Preparation of the Biochip experiment on the EXPOSE-R2 mission outside the International Space Station

Biochips might be suited for planetary exploration. Indeed, they present great potential for the search for biomarkers – molecules that are the sign of past or present life in space – thanks to their size (miniaturized devices) and sensitivity. Their detection principle is based on the recognition of a target molecule by affinity receptors fixed on a solid surface. Consequently, one of the main concerns when developing such a system is the behavior of the biological receptors in a space environment. In this paper, we describe the preparation of an experiment planned to be part of the EXPOSE-R2 mission, which will be conducted on the EXPOSE-R facility, outside the International Space Station (ISS), in order to study the resistance of biochip models to space constraints (especially cosmic radiation and thermal cycling). This experiment overcomes the limits of ground tests which do not reproduce exactly the space parameters. Indeed, contrary to ground experiments where constraints are applied individually and in a limited time, the biochip models on the ISS will be exposed to cumulated constraints during several months. Finally, this ISS experiment is a necessary step towards planetary exploration as it will help assessing whether a biochip can be used for future exploration missions.     

PAMELA observational capabilities of Jovian electrons

PAMELA is a satellite-borne experiment that has been launched on June 15th, 2006. It is designed to make long duration measurements of cosmic radiation over an extended energy range. Specifically, PAMELA is able to measure the cosmic ray antiproton and positron spectra over the largest energy range ever achieved and will search for antinuclei with unprecedented sensitivity. Furthermore, it will measure the light nuclear component of cosmic rays and investigate phenomena connected with solar and earth physics. The apparatus consists of: a time of flight system, a magnetic spectrometer, an electromagnetic imaging calorimeter, a shower tail catcher scintillator, a neutron detector and an anticoincidence system. In this work a study of the PAMELA capabilities to detect electrons is presented. The Jovian magnetosphere is a powerful accelerator of electrons up to several tens of MeV as observed at first by Pioneer 10 spacecraft (1973). The propagation of Jovian electrons to Earth is affected by modulation due to Corotating Interaction Regions (CIR). Their flux at Earth is, moreover, modulated because every 13 months Earth and Jupiter are aligned along the average direction of the Parker spiral of the Interplanetary Magnetic Field.PAMELA will be able to measure the high energy tail of the Jovian electrons in the energy range from 50 up to 130 MeV. Moreover, it will be possible to extract the Jovian component reaccelerated at the solar wind termination shock (above 130 MeV up to 2 GeV) from the galactic flux.     

A steady-state model for the D- to F-region of the polar cap

For obvious reasons the ionosphere of the polar cap, surrounded by the auroral zone, is only poorly investigated. Even ionosonde data are very scant from geomagnetic latitudes beyond 70°. Since 1997 the European incoherent scatter radar facility EISCAT has an additional installation on Svalbard and has been providing electron density data nearly continuously ever since. These measurements which mainly cover the E- and F-regions are supplemented by rocket data from Heiss Island at a comparable magnetic latitude; these data are more sporadic, but cover lower altitudes and densities. A provisional, steady-state, neural network-based model is presented which uses the data of both sites.     

Relation between galactic and solar cosmic radiation at aviation altitude

Cosmic radiation bombards us at high altitude with ionizing particles; the radiation has a galactic component, which is normally dominant, and a component of solar origin. Cosmic ray particles are the primary source of ionization in the atmosphere above 1 km; below 1 km radon is a dominant source of ionization in many areas.     

Human response to high-background radiation environments on Earth and in space

The main long-term objective of the space exploration program is the colonization of the planets of the Solar System. The high cosmic radiation equivalent dose rate represents an inescapable problem for the safe establishment of permanent human settlements on these planets. The unshielded equivalent dose rate on Mars ranges between 100 and 200 mSv/year, depending on the Solar cycle and altitude, and can reach values as high as 360 mSv/year on the Moon. The average annual effective dose on Earth is about 3 mSv, nearly 85% of which comes from natural background radiation, reduced to less than 1 mSv if man-made sources and the internal exposure to Rn daughters are excluded. However, some areas on Earth display anomalously high levels of background radiation, as is the case with thorium-rich monazite bearing sand deposits where values 200–400 times higher than the world average can be found. About 2% of the world’s population live above 3 km and receive a disproportionate 10% of the annual effective collective dose due to cosmic radiation, with a net contribution to effective dose by the neutron component which is 3–4 fold that at sea level. Thus far, epidemiological studies have failed to show any adverse health effects in the populations living in these terrestrial high-background radiation areas (HBRA), which provide an unique opportunity to study the health implications of an environment that, as closely as possibly achievable on Earth, resembles the chronic exposure of future space colonists to higher-than-normal levels of ionizing radiation. Chromosomal aberrations in the peripheral blood lymphocytes from the HBRA residents have been measured in several studies because chromosomal damage represents an early biomarker of cancer risk. Similar cytogenetic studies have been recently performed in a cohort of astronauts involved in single or repeated space flights over many years. The cytogenetic findings in populations exposed to high dose-rate background radiation on Earth or in space will be discussed.     

Which solar EUV indices are best for reconstructing the solar EUV irradiance?

The solar EUV irradiance is of key importance for space weather. Most of the time, however, surrogate quantities such as EUV indices have to be used by lack of continuous and spectrally resolved measurements of the irradiance. The ability of such proxies to reproduce the irradiance from different solar atmospheric layers is usually investigated by comparing patterns of temporal correlations. We consider instead a statistical approach. The TIMED/SEE experiment, which has been continuously operating since February 2002, allows for the first time to compare in a statistical manner the EUV spectral irradiance to five EUV proxies: the sunspot number, the f10.7, Ca K, and Mg II indices, and the He I equivalent width.     

Current status of X-ray spectrometer development in the SELENE project

The X-ray spectrometer (XRS) on the SELENE (SELenological and ENgineering Explorer) spacecraft, XRS, will observe fluorescent X-rays from the lunar surface. The energy of the fluorescent X-ray depends on the elements of which the lunar soil consists, therefore we can determine elemental composition of the upper most lunar surface. The XRS consists of three components: XRF-A, SOL-B, and SOL-C. XRF-A is the main sensor to observe X-rays from the lunar surface. SOL-B is direct monitor of Solar X-ray using Si-PIN photodiode. SOL-C is another Solar X-ray monitor but observes the X-rays from the standard sample attached on the base plate. This enables us to analyze by a comparative method similar to typical laboratory XRF methods. XRF-A and SOL-C adopt charge coupled device as an X-ray detector which depletion layer is deep enough to detect X-rays. The X-ray spectra were obtained by the flight model of XRS components, and all components has been worked well to analyze fluorescent X-rays. Currently, development of the hardware and software of the XRS has been finished and we are preparing for system integration test for the launch.     

Lower-mesospheric inversion layers over brazilian equatorial region using TIMED/SABER temperature profiles

Lower-mesospheric inversion layers (MILs) were studied using the temperature profiles observed by TIMED/SABER over Cariri (7.5°S, 36.5°W), Brazil, in 2005. A total 175 MILs were identified with the maximum occurrence in April and October and the minimum in January and July. The lower MIL is located in a height region from 70 to 90 km, with the peak at around 83 ± 4 km with the temperature of 205 ± 5 K, and the thickness of 4–10 km. The results show large amplitudes of MILs during equinoxes and minimum in solstices, with a clear semiannual variation. A general feature of lower MIL in monthly mean profile was observed twice a year, one from February to May, and the other from August to October with a downward shift of the top level. These results suggest that formation and long persistence of MIL is an important factor to investigate propagation of atmospheric gravity waves in the mesosphere-lower thermosphere (MLT) region.