HR: 1340h
AN: P23A-0222    [Abstracts]
TI: Low Cost Precision Lander for Lunar Exploration
AU: * Head, J N
EM: jnhead@raytheon.com
AF: Raytheon, 1151 E Hermans Rd. P.O. Box 11337 Bldg. 848, M/S 6, Tucson, AZ 85734 United States
AU: Gardner, T G
EM: tggardner@raytheon.com
AF: Raytheon, 1151 E Hermans Rd. P.O. Box 11337 Bldg. 848, M/S 6, Tucson, AZ 85734 United States
AU: Hoppa, G V
EM: Gregory_V_Hoppa@raytheon.com
AF: Raytheon, 1151 E Hermans Rd. P.O. Box 11337 Bldg. 848, M/S 6, Tucson, AZ 85734 United States
AU: Seybold, K G
EM: kgseybold@raytheon.com
AF: Raytheon, 1151 E Hermans Rd. P.O. Box 11337 Bldg. 848, M/S 6, Tucson, AZ 85734 United States
AB: For 60 years the US Defense Department has invested heavily in producing small, low mass, precision guided vehicles. The technologies matured under these programs include terrain-aided navigation, closed loop terminal guidance algorithms, robust autopilots, high thrust-to-weight propulsion, autonomous mission management software, sensors, and data fusion. These technologies will aid NASA in addressing New Millennium Science and Technology goals as well as the requirements flowing from the Vision articulated in January 2004. Establishing and resupplying a long term lunar presence will require automated landing precision not yet demonstrated. Precision landing will increase safety and assure mission success. In the DOD world, such technologies are used routinely and reliably. Hence, it is timely to generate a point design for a precise planetary lander useful for lunar exploration. In this design science instruments amount to 10 kg, 16% of the lander vehicle mass. This compares favorably with 7% for Mars Pathfinder and less than 15% for Surveyor. The mission design flies the lander in an inert configuration to the moon, relying on a cruise stage for navigation and TCMs. The lander activates about a minute before impact. A solid booster reduces the vehicle speed to 300-450 m/s. The lander is now about 2 minutes from touchdown and has 600 to 700 m/s delta-v capability, allowing for about 10 km of vehicle divert during terminal descent. This concept of operations is chosen because it closely mimics missile operational timelines used for decades: the vehicle remains inert in a challenging environment, then must execute its mission flawlessly on a moment's notice. The vehicle design consists of a re-plumbed propulsion system, using propellant tanks and thrusters from exoatmospheric programs. A redesigned truss provides hard points for landing gear, electronics, power supply, and science instruments. A radar altimeter and a Digital Scene Matching Area Correlator (DSMAC) provide data for the terminal guidance algorithms. DSMAC acquires high-resolution images for real-time correlation with a reference map. This system provides ownship position with a resolution comparable to the map. Since the DSMAC can sample at 1.5 mrad, any imaging acquired below 70 km altitude will surpass the resolution available from previous missions. DSMAC has a mode where image data are compressed and downlinked. This capability could be used to downlink live images during terminal guidance. Approximately 500 kbitps telemetry would be required to provide the first live descent imaging sequence since Ranger. This would provide unique geologic context imaging for the landing site. The development path to produce such a vehicle is that used to develop missiles. First, a pathfinder vehicle is designed and built as a test bed for hardware integration including science instruments. Second, a hover test vehicle would be built. Equipped with mass mockups for the science payload, the vehicle would otherwise be an exact copy of the flight vehicle. The hover vehicle would be flown on earth to demonstrate the proper function and integration of the propulsion system, autopilots, navigation algorithms, and guidance sensors. There is sufficient delta-v in the proposed design to take off from the ground, fly a ballistic arc to over 100 m altitude, then guide to a precision soft landing. Once the vehicle has flown safely on earth, then the validated design would be used to produce the flight vehicle. Since this leverages the billions of dollars DOD has invested in these technologies, it should be possible to land useful science payloads precisely on the lunar surface at relatively low cost.
DE: 6250 Moon (1221)
DE: 6297 Instruments and techniques
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting