- Email: [email protected]
Searching for other worlds
features on the surface of Mars and certainly imply that Martian terrain with few craters is truly young.
below-ground wet habitat conducive to life. Future missions may provide the answers. Besides looking for changes in gullies, the Orbiter's camera team assessed the rate at which new impact craters appear. The camera photographed approximately 98% of Mars in 1999 and approximately 30% of the planet was photographed again in 2006. The newer images show 20 fresh impact craters, ranging in diameter from 2 to 148 metres, that were not present in 1999. These results, which are a fair approximation to prediction, have important implications for determining the ages of
Mars Global Surveyor began orbiting Mars in 1997, but has not heard from since early November 2006 though attempts to contact it continue. Its unprecedented longevity has enabled Mars to be monitored for several years past the projected lifetime of the mission.
Mars
For more information about NASA's missions, visit: www.nasa.gov/mars.
This set of images shows a comparison of the gully site (inside craters in the Terra Sirenum and the Centauri Montes regions of southern Mars) as it appeared on 22 December 2001 (left), with a mosaic of two images acquired after the change occurred (the two images are from 26 August 2005 and 25 September 2005). Sunlight illuminates each scene from the northwest (top left). Note the 150-metre scale bar (representing almost 500 ft). [Image courtesy: NASA/JPL/Malin Space Science.[ with an apogee of 896 km, has been designed to detect rocky planets (exoplanets), several times larger than Earth, around nearby stars. Its instrument payload comprises a 30-centimetre telescope (f 1.1 m) and two wide-field cameras. The telescope will be used to monitor closely changes in a star's brightness that result from a planet crossing in front of it. The circular, polar
Searching for Other Worlds [From CNES press release, 3 January 2007 and ESA press release, 24 January 2007]
T
he COROT (COnvection, Rotation and planetary Transits') satellite, which was
launched on 27 December 2006 by a Soyuz rocket from Baikonur into a polar orbit
35
Any such rocky planets that are identified by COROT would represent a new, and as yet undiscovered, class of world that it is believed do exist.
orbit facilitates continuous observations of two large and opposite regions in the sky for more than 150 days each. Within each region, there are many selected fields that will be monitored in turn. The reason for the oppositely sited regions is that, as a consequence of the Earth's movement around the Sun, the Sun's rays start to interfere with the observations after 150 days. COROT is then rotated by 180 ° and starts observing the other region. In each star field that COROT will observe, it is expected to find between 10 and 40 exoplanets that are smaller than gas giants, but several times larger than the Earth as well as tens o f new gas giants.
The method used depends on recording photometrically the small periodic drop of brightness of the disc of the star around which an exoplanet is orbiting and, in effect, utilizes 'planetary transits'. According to current theory, the COROT mission can be expected to discover, a few tens of rocky planets, as well as locate numerous gas giants and planetary satellites (possibly as Saturn-like rings) around giant extrasolar planets. The chromatic analysis of the COROT light curves, thanks to a dispersion device (prism) mounted in front of the exoplanet channel CCDs, will make it possible to identify precisely the different families of detected events (transits, stellar activity, eclipsing binaries, ...). More than 120 000 stars, with magnitude between 12 and 15.5, will be surveyed. While it is looking at a star, COROT will also be able to detect 'starquakes' acoustic waves generated deep inside a star that send ripples across the star's surface, altering its brightness. The exact nature of the ripples enables the star's precise mass, age and
Artist's representation of the way that planetary transits are utilized to discover exoplanets. [Image courtesy CNES]
,L
Star field observed by COROT, 17-18 January 2007 [Image courtesy: ESA and CNES.]
