Proceeding of the 6th International Symposium on Artificial Intelligence and Robotics & Automation in Space: i-SAIRAS 2001, Canadian Space Agency, St-Hubert, Quebec, Canada, June 18-22, 2001. The Mars Technology Program* James A. Cutts, Samad A. Hayati, Donald Rapp and Chengchih Chu Jet Propulsion Laboratory California Institute of Technology, Pasadena, CA 91109 and Joeseph C. Parrish, David B. Lavery and Ramon P. DePaula National Aeronautics and Space Administration Washington, DC 20456 [email protected] Keywords: technological innovations.1 The most important of these is the ability to make a safe landing at any locality on Mars, technology, exploration, lander, rover, sample Mars. These technology innovations would be carried return, technology plan, technology infusion forward into the 2011 mission, which is planned to be a Abstract sample return mission. The Mars Technology Program (MTP) is a NASA-wide The enabling technologies for the proposed 2007 and technology development program managed by JPL. It is 2011 surface missions will be addressed in a Focused divided into a Focused Program and a Base Program. Technology Program that is tightly tied to proposed The Focused Program is tightly tied to proposed Mars Mars Program mission milestones. It involves time- Program mission milestones. It involves time-critical critical deliverables that must be developed in time for deliverables that must be developed in time for infusion infusion into the proposed Mars 2007 and Mars 2011 into the proposed Mars 2007 and Mars 2011 missions. missions. This program bridges the gap between This program bridges the gap between technology and technology and projects by vertically integrating the projects by vertically integrating the technology work technology work with pre-project development in a with pre-project development in a project-like project-like environment. The technology work includes environment with critical dates for technology infusion. validation and risk reduction through simulation, A Base Technology Program attacks higher risk/higher laboratory and field tests and the use of flight payoff technologies not in the critical path of missions. experiments when required. 1. Introduction In addition, a Base Technology Program will address enhancing technologies for missions proposed for 2007 The NASA Mars Exploration Program has plans to and 2011, critical capabilities for Scout/competitive and implement a series of ambitious missions with launches Orbiter missions, and capabilities for all missions every two years, culminating in a sample return mission beyond 2011. The Base Program stresses breakthrough with a launch date in 2011. Launches will alternate technology elements that are not in critical path of between Orbiters and Landers at each Mars launch missions. It will address technology needs that are less opportunity. Orbiters would be launched on 4-year mature and higher risk (and higher payoff) than those centers in 2001, 2005, 2009, …, and will be used as constituting the Focused Program. The Base Program telecommunication relay stations after they carry out includes collaborative programs with the Outer Planets their primary science missions. Landers would be Program, competitive elements, and leveraged launched on 4-year centers in 2003, 2007, 2011,…. technology programs with other funding sources. A series of Scout missions have been proposed for The Focused Technology Program and the Base launch on 4-year centers starting in 2007. These Technology constitute the elements of the Mars missions would be competed for by the science Technology Program (MTP) that is managed by JPL, community. It is possible that they might involve but which is carried out by the full NASA community. airborne vehicles, balloons or networks of small landers, The relationship of the Focused Technology Program but the strongest proposals will be funded regardless of and Base Technology Program to the suite of planned the approach. NASA Mars missions for the next decade is illustrated The 2003 Mars Exploration Rovers (MER) mission in Figure 1. includes two rovers that are far more capable than the Pathfinder rover. The proposed 2007 Smart Lander mission would introduce a number of significant Mars Express Base Program • Breakthrough technologies • Broad impact • Support Scouts • Includes collaboration with other sponsors Focused Program • Enable MSL and MSR • Include risk reduction and validation • Run like a project Figure 1. Contributions of the Focused and Base Programs to Mars missions. resulting in a landing error ellipse ranging from 100 km In order to develop capabilities for these missions and cross range to 300 km along the downrange vector. The beyond, the NASA Mars Technology Program is being payload mass that can be delivered using existing or implemented under JPL leadership. This Program’s goal anticipated launch vehicles with this system is limited to is to develop and infuse key technologies needed to ~ 70 kg. enable proposed future Mars missions. In this paper, a synopsis of the plan for implementing the Mars Precision