Category: Observatories

Collimation testbed of the Dobson telescope. Image credit: Tom Segert. Click to enlarge
A novel suitcase-sized telescope could revolutionise the way we see the Earth and other planets. ESA has supported the work of a group of students in developing the Dobson Space Telescope, being tested this month aboard ESA’s parabolic flight campaign aircraft.

This experimental prototype launches in a compact configuration and then unfolds to provide a cost-effective space telescope. It could lead to fleets of low-cost telescopes, bigger than the Hubble Space Telescope.
Large payloads are difficult to put into space because they are usually heavy and expensive to launch. Now a revolutionary design of unfolding telescope, inspired by telescopes used by amateur astronomers, is ready to enter a phase of detailed testing. If successful, it could dramatically reduce the cost of placing telescopes in space.

The telescope is a project of the Department of Astronautics at the Technische Universit?t Berlin, Germany. “We called our project the Dobson Space Telescope because we borrowed the idea from the Dobsonian telescopes used by amateur astronomers,” says project manager Tom Segert, who has recently completed his degree at TU Berlin. Dobsonian telescopes are often comprised of two mirrors, held the correct distance apart by long poles. They can be dismantled and transported by car to a good observing site, where there are reassembled with nothing more complicated than a screwdriver.

In space, however, a screwdriver is useless unless you have an astronaut to turn it and so Segert plans to use a motor to unfold his telescope. Working on a shoestring budget, his first prototype used inflatable bicycle tyres to push the mirrors into position. When this proved incapable of aligning the telescope optics, Segert turned to metal truss rods and micromechanics to unfold everything into its correct place.

Using a grant from ESA’s General Studies Programme, Segert and other TU Berlin students have written a full technical report and built a prototype for testing in this month aboard ESA’s parabolic flight campaign aircraft. As the aircraft flies special manoeuvres, the prototype will experience periods of free-fall that mimic the conditions in space. During this time, Segert will test the telescope?s ability to unfold. Eventually, Segert hopes for a demonstration mission in space.

Currently, space-based observations account for just one tenth of the commercial Earth observation market. The rest is supplied by aeroplane reconnaissance, which is much cheaper. Space observations cost 20 Euros per kilometre whereas aeroplane data is twenty times cheaper. Segert believes that cost-effective Earth observation microsatellites, based on his telescope design, will allow all users access to space images.

There is also nothing to stop a Dobson Space Telescope from turning its attention from Earth to the wider cosmos. In fact, Segert imagines the first missions could ‘timeshare’ between Earth and astronomical observation. “When the telescope flies into the shadow of the Earth and so can’t take pictures of the ground, we could turn it around and observe astronomical targets,” he says.

Future versions could be sent to other planets. As the telescope is so lightweight, it could be mounted on a Mars Express-sized spacecraft and used to take pictures showing details as small as 30 cm across on the Martian surface.

Although the prototype contains a respectable 50 cm-diameter mirror, Segert believes that it can scaled up in the future to achieve space telescopes bigger than the Hubble Space Telescope but still at a fraction of the cost. “If we did that,” says Segert, “the astronomers would be in heaven.”

Original Source: ESA Portal

The APEX Telescope at Chajnantor. Image credit: ESO. Click to enlarge
The Atacama Pathfinder Experiment (APEX) project has just passed another major milestone by successfully commissioning its new technology 12-m telescope, located on the 5100m high Chajnantor plateau in the Atacama Desert (Chile). The APEX telescope, designed to work at sub-millimetre wavelengths, in the 0.2 to 1.5 mm range, has just performed its first scientific observations. This new front-line facility will provide access to the “Cold Universe” with unprecedented sensitivity and image quality.

Karl Menten, Director of the group for Millimeter and Sub-Millimeter Astronomy at the Max-Planck-Institute for Radio Astronomy (MPIfR) and Principal Investigator of the APEX project is excited: ” Among the first observations, we have obtained wonderful spectra, which took only minutes to take but offer a fascinating view of the highly complex organic chemistry in star-forming regions. In addition, we have also obtained exquisite images from the Magellanic Clouds and observed molecules in the active nuclei of several external galaxies. Traditionally, telescopes turn to weak extragalactic sources only after they are well in operation. With APEX, we could pick them amongst our first targets!”

