NASA almost immediately announced plans to fly Mars Observer's science instruments on an inexpensive Mars orbiter as soon as possible. This marked the genesis of the Mars Surveyor Program, which aimed to launch low-cost automated spacecraft to Mars every 26 months, at each minimum-energy launch opportunity. 18
Refreshed Dreams
In 1994, the JSC Planetary Projects Office, NASA's de facto focus for piloted Mars planning following abolition of the Headquarters Exploration Office, was downsized, then abolished. In February it became a branch of the JSC Solar System Exploration Division, and in June its remaining personnel were assigned to the JSC Office of the Curator, where they explored low-cost options for sending people to the Moon. 19 The Curator's Office managed disposition of Apollo lunar samples and meteorites, including one meteorite designated ALH 84001. Even as the Planetary Projects Office was abolished, ALH 84001 was determined to have originated on Mars.
On 7 August 1996, NASA, Stanford University, and McGill University scientists led by NASA scientist David McKay announced that they had discovered possible fossil microorganisms in Martian meteorite ALH 84001. In a NASA Headquarters press conference, the McKay team cited the evidence for past Martian life. This included the presence of complex carbon compounds resembling those produced when Earth bacteria die, magnetite particles similar to those in some Earth bacteria, and segmented features on the scale of some Earth nanobacteria. McKay told journalists,
There is not any one finding that leads us to believe that this is evidence of past life on Mars. Rather, it is a combination of many things that we have found. They include Stanford's detection of an apparently unique pattern of organic molecules, carbon compounds that are the basis of life. We also found several unusual mineral phases that are known products of primitive microorganisms on Earth. Structures that could be microscopic fossils seem to support all of this. The relationship of these things in terms of location—within a few hundred-thousandths of an inch of each other—is the most compelling evidence. 20
According to their analysis, the 1.9-kilogram rock soaked in carbonate-rich water containing the possible microorganisms 3.6 billion years ago. It lay in the Martian crust, shocked by the occasional local upheaval, until an asteroid impact blasted it off Mars 16 million years ago. After orbiting the Sun several million times, ALH 84001 landed in Antarctica 13,000 years ago, where it was collected on 27 December 1984 in the Allan Hills ice field. 21
The McKay team's discovery generated unprecedented public enthusiasm for Mars, which in turn provided the catalyst for reestablishment of the JSC Exploration Office in November 1996. The new office, managed by Doug Cooke, was reconstituted as part of the Advanced Development Office in the JSC Engineering Directorate. 22 Mars planners dusted off the 1993 DRM to serve as the point of departure for new planning.
At the same time, NASA Headquarters took an important step toward eventual piloted Mars exploration. On 7 November 1996, Associate Administrator for Space Flight Wilbur Trafton, Associate Administrator for Space Science Wesley Huntress, and Associate Administrator for Life and Microgravity Sciences and Applications Arnauld Nicogossian signed a joint memorandum calling for NASA's Human Exploration and Development of Space (HEDS) Enterprise and Space Science Enterprise to work together toward landing humans on Mars.
They told Jet Propulsion Laboratory director Edward Stone and JSC director George Abbey that "[r]ecent developments regarding Mars and the growing maturity of related programs lead us to believe that this is the right time to fully integrate several areas of robotic and human Mars exploration study and planning." 23 The Associate Administrators then gave Stone and Abbey until 1 February 1997, to produce "a proposal that NASA can bring forward, after successful deployment of the International Space Station, for human exploration missions beginning sometime in the second decade of the next [21st] century." 24
Trafton, Huntress, and Nicogossian also asked for "a credible approach to achieving affordable human Mars exploration missions." They defined "a credible cost" as "the amount currently spent by NASA on the International Space Station"—that is, less than $2 billion annually. This was a dramatic reduction over the $15 billion per year proposed in the excised cost section of The 90-Day Study. They asked that Stone and Abbey identify "technology investments and developments that could dramatically decrease the cost of human and robotic missions." 25
In March 1997, the HEDS and Space Science Enterprises agreed that the 2001 Mars Surveyor lander should include instruments and technology experiments supporting piloted Mars exploration. Among the planned experiments was a compact system for testing ISRU propellant manufacture on Mars. In a press conference, Huntress called it "the first time since the 1960s" that "NASA's space science and human space flight programs are cooperating directly on the exploration of another planetary body." Trafton called the joint effort "a sign that NASA is acquiring the information that will be needed for a national decision, perhaps in a decade or so, on whether or not to send humans to Mars." 26
In addition to stating that NASA's robotic program would complement its piloted Mars flight planning efforts, the joint memorandum showed that, at a high managerial level, NASA had not abandoned its plans to eventually send people to Mars despite SEI's collapse. There was no firm timetable for accomplishing the piloted Mars mission and no Presidential declaration. Instead, there was a new philosophy—continuing low-level, low-cost planning, much of it in-house, and low-level Earth-based technology research accompanied by efforts to use the existing low-cost robotic exploration program to answer questions relevant to piloted exploration. In short, the Agency accepted publicly for the first time that it might eventually send people to Mars without recourse to a new large program—without a new Space Exploration Initiative or Apollo program. This philosophy continues to guide NASA Mars planning at the time of this writing (mid-2000).
