Category: Observatories

The largest ground-based optical telescopes in use today use mirrors that are 10 m (33 ft) across. But the prospects for future Extremely Large Telescopes (ELTs) are looking up. According to recent studies by international teams of astronomers and leading astronomical organisations, the next generation of optical telescopes could be 50-100 metres (165 330 ft) in diameter – big enough to fill a sports stadium.

This quantum leap in size has important implications, since astronomers want to capture every photon of light that comes their way, and a 100 m mirror has a collecting area up to 100 times greater than existing instruments. Furthermore, a 100 m telescope would have extremely sharp vision, with the ability to see objects at up to 40 times the spatial resolution of the Hubble Space Telescope.

On Friday 8 April, Dr. Isobel Hook of Oxford University told the RAS National Astronomy Meeting in Birmingham about the compelling scientific case for Extremely Large Telescopes which has been developed at a series of meetings over the past four years. The results of this evaluation process, which involved more than 100 astronomers, have recently been published, coinciding with the start of the European Extremely Large Telescope Design Study. (See Web details at the end of this release).

A team of over 100 European Astronomers has recently produced a brochure summarising the science that could be done, said Dr. Hook. This work is the result of a series of meetings held in Europe over the last 4 years, sponsored by the EC network OPTICON. The new report explains how an ELT will revolutionise all aspects of astronomy, from studies of our own solar system – by producing images of comparable detail to those from space probes – to the edge of the observable Universe.

As the report states: The vast improvement in sensitivity and precision allowed by the next step in technological capabilities, from todays 6-10 m telescopes to the new generation of 50-100 m telescopes with integrated adaptive optics capability, will be the largest such enhancement in the history of telescopic astronomy. It is likely that the major scientific impact of these new telescopes will be discoveries we cannot predict, so that their scientific legacy will also vastly exceed even that rich return which we can predict today.

Astronomers believe that with an ELT it will not only be possible to find planets orbiting other stars, but also to identify and study habitable Earth-like planets by identifying the presence of liquid water, oxygen and methane. Many of the mysteries about the high-energy Universe will also be answered. An ELT would be able to provide key insights into the nature of black holes, galaxy formation, the mysterious dark matter pervading the Universe and the even more mysterious dark energy that is pushing the Universe apart. An ELT will also be sensitive enough to detect the first galaxies that were born only a few hundred million years after the Big Bang, as well as very early supernova explosions, whose light has travelled for over 10 billion years to reach us.

Some of the most exciting discoveries cannot be predicted now, said Dr. Hook. New astronomical instruments have always surprised us with the unexpected. An ELT would make such advances possible for two main reasons – the large collecting area enables it to detect the faintest sources, and the telescopes huge diameter allows extremely sharp images (provided the effects of atmospheric turbulence are corrected by adaptive optics).

Would it be possible to build such a telescope?

Initial studies are very positive, suggesting that a 50-100 m segmented telescope could be built within 10-15 years for a cost of around 1 billion Euros, said Dr. Hook. A major design study is now starting in Europe, aimed at developing the technology needed to build Extremely Large Telescopes. The study has been awarded 8 million Euros from the EC Framework Programme 6 plus additional funds from the participants (the European Southern Observatory, together with universities, institutes and industry around Europe, including the UK).

Original Source: RAS News Release

Image credit: University of Arizona
Over 30 years ago, Dr. Roger Angel came to the University of Arizona, drawn by the favorable conditions for astronomical observing in the Tucson, Arizona area: several telescopes are conveniently nearby, and of course, the weather is wonderfully temperate. But now, Angel proposes to build a telescope in a location somewhat more remote and not quite so balmy: a polar crater on the moon.

Known for his innovations in lightweight telescope mirrors and adaptive optics, Angel now leads a team of scientists from the U.S. and Canada who are exploring the feasibility of building a Deep-Field Infrared Observatory near one of the lunar poles using a Liquid Mirror Telescope (LMT).

This concept is one of 12 proposals that began receiving funding last October from the NASA Institute for Advanced Concepts (NIAC). Each gets $75,000 for six-months of research to make initial studies and identify challenges in development. Projects that make it through the first phase are eligible for as much as $400,000 more over two years.

LMTs are made by spinning a reflective liquid, usually mercury, on a bowl-shaped platform to form a parabolic surface, perfect for astronomical optics. Isaac Newton originally proposed the theory, but the technology to actually create such a device successfully has only recently been developed. Just a handful of LMTs are being used today, including a 6-meter LMT in Vancouver, Canada, and a 3-meter version that NASA uses for its Orbital Debris Observatory in New Mexico.

On Earth, LMTs are limited in size to about 6 meters in diameter because the self-generated wind that comes from spinning the telescope disturbs the surface. Additionally, like other Earth-based telescopes, LMTs are subject to atmospheric absorption and distortion, greatly reducing the range and sensitivity of infrared observing. But the atmosphere-free moon, Angel says, provides the perfect location for this type of telescope while supplying the gravity necessary for the parabolic mirror to form.

The potential of an LMT on the moon is to make a very big telescope. For reference, the Hubble Space Telescope has a 2.4 meter mirror, and the James Webb Space Telescope (JWST) being developed for launch in 2011 will have a 6 meter mirror. The concept for Angel’s NIAC proposal is a 20 meter mirror, but with the research the team has done so far, they are now looking at creating very large mirrors, with 100 meters being the big end option. They are considering smaller LMTs as well. “We obviously can’t go to the moon and make a 100 meter mirror the first thing,” Angel said. “We’re looking at a sequence of scale sizes of 2 meters, 20 meters, and 100 meters, and are looking at what the potential is for each one.” Angel believes the 2 meter telescope could be made without any human presence on the moon, and set up as a robotic telescope, much like the scientific instruments on the Mars rovers are operating now.