Because sub-millimetre radiation from space is heavily absorbed by water vapour in the Earth’s atmosphere, APEX is located at an altitude of 5100 metres in the high Chilean Atacama desert on the Chajnantor plains, 50 km east of San Pedro de Atacama in northern Chile. The Atacama desert is one of the driest places on Earth, thus providing unsurpassed observing opportunities – at the costs of the demanding logistics required to operate a frontier science observatory at this remote place.

Along with the Japanese 10-m ASTE telescope, which is operating at a neighbouring, lower altitude location, APEX is the first and largest sub-millimetre facility under southern skies. With its precise antenna and large collecting area, it will provide, at this exceptional location, unprecedented access to a whole new domain in astronomical observations. Indeed, millimetre and sub-millimetre astronomy opens exciting new possibilities in the study of the first galaxies to have formed in the Universe and of the formation processes of stars and planets. APEX will, among other things, allow astronomers to study the chemistry and physical conditions of molecular clouds, that is, dense regions of gas and dust in which new stars are forming.

APEX follows in the footsteps of the 15m Swedish-ESO Submillimetre Telescope (SEST) which was operated at ESO La Silla from 1987 until 2003 in a collaboration between ESO and the Onsala Space Observatory. SEST operated in the wavelength range from 0.8 to 3 mm. Says Catherine Cesarsky, ESO’s Director General: “SEST was for a long time the only instrument of its kind in the southern hemisphere. With it, ESO and our collaborators have gained valuable operational experience with regard to ground-based observations in the non-optical spectral domain. With APEX, we offer the ESO community a most exciting new facility that will pave the way for ALMA.”

As its name implies, APEX is the pathfinder to the ALMA project. It is indeed a modified ALMA prototype antenna and is located at the future site of the ALMA observatory. ALMA is planned to consist of a giant array of 12-m antennas separated by baselines of up to 14 km and is expected to start operation by the end of the decade. It will bring to sub-millimetre astronomy the aperture synthesis techniques of radio astronomy, enabling precision imaging to be done on sub-arcsecond angular scales, and will so nicely complement the ESO VLT/VLTI observatory.

In order to operate at the shorter sub-millimetre wavelengths, APEX presents a surface of exceedingly high quality: after a series of high precision adjustments, the APEX project team was able to adjust the surface of the mirror with remarkable precision: over the 12m diameter of the antenna, the deviation from the perfect parabola is now less than 17 thousandths of a millimetre. This is smaller than one fifth of the average thickness of a human hair!

“From the engineering point of view, APEX is already a big success and its performance surpasses our expectations”, says APEX Project Manager Rolf G?sten. “This could only be achieved thanks to the highly committed teams from the constructor, from the MPIfR and from the APEX project whose endless hours of work, often at high altitudes, made this project become reality.”

In parallel to the construction and commissioning of the APEX telescope, a demanding cutting-edge technology program has been launched to provide the best possible detectors for this outstanding facility. For its first observations, APEX was equipped with state-of-the-art sub-millimetre spectrometers developed by MPIfR’s Division for Sub-Millimetre Technology and, more recently, with the first facility receiver built at Chalmers University (OSO).

APEX is a collaboration between the Max-Planck-Institute for Radio Astronomy (MPIfR), Onsala Space Observatory (OSO), and the European Organisation for Astronomical Research in the Southern Hemisphere (ESO). The telescope was designed and constructed by VERTEX Antennentechnik GmbH (Germany), under contract by MPIfR, and is based on a prototype antenna constructed for the ALMA project. Operation of APEX in Chajnantor is entrusted to ESO.

Background information on sub-millimetre astronomy and on the first APEX results can be found as PDF files on the APEX Fact Sheets page.

Original Source: ESO News Release

Astronomers from across Europe today (July 7th) took a step closer to making their plans for a giant telescope a reality when they unveiled the scientific case for an Extremely Large Telescope (ELT) – a monster telescope with a light capturing mirror of between 50 and 100 metres, dwarfing all previous optical telescope facilities. The announcement was made at a meeting in Dwingeloo, the Netherlands and initiates the design phase of the project. Astronomers plan to use the ELT to search for planets like the Earth in other star systems and to find out when the first stars in the Universe began to shine.

The first step when selecting the specifications and design options for a new telescope is for astronomers to establish the science that could be achieved with the facility. The science case launched today will be used in a Design Study funded by the European Union’s Framework 6 Programme and a Europe-wide consortium of partners, including industry, aimed at evaluating critical technologies needed to build a giant telescope, and led by the European Southern Observatory (ESO). The UK part of this ?30M programme is led by the UK Astronomy Technology Centre (UK ATC) and partly funded by the Particle Physics and Astronomy Research Council (PPARC).

