Thursday11 March 20041:14am MST 12 March2004-03-12 UTC 0814 back top next  

The Asteroid/Comet Connection's
daily news journal about
asteroids, comets, and meteors

Today's issue status: done
The next news edition is planned for Saturday the 13th.

Cover: In Mexico a telescope grows atop a volcanic peak. The lower pictures were posted last week to LMT Current Construction slides showing foundation and reflector back structures for the 50m Large Millimeter Telescope that will observe where far infrared and microwave meet. Top picture by Carlos O. Ruiz last March, all images ©Copyright LMT Project, University of Massachusetts Amherst and Mexico National Institute of Astrophysics, Optics and Electronics. See A/CC's earlier report and below.

Sub/millimeter MO science – part 1/3 Major News for 11 March 2004 back top next  
Sub/millimeter MO science

Looking at drawings of the 50-meter radio dish (right) now under construction in Mexico (above), one might first think, "planetary radar," but there is nothing at the Large Millimeter Telescope (LMT) Web site about transmitting signals. Instead, the telescope will pick up thermal radiation in the millimeter and submillimeter band, where far infrared and radio/microwave meet. This part of the electromagnetic spectrum presents "exotic" new ways to study minor objects — comets, asteroids, and a growing list of distant objects of unknown nature, some large enough to be called "planetoids."

The history of such observation goes back to attempts at observing comets in the 1970s and 80s (reference IAUC 2982 in August 1976 and IAUC 4161 in January 1986) and takes off when the Instituto de Radioastronomia Milimetrica (IRAM) 30m telescope on Pico Veleta in Spain began observing comets (see, for example, the 1990 IAUCs 5020, 5027, and 5087, as well as IAUCs 5653 and 5664 in 1992). Several facilities succeeded quite well in 1996-97 with

Large Millimeter Telescope side view
(c)Copyright LMT Project

observing C/1995 O1 (Hale-Bopp) in this spectrum (e.g., IAUCs 6382, 6566, 6587, and 6591).

Detectors at this wave length are called "bolometers," and the names of the cameras that operate at a temperature of almost absolute zero are as well known as the telescopes that employ them — MAMBO on the IRAM 30m, SCUBA on the 15m James Clerk Maxwell Telescope (JCMT) on Mauna Kea in Hawaii, and Bolocam on the Caltech Submillimeter Observatory (CSO) 10.4m telescope on Mauna Kea, and also to be used on the LMT.

JCMT/SCUBA in April 2001 took the measure of what was then the largest known object beyond Pluto, 20000 Varuna, as told on David Jewitt's Varuna page.

part 2 >>

Sub/millimeter MO science – part 2/3 Major News for 11 March 2004 back top next  

<< continued from part 1

And on 7 October 2002 it was announced that the IRAM 30m and MAMBO had sized up four of the largest objects found out past Pluto, including what was by then the biggest known, the newly discovered 50000 Quaoar. Previous to this, during 1998-2000, the tact for studying Edgworth-Kuiper Belt Objects in the millimeter spectrum was to go mostly after the closer and maybe closely related Centaurs, such as 10199 Chariklo, then designated 1997 CU (see paper).

This Centaur and later work was calibrated in part by JCMT observation of seven Main Belt asteroids during 1993-95. Canadian participation brought the comment that the results offered "the possibility that remote prospecting for metals on the surfaces of asteroids can be done passively at submillimetre wavelengths as well as actively by high-power microwave radar."

There is a surge of sub/millimeter construction now in the works, from improved cameras for existing telescopes to the new LMT and a 25-meter telecope

announced two days ago by Cornell and Caltech to begin operation in 2012, plus an enormous array in Chile and the first space-based facility. The 3.5-meter ESA Herschel Space Observatory (HSO) is scheduled to launch in February 2007.

In preparation for the SCUBA-2 JCMT upgrade, a report arguing for a widefield camera included uses in minor object science. It notes that "polarization measurements promise to open a new window on the structure of asteroidal regoliths" (loose surface material), and that NEOs "too small to retain a regolith," because they are a representational sampling, "could reveal the properties of larger asteroids that are too far away to be observed."

Ground was broken last November 6th for the enormous ESO/NOAO Atacama Large Millimeter Array (ALMA) in the high desert of Chile that is to begin operation in 2007. When completed in 2012, it will have 64 12-meter dishes that can be configured as one telescope anywhere from 150 to 14,000 meters wide.

