[1] The selection of Meridiani Planum and Gusev crater as the Mars Exploration Rover landing sites took over 2 years, involved broad participation of the science community via four open workshops, and narrowed an initial $155 potential sites (80-300 Â 30 km) to four finalists based on science and safety. Engineering constraints important to the selection included (1) latitude (10°N-15°S) for maximum solar power, (2) elevation (less than À1.3 km) for sufficient atmosphere to slow the lander, (3) low horizontal winds, shear, and turbulence in the last few kilometers to minimize horizontal velocity, (4) low 10-m-scale slopes to reduce airbag spin-up and bounce, (5) moderate rock abundance to reduce abrasion or strokeout of the airbags, and (6) a radar-reflective, load-bearing, and trafficable surface safe for landing and roving that is not dominated by fine-grained dust. The evaluation of sites utilized existing as well as targeted orbital information acquired from the Mars Global Surveyor and Mars Odyssey. Three of the final four landing sites show strong evidence for surface processes involving water and appear capable of addressing the science objectives of the missions, which are to determine the aqueous, climatic, and geologic history of sites on Mars where conditions may have been favorable to the preservation of evidence of possible prebiotic or biotic processes. The evaluation of science criteria placed Meridiani and Gusev as the highest-priority sites. The evaluation of the three most critical safety criteria (10-m-scale slopes, rocks, and winds) and landing simulation results indicated that Meridiani and Elysium Planitia are the safest sites, followed by Gusev and Isidis Planitia.

[1] In January 2004 the Mars Exploration Rover mission will land two rovers at two different landing sites that show possible evidence for past liquid-water activity. The spacecraft design is based on the Mars Pathfinder configuration for cruise and entry, descent, and landing. Each of the identical rovers is equipped with a science payload of two remote-sensing instruments that will view the surrounding terrain from the top of a mast, a robotic arm that can place three instruments and a rock abrasion tool on selected rock and soil samples, and several onboard magnets and calibration targets. Engineering sensors and components useful for science investigations include stereo navigation cameras, stereo hazard cameras in front and rear, wheel motors, wheel motor current and voltage, the wheels themselves for digging, gyros, accelerometers, and reference solar cell readings. Mission operations will allow commanding of the rover each Martian day, or sol, on the basis of the previous sol's data. Over a 90-sol mission lifetime, the rovers are expected to drive hundreds of meters while carrying out field geology investigations, exploration, and atmospheric characterization. The data products will be delivered to the Planetary Data System as integrated batch archives.

We examine the current state of readiness of aerocapture at several destinations of interest, to identify what technologies are needed and to determine if a technology demonstration mission is required, before the first use of aerocapture for a science mission. The study team concluded that the current state of readiness is destination dependent, with aerocaptured missions feasible at Venus, Mars, and Titan with current technologies. The use of aerocapture for orbit insertion at the ice giant planets Uranus and Neptune requires at least additional study to assess the expected performance of new guidance, navigation, and control algorithms and possible development of new hardware, such as a mid-lift-to-drag entry vehicle shape or new thermal protection system materials. A variety of near-term activities could contribute to risk reduction for missions proposing the use of aerocapture, but an end-toend, system-level technology demonstration mission is not deemed necessary before the use of aerocapture for a NASA science mission.Nomenclature L∕D = lift-to-drag ratio of vehicle V ∞ = hyperbolic excess velocity, km∕s ΔV = velocity change, km∕s

No abstract

A discipline that might eventually become known as ‘plain language studies’ is beginning to emerge through the collaboration of individual plain language proponents (plainers for short). In 2008, the two main international umbrella organizations (Clarity and PLAIN) and the Center for Plain Language in the United States set up a joint working group to develop what they hoped would eventually become internationally recognized professional standards and accreditation. Law is only one aspect of the plain legal language movement; some plainers promote plain medicine, others plain government, plain technical writing, plain finance, and plain scientific papers. Some legal plainers are linguists, writers, editors, or legal translators. Some are practising lawyers who write plainly for their clients. This article provides a brief history of the plain legal language movement, discusses the advantages and disadvantages of using plain language to write legal documents, and examines attitudes to plain legal language. Finally, it considers plain language drafting techniques and presents an example of traditional writing made plain.

No abstract

No abstract

No abstract