Success or failure in the automated Mars program thus became success or failure for piloted Mars planners. The joint human-robotic Mars effort received a boost on 4 July 1997, when Mars Pathfinder successfully landed at Ares Vallis, one of the large outwash channels first spotted by Mariner 9 in 1971 and 1972. Pathfinder, the first U.S. Mars lander since the Vikings, dropped to the rock-strewn surface and bounced to a stop on airbags, then opened petals to right itself and expose instruments and solar cells. The technique was similar to the one the Soviets employed to land robots on the Moon in the 1960s and on Mars in the 1970s. The Sojourner rover—the first automated rover to operate on another world since the Soviet Union's Lunokhod 2 explored the Moon in 1972— crawled off its perch on one of Pathfinder's petals and crept about the landing area analyzing rock and dirt composition. Sojourner and Pathfinder—the latter renamed the Sagan Memorial Station—successfully completed their primary mission on 3 August.
As Mars Pathfinder bounced to a successful landing in Ares Vallis, the glossy report Human Exploration of Mars: The Reference Mission of the NASA Mars Exploration Study Team rolled off the presses. 27 In addition to a detailed description of the 1993 DRM, the July 1997 document contained general recommendations on the conduct of a piloted Mars program based on experience gained through SEI and the Space Station program.
The report recommended that NASA set up "a Mars Program Office . . . early in the process." It also proposed to avoid Space Station's redesigns and delays by establishing "a formal philosophical and budgetary agreement . . . as to the objectives and requirements imposed on the mission before development is initiated, and to agree to fund the project through to completion." Finally, taking into account the McKay team's discovery, it called for "adequate and acceptable human quarantine and sample handling protocols early in the Mars exploration program" to protect Earth and Mars from possible biological contamination. 28
The JSC Exploration Office called its report "another chapter in the ongoing process of melding new and existing technologies, practical operations, fiscal reality, and common sense into a feasible and viable human mission to Mars," adding that "this is not the last chapter in the process, but [it] marks a snapshot that will be added to and improved upon by others in the future." 29 In fact, by the time the report saw print, the next chapter was nearly complete.
Scrubbing the DRM
Subsequent DRM evolution focused on minimizing spacecraft weight in an effort to reduce estimated mission cost. The slang term engineers used to describe this process was "scrubbing." The 1997 "scrubbed" DRM went public in August 1997. 30 It minimized mass by reducing common Habitat diameter; combining the functions of the pressure hull, aerobrake heat shield, and Earth launch shroud; and employing lightweight composite structures. The nuclear stages for injecting the spacecraft toward Mars would be launched into Earth orbit without spacecraft attached, then docked with the spacecraft in Earth orbit. These steps and others allowed planners to eliminate the 1993 DRM's large heavy-lift rocket, potentially the costliest mission element.
Figure 28—NASA's 1997 Mars plan proposed to reduce weight by using an aerobrake integrated with the spacecraft hull and nuclear rockets. These steps would help eliminate need for a heavy-lift rocket, permitting a cheaper Shuttle-derived launch system. (NASA Photo S97-07844)
<!-- image -->To place the first crew on Mars, the 1997 DRM would require eight launches of a Shuttle-derived rocket capable of boosting 85 tons into Earth orbit. In the first launch opportunity, six of these rockets would launch payloads—three nuclear propulsion stages and three Mars spacecraft (cargo lander, ERV, and unpiloted Habitat). Each spacecraft would dock with its nuclear stage in Earth orbit, then launch toward Mars. In the second launch opportunity, 26 months later, six more Shuttle-derived rockets would launch three nuclear stages and three spacecraft, including a Habitat lander containing the crew. The spacecraft would dock with their nuclear stages and launch toward Mars. The rest of the mission plan closely resembled the 1993 DRM. To accomplish the first expedition, the 1997 DRM would launch 303 tons to Mars—75 tons less than the 1993 DRM.
Figure 29—Nuclear stages in NASA's 1997 Mars plan included engines (left) based on revived 1960s NERVA technology. (NASA Photo S97-07843)
<!-- image -->The new DRM was on the street, and a few weeks later, a new automated spacecraft was orbiting Mars. On 11 September 1997, the Mars Global Surveyor orbiter, the first spacecraft in the Mars Surveyor Program, arrived in an elliptical Mars orbit after a 10-month flight. Mars Global Surveyor carried backups of instruments lost with Mars Observer in 1993. It commenced a series of passes through Mars' upper atmosphere to reach a lower, more circular Mars orbit without using propellants. A damaged solar array threatened to collapse under the pressure of atmospheric drag, however, so the aerocapture maneuvers had to be extended over a year. Nevertheless, the spacecraft turned its instruments toward Mars and began initial observations.
Defining the Surface Mission
As Mars planners sought to minimize spacecraft weight, it became clear that they would require more data on the mission's Mars surface payload. Planners historically have spent little time detailing what astronauts would do once they landed on Mars. To begin the process of better defining the 500-to-600-day Mars surface mission, veteran Moon and Mars planner Michael Duke chaired a workshop held at the Lunar and Planetary Institute in Houston on 4-5 October 1997. 31
Workshop participants divided into two working groups. The Science and Resources group based its discussions on a "three-pronged approach" to Mars exploration. Mars explorers would seek evidence of life or its precursors and attempt to understand Mars climate history. They would also act as prospectors, seeking water, minerals, energy, and other resources for supporting future Mars settlements. This three-pronged science approach also guided the automated Mars Surveyor program. 32