing for Chemistry and Micro-Imaging,
located on the mast. Principal investigator: Roger Wiens, Los Alamos National
Laboratory. ChemCam will ablate surface coatings from materials at standoff dis-
tances of up to 10 meters and measure elemental composition of underlying rocks
and soils.
In-situ Instruments:
Mars Hand Lens Imager (MAHLI), located on the arm turret. Principal investiga-
tor: Kenneth Edgett, Malin Space Science Systems. MAHLI will image rocks, soil,
frost and ice at resolutions 2.4 ti
mes better, and with a wider field of view, than the
Microscopic Imager on the Mars Exploration Rovers.
Alpha Particle X-ray Spectrometer (APXS), located on the arm turret. Principal
investigator: Ralf Gellert, Max-Planck-Institute for Chemistry. APXS will deter-
mine elemental abundance of rocks and soil. APXS will be provided by the Canadian
Space Agency.
Radiation Assessment Detector (RAD), located on the rover body. Principal inves-
tigator: Donald Hassler, Southwest Research Institute. RAD will characterize the
broad spectrum of radiation at the surface of Mars, an essential precursor to human
exploration of the planet. RAD will be funded by the Exploration Systems Mission
Directorate at NASA Headquarters.
Dynamic Analysis of Neutrons (DAN), located in the rover body. Principal inves-
tigator: Igor Mitrofanov. DAN will perform an in situ analysis of the hydrogen con-
tent of the subsurface.
1.3 Becoming Mars Science Laboratory (2003–2004) 15
Rover Environmental Monitoring Station (REMS), in various locations on the
rover. Principal investigator: Luis Vázquez. REMS will measure temperature, pres-
sure, wind speed and direction, humidity, ultraviolet dose, atmospheric dust, and
local fluctuations in magnetic field.
Laboratory Instruments:
CheMin, located in the rover body. Principal investigator: David Blake, NASA’s
Ames Research Center. CheMin is an X-ray Diffraction/X-ray Fluorescence
(XRD/XRF) instrument that will identify and quantify all minerals in complex
natural samples such as basalts, evaporites and soils.
Sample Analysis at Mars (SAM), located in the rover body. Principal investigator:
Paul Mahaffy, NASA’s Goddard Space Flight Center. SAM consists of a gas chro-
matograph mass spectrometer and a tunable laser spectrometer. SAM will perform
mineral and atmospheric analyses, detect a wide range of organic compounds, and
perform stable isotope analyses of organics and noble gases.
a high-powered laser zapping rocks. RAD would make measurements that would pave the
way for human exploration of Mars. DAN would bring to the surface the neutron- detection
capability that had led to the Odyssey discovery of ground ice.
But the pièce de résistance was the analytical laboratory comprising CheMin and
SAM. Geologists salivated over the prospect of performing X-ray Diffraction/X-Ray
Fluorescence (XRD/XRF) on Mars with CheMin. All previous methods of mineral iden-
tification on the surface of Mars were indirect; XRD/XRF measurements are diagnostic,
as long as the samples contain crystals. And SAM would sensitively study atmospheric
gas isotopes, could follow up on the possible discovery of methane, and would be capable
of detecting organics, dangling the possibility of finding direct evidence for Martian life.
The selected instrument package contained many items from the wish list the Science
Definition Team had drawn in 2001 (see section 1.2.2). The final science package lacked a dedicated mast-mounted thermal infrared spectrometer like the Mini-TES on the Mars
Exploration Rovers and significantly, a near-infrared spectrometer that could follow up on
discoveries from OMEGA on Mars Express and CRISM on Mars Reconnaissance Orbiter
that played a major role in landing site selection. (ChemCam can be used in a passive
spectroscopic mode, but its sensitivity barely reaches into the near-infrared.) There was no arm-mounted mineralogical analyzer, no ground-penetrating radar, and no seismology
package. But everything else was there.
One group was both excited and dismayed by the list of instruments: the engineers,
who would have to find space, mass, and power to accommodate them all in their rover,
never mind operating a machine with so many capabilities.