The limitation of a liquid mirror is that it only points straight up, so it’s not like a standard telescope that can be pointed in any direction and track objects in the sky. It only looks at the area of sky that is directly overhead.

So, the scientific goal for a LMT is to not look over the whole sky, but to take one area of space and look at it intensely. This type of astronomy has been very “profitable,” as Angel described it, in terms of the wealth of information that?s been gathered. Some of the most productive scientific efforts from the Hubble Space Telescope have been its “Deep Field” photographs.

To be able to look at only one area of space at all times drives Angel and his team to look to one of the lunar poles for the best location for this telescope. As at Earth’s poles, looking straight up from the poles on the moon always provides the same extragalactic field of view. “If we go to the North or South Pole of the moon, we?re going to image one patch of sky all the time, and so that allows you to make an extremely deep integration, much deeper even than the Hubble Deep Field.” Combine that with a large aperture, and this telescope would provide a depth of observation which would be unmatched with any telescope on Earth or in space. “That?s the niche or particular strength of this telescope,” Angel said.

Another upside of liquid mirrors is that they are very inexpensive compared to the process of making a standard mirror by creating, polishing and testing a big, rigid piece of glass, or creating smaller pieces which have to be polished, tested and then joined together very accurately. Also, LMTs don’t need expensive mounts, supports, tracking systems, or a dome.

“The total cost of the James Webb Telescope is expected to exceed a billion dollars, with the price tag on the mirror alone around a quarter of a million dollars,” Angel said. “That mirror is 6 meters, so if we scale that technology to even bigger mirrors in space, we?re eventually going to break the bank, and we won?t be able to afford them by the present technology of making the polished mirror and getting it up to space.”

Even though the 2 meter telescope would be a prototype, it would still be astronomically valuable. “We could do things that are complimentary to the Spitzer Space Telescope and the Webb Telescope, as the 2 meter telescope on the moon would fill the territory in between those two telescopes.” A 20 meter mirror would provide resolution 3 times greater than the JWST, and by integrating, or leaving the “shutter” open for long periods, like a year, objects 100 times fainter could be viewed. A 100 meter mirror would provide data that is off the charts.

One of the challenges in developing an LMT on the moon is to create the bearings to spin the platform smoothly and at a constant speed. Air bearings are used for LMTs on Earth, but with no air on the moon, that is impossible. Angel and his team are looking at cryogenic levitation bearings, similar to what?s used for magnetic levitation trains to get a frictionless motion by using a magnetic field. Angel added, “As a bonus, with the low temperatures on the moon you can do that without expending any energy because you can make a superconducting magnet that allows you to make a levitation bearing that doesn’t require a continuous input of electrical power.”

Angel called the bearings a critical component of the telescope. “With no air on the moon to create wind, there?s no limit to size or reaching the accuracy that you require as long as the bearing is alright,” Angel said.

One evolution of the project since receiving the NIAC funding is the location of the telescope. In the initial proposal, Angel’s team favored the south pole of the moon in the Shackleton crater. But the north pole actually offers a better field of view for extragalactic observation, they realized, and Angel awaits data from the European Space Agency’s SMART-1 lunar orbiter that recently began surveying the polar regions of the moon.

“In the polar regions there are some craters where the sun never illuminates and never heats the ground,” Angel said. “It is extremely cold there, not too far above absolute zero. Rather than build the telescope under such hostile conditions, we would attempt to build the telescope on a peak of the either of the poles, where there would be sunshine almost continuously. This would provide solar power and the conditions would be better for the people living there. All you have to do is put a cylindrical Mylar screen around the telescope to prevent the sun from ever hitting it and it will cool off just like in the bottom of the craters.”

With infrared observing, a cold telescope is vital to be able to see colder and fainter objects in space. Having the telescope at near absolute zero (0 degrees Kelvin, -273 C, -460 F) would be ideal. Since mercury will freeze at those temperatures, another challenge for the project is finding the right liquid to spin for the mirror. Some of the candidates are ethane, methane, and other small hydrocarbons, like the liquids that were found on Titan by the Huygens probe, which landed on Saturn’s largest moon on January 14.

“But these liquids are not shiny, so you have to figure out how to deposit a shiny metal like aluminum directly onto the surface of the liquid,” Angel said. “Normally when we make an astronomical telescope we make the mirrors out of glass, which doesn?t reflect very much and then you evaporate aluminum or silver onto the glass. On the moon we would have to evaporate the metal onto the liquid rather than the glass.”

That’s one of the key areas of research under the NIAC award. In initial studies, Angel’s team has been able to evaporate a metal onto a liquid, although not yet at the cold temperatures required. However, they are encouraged by the results so far.

Angel’s team is atypical for a NIAC project, in that it’s an international collaboration, and NIAC doesn’t fund international partners. “It happens that the world experts on making spinning liquid mirror telescopes are all in Canada, so it was kind of essential that if we’re thinking of doing that on the moon that we bring them in,” Angel said. “Luckily, they have come in on their own ticket, so to speak, and are excited by the project.”

The Canadian members of the team are Emanno Borra, from Laval University in Quebec, who has been researching and building LMTs since the early 1980’s, and Paul Hickson, from University of British Columbia, who, with Borra’s help, built the 6 meter LMT in Vancouver. Other collaborators include Ki Ma at the University of Texas at Houston who is an expert on the cryogenic bearings, Warren Davison from the University of Arizona who is a mechanical engineering expert in telescopes, and graduate student Suresh Sivanandam.

