by The Design
from the start. In fact, they would consume so much power that they would leave the
rover’s battery depleted, with little power remaining to drive or do science.31
Steel motors were also heavier than the titanium ones would have been. The mass of the
robotic arm increased by 14%, sending engineers back to the drawing board to make sure
all the parts would be up to the stresses of landing and driving at their new masses.32 The motors were supplied by one vendor; the arm was being manufactured by a different vendor. Wherever the two components interacted, it took a tremendous amount of planning
and work to coordinate the design efforts of the two companies. Engineers tried to mini-
mize the mass of the heavier motors, but that meant repeatedly changing their specifica-
tions, delaying their delivery. Arm development was delayed. Meanwhile, the late redesign
of the sample handling system meant that requirements for the motors in the arm kept
changing even as design of the new motors had already begun.33
The switch to wet-lubricated motors created new constraints for landing site selection.
Although the rover could theoretically operate at high altitudes and high latitudes, severe winter cold would leave the rover without sufficient power to warm up its motors and
drive. The Mars Exploration Rovers mostly parked in winter because shorter days without
overhead sunlight limited their power. MSL could potentially suffer the same problem, if
sent to a landing site more than 15° south of the equator.34 (Southern winters are harsher than northern winters, due to the combination of higher average elevations, seasonal timing, and elliptical shape of Mars’ orbit.) Winter immobility was acceptable for Spirit and
Opportunity because the rovers had never been intended to last into the Martian winter
anyway. But for MSL, which was supposed to be able to land nearly anywhere on Mars and
operate for a full Martian year, cold-weather inactivity could prevent mission success.
Even the science instruments were affected. Power limitations meant that activities
requiring rover motion would need to be planned for the warmest part of the Martian day.
But some instruments, like ChemCam, had detectors that worked best when cold. It looked
like ChemCam was stuck between a rock and a hard place, as principal investigator Roger
Wiens explained in a memoir:
With the change in motor lubrication, normal operations became restricted to between
10 am and 4 pm local time to avoid excessive energy use. MSL was short on system
engineering help, but eventually the combined impact of these decisions was noticed.
There was an MSL leadership meeting in late 2007 in which the issue was addressed.
A chart was displayed showing in one color the times of day during which ChemCam’s
detectors would be cool enough to meet its science requirements, with another color
indicating the times of day that the rover’s mast would be warm enough to point to
targets. I was told that the room erupted in laughter. The two colors never overlapped.
ChemCam was cool enough only at night and the mast gimbals were warm enough
only in the middle of the day. It was a perfect mismatch. 35
31 Manning and Simon (2014)
32 Billing and Fleischner (2011)
33 JPL (2014a)
34 Watkins and Steltzner (2007)
35 Wiens (2013) Red Rover
1.5 The Cost of Complexity (2007–2008) 27
Despite a massive effort to adjust designs to cool the ChemCam detectors, it looked like
the instrument might only be usable for half an hour at each end of an operational day.
1.5.3 Heat shield failure
The other disaster of 2007 involved the mission’s heat shield. All NASA Mars missions to
date had used a material for the heat shield called Super Lightweight Ablator, or SLA. The
material consisted of a mixture of corkwood, epoxy, and gas-filled silica-glass spheres that is packed into a honeycomb structure pre-shaped into the blunt cone of the heat shield,
allowing SLA to be used for heat shields of any size and shape. So MSL’s larger size
didn’t present a manufacturing problem. But MSL was more massive and it would be
arriving at Mars at a higher speed than previous spacecraft, imposing higher pressure and
temperature on it, and causing air to flow around it turbulently rather than smoothly. And
the heat shield would be tilted at an angle as the spacecraft performed its guided entry,
heating it asymmetrically. The first great challenge of developing the heat shield was to
develop new ways to test all these more-extreme conditions.
The heat shield failed these new tests “drastically.” 36 Instead of receding slowly, the material emptied out of the honeycomb cells catastrophically, in mere seconds. The engineers couldn’t figure out why, so they couldn’t even attempt to modify the design to pre-
vent failure. They had to start from scratch – and had only 18 months to find a new
solution.
NASA’s human exploration program came to the rescue. An alternative heat shield
material had recently been developed and tested for use in a large heat shield. The mate-
rial, called Phenolic Impregnated Carbon Ablator (PICA), was first used successfully on
the Stardust sample return capsule, which returned to Earth in January 2006. The same
year, the Orion human exploration program adopted PICA for their capsule, and subjected
it to intensive tests at even more extreme conditions than MSL faced. To support the Orion
effort, the manufacturer worked to double their manufacturing capacity, bringing the new
capability online exactly on time to produce a heat shield for MSL.