landing reduces the risk of encountering Technology Program is provided. hazardous areas such as large craters and steep canyons at any given region of Mars where it is desired to land. 2. Focused Technology Program Our goal is to develop new technology to reduce the 2.1 Mars 2007 Smart Lander landing error ellipse to smaller than 3 x 10 km. In One of the main goals is to develop the capability to addition the payload mass will be raised to ~ 300 kg. To land safely near any chosen site (including higher achieve this goal, each step of the EDL process is elevations) in order to provide a global access to Mars. upgraded with new technology. Figure 2 illustrates the To achieve this ability to land safely at any locality on steps involved in precision EDL. Each step is being Mars, the entire process of entry, descent and landing developed with advanced technology, with systems was reviewed and innovations are planned to provide integration used to assure that all the pieces fit together. the needed capabilities. To achieve this goal, three complementary technologies The present state of the art for EDL on Mars utilizes are being developed: radio-based approach navigation, no control of the lift • Precision landing vector during entry, a single stage parachute, and hazard tolerance only to the extent that either airbags or landing • Hazard avoidance struts are utilized. There is no hazard • Robust landing detection/avoidance capability. Variants of this approach were used on Viking and Pathfinder and will be used on the Mars 2003 mission. The errors in approach navigation propagate through the trajectory, Page 2 Deploy hypersonic chute @ 10-12 km Jettison backshell & hyper chute (7-9 km) Deploy subsonic chute; jettison heat shield (7-9 km) Generate terrain map with RADAR; compute landing area (7-9 km) Generate terrain map with LIDAR and RADAR; Designate safe landing area (1.5 km) Jettison subsonic chute, ignite descent engines (.5-.7 km) 30- 45 sec to touchdown Continue computing reachable landing site ellipse. Compute desired acceleration to achieve touchdown condition Designate a new landing site, if available, to avoid hazards Descend to 15 m above landing site Descend at constant acceleration Shut engine 1 m above surface Figure 2. Schematic steps involved in precision descent and landing. lander to a safe landing area. A RADAR sensing system 2.1.1 Precision Landing for 0-7 km altitudes will be developed to generate initial A new optical navigation camera is being developed to terrain maps and create initial estimates of the landing use the Martian moons Phobos and Deimos as reference area at ~ 7 km altitude. When the capsule descends to ~ targets for precise entry. A lifting entry vehicle is being 1.5 km, LIDAR is used to augment the RADAR terrain developed with L/D ~ 0.25 that is capable of actively maps, and alternate landing sites are designated if guiding itself from entry to parachute deployment hazards are detected. Field tests will be conducted with despite uncertainties in the entry conditions, rocket sled and helicopter test platforms to validate atmospheric density profile, winds and aerodynamic these technologies. performance (Figure 3). A two-stage parachute system will be developed with the subsonic parachute having the potential for para-guidance. Improved descent propulsion will be achieved by recapturing Viking technology with new miniaturized components. 2.1.2 Hazard Avoidance Hazard avoidance provides an “eyes wide open” capability at landing. The overall process is illustrated in Figure 2. This makes it possible to make last-minute adjustments to landing location to avoid large craters, large rocks and steep local slopes. (Figure 4) The MTP will develop an integrated terminal guidance, navigation and control system that predicts the descent flight path after the subsonic parachute is deployed, detects hazards such as rocks and slopes using active sensors, and after jettisoning the parachute, steers the Figure 3. Schematic of Controlled Entry Page 3 2.1.3 Robust Landing Once landing is committed to, this technology makes it possible to tolerate the unexpected or provide resilience to failures in either precision landing or hazard avoidance systems (Figures 5 and 6). Two approaches are under study, one involving airbags and the other a pallet system. A down-select to choose the optimum approach is expected by the end of FY2001. 2.1.4 Long Life Surface Power There are two potential approaches for surface power on Mars: radioisotope power and solar photovoltaic power. The Viking missions used small radioisotope thermoelectric generators (RTGs) as power sources. The Mars Pathfinder mission utilized solar photovoltaic power. Each of these approaches has advantages and disadvantages, with significant implications for mission Figure 4. Schematic Hazard Avoidance design. Solar power may be feasible for some surface missions on Mars. Surface missions powered by photovoltaics carry out most operations during a ~ 7 hour period centered on solar noon, and use batteries to provide survival levels of power overnight.