NIAC was created in 1998 to solicit revolutionary concepts from people and organizations outside the space agency that could advance NASA’s missions. The winning concepts are chosen because they “push the limits of known science and technology,” and “show relevance to the NASA mission,” according to NASA. These concepts are expected to take at least a decade to develop.

Angel says that receiving the NIAC award is a great opportunity. “We will undoubtedly write a proposal for Phase II (of the NIAC funding),” he said. “We’ve identified during Phase I what are some of the most critical issues in this project, and what practical steps we should take now. We’ve opened some questions, and there are some simple tests we can do to see if there are any show stoppers or not.”

The biggest hurdle in making the Lunar Infrared Observatory a reality is, most likely, completely out of Angel’s hands. “The moon is a very interesting place to do science,” Angel said. “However, it’s predicated on a substantial commitment of resources by NASA to return to the moon.” Certainly, to build the large 20 or 100 meter telescopes there would have to be a manned presence on the moon. “So,” Angel continued, “by hitching your science in that direction, you become the tail of a very big dog over which you have absolutely no control”?

Angel hopes that NASA and the United States can maintain the momentum of the Vision for Space Exploration and return to the moon. “I think ultimately that moving out into space is something that humans have an urge to do and will do sometime,” Angel said. “When that happens, having interesting things to do once we get there is important. We have to know why we left the surface of this planet to go to the moon. We’re exploring, yes, but we can explore not only the moon, but use that as a place to do scientific research beyond the moon. I think it’s something that in the big picture should happen.”

Nancy Atkinson is a freelance writer and NASA Solar System Ambassador. She lives in Illinois.

The Carnegie Observatories of the Carnegie Institution, and the University of Arizona, Steward Observatory Mirror Lab, have signed an agreement to produce the first mirror for the Giant Magellan Telescope (GMT)?the first telescope of the next-generation of extremely large ground-based telescopes ( ELT) to begin mirror production. The telescope primary mirror will have a diameter of 83 feet (25.4 meters) with more than 4.5 times the collecting area of any current optical telescope.

?This agreement is historic for the future of astronomy,? stated Dr. Richard Meserve, president of the Carnegie Institution. ?It is the first of many milestones that we and our partners look forward to?both in constructing an enormous ground-based telescope and in the scientific discoveries that will result. Everyone in the eight-member GMT consortium is extremely excited by this step,? he added. The consortium includes the Carnegie Observatories, Harvard University, Smithsonian Astrophysical Observatory, University of Arizona, University of Michigan, Massachusetts Institute of Technology, University of Texas at Austin, and Texas A&M University.

The GMT is slated for completion in 2016 at a site in Northern Chile. Viewing conditions in Chile, such as at Carnegie’s Las Campanas Observatory, are some of the best in the world. The GMT will have ten times the resolution of the Hubble Space Telescope. With its powerful resolution and enormous collecting area, the GMT will be able to probe the secrets of planets that have formed around other stars in the Milky Way, peer back in time toward the Big Bang with unprecedented clarity, delve into the nature of dark matter and dark energy, and explore the formation of black holes?the most important questions in astronomy today.

?The Giant Magellan Telescope will allow an unprecedented view of extrasolar planets as well as a window out to the largest scales and back to the earliest moments of the universe. We plan to complete the GMT so that it will work in tandem with the future generation of planned ground- and space-based telescopes,? stated Dr. Wendy Freedman, director of the Carnegie Observatories. ?The real distinction of the GMT, however, is that it is building on a heritage of successful technology developed for the twin 6.5-meter Magellan telescopes at Las Campanas. Their performance has far exceeded our expectations. The Magellan telescopes have proven to be the best natural imaging telescopes on the ground, due in large part to the genius of its Project Scientist, Carnegie Observatories? Stephen Shectman, and Roger Angel and his team at the Steward Mirror Lab,? she continued.

The mirrors for the GMT will be made using the existing infrastructure at Steward that made the 6.5-meter Magellan mirrors and the 8.4-meter Large Binocular Telescope mirrors on Mt. Graham. The new telescope will be composed of seven, 8.4-meter primary mirrors, arranged in a floral pattern. One spare off-axis mirror will also be made. Seven of the eight mirrors will be off-axis and require new techniques in casting and polishing. The first off-axis mirror will be cast this coming summer (2005) to address the new challenges. ?The upcoming decade promises to be a very exciting one for astronomy. The National Academy of Sciences Astronomy and Astrophysics Survey Committee Report (2001) ranked the science for extremely large telescopes as the highest priority for ground-based optical astronomy,? said Jeremy Mould, Director of the National Optical Astronomy Observatory. Site testing at the Las Campanas Observatory is also underway along with many other aspects of the project. Detailed information about the design of the GMT and the science that it will perform is located at http://www.gmto.org/.

Original Source: Carnegie News Release

A new page is set to be written in Australian scientific history with the establishment of new buildings at Mt Stromlo Observatory.

Staff at the ANU Research School of Astronomy and Astrophysics are celebrating not just the commencement of the $36 million first stage of the historic observatory?s redevelopment; but also the announcement that the site will re-open to the public on Saturday, 30 October 2004, with self-guided tours of the site and a night sky viewing program.

?After getting an average of 70,000 visitors per year and conducting some of the world?s leading astronomical research from Mt Stromlo, the fires of January 2003 were a huge blow not just for our staff, but for the global astronomical community,? the Research School?s Director, Professor Penny Sackett, said.