Lockheed Martin started developing a new PICA heat shield in October 2007 on a fast-
tracked schedule that had a Preliminary Design Review on February 7 and Critical Design
Review on June 13, 2008. A major challenge was that PICA could not be built in large
custom-shaped pieces. Individual pieces were limited to the 0.81-meter diameter of the
Stardust sample return capsule. MSL’s heat shield was 4.5 meters across. It would have to
be tiled, like the Space Shuttle’s ceramic exterior, in Stardust-capsule-sized pieces.
1.5.4 Critical Design Review
The MSL project had had its Critical Design Review in June 2007, before either the actua-
tor or heat shield problems had fully come to light. The project passed, but the review
panel noted two very serious problems. The first was that the sample handling mechanism
design was not nearly mature enough. The second was that schedule pressure and
36 Slimko et al (2011)
28 Mars Science Laboratory
development problems likely meant that the mission would need a budget increase of
about $75 million.
1.5.5 Stern descopes
The mission requested more money at an unfortunate time. There was a new Associate
Administrator of the Science Mission Directorate at NASA: Alan Stern, a planetary
astronomer and aerospace engineer best known for being the principal investigator of the
New Horizons mission to Pluto and the Kuiper Belt. Stern had already publicly expressed
frustration with cost overruns on some NASA missions harming others. In a period of 5
years, he noted, a total of $5 billion worth of cost overruns had diverted funds from
research programs and caused opportunities for other missions to be lost. Also, Stern
shared with other members of the science community a concern that NASA was focusing
&nbs
p; too much of its limited resources on Mars, to the detriment of all the other compelling
destinations in the solar system.
Stern told the MSL project that they could not have their requested budget increase.
Rather, they had to descope their mission – remove capabilities in order to keep the mis-
sion within its original budget. Whatever savings could not be realized with descopes, they would have to take out of other missions within NASA’s Mars Exploration Program. Stern
asked JPL for suggestions of what could be cut.
There were not many options. Most of the rover’s planned hardware was exactly what
was needed to get the spacecraft safely to the surface. They cut a planned rock-grinding
tool, replacing it with a simpler brushing tool. Richard Cook had no choice but to put sci-
ence instruments on the list of things to be cut. The mission drew up a list and sent it to NASA: ChemCam, Mastcam, and MARDI. NASA accepted the cutting of ChemCam and
MARDI, but pushed back on Mastcam, knowing that it would be hard to justify to the
public the removal of all color photo capability from the rover. Could Mastcam be built
cheaper? JPL knew that the electronics were already complete, but the optics were not, so
they offered up the Mastcam optics, descoping the zoom and focus capability, leaving the
rover with cameras of two different, fixed, focal lengths, and fixed focus. 37
The descopes were announced in a press release from NASA on September 17, 2007:
The MSL project required some focused and prudent reductions in scope in order to
better ensure project success. Furthermore, because all of the funds MSL requested
were not available in the Mars Exploration Program reserves pool, and because
SMD did not want to impact other current or future science missions to fund these
new costs, the Science Mission Directorate at NASA Headquarters has been work-
ing closely with the MSL project and the science community to identify mission
scope reductions to minimize the project’s need for funds, while minimizing both
technical risk and impacts to the mission’s science return.
As a result of this careful process, a combination of low-impact mission scope
reductions and some new funding from the Mars Program’s reserves pool, has been
37 Michael Malin, personal communication, interview dated June 11, 2014
1.5 The Cost of Complexity (2007–2008) 29
agreed upon. Together these measures effectively resolve the MSL cost increase
issues identified at its [Critical Design Review].
Engineering changes to the mission include some reductions in design complexity,
reductions in planned spares, some simplifications of flight software, and some
ground test program changes. These changes were selected largely to help reduce
mission risks. Changes in mission science content were limited to removal of the
Mars Descent Imager (MARDI), the MASTCAM zoom capability from the mis-
sion, and a change from a rock grinding tool to a rock brushing tool. As noted by the
science input NASA received, most of MARDI’s capability can be provided by the
Mars Reconnaissance Orbiter’s HiRise camera now in orbit and working success-
fully. Furthermore, NASA has directed that the project expend no additional funds
on ChemCam, and cost-cap SAM and CheMin at their current budgets. Future bud-
get requests for these instruments cannot be funded.
In total, the cuts would theoretically free up about $26 million to augment mission
reserves, although that number failed to account for the termination costs of the contracts with industry partners. The impact on MSL’s science capability was severe. The most
painful loss was ChemCam, which could not be included on the rover without further
expenditure of funds. The laser instrument represented the rover’s only capability to mea-
sure rock composition from a distance. Without ChemCam, the rover would need to drive
up and touch with APXS every rock it might want to explore in situ, at enormous cost to
operational efficiency. The loss of zoom capability on Mastcam would be detrimental to
its usefulness for studying the landscape at various spatial scales. And the budget axe
loomed over SAM and CheMin. The Mars science community decried the cuts as being
penny-wise and pound-foolish.