Roberto Gilmozzi, ESO’s coordinator of the ELT Design Study said, “The ELT Design Study initiative, a 31 MEuro activity partially funded by the FP6, shows the willingness of Europe to pursue a common path towards the eventual construction of an ELT. It is a design independent study of enabling technologies that brings together European institutes and industry to define a palette of ELT “building blocks” that indicate the way in which the telescope design should evolve to take advantage of the directions industry believes are most appropriate and cost effective.”

Bigger is better

The power of optical telescopes is limited by the size of the mirror that is used to collect light, which in turn determines how well they can distinguish between faint objects – the bigger the mirror, the fainter the object that the telescope will be able to see. For example, a 100m telescope with perfect compensation for atmospheric disturbances would be able to separate two points on the moon two metres apart, compared with 95m apart for the Hubble Space Telescope.

The quest for bigger mirrors has pushed current technologies to their limits. Some of the most advanced 8-10 metre telescopes now rely on mirrors constructed from smaller mirror segments, controlled by computers to act as a single large surface. These new techniques offer astronomers the opportunity for an unprecedented step-up in size. A 100m telescope would use a greater area of precision mirrors than has been made for all the previous telescopes ever built!

Dr Isobel Hook from the University of Oxford has led the working group producing the science case. She says “An Extremely Large Telescope is a very exciting prospect for astronomers. Something with a 50 or even 100 metre mirror could completely change our understanding of the Universe and answer truly fundamental questions such as ‘Is the Earth unique?’ and ‘How did the first stars and galaxies form?’. We will have much more information than ever before – it will be a bit like being there when the first telescopes were pointed at the sky.”

The next step

The European ELT Design Study is a five year project to explore the challenges of building an ELT, with most of the work being done in the initial three years. Every aspect of the ELT project will be examined, from site selection to instrumentation. It is due to report in 2008 at which time it will present a range of options to funding agencies.

The design study will provide the crucial technical information needed to make tough decisions at the next stage. This will involve balancing the size and design of the telescope against cost and time of first operation. Building work is likely to start in the next decade and the telescope could start scientific operations from 2015!

Professor Gerry Gilmore of the Institute of Astronomy Cambridge and Chair of the EU OPTICON network, said “Development of the ELT science case has involved over 100 European astronomers, and 3 years of work. All this happened because the astronomers want it: an ELT is overwhelmingly the scientifically favoured next major astronomy development, with widespread and strong community support. Turning this bottom-up support into a science case and a design study proposal needed some resources, and a trans-national support structure, both naturally available and provided by the EC-funded OPTICON infrastructure network. This proves that European astronomers are becoming a single community, and as such are now international leaders in astronomy.”

PPARC, the UK funding agency for astronomy, has earmarked ?2million for research and development of an ELT for the period to April 2008. ?500,000 of this is to support the design study concentrating on UK strengths in instrumentation and adaptive optics led by the UK ATC, in partnership with Durham and Oxford Universities. The remainder of the programme is under evaluation, but will concentrate on key technologies such as lightweight and adaptive mirrors to enable the science goals to be met at an affordable cost.

Colin Cunningham, Director of Technology Development at the UK ATC says “A telescope of 50 to 100m in diameter will have outstanding sensitivity and resolution -but to reach this performance at an affordable cost requires us to address many engineering and technology challenges. The UK will be at the heart of these efforts through its part in the EU-supported ELT Design Study and our UK R&D programme which will bring together academic and industrial partners in preparation for the design and construction phase of this exciting project.”

Original Source: PPARC News Release

Workers completing the mold of the 8.4 metre mirror for the Giant Magellan Telescope mirror. Image credit: Lori Stiles/UA. Click to enlarge.
The University of Arizona’s Steward Observatory Mirror Lab is pre-firing its huge spinning furnace and inspecting tons of glass for casting a first 8.4-meter (27-foot) diameter mirror for the Giant Magellan Telescope (GMT). The casting is scheduled for Saturday, July 23.

With this milestone step, the GMT becomes the first extremely large ground-based telescope to start construction.

The completed GMT telescope primary mirror will consist of six 8.4-meter off-axis mirrors surrounding a seventh, on-axis central mirror. (An off-axis mirror focuses light at an angle away from its axis, unlike a symmetrical mirror that focuses light along its axis.) This arrangement will give the GMT four-and-one-half times the collecting area of any current optical telescope and the resolving power of a 25.6-meter (84-foot) diameter telescope, or 10 times the resolution of the Hubble Space Telescope.