?Now, 21 months after the fire, it is really exciting to commence construction of the first stage of the new Stromlo. This stage will involve the construction of an Advanced Instrumentation Technology Centre, the rebuild of a destroyed multi-million dollar optical instrument and the construction of a new telescope. Plans for the second stage of redevelopment are already well advanced.

?A huge volume of work has preceded this moment. Plans for each building have had to comply with heritage considerations and with much data about the history of the site lost in the fires, that process has taken quite a lot of time.

?We are also hopeful that insurance issues will be settled soon, enabling us to plan for the full redevelopment of the Observatory.

?It is vital to recognise that despite the fires and subsequent delays in reconstruction, Mt Stromlo has continued to be a major international centre for astronomical research. Our staff have used telescopes at the ANU Siding Spring Observatory near Coonabarabran and other telescopes around the world for their research and continue to make some of the most exciting discoveries in astronomy and astrophysics.?

The 2003 fires destroyed a superbly-equipped workshop complex, seven houses, five telescopes and a historic administration building. Demolition of parts of several buildings was allowed to commence in August after permission was granted by the Department of Environment and Heritage and the National Capital Authority, pending final approval of the redevelopment plan. The demolition process has now made the site safe for public access.

?It is fantastic to once more be able to welcome the public back to Mt Stromlo. We weren?t able to make the site safe for public visits until demolition and reconstruction plans were approved. The commencement of our night viewing program on Saturday marks an important milestone in our recovery, allowing the public to experience some of the same excitement about the Universe that we feel in our daily work at the Observatory.?

Funding for the redevelopment will come from a Federal Government grant, donations and partial payments from insurance companies. Money donated by the public will be used to fund domes that will house small telescopes for public viewing of the night sky, one of which is a historic telescope salvaged from the heritage Commonwealth Solar Observatory building.

The key ingredients of the first stage of redevelopment are:

? The Advanced Instrumentation and Technology Centre, which will replace the workshops destroyed in the blaze, offering expanded design, manufacturing and testing capabilities for precision optical instruments, opportunities for higher degree student participation in technical projects, and a research and development program focusing on Extremely Large Telescopes.

? The world?s fastest sky-mapping telescope, the SkyMapper, to be installed at the ANU Siding Spring Observatory, but controlled from Mt Stromlo through an ultra-fast broadband link. SkyMapper will complete the first digital all-sky map of the Southern Sky.

? The $6 million Near-infrared Integral-Field Spectrograph, being rebuilt for the Gemini Observatory in Hawaii in partnership with Auspace.

Construction of Stage Two will commence as further insurance money is received in compensation for the fires. ANU is still in active discussions with three insurers over full payment for damage of Mt Stromlo.

Mt Stromlo will be open from 10am-3pm on Saturday 30 October and 10am-5pm on Sunday 31 October. Mt Stromlo will then open to the public every Wednesday to Sunday between 10am-5pm. Saturday night sky viewing (Saturday Stargazing) will commence on Saturday 30 October. Bookings essential, call Natalie T: 02 6125 0232.

Original Source: ANU News Release

Today, the world of astronomy meets the science fiction world of Isaac Asimov’s “I, Robot” with the commissioning of a new robotic telescope. While it lacks the humanoid qualities of the movie version, this robot will aid in humanity’s quest to understand the early universe by observing the most distant and powerful explosions known.

Located at the Fred L. Whipple Observatory on Mt. Hopkins, Arizona, the Peters Automated Infrared Imaging Telescope (PAIRITEL) is the first fully “robotic” infrared telescope in North America dedicated to observing transient astronomical events. The telescope, used for several years in a major all-sky survey (2MASS), has been refurbished to work autonomously. It will operate in tandem with NASA’s new gamma-ray burst satellite “Swift,” to be launched on November 8 from Kennedy Space Center.

With PAIRITEL, a team of astronomers led by Dr. Joshua Bloom of the Harvard Society of Fellows, Harvard-Smithsonian Center for Astrophysics (CfA) and UC Berkeley, hopes to pinpoint the gamma-ray burst explosions from the first and most distant stars in the universe. A gamma ray burst (GRB) is a quick flash of gamma-ray radiation lasting about a minute, accompanied by an afterglow emission of X-rays, visible, infrared, and radio light. The afterglow may be observable for days to weeks afterward. The majority of GRBs are believed to be due to massive stars that explode violently and release tremendous blasts of energy.

“Innovatively exploring the night sky in the time domain – seeing how things change from night to night, and even from minute to minute – is the next big frontier in astronomy,” said Bloom. “PAIRITEL was optimized to study cosmic events like GRBs that are here today and gone tomorrow.”

Peering back to a time when the universe was less than 1 billion years old is the holy grail of observational astronomy. So far, only energetic galaxy cores known as quasars have been used to probe the early universe. But gamma-ray burst afterglows, if astronomers are able to image them quickly, hold clear advantages over quasars. For up to one hour after the burst, afterglow brightnesses can reach up to 1000 times that of the brightest known quasar in the universe.

Also, explained Bloom, “The stars that create GRBs likely formed before the black holes that create quasars. So by looking for the youngest and most distant GRBs, we can study the earliest epochs of the universe.”

A key feature of PAIRITEL that will allow the location of distant GRBs is its rapid response time. PAIRITEL will receive signals from Swift and automatically move, in under 2 minutes, to the part of the sky where a GRB has appeared.