16 Mars Science Laboratory
1.4 PRELIMINARY DESIGN (2005–2006)
A developing NASA mission faces many hurdles on the way to its destination, but there
are five formal ones. First is the Preliminary Design Review, which usually takes place
about four years (give or take) before launch. At the Preliminary Design Review, the mis-
sion team has to demonstrate that they have a sound concept for the mission and all its
technically challenging components. Passing a Preliminary Design Review unlocks
NASA’s coffers, allowing a mission to spend money turning concepts into detailed
designs. About a year later comes the Critical Design Review, when the mission has to
present blueprints to the review panel. Passing the Critical Design Review allows a mis-
sion to transition to the third phase, Assembly, Test, and Launch Operations (ATLO), usu-
ally about two years before launch. The final hurdles are launch and arrival. MSL’s
Preliminary Design Review was scheduled for June, 2006. The project had a lot of work
to do before then.
1.4.1 Technology development
To succeed, MSL required several new technologies for landing and surface operations.15
Guided entry required alteration of existing ballistic-entry vehicle designs into a lifting body that could fly through the Martian atmosphere. The steerable spacecraft also needed
a new guidance and control system. For sky crane, they needed more powerful descent
engines that could support the massive weight of the rover and descent stage, as well as a
special reel for the rope that would lower the rover slowly and gently to the surface.
For surface systems, the main challenges were longevity and sample handling. In par-
ticular, the motors (also known as actuators) for all the rover’s moving parts were required to survive testing 20 times longer than those developed for the Mars Exploration Rovers.
The MSL mission decided to develop a new type of actuator that relied upon a dry rather
than liquid lubricant. Liquid-lubricated motors must usually be heated on Mars in order
for their lubricant to function, particularly at night. Dry-lubricated motors wouldn’t need heaters, so would be less complex and would save the mission a considerable amount of
power and complexity. Heating costs both time and energy, and scheduling time enough
for heating increases the burden of tactical planning.
For sample handling, they needed to develop the arm (by now, the design included only
one) and a deck-mounted rock corer, rock crusher, and sample portioning and delivery
system. There was also the problem of scaling up the Mars Exploration Rover mobility
system – the wheels, rocker and bogie arms, and the differential that connected them – by
a factor of more than two, without scaling up their mass by a factor of eight. Because the
mobility system was also their landing gear, the engineers prototyped it early, developing
a physical model that they could test across a wide range of landing scenarios.
The unusual entry, descent, and landing system proposal attracted the attention and
concern of NASA officials and review panels. In early 2005, NASA Administrator Mike
Griffin, speaking in the context of financial pressures on NASA in general, floated the idea
of delaying MSL to 2011.16 Griffin personally visited JPL in June 2005. JPL director 15 Udomkesmalee and Hayati (2005)
16 Cooper (2005)
1.4 Preliminary Design (2005–2006) 17
Charles Elachi reportedly lobbied Griffin hard not to delay the mission. Buoyed by their
confidence in the wake of the successful landings of both Mars Expl
oration Rovers, the
JPL team assured Griffin they would be ready for 2009.
1.4.2 Shifting design, early 2006
One particular decision made early on to reduce costs would wind up haunting the rest of
the mission. They decided to give the spacecraft only one main computer, located in the
rover, instead of having distinct boxes for cruise, landing, and surface operations. The shift toward fewer electronics boxes was enabled by improvements in commercial electronics
technology. 17 High-density field-programmable gate arrays (FPGAs), in particular, allowed the rover to have less hardware, but it made the spacecraft more dependent on software
development. Software could, in theory, be developed by multiple teams in parallel. But
with only one main computer, all that software had to be tested in series; adding more
engineers wouldn’t make the test program go faster.
Late in 2005 NASA and JPL management decided to double the rover’s electronic
brains, giving it a complete backup system in case any of its critical electronic components failed. There was space for a second set of computers inside the rover, but it added mass,
significantly set back the avionics development schedule, and added complexity to the test
program. There were now two computers to test, but both were inside the same piece of
hardware, and through cross-strapping, both had interfaces with many of the same pieces
of equipment, increasing the number and variety of tests that were needed exponentially.
On March 10, 2006, Mars Reconnaissance Orbiter successfully entered orbit. The first
new NASA orbiter since 2001 Mars Odyssey brought many capabilities to Mars that would
be essential to the success of MSL. Its science payload, which would begin regular
Figure 1.4. Comparison of Mars Reconnaissance Orbiter with the two older NASA Mars orbiters. A 2010 photo of the MSL rover has been added in for scale. NASA/JPL-Caltech/
Emily Lakdawalla.
17 Cook (2011)
18 Mars Science Laboratory
Figure 1.5. Concept art of the MSL rover prepared for the Preliminary Design Review. From Vasavada (2006 ).