Thus declared William O’Neil and Christian Cazaux in October 1999 as they described U.S. and French plans for a joint robotic Mars Sample Return (MSR) mission. O’Neil was MSR Project Manager at the Jet Propulsion Laboratory (JPL) in Pasadena, California, while Cazaux was his counterpart at the Centre National d’Etudes Spatiales (CNES) in Toulouse, France. They spoke before a crowd of aerospace engineers and planetary scientists at the 50th International Astronautical Federation (IAF) Congress in Amsterdam.
JPL and CNES had begun to work together toward an MSR mission in mid-1998, as it became increasingly obvious that JPL’s planned Mars Sample Return mission design was too massive and thus would need a large launch vehicle that would cost more than NASA could readily afford. The decision to add a second MSR lander, Mars Ascent Vehicle (MAV) and rover to help to ensure mission success through redundancy compounded the problem. By contributing one large launch vehicle and the MSR Earth-return vehicle, CNES could save NASA hundreds of millions of dollars and permit JPL to fly the hefty rovers it saw as central to its MSR mission. For CNES, the payoff was in large part prestige; its spacecraft would, in addition to delivering to Mars the first European Mars landers, transport to Earth’s vicinity the first samples collected from the surface of Mars.
O’Neil and Cazaux told their IAF audience that the MSR mission, the planned culmination of NASA’s on-going Mars Surveyor Program, would start in May 2003 with the launch of a U.S. Delta III or Atlas III rocket bearing a saucer-shaped aeroshell containing a flat-topped, three-legged Mars Surveyor-type lander similar to the Mars Polar Lander, which was on its way to Mars as they presented their paper. The lander would carry an Athena-type rover similar to the one then under development for the Mars Surveyor 2001 mission, and a solid-propellant MAV. The MAV would lay horizontally atop the lander, and the six-wheeled rover would straddle the MAV. Lander, rover, and MAV would together have a mass of about 1830 kilograms.
Solar cells on a cruise stage attached to the aeroshell would provide “keep-alive” electricity during the seven-month flight to Mars. The aeroshell would reach Mars in December 2003, cast off the cruise stage, and enter Mars’s atmosphere directly. After a fiery atmosphere entry, the lower aeroshell would separate and a parachute atop the upper aeroshell would open. During terminal descent, the lander would drop free of the upper aeroshell and parachute, fire landing rockets, and unfold three landing legs. After touchdown, twin ten-sided solar arrays would unfold to make electricity.
Lost in space: if the Mars Polar Lander, pictured above, had not disappeared during landing in December 1999, NASA would have used a similar design as the basis for its 2003 and 2005 MSR landers. Image: NASA JPL/Corby Waste
Between December 2003 and March 2004, controllers on Earth would extend a ramp from the lander’s 2.6-meter-wide top deck and drive the Athena rover down it onto the martian surface. Solar-powered Athena would have a mass of 80 kilograms – nearly eight times greater than Sojourner, the “minirover” deployed during the Mars Pathfinder Discovery mission in July 1997.
Scientists would use images from Athena’s boom-mounted panoramic camera (Pancam) to select a nearby sampling site, then controllers would remotely drive the rover to the site and examine it using spectrometers and a microscope imager. If the science team judged the site to be worth sampling, then controllers would deploy the mini-corer device. This would drill down up to half a meter to collect a core sample eight millimeters wide by 25 millimeters long. As many as 60 samples – a total of 250 carefully selected grams of Mars – might be collected at as many as 20 sites over 90 martian days (known as Sols). A drill on the lander, meanwhile, would collect an equal amount of Mars sample material at the site where it happened to touch down. This less discriminate “grab sample” would help to ensure that martian material could reach Earth even if the Athena rover failed.
In March 2004, the rover would climb back onto the lander’s broad top deck, straddle the MAV, and transfer its cargo of Mars cores into the spherical, grapefruit-sized Orbiting Sample (OS) canister. After the transfer was complete, controllers would drive Athena off the lander and park it some distance away. The 120-kilogram MAV would then tip upright to point its streamlined nose at the butterscotch-colored martian sky.