“My ultimate vision is to have astronomy robots talking to robots, deciding what to observe and how, with no human intervention,” said Bloom. “As it is, PAIRITEL only e-mails us when it’s found a particularly interesting source, or when something goes wrong and it needs help!”

Another key feature of PAIRITEL is its sensitivity at infrared wavelengths, setting this system apart from the bevy of visible-light robotic telescopes already in existence. Images taken with infrared filters (about twice the wavelength of visible light) are indispensable: visible light emitted from more than 12 billion light-years away is completely extinguished for observers on Earth. Bloom explained, “Forget about the dimming due to the extreme distances: the hydrogen gas between us and the explosions makes it like searching for a firefly behind a thick London fog. In the infrared we can peer through the shroud to the good stuff.” In addition, the unique camera on PAIRITEL takes pictures simultaneously at three different wavelengths of light, allowing for instantaneous full-color snapshots.

The Swift spacecraft will find GRBs at a rate 10 to 20 times higher than currently feasible, and should find more bursts in 6 months than all well-studied bursts to date. Bloom said he is most excited about using Swift and PAIRITEL “together to find the golden needle in the haystack – a high-redshift GRB that’s farther away than the most distant known galaxy or quasar.”

When PAIRITEL is not chasing down GRBs, it will be used to make precision measurements of supernovae to help determine the few fundamental parameters that dictate the expansion of the universe. Among other projects, Dr. Michael Pahre (CfA) will use PAIRITEL to study the near-infrared light of nearby galaxies to compare it with mid-infrared light in images obtained with NASA’s Spitzer Space Telescope. Harvard graduate student Cullen Blake, who has written software for the project, will also use PAIRITEL to try to find Earth-mass planets around brown dwarfs. Other PAIRITEL team members include: Prof. Mike Skrutskie (Univ. of Virginia), Dr. Andrew Szentgyorgyi (CfA), Prof. Robert Kirshner (Harvard University/CfA), Dr. Emilio Falco (CfA), Dr. Thomas Matheson (NOAO), and Dan Starr (Gemini Observatory, Hawaii). The staff of Mt. Hopkins-Wayne Peters, Bob Hutchins, and Ted Groner-worked on the automation of the telescope.

PAIRITEL, nearly 2 years after the inception of the project, is being dedicated today to the late Jim Peters, who worked for the Smithsonian Astrophysical Observatory, first on satellite tracking and then as a telescope operator on Mt. Hopkins for 25 years. His widow and son will be in attendance at the ceremony.

The project was funded by a grant from the Harvard Milton Fund. The telescope is owned by the Smithsonian Astrophysical Observatory and the infrared camera is on loan from the University of Virginia.

Additional information about Swift and PAIRITEL is available online at:

http://swift.gsfc.nasa.gov/docs/swift/swiftsc.html
http://pairitel.org/

Original Source: CfA News Release

European and US radio astronomers have demonstrated a new way of observing the Universe – through the Internet!

Using cutting-edge technology, the researchers have managed to observe a distant star by using the world’s research networks to create a giant virtual telescope. The process has allowed them to image the object with unprecedented detail, in real-time; something which only a few years ago would have been impossible. The star chosen for this remarkable demonstration, called IRC+10420, is one of the most unusual in the sky. Surrounded by clouds of dusty gas and emitting strongly in radio waves, the object is poised at the end of its life, heading toward a cataclysmic explosion known as a ‘supernova’.

These new observations give an exciting glimpse of the future of radio astronomy. Using research networks, not only will radio astronomers be able to see deeper into the distant Universe, they’ll be able to capture unpredictable, transient events as they happen, reliably and quickly.

Astronomers are always seeking to maximise the resolution of their telescopes. Resolution is a measure of the amount of detail it can pick out. The bigger the telescope, the better the resolution. VLBI (or Very Long Baseline Interferometry) is a technique used by radio astronomers to image the sky in supreme detail. Instead of using a single radio dish, arrays of telescopes are linked together across whole countries or even continents. When the signals are combined in a specialised computer, the resulting image has a resolution equal to that of a telescope as large as the maximum antenna separation.

In the past, the VLBI technique was severely hampered because the data had to be recorded onto tape and then shipped to a central processing facility for analysis. Consequently, radio astronomers were unable to judge the success of their endeavours until many weeks, even months, after the observations were made. The solution, to link the telescopes electronically in real-time, enables astronomers to analyse the data as it happens. The technique, naturally called e-VLBI, is only possible now that high-bandwidth network connectivity is a reality.

The recent 20-hour long observations, performed on 22nd September using the European VLBI Network (EVN), involved radio telescopes in the UK, Sweden, the Netherlands, Poland and Puerto Rico. The maximum separation of the antennas was 8200 km, giving a resolution of at least 20 milliarcseconds (mas); this is about 5 times better than the Hubble Space Telescope (HST). This level of detail is equivalent to picking out a small building on the surface of the moon! The inclusion of the antenna at Arecibo, in Puerto Rico, also increased the sensitivity of the telescope array by a factor of 10. Even so, observing at a frequency of 1612 MHz, the signal from the distant star was more than a billion billion times weaker than a typical mobile phone handset!

