ESA Science & Technology - Publication Archive
Chronology is the key to understanding climatically and tectonically driven changes on Mars. The objective of the present proposal was to assess the potential of in-situ Martian sediment dating using luminescence techniques. The work was divided into two parts:
- a) Work package 1 : Review and optimisation of appropriate techniques and instrumentation
b) Work package 2 : Laboratory measurements and proposals for instrumentation.
The aim of the activity was to develop and test an Instrumented Mole System (IMS) - i.e. a system able to deploy a mobile penetrometer carrying a payload of sensors for sub-surface measurements - to be mounted on a Planetary Lander.
This IMS could potentially be used on future planetary missions such as those for the exploration of the surface of Mercury or on other planets.
Context: In 2004 asteroid (2867) Steins has been selected as a flyby target for the Rosetta mission. Determination of its spin period and the orientation of its rotation axis are essential for optimization of the flyby planning.
Aims: Measurement of the rotation period and light curve of asteroid (2867) Steins at a phase angle larger than achievable from ground based observations, providing a high quality data set to contribute to the determination of the orientation of the spin axis and of the pole direction.
Methods: On March 11, 2006, asteroid (2867) Steins was observed continuously for 24 h with the scientific camera system OSIRIS onboard Rosetta. The phase angle was 41.7 degrees, larger than the maximum phase angle of 30 degrees when Steins is observed from Earth. A total of 238 images, covering four rotation periods without interruption, were acquired.
Results: The light curve of (2867) Steins is double peaked with an amplitude of 0.23 mag. The rotation period is 6.052 +- 0.007 h. The continuous observations over four rotation periods exclude the possibility of period ambiguities. There is no indication of deviation from a principal axis rotation state. Assuming a slope parameter of G = 0.15, the absolute visual magnitude of Steins is 13.05 +/- 0.03.
- Hubble's Bequest to Astronomy
- PHLAG: Pipeline for Hubble Legacy Archive Grism Data
- ESA-ESO Topical Science Working Groups
- Solar System Bodies in Hubble Observations
- Staff Update
- Communication of the "Pluto Affair"
- NASA Award for ST-ECF Staff
- The International Year of Astronomy 2009
- Servicing Mission 4
We present the first identification of large-scale structures (LSS) at z < 1.1 in the Cosmic Evolution Survey (COSMOS). The structures are identified from adaptive smoothing of galaxy counts in the pseudo-3d space (R.A., Dec., z) using the COSMOS photometric redshift catalog. The technique is tested on a simulation including galaxies distributed in model clusters and a field galaxy population - recovering structures on all scales from 1 to 202 without a priori assumptions for the structure size or density profile. Our procedure makes no a priori selection on galaxy spectral energy distribution (SED, for example the Red Sequence), enabling an unbiased investigation of environmental effects on galaxy evolution. The COSMOS photometric redshift catalog yields a sample of 1.5 × 105 galaxies with redshift accuracy, delta zFWHM/(1 + z) d 0.1 at z < 1.1 down to IAB d 25 mag. Using this sample of galaxies, we identify 42 large-scale structures and clusters. Projected surface-density maps for the structures indicate multiple peaks and internal structure in many of the most massive LSS. The stellar masses (determined from the galactic SEDs) for the LSS range from M* ~ 1011 up to ~ 3 × 1013 Msun. Five LSS have total stellar masses exceeding 1013 Msun. (Total masses including non-stellar baryons and dark matter are expected to be ~ 50 - 100 times greater.) The derived mass function for the LSS is consistent (within the expected Poisson and cosmic variances) with those derived from optical and X-ray studies at lower redshift.
Venus Express was launched in late October, 2005, and arrived at the planet in April 2006, where it is now in orbit and the return to Earth of new information about Venus' atmosphere, surface, and space environment has begun. The purpose of this special issue of Planetary and Space Science is to lay out the background to the mission, in terms of the planet and its mysteries as well as the spacecraft, its instruments, and the planned observations, in order to review the context in which the new results will be analysed and interpreted.
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