Posted on by Nancy Atkinson

Why Dying Stars Might be a Good Place to Look for Life

A ghostly blue ring is a planetary nebula - hydrogen gas the star ejected as it evolved from a red giant to a white dwarf. Credit: David A. Aguilar (CfA)

We’ve currently found 867 different exoplanets, but have yet to definitely determine if one of those harbors life. How will astronomers make that determination? They’ll look at things such as its composition, orbital properties, atmosphere, and potential chemical interactions. While oxygen is relatively abundant in the Universe, finding it in the atmosphere of a distant planet could point to its habitability because its presence – in large quantities — would signal the likely presence of life.

But where to look first? A new study finds that we could detect oxygen in the atmosphere of a habitable planet orbiting a white dwarf – a star that is in the process of dying — much more easily than for an Earth-like planet orbiting a Sun-like star.

“In the quest for extraterrestrial biological signatures, the first stars we study should be white dwarfs,” said Avi Loeb, theorist at the Harvard-Smithsonian Center for Astrophysics (CfA) and director of the Institute for Theory and Computation.

Loeb and his colleague Dan Maoz from Tel Aviv University estimate that a survey of the 500 closest white dwarfs could spot one or more habitable Earths.

Potential habitable exoplanets, as of Feb. 18, 2013. Credit: The Planetary Habitability Labratory at UPR/Arecibo.
Potential habitable exoplanets, as of Feb. 18, 2013. Credit: The Planetary Habitability Labratory at UPR/Arecibo.

A white dwarf is what stars like the Sun become after they have exhausted their nuclear fuel. It puffs off its outer layers, leaving behind a hot core which can be about the size of Earth. It slowly cools and fades over time, but it can retain heat long enough to warm a nearby world for billions of years.

Currently, most planets that we’ve found orbit close to their parent star, since astronomers find planets using astrometry by the gravitational influence the planet has on the star, causing it to wobble ever so slightly. Massive planets close to the star have the biggest effect and so are the easiest to detect.

Using the photometry, astronomers see a dip in the amount of light a star gives off when a planet passes in front of the star. Since a white dwarf is about the same size as Earth, an Earth-sized planet would block a large fraction of its light and create an obvious signal. Photometry, or the transit method, has proven the best way to find exoplanets.

A white dwarf is much smaller and fainter than the Sun, and a planet would have to be much closer in to be habitable with liquid water on its surface, so that should make planets around a white dwarf star easier to detect. A habitable planet would circle the white dwarf once every 10 hours at a distance of about a million miles.

More importantly, we can only study the atmospheres of transiting planets. When the white dwarf’s light shines through the ring of air that surrounds the planet’s silhouetted disk, the atmosphere absorbs some starlight. This leaves chemical fingerprints showing whether that air contains water vapor, or even signatures of life, such as oxygen.

But there’s a caveat: Before a star becomes a white dwarf it swells into a red giant, engulfing and destroying any nearby planets. Therefore, a planet would have to arrive in the habitable zone after the star evolved into a white dwarf. Either it would migrate towards the star from a more distant orbit or be a new planet formed from leftover dust and gas.

However, we have yet to find a exoplanet around a white dwarf, even though Loeb and Moaz say the abundance of heavy elements on the surface of white dwarfs suggests that a significant fraction of them have rocky planets.

We need a better eye in the sky to find planets around white dwarfs, say Loeb and Maoz, and the James Webb Space Telescope (JWST), scheduled for launch by the end of this decade, promises to sniff out the gases of these alien worlds.

Loeb and Maoz created a synthetic spectrum, replicating what JWST would see if it examined a habitable planet orbiting a white dwarf. They found that both oxygen and water vapor would be detectable with only a few hours of total observation time.

“JWST offers the best hope of finding an inhabited planet in the near future,” said Maoz.

