Andre Yavrouian

Balloons for controlled roving/landing on mars

Abstract Until now, the only practical balloon systems proposed to explore the martian atmosphere have been superpressure balloons, which fly at a constant altitude, or short-lived helium balloons, which precariously drag a snake through all types of surface weather, or a day/night combination of the two. For the first time, two novel atmospheric balloon systems now appear quite viable for controlled balloon landings at selected martian surface locations. These balloons could softland payload packages, such as lightweight surface roving vehicles. The two balloon approaches and a land rover concept are described below, along with a combination of the two approaches. Solar Hot-Air Balloons: These “Montgolfiere” balloons are named after the 18th-century French brothers Joseph-Michel and Jacques-Etienne Mongolfier, who first flew hot-air balloons. Using entirely solar heat, they are ideal for landing at the martian poles during summer or for shorter flights at lower latitudes. Recent tests have already confirmed the ease of altitude deployment and filling of these solar hot-air balloons. Furthermore, actual landings and reascents of solar hot-air balloons have been recently demonstrated by JPL, using a novel, lightweight, top air vent that is radio controlled. One particularly useful application of these balloons is their use as a parachute to soft-land packages that are up to 50% of the total entry mass, which represents a fivefold improvement over present retrorocket landing systems . Variable-Emissivity Balloons: A second atmospheric balloon system uses a variable-emissivity superpressure helium balloon that can land at night at any martian latitude. These balloons would be gold-coated, superpressure helium balloons during both night and day. They could land at prescribed targets by exposing a section of the upper white balloon surface to the radiant cooling of deep space during the night. This reduces the temperature and pressure in the balloon to create negative buoyancy, thus causing descent, while replacement of the gold top cover causes reascent. Specific areas could be targeted for landings by using atmospheric currents at various altitudes, similar to techniques used by balloonists flying over the Earth. Inflatable Roving Vehicles: JPL has recently fabricated and tested a number of roving vehicles with large inflatable balloons that act as tires. One version, with 75-cm-diameter wheels, has already demonstrated the ability to make large traverses in JPLs simulated “Mars Yard.” A full-scale version, with 1.5-m-diameter wheels, should be capable of climbing large rocks (≤ 0.5 m), traveling reasonably fast (≈ 500 m/h) and far (≈ 10 km), and yet have very low mass (≈ 6 kg). Low-Cost Combined Atmospheric/Surface Mission: A simple, solar hot-air balloon would act as a parachute to land a 6-kg inflatable rover. The balloon would then rise to a 3-km altitude while carrying a 2-kg camera/magnetometer/communications package for the remainder of daylight hours. The entire package would then soft-land at dusk. Total Mars entry mass would be about 20 kg, and the mission could be flown to Mars at very low cost (≈

Balloon precursor mission for Venus Surface Sample Return

5M total launch costs) via one of the CNES Ariane 5 GTO piggyback launches.

Venus Surface Sample Return: Role of Balloon Technology

This paper proposes a precursor mission to the Venus Surface Sample return Mission (VSSR). The present scenario of the VSSR includes delivery by a balloon of the Venus Ascent Vehicle (VAV) from the surface to an altitude of approximately 60 km, where it can be launched without huge penalty for atmospheric losses. The mission includes a number of critical technologies that can be validated in this proposed precursor mission. The other objective of the proposed mission is to collect more accurate data on the Venus atmosphere that is essential for the VSSR mission design. The paper discusses the basic mission and system elements for the proposed precursor mission.

Polymer material for electrolytic membranes in fuel cells

The rocks and soils on the surface of Venus record the secrets of why this planet evolved so differently from its sister planet Earth: Both NASA and the European Space Agency are now studying missions for bringing samples from the surface of Venus back to Earth where they can be analyzed with state-of-the-art techniques. Balloon technology will play a key role in such a mission. It will be used for raising samples from the Venus surface when the temperature is 460C and the pressure is 90 bars to the upper atmosphere from where the samples can be launched into orbit around Venus. Three approaches to the implementation of a solidrocket based Venus Ascent Vehicle (VAV) have been considered in the NASA study carried out at JPL. In the first approach, similar to the ESA concept, the solid rocket is an integral part of the surface sampling system, is carried to the surface of Venus and lifted back to the upper atmosphere on the same balloon. In the second approach, the VAV is deployed in the upper atmosphere and suspended there on a blimp which performs a rendezvous with the balloon carrying the surface sample and effects a sample transfer. In the third approach, the VAV is deployed into the atmosphere on a winged vehicle that performs a rendezvous with the balloon carrying the surface sample and also performs sample transfer. The paper compares the three approaches. It also includes the developments in balloon technology and in materials and devices for use in severe environments. INTRODUCTION Thirty years ago, human and robotic missions to the moon, performed the first sample return of extraterrestrial materials. The Apollo astronauts Affiliations: (1) Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California (2) Winzen Engineering, San Antonio, Texas brought back lunar rock, soil and drill core samples in six successful manned missions between 1969 and 1972. The Soviet Union carried out two successful robotic lunar sample return missions in the same period: Luna 16 and Luna 20 that returned drill core samples. A second wave of sample return missions is now under way. On February 7, 1999, NASA launched the STARDUST mission that will fly through the tail of a comet at more than 6km/sec, capture intact particles of comet dust in a low density aerogel collector and bring the samples back to Earth five years later. In January 2001, NASA will launch the GENESIS spacecraft to collect samples of the solar wind in an ultrapure silicon wafer. Then in 2003, NASA in collaboration with CNES (the French Space Agency), will launch the first phase of the Mars Surface Sample Return (MSSR) mission that will collect surface soil, rock core and atmospheric samples from Mars. The samples will be returned to Earth in 2008. With the launch of the first element of the Mars Surface Sample Return mission only four years away, both NASA and the European Space Agency (ESA) are now turning their attention to sample return from other solar system bodies. Earth’s sister planet Venus has high priority for a sample return mission. However, the problems of acquiring and returning samples from Venus are formidable. Venus is comparable in size to Earth and almost 10 times the mass of Mars, but it possesses an inhospitable surface environment with temperatures near 460C, surface pressures of 90 bars and sulfuric acid particles in the upper atmosphere. As discussed in companion papers in this issue, advanced balloon technology can play a key role in carrying out the in situ exploration of Venus including close up observations of the surface. Balloon technology also will play a critical role in returning samples of soils and rocks from the surface of Venus. 1 American Institute of Aeronautics and Astronautics ARCHITECTURE OF MARS SURFACE SAMPLE RETURN MISSION The philosophy underlying the NASA approach to Venus Surface Sample Return (VSSR) is to build on the mission architecture used for the Mars Surface Sample Return (MSSR) mission. In this section, we first give a simplified description of the architecture of the MSSR mission and then describe how a VSSR mission can incorporate key subsystem elements. In the MSSR, a vehicle is delivered to the Mars surface consisting of sample collection equipment and a three-stage solid-rocket Mars Ascent Vehicle (MAV). Once samples have been placed in a canister in the MAV, the canister is propelled into a low but stable near-circular orbit around Mars. A second spacecraft performs an autonomous rendezvous with the sample canister, solid rockets and minimal overhead in guidance and control systems such that it can lift a sample from the surface and delivering it to a stable although not precisely defined orbit. VENUS SURFACE SAMPLE RETURN The philosophy of the recent JPL study of VSSR was to apply as much as possible of the architecture, technology and, where possible, specific hardware of the MSSR to sample return from Venus. However, there are significant differences in the operating enviornment (Table 1) that require significant modification to the MSSR architecture.