Stories tagged pulsar


The Arecibo Observatory with the Angel Ramos Visitor Center in the foreground: Image courtesy of the NAIC - Arecibo Observatory, a facility of the NSF.
The Arecibo Observatory with the Angel Ramos Visitor Center in the foreground: Image courtesy of the NAIC - Arecibo Observatory, a facility of the NSF.
What’s the coolest radio telescope (sorry Green Bank) and the largest single-aperture telescope on Earth? What radio scope has been featured in a James Bond movie? And a Jodie Foster movie? And collects data for the [email protected] project?


Arecibo is an amazingly awesome project that has a history of discoveries since its construction in 1963. In 1964 scientists using it determined Mercury’s rotation was 59 days, not 88 days as previously thought. The telescope helped prove that neutron stars exist. It aided scientists in discovering the first binary pulsar. It aided scientists in finding the first extrasolar planets. It is able to track asteroids with enough precision to determine which ones might impact the Earth. And, back during more paranoid times, the telescope was used to look for Soviet Union radar installations by detecting their signals bouncing off of the Moon. The telescope also beamed into space a radio message in 1974 towards star cluster M13. The telescope also studies space weather (specifically the impact of solar flares on satellite and cell phones) and climate change. The telescope has a visitor center (Angel Ramos Visitor Center) attached that brings in more than 100,000 visitors a year.

Recently, the National Science Foundation, a long time funder for the telescope and its various scientific programs, has told Arecibo that it will need to close if it cannot find $4 million, or half the $8 million annual operating budget. In part, the idea is to free up funds for other, new, projects. This all makes total sense to me, but I am somehow emotionally attached to this thing, having never been there (its in Puerto Rico), but having written a report on it when I was in 5th grade.

Just last week, however, Cornell University’s National Astronomy and Ionosphere Center held a meeting, “Frontiers of Astronomy with The World’s Largest Radio Telescope,” with astronomers from around the world to discuss plans for future research using Arecibo over the next 5 to 15 years. Hopefully, this meeting will lead to securing the funding needed to keep the telescope operational.

Below is part of a report commissioned by NSF, charging a Senior Review Committee with the task of examining the Division of Astronomical Sciences portfolio of facilities and with the goal of redistributing roughly $30 million of annual spending. There’s a lot of stuff in the section below, and I’ve tried to hyperlink as much as possible so you can learn more. Again, I think NSF is making total sense, but man, change is hard...I’m going to miss Arecibo.

The Senior Review Committee (SR) recognizes the significant and unique scientific contributions that the Arecibo Observatory has made to astronomy and astrophysics and it congratulates National Astronomy and Ionosphere Center (NAIC) and Cornell on operating the facility so effectively. The current scientific program set out for Arecibo involving a combination of survey work and competed, smaller observing programs is very strong and is already producing important discoveries. The SR endorses its future discovery potential and archival value. Roughly 200 scientists from all around the world are working with the three Arecibo L-Band Feed Array surveys, all three of which promise important scientific results.

However, the committee was not persuaded of the primacy of the science program beyond the end of the decade and found that the case for long term support at the present level was not as strong as that for other facilities. Much of the survey work will be completed by 2010 when the current NAIC contract expires and the proposed extensions to higher Galactic latitude do not seem as likely as the current surveys to have a large scientific impact. The SR was advised that the minimum feasible operating cost for Arecibo is $8M, even when it is largely working in survey mode. Therefore, invoking Principle 1, [Principal 1 - Optimizing the Science. The prime criterion, when making difficult choices between operating existing facilities and investing in new ones, is maximizing the integrated science impact for the overall US financial investment] the SR recommends a decrease in Division of Astronomical Sciences (AST) support for Arecibo to $8M (plus the $2M from Division of Atmospheric Sciences over the next three years. Roughly 20 percent of the observing time should be set aside for individual (non-survey) proposals in order to retain some discovery potential. This should permit a reduction in the scientific and observing support staff and a discontinuation of the future instrumentation program without compromising the main science program. Thereafter, the SR recommends that NAIC plan either to close Arecibo or to operate it with a much smaller AST budget. This will require that NAIC seek sufficient external funding to continue to operate it fully. This support might be coupled to Arecibo’s status as one of the most important and visible high technology enterprises in the Commonwealth of Puerto Rico. An alternative possibility is to seek one or more foreign partners. This could have appeal to countries that wish to build up a capability in radio astronomy or communications technology. The SR recommends closure after 2011 if the necessary support is not forthcoming. It recommends that operation of the Angel Ramos Visitor Center continue, consistent with Principle 3. [Principal 3 - The Public Dividend. Public awareness of astronomical discoveries, the observatories that produce them, and the personnel who are responsible for them, are a critical part of the current AST program that must be maintained.]

If Arecibo is kept operating beyond 2011, it is expected that this will only be a limited term extension, pending the deliberations of the next decadal survey. In any case, Arecibo’s longer term future depends upon progress with the Square Kilometer Array which will be fully steerable, have ten times the collecting area, will access more of the sky to higher frequency and will have the angular resolution of an interferometer, leaving Arecibo as a niche telescope. This raises the important question of the cost of decommissioning the telescope, which could be prohibitively large. The committee concluded that there were no reliable de-commissioning estimates and recommends that AST engage an independent study to advise on the viability and cost of decommissioning the telescope. Obtaining this information is a pre-requisite to long term planning.

(Oh. And I hope that something else out there is tracking asteroids. That whole monitoring them for Earth impact seems important to me.)


Astronomers at the University of Minnesota studying the Crab Nebula with the Spitzer Space Telescope have found that a type of dust has gone missing from the nebula.

A nebula is a cloud of dust and gas in space which can be, depending on the type of nebula, the birthplace of stars. The Crab Nebula formed after a star went supernova (exploded), and hurled remnants of itself into space (called supernova remnants). Within the nebula molecular clouds collapse and fragment under their own gravity forming new stars.

The team at the University of Minnesota was looking for very small cosmic dust in the Crab Nebula. This small cosmic dust is composed of very small solid particles in space, except ice. This fine cosmic dust was observed to form in supernova remnants of a star only a few years after the star exploded (Supernova 1987A) so the astronomers at the University of Minnesota expected to find the cosmic dust in the Crab Nebula. What they found, using the Spitzer Space Telescope, was that the dust present in the Crab Nebula, while still very small, was 10 to 100 times larger than the small particles they expected to find.

So, where did the finer dust go? One idea is that the pulsar at the center of the Crab Nebula, which spins at a rate of 30 times a second, is sending out ultraviolet radiation as well as protons and electrons at close to the speed of light, which could be destroying the smaller dust particles.