The James Webb Space Telescope. Credit: NASA
The James Webb Space Telescope. Credit: NASA

Recent research by CfA astronomers Courtney Dressing and David Charbonneau showed that the closest habitable planet is likely to orbit a red dwarf star (a cool, low-mass star undergoing nuclear fusion). Since a red dwarf, although smaller and fainter than the Sun, is much larger and brighter than a white dwarf, its glare would overwhelm the faint signal from an orbiting planet’s atmosphere. JWST would have to observe hundreds of hours of transits to have any hope of analyzing the atmosphere’s composition.

“Although the closest habitable planet might orbit a red dwarf star, the closest one we can easily prove to be life-bearing might orbit a white dwarf,” said Loeb.

Read their paper here.

Source: CfA

Posted on by Nancy Atkinson

Watch the James Webb Telescope Being Built Via “Webb-cam”

Want to watch the highly anticipated James Webb Space Telescope come together? NASA has set up a webcam – in this case a “Webb-cam” — for anyone to track the progress JWST inside a clean room at Goddard Space Flight Center. Recently, the Mid-Infrared Instrument (MIRI) was delivered and it will be integrated into the science instrument payload. Two cameras show the action, although the cameras will show just screen shots that are updated once every minute.

When is the best time to watch? The clean room is generally occupied Monday through Friday from 5 a.m. to 1:30 p.m. PDT (8 a.m. to 4:30 p.m. EDT).

Click the image above for access to the Webb-cams, or visit the Webb-cam website.

Of the James Webb Space Telescope’s four science instruments, only MIRI can see light in the mid-infrared region of the electromagnetic spectrum. This unique capability will allow the Webb telescope to study physical processes occurring in the cosmos that the other Webb instruments cannot see.

MIRI’s sensitive detectors will allow it to make unique observations of many things, including the light of distant galaxies, newly forming stars within our own Milky Way, and the formation of planets around stars other than our own, as well as planets, comets and the outermost debris disk in our own solar system.

Posted on by John Williams

Build a NASA Satellite, Study the Universe Online

Thanks to a new online game from NASA, everyone can be an engineer or astronomer and build a satellite to uncover planets orbiting distant stars, unravel the secrets of a black hole, or tease out the faint glow of the early Universe.

NASA Goddard Space Flight Center in Greenbelt, Maryland, launched the new game, called “Build it Yourself: Satellite!” The Flash-based game, a learning tool for students and adults, is just a click away at http://www.jwst.nasa.gov/build.html.

“It’s fun to play and users will learn something about satellite instrumentation and optics, and how they are used to make scientific discoveries, as well about a large range of different existing astronomical missions,” said Maggie Masetti, NASA webmaster who authored and created the game. Artwork for the game is by Susan Lin and programmed by Kent deVillafranca.

Players begin by choosing what science their satellite will study; whether it’s black holes, star formation, early Universe, galaxies, or explanets. Then online engineers will decide the wavelengths – optical, infrared, ultraviolet – that their spacecraft will study. Finally, a choice must be made on the instruments and optics the mission will carry. Along the way, information bubbles explain each of the pieces you choose. After “launch,” the player sees what the satellite might look like and learn what real mission has data similar to what they created. Along the way, players learn about the different instruments added to various space missions and see the cosmic discoveries they might make.

Players can create a wide-range of satellites from small X-ray telescopes like NASA’s Rossi X-ray Timing Explorer, launched in 1995, to large orbiting telescopes like the NASA/ESA Hubble Space Telescope. Play it right, putting the right pieces together, and you can assemble a satellite superior to NASA’s huge, multi-mirrored James Webb Space Telescope, the original inspiration for the game. The Webb telescope currently is being built and will launch in 2018. With the Webb, scientists will be able to study the Universe nearly to the time of the Big Bang with infrared instruments.