36
chemical composition to be calculated. The technique is known as asteroseismology: ESA's Solar and Heliospheric Observatory (SOHO) has been taking similar observations of the Sun for over a decade. The COROT data are therefore essential to compare the Sun with other stars. The purpose of stellar seismology is to analyse the vibration modes of the stars which, submitted to forces of gravity, pressure and Coriolis, behave as oscillators with many specific modes. The eigen frequency (between 1 minute and 3 hours), the amplitude (a few ppm in Fourier space) and the lifetime (a few days) of these modes make it possible to determine some important parameters of stellar physics, such as the size and the composition of the core, the limits between radiative and convective zones, or the internal profile of rotation. These oscillating modes, which generate variations of luminosity at the surface of the star, are the only information, apart from neutrinos, coming from the depth of the stars. Acquired and collected from stars with different masses, ages and chemical composition, the COROT light curves will bring a significant amount of data of a new kind about stellar evolution. It is planned to study a hundred of stars with magnitude between 6 and 9.COROT is a mission led by the French national space agency, CNES. ESA has joined the mission by providing the optics for the telescope and testing of the payload. Through this collaboration a number of European scientists have been selected as CoInvestigators in open competition. They come from Denmark, Switzerland, the UK and Portugal. As a result of ESA's participation in COROT, scientists from ESA's Member States
ESA plans to continue its search for Earth-like worlds into the second decade of the century with the launch of the Darwin mission. This flotilla of four or five spacecraft will take pictures of Earth-like worlds thereby enabling a search for signs of life to be made.
[ Brief Notes Ares-I Development Contract [From NASA Release, 5 January 2007 ] ASA has completed its review of the requirements for the Ares-I crew launch vehicle system - bringing the agency one step closer in its plans to the development of a new mode of transporting astronauts on missions to explore the Moon, Mars and other extra-terrestrial bodies. The system requirements review confirmed that the Ares-I system requirements were complete, validated and responsive to mission requirements.
N
On the night of 17/18 January 2007, first light - from the Unicorn constellation which is near that of Orion - was observed. The ground stations used for COROT are located in Kiruna (Sweden), Aussaguel (France) Hartebeesthoek (South Africa), Kourou (French Guyana), with missionspecific ground stations in Alcantara (Brazil) and Vienna (Austria).
An impression of the Ares-I launch vehicle that is visualized by NASA as a new mode of launching astronauts into space. [Image courtesy: NASA.] In consequence, NASA has authorized a contract action having a value of $48 million with ATK Thiokol of Brigham City, Utah, to continue the design and development of the first stage for the Ares-I crew launch vehicle.
37
below-ground wet habitat conducive to life. Future missions may provide the answers. Besides looking for changes in gullies, the Orbiter's camera team assessed the rate at which new impact craters appear. The camera photographed approximately 98% of Mars in 1999 and approximately 30% of the planet was photographed again in 2006. The newer images show 20 fresh impact craters, ranging in diameter from 2 to 148 metres, that were not present in 1999. These results, which are a fair approximation to prediction, have important implications for determining the ages of
Mars Global Surveyor began orbiting Mars in 1997, but has not heard from since early November 2006 though attempts to contact it continue. Its unprecedented longevity has enabled Mars to be monitored for several years past the projected lifetime of the mission.
Mars
For more information about NASA's missions, visit: www.nasa.gov/mars.
This set of images shows a comparison of the gully site (inside craters in the Terra Sirenum and the Centauri Montes regions of southern Mars) as it appeared on 22 December 2001 (left), with a mosaic of two images acquired after the change occurred (the two images are from 26 August 2005 and 25 September 2005). Sunlight illuminates each scene from the northwest (top left). Note the 150-metre scale bar (representing almost 500 ft). [Image courtesy: NASA/JPL/Malin Space Science.[ with an apogee of 896 km, has been designed to detect rocky planets (exoplanets), several times larger than Earth, around nearby stars. Its instrument payload comprises a 30-centimetre telescope (f 1.1 m) and two wide-field cameras. The telescope will be used to monitor closely changes in a star's brightness that result from a planet crossing in front of it. The circular, polar
Searching for Other Worlds [From CNES press release, 3 January 2007 and ESA press release, 24 January 2007]
T
he COROT (COnvection, Rotation and planetary Transits') satellite, which was
launched on 27 December 2006 by a Soyuz rocket from Baikonur into a polar orbit
35
Any such rocky planets that are identified by COROT would represent a new, and as yet undiscovered, class of world that it is believed do exist.
orbit facilitates continuous observations of two large and opposite regions in the sky for more than 150 days each. Within each region, there are many selected fields that will be monitored in turn. The reason for the oppositely sited regions is that, as a consequence of the Earth's movement around the Sun, the Sun's rays start to interfere with the observations after 150 days. COROT is then rotated by 180 ° and starts observing the other region. In each star field that COROT will observe, it is expected to find between 10 and 40 exoplanets that are smaller than gas giants, but several times larger than the Earth as well as tens o f new gas giants.