O’Neil and Cazaux wrote that “the concept of a very simple, spinning, unguided, solid propellant” MAV, introduced by JPL engineer Brian Wilcox at JPL-sponsored Mars Sample Return Architecture Workshops in mid-1998, was “adopted by [the] MSR Project as most robust and simple enough to [design and build] in time for the 2003 mission.” (Other engineers, mainly outside JPL, expressed skepticism, for they felt that the proposed MAV system was too bare-bones to be workable; this opinion was in fact the basis for the decision to fly two lander/Rover/MAV combinations.) First-stage ignition would launch the MAV skyward (image at top of post) and spin it about its long axis to create gyroscopic stability.
After the first stage exhausted its solid propellant and fell away, the second stage would boost the OS canister into a 600-kilometer-high near-circular orbit tipped 45° relative to Mars’s equator. The OS canister would then separate from the second stage and activate its solar-powered radio beacon so that controllers on Earth could track it to determine its orbit.
In August 2005, an uprated CNES Ariane 5 rocket – at the time the largest planned for the Ariane family – would lift off from Kourou in French Guiana, South America, bearing a lander/Athena/MAV payload nearly identical to that flown in 2003, plus a French-built Earth-return vehicle with a cruise stage bearing four CNES/European Space Agency Netlander rough-landing probes. The 2700-kilogram Earth-return vehicle would include two NASA-built Earth Entry Vehicles (EEVs) with bowl-shaped, 0.75-meter-diameter heat shields. The 2005 NASA lander would ride above the CNES Earth-return vehicle on an adapter in the Ariane 5’s large streamlined launch shroud.
In Earth orbit, the Ariane 5’s L9 upper stage would ignite to place French Earth-return vehicle and U.S. lander on course for Mars. After L9 stage shutdown, the Earth-return vehicle and lander would separate from the stage and from each other and coast to Mars independently.
Brawny CNES Earth-return vehicle: visible are the back side of the aerocapture heat shield, one of two U.S. EEVs, four Netlanders, folded solar arrays for Mars-orbital operations and the flight from Mars to Earth, and a fanciful background. Image: ESA/David Ducros
In July 2006, the U.S. lander would descend through Mars’s atmosphere and land in much the same way as its Mars Surveyor 1999, 2001, and 2003 predecesssors would have done. The French Earth-return vehicle, meanwhile, would release its cruise stage. The Netlanders would separate from the discarded cruise stage, enter the martian atmosphere, and rough-land at widely scattered sites. The cruise stage would be destroyed. The Earth-return vehicle would then dive deep into Mars’s atmosphere. This maneuver, called aerocapture, would allow it to slow down and enter Mars orbit while using only minimal braking propulsion. O’Neil and Cazaux estimated that propellants for slowing the Earth-return vehicle so that Mars’s gravity could capture it might have a mass of more than 1000 kilograms; the bowl-shaped aerocapture heat shield, on the other hand, would have a mass of only about 400 kilograms. After aerocapture, the CNES Earth-return vehicle would unfold twin solar arrays that would take over for those discarded with the cruise stage.
The 2005 Athena rover would collect samples on Mars between July and October 2006. The Earth-return vehicle, meanwhile, would begin tracking the 2003 OS canister’s radio beacon. Over six months controllers on Earth would guide the Earth-return vehicle to within two kilometers of the spherical canister, then an onboard lidar rendezvous system would take over. A U.S.-built “capture basket” would then “swallow” the 2003 OS canister and transfer it to one of the EEVs attached to the Earth-return vehicle.
French Earth-return vehicle aerocaptures into Mars orbit. Image: NASA JPL/Corby Waste
In October 2006, after 90 martian days, the 2005 MAV would launch its OS canister into Mars orbit. The French Earth-return vehicle would set out in slow pursuit, swallow the 2005 canister, and transfer it to the second EEV. It would then loiter in Mars orbit until Earth and Mars became aligned to permit a minimum-energy transfer nine months later (July 2007). The Earth-return vehicle would first fire its rockets to move into a highly elliptical Mars orbit. At the proper time, as it reached periapsis (the point in its orbit nearest the planet), it would fire its rockets again to escape Mars and put itself on course for Earth.