‘Spin-casting’ single-piece telescope mirrors that are giant, stiff yet lightweight is an ingenious, awesome process that was conceived and developed by University of Arizona Regents’ Professor of astronomy J. Roger P. Angel. Casting giant monolithic mirrors is accomplished at only one place in the world — the Steward Observatory Mirror Laboratory.

The casting team, headed by Randy Lutz, installed about 50 cores a day for a total 1,681 cores during seven weeks in April – May. The team bolted each core at precisely measured angles to hearth tile and adjoining cores in this operation. The crew daubed all the glued junctures with blue “smurf” – a concoction the color of the blue smurf cartoon characters — to prevent glass from sticking to the mold.

At this point, the mold holds 17,000 pounds of hearth tiles, 16,000 pounds in fiber tub walls, and 15,000 pounds of cores and pins. The casting team has now cleaned and inspected the completed mold, lowered the furnace cover into place, and begun pre-firing on June 16.

Team members actively ‘pilot’ the furnace by computer as temperatures ramp up during the first 8 days of the heating process, then shut power off to complete the two-week pre-firing. Pre-firing centers core glue joints, burns out any impurities and stresses the mold. The casting team will inspect the mold for any needed repairs after pre-firing.

Some of the most visually stunning steps in casting are glass inspection and loading. The team began inspecting 90 shipping crates of glass on June 24. Glass loading is scheduled for the second week of July, said Steve Miller, Mirror Lab manager.

The 40,000 pounds of borosilicate glass that will make the 27-foot diameter (8.4 meter) GMT mirror comes from Ohara Glassworks in Japan. Ohara made the glass from sand that comes from the gulf coast of Florida.

The Mirror Lab will start heating the furnace July 18. It takes six days for the glass to reach peak temperature at 2,150 degrees Fahrenheit (1178 Celsius). At this temperature, the glass begins to flow like honey at room temperature. The thick liquid glass flows between the hexagonal cores in the mold to create a “honeycomb” structure. The final honeycomb mirror blank will weigh about a fifth as much as a solid glass mirror of its size.

The bearings on the rotating furnace will turn a 100-ton load during spincasting. The furnace can be supplied with up to 1.1 Megawatts of electricity during casting — enough to power an average 750 to 1,100 Tucson households, depending on the time of year.

The oven’s rotation rate determines the depth of the curve spun into the shape of the mirror, or the mirror’s focal length. The GMT mirror will spin 5 times a minute, slower than the two 8.4-meter mirrors the Lab made for the Large Binocular Telescope (LBT), because the off-axis GMT mirror is to be a shallower, longer focal-length mirror than the symmetric LBT primaries.

“This is a new epoch for astronomy,” Richard Meserve, president of the Carnegie Institution, said. “The fabrication of the off-axis mirror is a path-breaking event that will advance scientific discovery. Everyone in the eight-member GMT consortium is excited that we’re in production.”

The Giant Magellan Telescope consortium currently 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 fact that we are already in production is directly related to the successful technology developed for the twin 6.5-meter (21-foot) Magellan telescopes at Carnegie’s Las Campanas Observatory in Chile,” said Matt Johns, assistant director of the Carnegie Observatories and GMT project manager. “The Magellan telescopes have proved to be the best natural imaging telescopes on the ground.”

Mirror cooling is a carefully controlled process that will take 11 to 12 weeks. After the mirror is completely cooled, the lab will wash the ceramic cores out of the mirror’s glass honeycomb cells. Then the mirror will be ground and polished to an accuracy of plus-or-minus 15 to 20 nanometers (a nanometer is a billionth of a meter). The mirror will be coated with a layer of reflective aluminum only 100 nanometers thick at the observatory site.

The GMT is slated for completion in 2016 at a site in northern Chile. With its powerful resolution and enormous collecting area, it will be able to probe the most important questions in astronomy, including the birth of stars and planetary systems in our Milky Way, the mysteries of black holes, and the genesis of galaxies.

Detailed information about the GMT design and science goals is online at http://www.gmto.org/

Original Source: UA News Release

ULTRACAM instrument mounted on the Very Large Telescope. Image credit: ESO. Click to enlarge.
British scientists have opened a new window on the Universe with the recent commissioning of the Visitor Instrument ULTRACAM on the European Southern Observatory’s (ESO) Very Large Telescope (VLT) in Chile.