At the same time, Stern directed that MSL actually add something to its design: a sample
cache, a simple basket designed to hold Mars rock samples. The sample cache was intended
as a first step towards Mars sample return. Stern specified that funds would come from
within the Science Mission Directorate, but outside the Mars Exploration Program. Even
so, members of the Mars community were angry that Stern had cut science instruments
from MSL to save relatively small amounts of money, while spending for a sample cache
that few people believed would ever be picked up by a future sample return mission.
Representatives of the Mars Exploration Program Analysis Group (MEPAG), led by
Jack Mustard (who was not a Mars Science Laboratory science team member), met with
Stern and other Headquarters personnel on September 24, 2007. In a summary of the
meeting, Mustard wrote: “Almost all comments relayed to the MEPAG chair preceding
the meeting were related to ChemCam, noting the loss of remote geochemical capability
and the significant investments of the French science and technology communities.
MEPAG relayed concerns regarding the international implications of the stop funding
order for ChemCam.” The group also expressed their reservations about the proposed
sample cache: “The MEPAG group re-iterated the need for appropriate samples for [Mars
Sample Return], and that poorly documented rock fragments in an open sieve basket will
not meet the criteria for science as outlined in numerous National Academy and MEPAG
reports.”
30 Mars Science Laboratory
1.5.6 Second site selection workshop
The landing site selection committee convened the second community workshop on
October 23, 2007. The mood at the second meeting was anxious, to say the least. Scientists
were still reeling from the instrument descopes. Many scientists learned for the first time about the failures in the heat shield and motor development process. The motor problems
threatened to take many favorite southern hemisphere sites out of consideration.
Engineers Mike Watkins and Adam Steltzner told the scientists that higher-elevation
landing sites were substantially riskier than lower-elevation sites, another blow to south-
ern hemisphere fans.38 In fact, the highest-elevation sites were so risky that Watkins and Steltzner requested that scientists proposing high-elevation sites develop a related “safe
haven” site at similar latitude but much lower elevation. At the end of the workshop, the
list of possible sites had formally narrowed to 11, but there was a great deal of uncertainty about whether MSL would be capable of landing at any of them, and what the quality of
its science would be without ChemCam and the other cut instruments.
Just weeks later, ChemCam and MARDI were saved. The good news was announced in
a letter from Alan Stern and Jim Green on November 8:
Malin Space Science Systems has agreed that there will be no additional costs to
NASA for the completion of the Mars Descent Imager (MARDI). Furthermore,
funds returned to the Mars Exploration Program from the unfortunate elimination o
f
MARDI operations on Phoenix will be used to support MARDI integration on MSL.
In the case of ChemCam, LANL, the French Space Agency (CNES), and even other
MSL instrument team members have developed a series of descopes and support
arrangements to allow instrument completion, reducing the development cost- to- go
by a little over 80%; i.e., from $2.5M to about $400K. As a result, ChemCam will be
funded another $400K by the Mars Exploration Program, allowing them to complete
development.
1.5.7 MARDI wheeling and dealing
MARDI was returned to MSL at its principal investigator Mike Malin’s personal expense,
with the help of a behind-the-scenes agreement with the University of Arizona’s Peter
Smith, the principal investigator of the recently-launched Phoenix Mars lander. At the
moment that it was descoped, Malin says, NASA saved about $80,000 by doing so. This
was such a relatively tiny number that unusual funding sources might work to meet the
shortfall. The Planetary Society, a nongovernmental organization, discussed with Malin
running a fundraiser among its members to complete it. In the end, Malin decided to put
up the money himself.39
So MARDI was finished, but there was still no money to put it on the rover. That money
came from Phoenix. MSL was not the first spacecraft with a MARDI. There had been one
on Mars Polar Lander, and consequently there was one on the backup lander hardware that
later became the Phoenix mission. Peter Smith had invited Malin to operate MARDI on
38 Watkins (2007)
39 The details of the impacts of the MARDI and Mastcam descopes and subsequent redesign effort of fixed-focus Mastcams are based on an interview with Michael Malin dated June 11, 2014
1.5 The Cost of Complexity (2007–2008) 31
the Phoenix mission. But there was a problem with the interface between MARDI and
Phoenix’ main computer, and ultimately Phoenix MARDI was not used at all during the
mission. Smith offered to give to JPL the money that he would have paid Malin to support
Phoenix MARDI operations. It was enough to pay to integrate MARDI on the rover. JPL
agreed, but said that the integration had to happen immediately.
