Objectivesa) Bring together required Earth II characteristics mentioned in other chapters
b) Review what is possible today from ground base observatories, orbiting satellites and spacecraft which have visited other planets in the Solar System
Required Earth II characteristicsAn article in
Astronomy Now indicated that plate techtonics is essential to life on Earth and therefore a requirement for an exoplanet to be considered as inhabitable by humans. See;
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http://www.astrobio.net/news-exclusive/ ... -for-life/
http://www.astrobio.net/ looks quite an interesting site.
Current and future capabilitiesESA's SMOS satelliteESA’s S(oil) M(oisture) O(cean) S(satellite),
http://www.esa.int/Our_Activities/Obser ... Earth/SMOS, has clocked up more than one billion kilometres orbiting Earth to improve our understanding of our planet’s water cycle. Marking its fifth birthday, all the data collected over land and ocean have been drawn together to show how moisture in the soil and salinity in the ocean change over the year.
Transiting Exoplanet Survey SatelliteThe Transiting Exoplanet Survey Satellite (TESS) (
http://tess.gsfc.nasa.gov/index.html) is an Explorer-class planet finder. In the first-ever spaceborne all-sky transit survey, TESS will identify planets ranging from Earth-sized to gas giants, orbiting a wide range of stellar types and orbital distances. The principal goal of the TESS mission is to detect small planets with bright host stars in the solar neighborhood, so that detailed characterizations of the planets and their atmospheres can be performed. TESS is scheduled to launch in August 2017.
ESA's GOCE satelliteAlthough not designed to map changes in Earth’s gravity over time, ESA’s extraordinary satellite has shown that the ice lost from West Antarctica over the last few years has left its signature. More than doubling its planned life in orbit, GOCE spent four years measuring Earth’s gravity in unprecedented detail. Scientists are now armed with the most accurate gravity model ever produced. This is leading to a much better understanding of many facets of our planet – from the boundary between Earth’s crust and upper mantle to the density of the upper atmosphere.
http://www.esa.int/Our_Activities/Obser ... m_ice_lossHubble Spitzer and Kepler Space Telescopes, Astronomers using data from the NASA/ESA Hubble Space Telescope, the Spitzer Space Telescope, and the Kepler Space Telescope have discovered clear skies and steamy water vapour on a planet outside our Solar System. The planet, known as HAT-P-11b, is about the size of Neptune, making it the smallest exoplanet ever on which water vapour has been detected. The results will appear in the online version of the journal Nature on 24 September 2014.
http://sci.esa.int/hubble/54681-clear-s ... -heic1420/Sentinel -1AAlthough it was only launched a few months ago and is still being commissioned, the new Sentinel-1A radar satellite has already shown that it can be used to generate 3D models of Earth’s surface and will be able to closely monitor land and ice surface deformation.
http://www.esa.int/Our_Activities/Obser ... tor_motionSentinel-1A has added yet another string to its bow. Radar images from this fledgling satellite have been used to map the rupture caused by the biggest earthquake that has shaken northern California in 25 years.
http://www.esa.int/Our_Activities/Obser ... earthquakeESA's CryoSat missionMeasurements from ESA’s CryoSat mission have been used to map the height of the huge ice sheets that blanket Greenland and Antarctica and show how they are changing. New results reveal combined ice volume loss at an unprecedented rate of 500 cubic kilometres a year.
http://www.esa.int/Our_Activities/Obser ... s_and_lossNASA's Soil Moisture Active Passive (SMAP) satellite. The mission, scheduled to launch this winter, will collect the kind of local data agricultural and water managers worldwide need. SMAP uses two microwave instruments to monitor the top 2 inches (5 centimeters) of soil on Earth's surface. Together, the instruments create soil moisture estimates with a resolution of about 6 miles (9 kilometers), mapping the entire globe every two or three days. Although this resolution cannot show how soil moisture might vary within a single field, it will give the most detailed maps yet made. See
http://www.jpl.nasa.gov/news/news.php?r ... ly20140818ESA's CHEOPS exoplanet missionCHEOPS (
http://sci.esa.int/cheops/) is targetted to launch by December 2017. It will target nearby bright stars that are already known to have exoplanets in orbit around them. The science goals of the CHEOPS mission will be to measure the bulk density of exoplanets with sizes/masses in the super-Earth – Neptune range orbiting bright stars. With an accurate knowledge of masses and radii, CHEOPS will set new constraints on the structure and therefore on the formation and evolution of planets in this mass range. CHEOPS will perform first-step characterisations of super-Earths, by measuring the radii and densities and identifying planets with significant atmospheres as a function of their mass, distance to the star, and stellar parameters.
