Cosima – High Resolution Time-of-Flight Secondary Ion Mass Spectrometer for the Analysis of Cometary Dust Particles onboard Rosetta

The ESA mission Rosetta, launched on March 2nd, 2004, carries an instrument suite to the comet 67P/Churyumov-Gerasimenko. The COmetary Secondary Ion Mass Anaylzer – COSIMA – is one of three cometary dust analyzing instruments onboard Rosetta. COSIMA is based on the analytic measurement method of secondary ion mass spectrometry (SIMS). The experiment’s goal is in-situ analysis of the elemental composition (and isotopic composition of key elements) of cometary grains. The chemical characterization will include the main organic components, present homologous and functional groups, as well as the mineralogical and petrographical classification of the inorganic phases. All this analysis is closely related to the chemistry and history of the early solar system. COSIMA covers a mass range from 1 to 3500 amu with a mass resolution m/Δm @ 50% of 2000 at mass 100 amu. Cometary dust is collected on special, metal covered, targets, which are handled by a target manipulation unit. Once exposed to the cometary dust environment, the collected dust grains are located on the target by a microscopic camera. A pulsed primary indium ion beam (among other entities) releases secondary ions from the dust grains. These ions, either positive or negative, are selected and accelerated by electrical fields and travel a well-defined distance through a drift tube and an ion reflector. A microsphere plate with dedicated amplifier is used to detect the ions. The arrival times of the ions are digitized, and the mass spectra of the secondary ions are calculated from these time-of-flight spectra. Through the instrument commissioning, COSIMA took the very first SIMS spectra of the targets in space. COSIMA will be the first instrument applying the SIMS technique in-situ to cometary grain analysis as Rosetta approaches the comet 67P/Churyumov-Gerasimenko, after a long journey of 10 years, in 2014.     

Towards a new remote sensing order?

This Viewpoint argues that the 1986 UN Principles on Remote Sensing have failed to anticipate the growth and broadening of the Earth observation field and are now less relevant. It traces the development of remote sensing: from a narrow government-controlled base, three distinct sectors of military, civil (i.e. public) and commercial Earth observation can now be distinguished and the latter is making images ever more widely and easily available. There has been no international effort to adjust the international legal regime to this changing environment and even the USA's remote sensing policy has basically been reactive. It is impossible now to conceive an overarching remote sensing policy and the challenge will be to shape each sectoral regime appropriately.     

The rapid neutron-capture process and the synthesis of heavy and neutron-rich elements

Recent developments in theoretical model-calculations for the synthesis of heavy and neutron-rich chemical elements by means of the rapid neutron-capture process are reviewed. Special emphasis is put on a discussion of possible astrophysical sites, e.g. supernova models, and extrapolated nuclear input data as well. Numerical methods to solve complex nuclear reaction-networks are presented.     

A European probe to comet Halley

A European probe to comet Halley is proposed. The probe's model payload consists of 8 scientific instruments, viz. neutral, ion and dust impact mass spectrometers, magnetometer, medium energy ion and electron analyzer, camera, dust impact detectors and plasma wave experiment. Fly-by of the comet Halley nucleus will take place on November 28th, 1985, at about 500 km miss distance. The main spacecraft serves as relay link to transmit the observed data to Earth. As probe, a modified ISEE 2 design is proposed. Because of the cometary dust hazard expected in the coma a heavy dust shield (27 kg) is required, consisting of a thin front sheet and a 3 layer rear sheet. The probe is spin-stabilized (12 rpm), has no active attitude and orbit control capability and uses battery power only to provide about 1000 Wh for a measuring phase. A despun antenna transmits up to 20 kbit/s, in X-band. The total probe mass is estimated at 250 kg. The 3 model development programme should start in mid 1981 with Phase B.     

Outer space and cosmopolitics

The two superpowers engaged in power politics on Earth, the USA and the USSR, have devoted great financial and technical efforts to the exploration, control and use of outer space, primarily to gain power-political advantages. This article considers the issue of power politics in outer space. The history and the instruments of ‘cosmopolitical power’ are discussed, as well as the attempts to limit the superpowers' dominance. A united Western Europe is seen to have a major role to play in providing a counterbalance to the concentration of space power.     

Quantification of spatial structure of human proximal tibial bone biopsies using 3D measures of complexity

Changes in trabecular bone composition during development of osteoporosis are used as a model for bone loss in microgravity conditions during a space flight. Symbolic dynamics and measures of complexity are proposed and applied to assess quantitatively the structural composition of bone tissue from 3D data sets of human tibia bone biopsies acquired by a micro-CT scanner. In order to justify the newly proposed approach, the measures of complexity of the bone architecture were compared with the results of traditional 2D bone histomorphometry. The proposed technique is able to quantify the structural loss of the bone tissue and may help to diagnose and to monitor changes in bone structure of patients on Earth as well as of the space-flying personnel.