Play the game at: http://www.jwst.nasa.gov/build.html

Find out more information about the James Webb Space Telescope here

Image caption: Front page of the Webb telescope on-line game, “Build It Yourself: Satellite!” Credit: NASA, M.Masetti

Posted on by Nancy Atkinson

Meet MIRI, Infrared Camera for Webb Telescope

MIRI, ( Mid InfraRed Instrument ), during ambient temperature alignment testing in RAL Space's clean rooms. Image Credit: STFC/RAL Space

Our friend Will Gater from the BBC’s Sky At Night Magazine had the chance to get a behind-the-scenes tour of the facility that is building the Mid-Infrared Instrument on the long-awaited James Webb Space Telescope. You’ll meet MIRI inside clean room at the Rutherford Appleton Laboratory in the UK, before it is packaged up and sent over to NASA Goddard in the US. You’ll also hear from some of the scientists involved in the project.

MIRI is expected to make important contributions to all four of the primary science themes for JWST: 1.) discovery of the “first light”; 2.) assembly of galaxies: history of star formation, growth of black holes, production of heavy elements; 3.) how stars and planetary systems form; and 4.) evolution of planetary systems and conditions for life.

Lead image caption: MIRI, ( Mid InfraRed Instrument ), during ambient temperature alignment testing in RAL Space’s clean rooms. Image Credit: STFC/RAL Space

Posted on by Nancy Atkinson

Rumors of Continued Soaring Life-Cycle Costs for Webb Telescope

Artists concept of the James Webb Space Telescope in space. Credit: NASA

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Under the threat of cancellation because of cost overruns, this is about the worst news the James Webb Space Telescope could get. A report in Aviation Week & Space Technology says the life cycle costs for developing, launching and managing a five-year mission for the giant space telescope has risen to $8.7 billion, up from the previous estimate of $6.5 billion.

This past July, the U.S House of Representatives’ appropriations committee on Commerce, Justice, and Science proposed a budget for fiscal year 2012 that would cancel JWST’s funding. No final decision has been made on the fate of JWST, but this latest increase – just one of many life cycle increases of the telescope – does not bode well for NASA’s successor to the Hubble Space Telescope.

Aviation Week said managers at NASA have been re-planning the James Webb Space Telescope program after an independent cost analysis found it over budget and behind schedule. The independent analysis was headed by John Casani, a special assistant to the director of the Jet Propulsion Laboratory with long experience developing scientific spacecraft, and that report found the $5.1 billion estimate to completion was at least $1.4 billion short.

Now, tack on an additional $2.2 billion.

No details were provided of what the $2.2 billion includes, but the launch of JWST would be no earlier than 2018.

Details of how the agency will pay the cost will be covered in the fiscal 2013 NASA budget request now in preparation, Aviation Week quoted a NASA spokesman.

Of course, NASA’s entire budget is threatened to be cut by at least 10%, as President Obama has asked federal agencies to cut their budgets by that amount to enable a chance at balancing the federal budget.

But today, Nature News reports that NASA is looking at funding the flagship observatory in a different manner. JWST is currently funded entirely through NASA’s science division; now NASA is requesting that more than $1 billion in extra costs be shared 50:50 with the rest of the agency. Nature News said the request reflects administrator Charles Bolden’s view, expressed earlier this month, that the telescope is a priority not only for the science program but for the entire agency.

If ‘creative’ funding for JWST is not worked out, it would mean other programs would suffer greatly or be cut.

NASA made personnel changes at Goddard Spaceflight Center, the home of JWST, after Casani’s group concluded the majority of costs overruns were managerial rather than technical.

Sources: Aviation Week & Space Technology, Nature News

Posted on by Nancy Atkinson

New Webb Telescope Technologies Already Helping Human Eyes

Image of the Scanning Shack Hartmann System (SSHS), a pair of large mirror test stations used to measure the mirror segments of the Webb telescope. As part of that SSHS program, several improvements were made to the wavefront sensor technology that now allow eye health instruments to be aligned more precisely. Credit: Abbott Medical Optics Inc.

