Rapid impactor sample return (RISR) mission scenario

Due to the long lead time and great expense of traditional sample return mission plans to Mars or other astronomical bodies, there is a need for a new and innovative way to return materials, potentially at a lower cost. The Rapid Impactor Sample Return (RISR) mission is one such proposal. The general mission scenario involves a single pass of Mars, a Martian moon or an asteroid at high speeds (7 km/s), with the sample return vehicle skimming just 1 or 2 m above a high point (such as a top ridge on Olympus Mons on Mars) and releasing an impactor. The impactor strikes the ground, throwing up debris. The debris with roughly the same forward velocity will be captured by the sample return vehicle and returned to Earth. There is no delay or orbit in the vicinity of Mars or the asteroid: RISR is a one-pass mission. This paper discusses some of the details of the proposal. Calculations are presented that address the question of how much material can be recovered with this technique. There are concerns about the effect of Mars tenuous atmosphere. However, it will be noted that such issues do not occur for RISR style missions to Phobos, Deimos, or asteroids and Near Earth Objects (NEOs). Recent test results in the missile defense community (IFTs 6–8 in 2001, 2002) have scored direct hits at better than 1 m accuracy with closing velocities of 7.6 km/s, giving the belief that accuracy and sensing issues are developed to a point that the RISR mission scenario is feasible.     

An Improved Piezoelectric Balance for Aerodynamic Force

A method for measuring model forces in the shock tunnel by means of an acceleration-compensated balance has been reported by the authors.1 Since that time, a continuing program of research and development on advanced shock-tunnel instrumentation at Cornell Aeronautical Laboratory, Inc. has led to a promising new balance configuration. This balance is inherently more compact than previous designs, and allows testing of higher lift/drag (L/D) configurations than before. The increased high-pressure capability of the shock tunnel, and the growing recognition of the importance of the shock tunnel as a means of generating large Reynolds number flow, have thus added to the importance of this new higher load, more compact balance concept. An experimental balance has been built and calibrated. The performance of this balance is presented in this paper.     

Reentry Vehicle Radar Altimeter Antenna Patterns

An analytical technique is proposed for investigating the effect of antenna pattern shape on reentry vehicle radar altimeter performance. Initially, a method is presented that computes the average performance under all roll positions. This method is then extended to allow performance to be determined at each roll position. Some numerical results are included that show roll effects for a typical antenna pattern.     

Venus: The Atmosphere,Climate, Surface,Interior and Near-Space Environment of an Earth-Like Planet

This is a review of current knowledge about Earth’s nearest planetary neighbour and near twin, Venus. Such knowledge has recently been extended by the European Venus Express and the Japanese Akatsuki spacecraft in orbit around the planet; these missions and their achievements are concisely described in the first part of the review, along with a summary of previous Venus observations. The scientific discussions which follow are divided into three main sections: on the surface and interior; the atmosphere and climate; and the thermosphere, exosphere and magnetosphere. These reports are intended to provide an overview for the general reader, and also an introduction to the more detailed topical surveys in the following articles in this issue, where full references to original material may be found.     

Interactivity in map learning: The effect of cognitive load

The hypothesis that active learning is beneficial relative to passive observation was assessed in the context of spatial knowledge derived from maps. Active and passive participants studied a map either while performing a simultaneous spatial tapping task (high cognitive load) or in the absence of this task (low cognitive load). Active participants controlled how the map was learned, with passive participants observing map learning without exercising control. Spatial recall was assessed in two tests, directional judgements and map drawing. Map drawing and directional judgments showed a similar pattern of results, with performance detrimentally affected by a high load for active participants, but not for passive participants. The results indicate that activity and cognitive load interact, suggesting that active learning can be detrimental to spatial learning in cognitively demanding tasks.     

Planned Products of the Mars Structure Service for the InSight Mission to Mars

Space Science Reviews - The InSight lander will deliver geophysical instruments to Mars in 2018, including seismometers installed directly on the surface (Seismic Experiment for Interior Structure,...     

The Student Dust Counter on the New Horizons Mission

The Student Dust Counter (SDC) experiment of the New Horizons Mission is an impact dust detector to map the spatial and size distribution of dust along the trajectory of the spacecraft across the solar system. The sensors are thin, permanently polarized polyvinylidene fluoride (PVDF) plastic films that generate an electrical signal when dust particles penetrate their surface. SDC is capable of detecting particles with masses m>10^?12 g, and it has a total sensitive surface area of about 0.1 m², pointing most of the time close to the ram direction of the spacecraft. SDC is part of the Education and Public Outreach (EPO) effort of this mission. The instrument was designed, built, tested, integrated, and now is operated by students.     

The Mercury Laser Altimeter Instrument for the MESSENGER Mission

The Mercury Laser Altimeter (MLA) is one of the payload science instruments on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, which launched on August 3, 2004. The altimeter will measure the round-trip time of flight of transmitted laser pulses reflected from the surface of the planet that, in combination with the spacecraft orbit position and pointing data, gives a high-precision measurement of surface topography referenced to Mercury’s center of mass. MLA will sample the planet’s surface to within a 1-m range error when the line-of-sight range to Mercury is less than 1,200 km under spacecraft nadir pointing or the slant range is less than 800 km. The altimeter measurements will be used to determine the planet’s forced physical librations by tracking the motion of large-scale topographic features as a function of time. MLA’s laser pulse energy monitor and the echo pulse energy estimate will provide an active measurement of the surface reflectivity at 1,064 nm. This paper describes the instrument design, prelaunch testing, calibration, and results of postlaunch testing.     

月球阿波罗盆地区域月壳结构及光谱特征

位于月球南极–艾肯(South Pole-Aitken Basin,SPA)盆地内的前酒海纪阿波罗盆地跨越了SPA盆地的瞬时穴和盆缘。SPA盆地是已确认的月球上最大最古老的撞击盆地,因此阿波罗盆地对于认识月球的内部结构和成分、区域地质作用和演化历史具有不可替代的作用。阿波罗盆地区域月壳具有很强的不对称性,靠近SPA盆缘处厚而靠近SPA盆地中心处薄,其峰环内部拥有最薄的月壳厚度。阿波罗盆地区域具有不同的光谱吸收特征。在阿波罗盆地外,靠近SPA盆缘具有更多Mg辉石吸收特征的短波吸收,而靠近SPA中心区域具有更多高Ca辉石吸收特征的长波吸收。盆地内部不同地质单元的光谱吸收特征也有差异,月海为高Ca辉石的吸收特征,峰环为Mg辉石的短波长吸收。阿波罗盆地具有最薄的月壳厚度、高程差达8 km的地层剖面、位于月球背面SPA盆地内的月海、发育充分的中央峰环,其独特性使它成为最有价值的采样点。