The method used depends on recording photometrically the small periodic drop of brightness of the disc of the star around which an exoplanet is orbiting and, in effect, utilizes 'planetary transits'. According to current theory, the COROT mission can be expected to discover, a few tens of rocky planets, as well as locate numerous gas giants and planetary satellites (possibly as Saturn-like rings) around giant extrasolar planets. The chromatic analysis of the COROT light curves, thanks to a dispersion device (prism) mounted in front of the exoplanet channel CCDs, will make it possible to identify precisely the different families of detected events (transits, stellar activity, eclipsing binaries, ...). More than 120 000 stars, with magnitude between 12 and 15.5, will be surveyed. While it is looking at a star, COROT will also be able to detect 'starquakes' acoustic waves generated deep inside a star that send ripples across the star's surface, altering its brightness. The exact nature of the ripples enables the star's precise mass, age and
Artist's representation of the way that planetary transits are utilized to discover exoplanets. [Image courtesy CNES]
,L
Star field observed by COROT, 17-18 January 2007 [Image courtesy: ESA and CNES.]
36
chemical composition to be calculated. The technique is known as asteroseismology: ESA's Solar and Heliospheric Observatory (SOHO) has been taking similar observations of the Sun for over a decade. The COROT data are therefore essential to compare the Sun with other stars. The purpose of stellar seismology is to analyse the vibration modes of the stars which, submitted to forces of gravity, pressure and Coriolis, behave as oscillators with many specific modes. The eigen frequency (between 1 minute and 3 hours), the amplitude (a few ppm in Fourier space) and the lifetime (a few days) of these modes make it possible to determine some important parameters of stellar physics, such as the size and the composition of the core, the limits between radiative and convective zones, or the internal profile of rotation. These oscillating modes, which generate variations of luminosity at the surface of the star, are the only information, apart from neutrinos, coming from the depth of the stars. Acquired and collected from stars with different masses, ages and chemical composition, the COROT light curves will bring a significant amount of data of a new kind about stellar evolution. It is planned to study a hundred of stars with magnitude between 6 and 9.COROT is a mission led by the French national space agency, CNES. ESA has joined the mission by providing the optics for the telescope and testing of the payload. Through this collaboration a number of European scientists have been selected as CoInvestigators in open competition. They come from Denmark, Switzerland, the UK and Portugal. As a result of ESA's participation in COROT, scientists from ESA's Member States
ESA plans to continue its search for Earth-like worlds into the second decade of the century with the launch of the Darwin mission. This flotilla of four or five spacecraft will take pictures of Earth-like worlds thereby enabling a search for signs of life to be made.
[ Brief Notes Ares-I Development Contract [From NASA Release, 5 January 2007 ] ASA has completed its review of the requirements for the Ares-I crew launch vehicle system - bringing the agency one step closer in its plans to the development of a new mode of transporting astronauts on missions to explore the Moon, Mars and other extra-terrestrial bodies. The system requirements review confirmed that the Ares-I system requirements were complete, validated and responsive to mission requirements.
N
On the night of 17/18 January 2007, first light - from the Unicorn constellation which is near that of Orion - was observed. The ground stations used for COROT are located in Kiruna (Sweden), Aussaguel (France) Hartebeesthoek (South Africa), Kourou (French Guyana), with missionspecific ground stations in Alcantara (Brazil) and Vienna (Austria).
An impression of the Ares-I launch vehicle that is visualized by NASA as a new mode of launching astronauts into space. [Image courtesy: NASA.] In consequence, NASA has authorized a contract action having a value of $48 million with ATK Thiokol of Brigham City, Utah, to continue the design and development of the first stage for the Ares-I crew launch vehicle.
37