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Editor’s note: This NASA press release provides just one example of how developing technology for space missions often has practical, beneficial and sometimes unintended applications on Earth.

Even while construction of the James Webb Space Telescope is underway on the most advanced infrared vision of any space observatory, its technologies are already proving useful to human eye health here on Earth.

“The Webb telescope program has enabled a number of improvements in measurement technology for astronomy, mirror fabrication, and measurement of human eyes, diagnosis of ocular diseases and potentially improved surgery,” said Dr. Dan Neal, Research Fellow at Abbott Medical Optics Inc. in Albuquerque, N.M.

The Webb telescope will be the most scientifically powerful telescope NASA has ever built — 100 times more powerful than the Hubble Space Telescope. The Webb telescope will find the first galaxies that formed in the early universe, connecting the Big Bang to our own Milky Way Galaxy. It will also peer through dusty clouds to see stars and planets being born, connecting star formation in our own galaxy with the solar system.

“The advanced wavefront sensing technology developed for testing the Webb telescope’s 18 primary mirrors led to the new applications in other areas,” said Tony Hull of L3 Integrated Optical Systems Division-Tinsley Facility in Richmond, Calif., where the Webb’s mirrors were recently polished to accuracies of less than one millionth of an inch.

“Wavefront sensing” is used to measure shape of the mirrors during fabrication and control the optics once the telescope is in orbit.

Ophthalmologists routinely use wavefront technology to measure aberrations of the eye. Those measurements help with diagnosis, research, characterization and planning treatment of eye health issues.

“The technology also provides more accurate eye measurements for people about to undergo Laser Refractive Surgery,” Neal said. “To date 10-12 million eyes have been treated with Lasik procedures in the U.S. alone. As technology improves, so does the quality of these procedures.”

James Webb Space Telescope. Credit: NASA

A new “scanning and stitching” technology developed for the Webb telescope led to a number of innovative instrument concepts for more accurate measurement for contact lenses and intra-ocular lenses. Another benefit to eye health is that this technique can help “map” the topography of the eye more accurately.

Think of the surface of your eye as being as dented as the surface of the moon. Precise measurements of your eye’s surface are helpful when assessing eyes for contact lenses. The scanning and stitching technology improvements have enabled eye doctors to get much more detailed information about the shape and “topography” of your eye, and do it in seconds rather than hours. Four patents have been issued as result of innovations driven by the Webb telescope program. “These tools are now used to align and build the next generation of measuring devices for human eyes,” Neal said.

“The lasting impact of the Webb telescope may go beyond the vision of astronomers seeking to see the distant universe; the impact may be a better national technology base and better vision for people everywhere,” Hull said.

NASA’s Innovative Partnerships Program Office (IPPO) is making available wavefront sensing and adaptive optics technologies, procedures and lab equipment to private industry through its “Can you See it Now?” campaign. All of the technologies associated with the campaign are available for licensing and can be found at http://ipp.gsfc.nasa.gov/wavefront.

Posted on by Nancy Atkinson

Webb Telescope FAQs

How is the James Webb Space Telescope different than the Hubble Space Telescope? What will JWST be looking for when it begins operating? In this short video, NASA astrophysicist Dr. Amber Straughn answers questions, and offers facts and images to explain what the Webb Space Telescope will tell us about the cosmos.

Posted on by Nancy Atkinson

JWST Sunscreen Offers SPF 1,000,000

The James Webb Space Telescope will have a sunshield that is about the size of a tennis court, and mission managers say it will offer the best “SPF” (Sun Protection Factor) in the Universe.

“Each of the five layers of the shield is less than half the thickness of a piece of paper,” said John Durning, Deputy Project Manager for JWST. “The five work together to create an effective SPF of 1,000,000.”

This sunshield protects the observatory from unwanted light, keeping it cool and allowing it to detect heat from faraway objects in the universe. So, how do you get something that large into orbit?
Continue reading “JWST Sunscreen Offers SPF 1,000,000”