April 30, 2013
The Herschel Space Telescope was never meant for hot astronomy topics. It was meant for the cool ones. The European Space Agency spacecraft officially ended its observations yesterday when the last of its liquid helium, used to keep the telescope’s temperature close to absolute zero, was exhausted after three years of operation.
Herschel was launched in 2009 and spent its mission orbiting at L2, one of five Lagrangian points in the Earth-Sun system that are gravitationally stable. L2 is nearly a million miles farther from the sun than Earth is — ESA’s Planck Space Telescope, among others, is already stationed there, and it’s the future location of NASA’s James Webb Space Telescope. That far from the Sun is an ideal place to look at cool objects.
Observing in a broad spectral range from the far infrared to submillimeter wavelengths, Herschel could study dim objects, like asteroids in the Kuiper belt at the edge of our solar system, or debris disks where planets are forming around other stars. It also saw red-shifted light from early and active star-forming galaxies. Herschel hunted for water around the universe, finding ice particles heated by ultraviolet light from stars in many protoplanetary disks, and discovering that nearly all the water in Jupiter’s atmosphere was brought to the planet by comet Shoemaker-Levy 9 in 1994.
Herschel had the largest infrared mirror ever launched into space — at 3.5 meters in diameter, it’s more than a meter bigger than the Hubble Space Telescope’s. (JWST’s mirror, however, will be almost twice as big as Herschel’s.) Scientists are still reviewing data from the space observatory, so even though the spacecraft has gone dead, discoveries will likely still be made. Indeed, astronomers are hoping that a brand new ground-based observatory can leapfrog off of Herschel’s contributions in studying the “cool” universe: ALMA, the Atacama Large Millimeter/submillimeter Array in Chile, began operating earlier this year and should be fully operational in September. Combining their data should tell us much about the early universe and galaxy formation.
January 9, 2013
A tweet from science fiction writer David Brin alerted me to some of the fun and innovative things people are doing with space-y graphics and visualizations—everything from a weightless Google page to an animation of the Sun and planets moving together through the Milky Way.
My favorite is this simulation, created by software engineer Ian Webster, of all the asteroids orbiting the Sun in Earth’s vicinity. The simulation is designed for Chrome, but works in some other browsers, too. (If you don’t see a giant swarm of asteroids, you’re not getting the full effect.)
Webster even lets you sort the rocks by their accessibility and economic value. Watching all these would-be impactors crossing Earth’s orbit makes me glad that asteroids are small and space is big.
December 3, 2012
If you grew up near Bethpage, New York in the early 1960s, you probably were obsessed with the Apollo Lunar Module built by the Long Island-based Grumman Corporation. And if you were an extremely prescient teenager, you might have started amassing your own world-class collection of space-related items, including photographs, manuscripts, and prints.
This Wednesday, Bonhams is auctioning off one such private collection. In a video on Bonhams’ Website, the collector (who wishes to remain anonymous) explains that he grew up “during the height of the windup to the Apollo era,” just a few miles from Grumman, and many of the fathers in his neighborhood worked on the Lunar Module. “I was working towards a goal fairly early on,” he recalls in the video. “In my early- to mid-teens, what I wanted to do was to have an exhibition focusing on unmanned space travel.”
Many of the items are one-of-a kind. The lunar photomosaic above (see the full image here), was made as a five-foot-wide presentation piece in 1966, and was painstakingly assembled by Kay Larson of the U.S. Geological Survey using images captured by Surveyor 1. “I’m lucky to have found this—it would have been thrown in the trash, eventually,” the collector notes.
There are objects relating to Mars, Mercury, Venus, and Jupiter, but Earth’s moon is the centerpiece of this show. Some of the items predate the space age. One particularly lovely object is a photograph made up of four large-format quadrants of the moon, taken in 1899, and probably created for the 1900 Paris Exposition. The photogravures, by Pierre Henri Puiseux and Maurice Loewy, were taken at the Paris Observatory. “It was only with NASA’s Lunar Orbiters in the 1960s,” reads the collection note, “that images substantially better than those of Loewy and Puiseux were obtained.” The plates are from Puiseux and Loewy’s Atlas photographique de la lune. The two men were able to photograph the moon only during perfect weather, the catalog notes, which meant just 50 or 60 nights each year—explaining why the Atlas took 14 years to complete. These may be the first oversize plates from the Atlas to come up for auction, and are expected to bring $12,000 to $18,000.
British pastel portraitist John Russell (the appointed painter to the King and the Prince of Wales) was so fascinated with the moon that he created a lunar globe in 1797, which he called a Selenographia. Russell spent many years drawing and observing the moon; his globe even accounts for lunar motion, or libration. No more than 11 Selenographias are believed to exist; six are in public collections. This example, lot number 23, is expected to fetch between $200,000 to $300,000.
August 31, 2012
NASA is asking astronomers for help in figuring out what to do with a rare gift — a pair of half-assembled space telescopes, each the size of Hubble — donated earlier this year by the National Reconnaissance Office. The space agency’s astrophysics division is about to recruit members of a study team to look into how the telescopes might be used for either of two proposed missions — to study dark energy or to search for planets around other stars. The study group will hold its first meeting in November and report by the end of April. Their findings will then be folded into a wider study of possible uses for the telescopes, beyond just astrophysics.
How did NASA get such a windfall? The NRO, which builds and operates U.S. spy satellites, had two telescope assemblies (including 2.4-meter mirrors, but no instruments or spacecraft) left over from its canceled Future Imagery Architecture program. The mirrors are the same size as Hubble’s, and would offer a telescope with a wider field of view.
In different times, space scientists would be giddy at the prospect of free, Hubble-class mirrors. But NASA’s science budget has been so depleted by big-ticket items like the Mars Curiosity rover and the forthcoming James Webb Space Telescope that there’s no money left to turn the donated NRO mirror assemblies into completed space telescopes. Astronomers’ next priority for a large space mission is the Wide Field Infrared Survey Telescope (WFIRST), which would hunt for evidence of dark energy. Using the NRO hardware would save NASA some $250 million by some estimates, but the agency still doesn’t have enough money to finish the WFIRST project, which will cost upwards of $1.6 billion.
So, it’s a dilemma. And now it’s the astronomy community’s dilemma.
September 4 update: A workshop on the NRO telescopes is being held this week at Princeton University.
June 28, 2012
One of the solar system’s most interesting places just got even more interesting.
Scientists studying data from the U.S./European Cassini probe in orbit around Saturn report (in this week’s Science magazine) that the fog-covered moon Titan most likely has an ocean some 60 miles beneath its icy surface.
The Cassini team infers the ocean from the way the moon flexes due to gravitational tides as it circles Saturn. The amount of flexing is greater than one would expect if Titan were made entirely of solid rock.
Titan — already the only place in the solar system beside Earth with surface lakes — now joins a small group of water worlds: Europa, Ganymede, and Callisto, all moons of Jupiter.
The ocean had been predicted (below) but it’s nice to have empirical evidence.
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