NASA's Orbital Carbon Observatory-2The OCO-2 Project primary science objective is to collect the first space-based measurements of atmospheric carbon dioxide with the precision, resolution and coverage needed to characterize its sources and sinks and quantify their variability over the seasonal cycle. The ocean covers 71 percent of Earth's surface and affects weather over the entire globe. Hurricanes and storms that begin far out over the ocean affect people on land and interfere with shipping at sea. And the ocean stores carbon and heat, which are transported from the ocean to the air and back, allowing for photosynthesis and affecting Earth's climate. To understand all these processes, scientists need information about winds near the ocean's surface.
NASA's ISS-RapidScatSee
http://winds.jpl.nasa.gov/missions/RapidScat/Launches to the International Space Station Autumn 2014 and will watch those winds with a tried and true instrument called a scatterometer. Since satellite scatterometers began collecting data in the 1970s, their soundings have become essential to our understanding of Earth's ocean winds.
SwarmThe Swarm mission, consisting of 3 satellites, was launched in November 2013 and designed to last for 4 years. It was designed to measure the magnetic signals that stem from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere. This will lead to better understanding of the processes that drive Earth’s dynamo, which currently appears to be weakening. By studying the complexities of Earth’s protective shield, Swarm will provide a clear insight into processes occurring inside the planet. Along with measurements of conditions in the upper atmosphere, a better knowledge of the near-Earth environment and the Sun’s influence on the planet can be realised.
Earth's magnetic field serves to deflect most of the solar wind, whose charged particles would otherwise strip away the ozone layer that protects the Earth from harmful ultraviolet radiation. One stripping mechanism is for gas to be caught in bubbles of magnetic field, which are ripped off by solar winds. Calculations of the loss of carbon dioxide from the atmosphere of Mars, resulting from scavenging of ions by the solar wind, indicate that the dissipation of the magnetic field of Mars caused a near-total loss of its atmosphere. Suggestions that we might terraform Mars are thus questionable. An exoplanet may well be in the habitable zone but it will also need a magnetic field if we are to survive there.
Very Large Telescope (VLT), ChileUsing a Cryogenic high-resolution Infrared Echelle Spectrograph (CRIRES) astronomers have determined the rotation rate of Beta Pictoris b. This planet, 16x larger and 3000x more massive than Earth, completes one rotation in eight hours. Obviously not habitable (for Earthlings) but an Earth size planet with a similar rotation rate to ours is most desirable.
European Extremely Large Telescope (E-ELT)The E-ELT has embraced the quest for extrasolar planets — planets orbiting other stars. This will include not only the discovery of planets down to Earth-like masses through indirect measurements of the wobbling motion of stars perturbed by the planets that orbit them, but also the direct imaging of larger planets and possibly even the characterisation of their atmospheres. See
http://www.eso.org/public/teles-instr/e-elt/The future of spectroscopic life detection on exoplanets by Sara Seager was published in the Proceedings of the National Academy of Sciences of the USA and can be read at
http://www.pnas.org/content/111/35/1263 ... 36912a0266.
Abstract
The discovery and characterization of exoplanets have the potential to offer the world one of the most impactful findings ever in the history of astronomy—the identification of life beyond Earth. Life can be inferred by the presence of atmospheric biosignature gases—gases produced by life that can accumulate to detectable levels in an exoplanet atmosphere. Detection will be made by remote sensing by sophisticated space telescopes. The conviction that biosignature gases will actually be detected in the future is moderated by lessons learned from the dozens of exoplanet atmospheres studied in last decade, namely the difficulty in robustly identifying molecules, the possible interference of clouds, and the permanent limitations from a spectrum of spatially unresolved and globally mixed gases without direct surface observations. The vision for the path to assess the presence of life beyond Earth is being established.
'Is There Life Out There?' by Sara Seager can be found at
http://seagerexoplanets.mit.edu/ProfSeagerEbook.pdfAre planetary systems real?Not all exoplanet discoveries have turned out to be real. Computer modelling has shown that some of them are unstable and thus planets could not exist in the proposed orbits. A paper 'Testing proposed planetary systems - to destruction' by Horner, Wittenmyer, Marshall, Hinse and Robertson appeared in the 2014 August issue of the RAS publication Astronomy and Geophysics.
Mars Atmosphere and Volatile Evolution (MAVEN) spacecraftMAVEN (
http://mars.nasa.gov/maven/) monitored the effect of a coronal mass ejection causing atomic carbon, oxygen and hydrogen to escape to space as researchers expected. An example of what happens when solar energetic particles hit a planet without a protective magnetic field.