Each telescope was connected to its country’s National Research and Education Network (NREN), and the data routed at 32 Mbits/second per telescope through GEANT, the pan-European research network, to SURFnet, the Dutch network. The data were then delivered to the Joint Institute for VLBI in Europe (JIVE), the central processing facility for the EVN in the Netherlands. There, the 9 Terabits of data were fed in real-time into a specialised supercomputer, called a ‘correlator’, and combined. The same research networks were then used to deliver the final data product directly to the astronomers who formed the image. Until the network infrastructure provided GEANT became available, astronomers were unable to transfer the huge amounts of data required for e-VLBI across the Internet. In a very real sense, the Internet itself acts like a telescope, performing the same job as the curved surfaces of the individual radio dishes. Dai Davies, General Manager of DANTE who operate GEANT, said “e-VLBI performed successfully on an intercontinental basis demonstrates in the clearest possible terms the importance of data communications networks to modern science. Research networking is fundamental to this new radio astronomy technique and it is very satisfying indeed to see the benefits that are now resulting from it”.

Although the scientific goals of the experiment were modest, these e-VLBI observations of IRC+10420 open up the possibility of watching the structures of astrophysical objects as they change. IRC+10420 is a supergiant star in the constellation of Aquila. It has a mass about 10 times that of our own Sun and lies about 15,000 light years from Earth. One of the brightest infrared sources in the sky, it is surrounded by a thick shell of dust and gas thrown out from the surface of the star at a rate of about 200 times the mass of the Earth every year. Radio astronomers are able to image the dust and gas surrounding IRC+10420 because one of the component molecules, hydroxyl (OH), reveals itself by means of strong ‘maser’ emission. Essentially, the astronomers see clumps of gas where radio emission is strongly amplified by special conditions. With the zoom lens provided by e-VLBI, astronomers can make images with great detail and watch the clumps of gas move, watch masers being born and die on timescales of weeks to months, and study the changing magnetic fields that permeate the shell. The results show that the gas is moving at about 40 km/s and was ejected from the star about 900 years ago. As Prof. Phil Diamond, one of the research team at Jodrell Bank Observatory (UK), explained, “the material we’re seeing in this image left the surface of the star at around the time of the Norman Conquest of England”.

It is believed IRC+10420 is rapidly evolving toward the end of its life. At some point, maybe thousands of years from now, maybe tomorrow, the star is expected to blow itself apart in one of the most energetic phenomena known in the Universe – a ‘supernova’. The resulting cloud of material will eventually form a new generation of stars and planetary systems. Radio astronomers are now poised, with the incredible power of e-VLBI, to catch the details as they happen and study the physical processes that are so important to the structure of our Galaxy and to life itself.

The emergent technology of e-VLBI is set to revolutionise radio astronomy. As network bandwidths increase, so too will the sensitivity of e-VLBI arrays, allowing clearer views of the furthest and faintest regions of space. Dr Mike Garrett, JIVE Director, commented, “These results provide a glimpse of the enormous potential of e-VLBI. The rapid progress in global communications networks should permit us to connect together the largest radio telescopes in the world at speeds exceeding tens of Gigabits per second over the next few years. The death throes of the first massive stars in the Universe, the emerging jets of matter from the central black-holes of the first galaxies, will be revealed in exquisite detail.”

Original Source: Jodrell Bank News Release

Thirty Metre Optical and Infrared ground-based telescopes should be seeing first light in about 2011, and be fully operational by 2015. Four such instruments are in the works, CalTech?s TMT, Gemini?s GSMT, Canada?s VLOT, and Europe?s ELT. With 100 times the speed of Hubble, and three times the resolution of the Keck instruments, these tools will help unlock some new keys to our understanding the cosmos.

Earth-based thirty-metre telescopes are being funded, and designed now. Caltech’s TMT project will undergo design reviews in 2006 and 2007 with full construction funding scheduled to be given by the Gordon and Betty Moore Foundation in July 2008. Gordon Moore [of Moore?s Law fame] was the founder of Intel. His foundation supplied a 17 million dollar grant to design the TMT in October 2003. In total the instrument is expected to cost about 800 million dollars.

Adaptive optics have proved a tremendous success, and are one reason that there will be no replacement for the Hubble telescope as a space based tool for covering the optical and near infrared part of the spectrum. These three instruments will be getting first light with some segments about the same time that the 6.5 metre James Webb Space Telescope will begin its science mission in 2011-2.

Robert Gilmozzi?s OverWhelmingly Large Telescope [OWL project] is also trying to get first light by 2015, but faces more financial and technical obstacles than the 30-meter instruments. If the OWL doesn?t get built in this go-around, similar designs will likely be used for the following decade.

These instruments will be able to perform many tasks that the current generation of instruments either can?t do, or would require prohibitive amounts of observing time to accomplish including the following:

• Map the density and heavy element content of the intergalactic media from nearby to beyond z=1.5 by measuring the details absorption spectra of 100,000 QSOs.
• Observe the galaxy formation process by studying the movement of ionized gas clouds from z=3 to 8. Note these instruments can discern sources as close as 150 parsecs apart at z=3.
• Chart the distortion of images of background galaxies when looking through galactic clusters to map the presence of dark matter to an unprecedented level of detail.
• Chart the star populations of nearby galaxies observing element abundances, and determining formation histories.
• Observe planet formation around the nearest thousand new stars. This instrument will be able to resolve to 0.4AU when looking at objects 33 light-years away.
• Detect and characterize mature planets around nearby stars.

Caltech just put up a job posting for an Observatory Scientist for the TMT project. The Thirty metre telescopes are on their way.

Written by John A. Cross

Australian researchers have shown that a ground-based telescope in Antarctica can take images almost as good as those from the Hubble Space Telescope, at a fraction of the cost.

