Thursday, March 6, 2014

Exoplanet Atmospheric Pressure, an Indicator of Habitability for JWST in 2018 - Video CP 3.14

Hi Passengers !
Universum Observatorium presents tonight this selection of 15 videos showing different techniques to find habitable exoplanets in our near cosmos with the actual Hubble & Spitzer Space Telescope. 
But significant progress will be reached with next generation of space telescopes to be launched in 2018 with The James Webb Space Telescope.
New Technique Could Measure Exoplanet Atmospheric Pressure, an Indicator of Habitability
Measuring the atmospheric pressure of a distant exoplanet may seem like a daunting task but astronomers at the University of Washington have now developed a new technique to do just that.
When exoplanet discoveries first started rolling in, astronomers laid emphasis in finding planets within the habitable zone — the band around a star where water neither freezes nor boils. But characterizing the environment and habitability of an exoplanet doesn’t depend on the planet’s surface temperature alone. 
Atmospheric pressure is just as important in gauging whether or not the surface of an exoplanet may likely hold liquid water. Anyone familiar with camping at high-altitude should have a good understanding of how pressure affects water’s boiling point. The method developed by Amit Misra, a PhD candidate, involves isolating “dimers” — bonded pairs of molecules that tend to form at high pressures and densities in a planet’s atmosphere — not to be confused with “monomers,” which are simply free-floating molecules. 
While there are many types of dimers, the research team focused exclusively on oxygen molecules, which are temporarily bound to each other through hydrogen bonding. We may indirectly detect dimers in an exoplanet’s atmosphere when the exoplanet transits in front of its host star. As the star’s light passes through a thin layer of the planet’s atmosphere the dimers absorb certain wavelengths of it. 
Once the starlight reaches Earth it’s imprinted with the chemical fingerprints of the dimers. Dimers absorb light in a distinctive pattern, which typically has four peaks due to the rotational motion of the molecules. But the amount of absorption may change depending on the atmospheric pressure and density. This difference is much more pronounced in dimers than in monomers, allowing astronomers to gain additional information about the atmospheric pressure based on the ratio of these two signatures. 
While water dimers were detected in the Earth’s atmosphere as early as last year, powerful telescopes soon to come online may enable astronomers to use this method in observing distant exoplanets. The team analyzed the likelihood of using the James Webb Space Telescope to make such a detection and found it challenging but possible. 
Detecting dimers in an exoplanet’s atmosphere would not only help us evaluate the atmospheric pressure, and therefore the state of water on the surface, but other biosignature markers as well. Oxygen is directly tied to photosynthesis, and will most likely not be abundant in an exoplanet’s atmosphere unless it is regularly produced by algae or other plants. 
“So if we find a good target planet, and you could detect these dimer molecules — which might be possible within the next 10 to 15 years — that would not only tell you something about pressure, but actually tell you that there’s life on that planet,” said Misra in a press release.
Science by Shannon Hall
Shannon Hall is an aspiring science journalist and is an editorial intern at Sky & Telescope magazine.  
She holds two bachelor's degrees from Whitman College in astrophysics and philosophy, and recently received her master's degree in astrophysics from the University of Wyoming.
2018 - The launch of James Webb Space Telescope 
The James Webb Space Telescope (JWST), previously known as Next Generation Space Telescope (NGST), is a planned space telescope optimized for observations in the infrared, and a scientific successor to the Hubble Space Telescope and the Spitzer Space Telescope. 
The main technical features are a large and very cold 6.5-meter (21 ft) diameter mirror and four specialized instruments at an observing position far from Earth, orbiting the Earth–Sun L2 point.
The combination of these features will give JWST unprecedented resolution and sensitivity from long-wavelength visible to the mid-infrared, enabling its two main scientific goals – studying the birth and evolution of galaxies, and the formation of stars and planets. 
In planning since 1996, the project represents an international collaboration of about 17 countries led by NASA, and with significant contributions from the European Space Agency and the Canadian Space Agency. It is named after James E. Webb, the second administrator of NASA, who played an integral role in the Apollo program. JWST's capabilities will enable a broad range of investigations across many subfields of astronomy. 
One particular goal involves observing some of the most distant objects in the Universe, beyond the reach of current ground and space based instruments. This includes the very first stars, the epoch of reionization, and the formation of the first galaxies. Another goal is understanding the formation of stars and planets. 
This will include imaging molecular clouds and star-forming clusters, studying the debris disks around stars, direct imaging of planets, and spectroscopic examination of planetary transits. The mission was under review for cancellation by the United States Congress in 2011 after about $3 billion had been spent, and more than 75 percent of its hardware was either in production or undergoing testing. In November 2011, Congress reversed plans to cancel the JWST and instead capped additional funding to complete the project at $8 billion.
Program status
A review of the program released in August 2011, said the cost for the telescope and 5 years of operations will be $8.7 billion with a planned launch in 2018. Of that price about $800 million is for the five years of operations. 
The Webb will be launched from Arianespace's ELA-3 launch complex at European Spaceport located near Kourou, French Guiana. The planned launch vehicle is an Ariane 5 ECA with the cryogenic upper stage. 
Notably, this review commended the JWST project for being in excellent technical shape with most flight hardware making good progress to completion. The delay and cost overruns are due to an unrealistic original budget and insufficient program management. 
In response, NASA instituted significant management changes in the JWST project, but the need for increased funding has led to a substantial mission delay.
Partnership of 17 nations 
NASA, ESA and CSA have collaborated on the telescope since 1996. ESA's participation in construction and launch was approved by its members in 2003 and an agreement was signed between ESA and NASA in 2007. 
In exchange for full partnership, representation and access to the observatory for its astronomers, ESA is providing the NIRSpec instrument, the Optical Bench Assembly of the MIRI instrument, an Ariane-5 ECA launcher, and manpower to support operations. 
The CSA will provide the Fine Guidance Sensor and the Near-Infrared Imager Slitless Spectrograph plus manpower to support operations. 
Participating countries 
Austria Belgium Canada Czech Republic Denmark Finland France Germany Greece Ireland Italy Luxembourg Netherlands Norway Portugal Spain Sweden Switzerland United Kingdom United States.

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