ULTRACAM is an ultra fast camera capable of capturing some of the most rapid astronomical events. It can take up to 500 pictures a second in three different colours simultaneously. It has been designed and built by scientists from the Universities of Sheffield and Warwick (United Kingdom), in collaboration with the UK Astronomy Technology Centre in Edinburgh.

ULTRACAM employs the latest in charged coupled device (CCD) detector technology in order to take, store and analyse data at the required sensitivities and speeds. CCD detectors can be found in digital cameras and camcorders, but the devices used in ULTRACAM are special because they are larger, faster and most importantly, much more sensitive to light than the detectors used in today’s consumer electronics products.

In May 2002, the instrument saw “first light” on the 4.2-m William Herschel Telescope (WHT) on La Palma. Since then the instrument has been awarded a total of 75 nights of time on the WHT to study any object in the Universe which eclipses, transits, occults, flickers, flares, pulsates, oscillates, outbursts or explodes.

These observations have produced a bonanza of new and exciting results, leading to already 11 scientific publications published or in press.

To study the very faintest stars at the very highest speeds, however, it is necessary to use the largest telescopes. Thus, work began 2 years ago preparing ULTRACAM for use on the VLT.

“Astronomers using the VLT now have an instrument specifically designed for the study of high-speed phenomena”, said Vik Dhillon, from the University of Sheffield (UK) and the ULTRACAM project scientist. “Using ULTRACAM in conjunction with the current generation of large telescopes makes it now possible to study high-speed celestial phenomena such as eclipses, oscillations and occultations in stars which are millions of times too faint to see with the unaided eye.”

Observing Black Holes
The instrument saw first light on the VLT on May 4, 2005, and was then used for 17 consecutive nights on the telescope to study extrasolar planets, black-hole binary systems, pulsars, white dwarfs, asteroseismology, cataclysmic variables, brown dwarfs, gamma-ray bursts, active-galactic nuclei and Kuiper-belt objects.

One of the faint objects studied with ULTRACAM on the VLT is GU Muscae. This object consists of a black hole in a 10-hour orbit with a normal, solar-like star. The black hole is surrounded by a disc of material transferred from the normal star. As this material falls onto the black hole, energy is released, producing large-amplitude flares visible in the light curve. This object has magnitude 21.4, that is, it is one million times fainter than what can be seen with the unaided eye. Yet, to study it in detail and detect the shortest possible pulses, it is necessary to use exposure times as short as 5 seconds. This is possible with the large aperture and great efficiency of the VLT.

These unique observations have revealed a series of sharp spikes, separated by approximately 7 minutes. Such a stable signal must be tied to a relatively stable structure in the disc of matter surrounding the black hole. The astronomers are now in the process of analysing these results in great details in order to understand the origin of this structure.

Another series of observations were dedicated to the study of extrasolar planets, more particularly those that transit in front of their host star. ULTRACAM observations have allowed the astronomers to obtain simultaneous light curves, in several colour-bands, of four known transiting exoplanets discovered by the OGLE survey, and this with a precision of a tenth of a percent and with a 4 second time resolution. This is a factor ten better than previous measurements and will provide very accurate masses and radii for these so-called “hot-Jupiters”. Because ULTRACAM makes observations in three different wavebands, such observations will also allow astronomers to establish whether the radius of the exoplanet is different at different wavelengths. This could provide crucial information on the possible exoplanets’ atmosphere.

The camera is the first instrument to make use of the Visitor Focus on Melipal (UT3), and the first UK-built instrument to be mounted at the VLT. The Visitor Focus allows innovative technologies and instrumentation to be added to the telescope for short periods of time, permitting studies to take place that are not available with the current suite of instruments.

“These few nights with ULTRACAM on the VLT have demonstrated the unique discoveries that can be made by combining an innovative technology with one of the best astronomical facilities in the world,” said Tom Marsh of the University of Warwick and member of the team. “We hope that ULTRACAM will now become a regular visitor at the VLT, giving European astronomers access to a unique new tool with which to study the Universe.”

More information
The ULTRACAM team is composed of Vik Dhillon, Stuart Littlefair, and Paul Kerry (Sheffield, UK), Tom Marsh (Warwick, UK), Andy Vick and Dave Atkinson (UKATC, Edinburgh, UK). For the installation on the VLT, they received support from Kieran O’Brien and Pascal Robert (ESO, Chile). The ULTRACAM project page can be found at http://www.shef.ac.uk/~phys/people/vdhillon/ultracam.

Original Source: ESO News Release

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