“It represents arguably the most dramatic breakthrough in the potential for ground-based optical astronomy since the invention of the telescope,” says University of New South Wales Associate Professor Michael Ashley, who co-authored the Nature paper. “The discovery means that a telescope at Dome C on the Antarctic plateau could compete with a telescope two to three times larger at the best mid-latitude observatories, with major cost-saving implications. Dome C could become an important ‘test-bed’ for experiments and technologies that will later be flown as space missions. Indeed, for some projects, the site might be an attractive alternative to space based astronomy.”

Astronomical observations made by Australian astronomers at Dome C on the Antarctic Plateau, 3250 m above sea-level, prove that the site has less “star jitter” than the best mid-latitude observatories in Hawaii, Chile and the Canary Islands. While Antarctica has long been recognised as having characteristics that make it a potentially excellent site for astronomy, seeing conditions at the South Pole itself (latitude 90 degrees south) are poor due to atmospheric turbulence within 200 – 300 m of the ground.

By contrast, Dome C, located at latitude 75 degrees south, has several atmospheric and site characteristics that make it ideal for astronomical observations. The site’s atmospheric characteristics include low infrared sky emission, extreme cold and dryness, a high percentage of cloud free time, and low dust and aerosol content – features that confer significant benefits for all forms of astronomy, especially infrared and sub-millimetre.

Dome C is 400 m higher than the South Pole and further inland from the coast. Being a “dome” – a local maximum in the elevation of the terrain – it experiences much lower peak and average wind speeds, which has a profound beneficial effect on the performance of astronomical instruments. Like other regions on the Antarctic plateau, it shares the advantages of a lack of seismic activity and low levels of light pollution.

A key issue in considering where to locate new generation ground-based optical telescopes is to choose a site with excellent ‘seeing’. Seeing is defined as the amount of star jitter or sharpness of astronomical images, which is affected by atmospheric conditions close to Earth.

“The sharpness of the astronomical images at Dome C is two to three times better than at the very best sites currently used by astronomers, including those in Chile, Hawaii and the Canary Islands,” says A/Prof Ashley. “This implies a factor of ten increase in sensitivity. Put another way, an 8 metre infrared telescope on the Antarctic Plateau could achieve the sensitivity limits of a hypothetical 25 metre telescope anywhere else.

“It means there’s now a fantastic opportunity now for Australian astronomers to build world-beating telescopes at the site. I expect the romance and adventure of this combination of astronomy and Antarctica will inspire the next generation of young scientists.”

The observations at Dome C represent a stunning technical achievement, according to the paper’s lead author, Dr Jon S. Lawrence, a University of New South Wales Postdoctoral Fellow.

“We set up a self contained robotic observatory called AASTINO (Automated Astronomical Site Testing International Observatory) at Dome C in January 2004. Powered by two engines, the facility has heat and electrical power that allowed us to communicate with site testing equipment, computers and telescopes via an Iridium satellite network. The entire experiment was controlled remotely — we didn’t turn the telescope on until we returned home,” says Dr Lawrence. “When we left there in February we said goodbye to it knowing all that we could do was communicate with it by the phone and the Internet. If we’d needed to press a reset button on a computer or something, there was no way to do so, and the entire experiment could have failed.

“As it turns out, we’ve made some exceptional findings and published a paper in Nature before even returning to the site. We’re pretty thrilled about it.”

Original Source: UNSW News Release

The project plans are being developed by a consortium of institutions headed up by Cornell, and funded by the National Science Foundation among others. The SKA plans are loosely based on the ideas being implemented by the Allen Telescope Array (ATA). The ATA is an array of 350 six meter dishes funded by Microsoft philanthropist Paul Allen specifically for SETI research. Note that the science and technology for using interferometers for radio has now reached a stage where this instrument can be built. While this transcontinental technique may be employable for microwaves in the decades ahead, infrared, optical, and x-ray interferometers (several connected telescopes) still require a short direct path of the light to follow, so that the images can be combined using optical, not electronic, means.

The 1.4 billion dollar SKA project should have a final design, and locations defined by 2007, with construction beginning by 2010, and it should be complete and operational by 2015. The array itself will have a core central array of 3300 dishes, and 160 outlying stations of about 7 dishes each covering a broad area of North and Central America.

When complete this tool will have the sensitivity of a single dish, 800 meters in diameter, which is on the order of a hundred times more sensitive than any steerable dish on the planet today. It is also about ten times the sensitivity of the giant dish at Arecibo, which is also operated by Cornell. At its shortest wavelength, the array will be able to image sources to a scale of 500 micro-arcseconds, which is about 15 light-years at the Andromeda galaxy [M31], or a few hundred AU when mapping nearby molecular clouds in our own galaxy.

With all this new detection capability will come a great deal of new science. This month, peer review journals and other sources are getting ready to print numerous papers proposing work that can be done with this instrument. Some of the science goals will help us observe the universe before the first stars formed, and will answer detailed questions about an epoch much earlier than will be seen by the upcoming James Webb Space Telescope. Among the science goals are: Mapping the star formation history and large-scale structure of the Universe, tracing the star formation history over cosmological time, and studying of the Sunyaev-Zel’dovich effect at high redshifts, which some say may have contaminated observed Cosmic Microwave background radiation, and altered the apparent age and dark matter density of the universe. Many of these observations will be done looking at the highly redshifted 21-cm line from neutral hydrogen.