The Earth-return vehicle would fly past Earth in April 2008 so that its gravity could bend the spacecraft’s course. O’Neil and Cazaux explained that the minimum-energy Mars-Earth transfer trajectory selected for the 2003-2005 joint mission meant that the Earth-return vehicle would pass over Earth’s southern hemisphere during its first Earth encounter. The April 2008 flyby would bend the spacecraft’s course to ensure that the EEVs would land on U.S. soil when the Earth-return vehicle again encountered Earth in October 2008.
As Earth loomed large a second time, the EEVs would separate and the Earth-return vehicle would fire its rockets so that it would either miss Earth or reenter over uninhabited, little-trafficked ocean. The EEVs would enter Earth’s atmosphere directly and lower to the ground on parachutes. During descent, they would activate radio beacons so that their precious cargoes could be found and recovered quickly.
A month before O’Neil and Cazaux presented their paper, JPL and its contractor, Lockheed Martin, had accidentally destroyed Mars Climate Orbiter (MCO), the second spacecraft of the Mars Surveyor Program. Through an almost comical failure of communication, the two organizations had used different units of measurement when guiding MCO to Mars, so that when it arrived at the planet it entered Mars’s atmosphere and burned up.
Two months after the Amsterdam IAF Congress, the third Mars Surveyor Program spacecraft, Mars Polar Lander, disappeared without a trace during descent to a landing in Mars’s south polar region. The failure was traced to a software error that caused the lander to turn off its descent rocket engines about 40 meters above Mars’s surface.
With embarrassment piled upon embarrassment, NASA created the Mars Program Independent Assessment Team to review the Mars Surveyor Program. In March 2000, the Team found fault with the Mars Surveyor Program’s aggressive pace. In October 2000, while the Acta Astronautica issue containing O’Neil and Cazaux’s conference paper was still current, NASA cancelled the Mars Surveyor Program and announced that no NASA MSR mission would launch before 2011.
Not surprisingly, the unilateral U.S. decision to abandon the 2003-2005 MSR project frustrated the French. For a time, NASA held out hope for a NASA/CNES MSR mission starting in 2011, and CNES also considered flying its MSR Earth-return vehicle to Mars alone in 2007 to drop off the Netlanders and test aerocapture and rendezvous technologies. The French determined, however, that an 11-year wait was unacceptable given the apparent instability of the U.S. Mars program, and that flying the Earth-return vehicle/Netlander combination alone would not yield scientific results commensurate with its cost.
CNES orbiter modified to operate without U.S. EEV capsules following U.S. withdrawal from the joint NASA-CNES MSR project. Image: ESA/David Ducros
Reference:
“The Mars Sample Return Project,” William J. O’Neil and Christian Cazaux, Acta Astronautica, Vol. 47, Nos. 2-9, July-November 2000, pp. 453-465; paper presented at the 50th International Astronautical Federation (IAF) Congress in Amsterdam, the Netherlands, 4-8 October 1999.
This post is the fifth (and last) in a series. Below are listed the posts in this series in chronological order.
Martian Weight Problem: Mars Sample Return Version 0.7 (1998) – http://more-deals.info/wiredscience/2013/12/mars-sample-return-version-0-7-1998/%3C/a%3E%3C/p%3E%3Cp class="paywall">Model Rockets on Mars (1998) – http://more-deals.info/wiredscience/2013/06/model-rockets-on-mars-1998/%3C/a%3E%3C/p%3E%3Cp class="paywall">Model Rockets on Mars Redux (1998) – http://more-deals.info/wiredscience/2013/07/model-rockets-on-mars-redux-1998/%3C/a%3E%3C/p%3E%3Cp class="paywall">Robot Rendezvous in Mars Orbit (1999) – http://more-deals.info/wiredscience/2013/11/robot-rendezvous-in-mars-orbit-1999/%3C/a%3E%3C/p%3E%3Cp class="paywall">Mars Sample Return: Vive le retour des échantillons martiens! (1999) – this post