Other science goals include tracing out the magnetic field structure in parsec to Megaparsec jets, in normal galaxies and in distant clusters of galaxies, as well as locate distant (z > 2) clusters, probing strong gravitational fields and the cosmological evolution of super-massive black holes, identifying radio transients 100 times fainter than we can now see, probing the scintillating universe and exploiting super-resolution phenomena, identifying the overall structure, discrete components, and turbulent and magnetic properties of the Milky Way and nearby galaxies, a Milky Way census of faint old pulsars and other compact objects, searching for brown dwarfs in the local Galactic environs and mapping thermal emission from nearby stars, as well as inventorying and tracking solar system debris such as asteroids, comets, and KBOs.

A recent paper points out that the SKA can be used to receive data rates hundreds of times faster than the current Deep Space Network from very distant space probes for short periods, such as from the ESA?s proposed tiny Pluto Orbiter Probe, or NASA?s New Horizons mission to the Kuiper belt.

The SKA will be a versatile instrument with capabilities far beyond what are available in today?s instruments. For radio astronomy, the SKA is the shape of things to come.

Links:
SKA site
SKA Design strawman paper
Allen Telescope Array website

Author: John A. Cross

British astronomers are celebrating a world first that could revolutionise the future of astronomy. They have just begun a project to operate a global network of the world’s biggest robotic telescopes, dubbed ‘RoboNet-1.0’ which will be controlled by intelligent software to provide rapid observations of sudden changes in astronomical objects, such as violent Gamma Ray Bursts, or 24-hour surveillance of interesting phenomena. RoboNet is also looking for Earth-like planets, as yet unseen elsewhere in our Galaxy.

Progress in many of the most exciting areas of modern astronomy relies on being able to follow up unpredictable changes or appearances of objects in the sky as rapidly as possible. It was this that led astronomers at Liverpool John Moores University (LJMU) to pioneer the development of a new generation of fully robotic telescopes, designed and built in the UK by Telescope Technologies Ltd.. Together the Liverpool Telescope (LT) and specially allocated time on the Faulkes North (FTN), soon to be joined by the Faulkes South (FTS), make up RoboNet-1.0.

Commenting on the need for a network of telescopes RoboNet Project Director, Professor Michael Bode of LJMU said “Although each telescope individually is a highly capable instrument, they are still limited by the hours of darkness, local weather conditions and the fraction of the sky each can see from its particular location on planet Earth.”

Prof. Bode added “Astronomical phenomena are however no respecters of such limitations, undergoing changes or appearances at any time, and possibly anywhere on the sky. To understand certain objects, we may even need round-the-clock coverage – something clearly impossible with a single telescope at a fixed position on the Earth’s surface.”

Thus was born the concept of “RoboNet” – a global network of automated telescopes, acting as one instrument able to search anywhere in the sky at any time and (by passing the observations of a target object from one telescope to the next in the network) being able to do so continuously for as long as is scientifically important.

The first mystery RoboNet will examine is the origin of Gamma Ray Bursts (GRBs). Discovered by US spy satellites in the late 1960’s, these unpredictable events are the most violent explosions since the Big Bang, far more energetic than supernova explosions. Yet they are extremely brief, lasting from milliseconds to a few minutes, before they fade away to an afterglow lasting a few hours or weeks. Their exact cause is still unknown, although the collapse of supermassive stars or the coalescence of exotic objects such as black holes and neutron stars are prime candidates. To study GRBs, telescopes need to be pointed at the right area of the sky extremely quickly.

In October this year, NASA will launch a new satellite named Swift, in which the UK has a major involvement, and which will pinpoint the explosions of GRBs on the sky more accurately and rapidly than ever before. The co-ordinates of each burst will be relayed to telescopes on the Earth, including those of RoboNet, within seconds of their occurrence, at the rate of one event every few days. Telescopes within the UK’s new RoboNet network are designed to respond automatically within a minute of an alert from Swift. It is in the first few minutes after the burst that observations are urgently required to enable astronomers to really understand the cause of these immense explosions, but until now such observations have been extremely difficult to secure.

RoboNet’s second major aim is to discover Earth-like planets around other stars. We now know of more than 100 extra-solar planets. However, all of these are massive planets (like Jupiter) and many are too near to their parent star, and hence too hot, to support life. RoboNet will take advantage of a phenomenon called gravitational microlensing (where light from a distant star is bent and amplified around an otherwise unseen foreground object) to detect cool planets. When a star that is being lensed in this way has a planet, it causes a short ‘blip’ in the light detected, which rapid-reacting telescopes such as the RoboNet network can follow up. In fact, the network stands the best chance of any existing facility of actually finding another Earth due to the large size of the telescopes, their excellent sites and sensitive instrumentation.

The Particle Physics and Astronomy Research Council (PPARC) have funded the establishment of RoboNet-1.0, based around using the three giant robotic telescopes at their sites across the globe. The “glue” that holds all this together is software developed by the LJMU-Exeter University “eSTAR” project, allowing the network to act intelligently in a co-ordinated manner.

Dr Iain Steele of the eSTAR project says “We have been able to use and develop new Grid technologies, which will eventually be the successor to the World Wide Web, to build a network of intelligent agents that can detect and respond to the rapidly changing universe much faster than any human. The agents act as “virtual astronomers” collecting, analysing and interpreting data 24 hours a day, 365 days a year, alerting their flesh-and-blood counterparts only when they make a discovery.”

If successful, RoboNet could be expanded to the development of a larger, dedicated global network of up to six robotic telescopes.

Professor Michael Bode of Liverpool John Moores University adds “We have led the world in the design and build of the most advanced robotic telescopes and now with RoboNet-1.0 we are set to lead the way in some of the most challenging and exciting areas of modern astrophysics”.

Original Source: PPARC News Release

What is the biggest telescope in the world?