<< part 1 | part 3 >>

Sub/millimeter MO science – part 3/3 Major News for 11 March 2004 back top next  

<< continued from part 2

It will have sufficient resolution to study the atmosphere of Pluto, to watch distant comets as they change between active and inactive states, to perform exact nucleus astrometry while a comet is active and thus better calculate non-gravitational forces, and to look for subtle activity in objects such as Centaurs.

The NOAO ALMA Solar System Working Group report states that, not only will ALMA be capable of "greater accuracy than is possible with visible wavelength systems" for NEO astrometry, but future "millimeter-wave radar" development should "enable high resolution radar images of these objects to be constructed using [ALMA] as a receiving station for radar beams transmitted from another location." So planetary radar is in the future of these or similar systems.

News briefs – part 1/2 Major News for 11 March 2004 back top next  
News briefs

Big NEO discoveries:  The first NEO discoveries to be announced since the full Moon are two big oddballs. Today's MPEC 2004-E35 puts 2004 EC at absolute magnitude (reflected brightness) of H=15.8, which converts to roughly 2.34 km. (1.45 miles) wide, with a preliminary eccentric orbit (e=0.83953) inclined at 32.1° that brings it as close to the Sun as Mercury. It was discovered yesterday morning by LINEAR in New Mexico and confirmed this morning by three observatories.

2004 EB is a bit less odd. It was discovered two mornings ago with NEAT's Mt. Palomar telescope in southern California and confirmed early yesterday and today from there and six other observatories. At H=17.0, according to MPEC 2004-E34, it is on the order of only 1.35 km. (0.84 mile) wide. It also has an eccentric (e=0.64619) orbit, one that extends from near Earth to near Jupiter.

more news >>

Distant object news:  Denis Denissenko recently told the Minor Planet Mailing list (MPML) that 2002 GO9 [link|alt] is a "quasi-Uranian Trojan (current elongation from Uranus about 105 deg West). This is the only known non-cometary object with 18.2<a<20.0 and a period of 86 years (compared to 84 for Uranus)." Pasquale Tricarico, who specializes in Trojan dynamics, investigated the possibility with ORSA and posted the result and an animation. He concludes that present data doesn't support a stable Trojan or co-orbital relationship with Uranus, as it appears this object will eventually have an orbit-changing close encounter.

2002 GO9, estimated at roughly 45 km. (30 miles) wide, hasn't been spotted since last June 1st. In other years it was seen during March-May, and the Minor Planet Center notes that further observation is "desirable" this year through April 10th.

Risk monitoring:  JPL yesterday made very, very slight changes in its risk assessments for two objects not under recent observation — 2000 UV36 (H=26.5) and 2002 VU17 (H=24.8), put respectively at 20 and 40 meters/yards wide.

News briefs – part 2/2 Major News for 11 March 2004 back top next  

<< continued from part 1

Rosetta asteroid visits:  ESA announced today Main Belt asteroid flybys in 2008 and 2010 for its Rosetta comet mission: 21 Lutetia and 2867 Steins.

Steins is relatively small, with a diameter of a few kilometres, and will be visited by Rosetta on 5 September 2008 at a distance of just over 1700 kilometres. This encounter will take place at a relatively low speed of about 9 kilometres per second during Rosetta's first excursion into the asteroid belt.
      Lutetia is a much bigger object, about 100 kilometres in diameter. Rosetta will pass within about 3000 kilometres on 10 July 2010 at a speed of 15 kilometres per second. This will be during Rosetta's second passage through the asteroid belt.
      Rosetta will obtain spectacular images as it flies by these primordial rocks. Its onboard instruments will provide information on the mass and density of the asteroids, thus telling us more about their composition, and will also measure their subsurface temperature and look for gas and dust around them.

Asteroid education:  The Sacramento, California Bee has an article today about grade school astronomy education and mentions how one class is using the Hands-On Universe (HOU) program "to request, receive and process their own astronomical images for projects like asteroid searches." HOU's Asteroid Search provides images from the Bell Labs Deep Lens Survey, which uses the NOAO 4m Blanco and Mayall telescopes in Chile. The survey's goal is to map "large-scale structure of the mass distribution beyond the local universe" but has the side benefit of picking up transient phenomena including moving objects.

Comet news: posted an image today of comet C/2001 Q4 (NEAT) along with some info.

Opera under the baobab:  The Milwaukee, Wisconsin Journal Sentinel has an article today that tells about the development and second staging of Francesca Zambello's opera, "The Little Prince," which premiered last June. It says a version will be shot for BBC TV later this year.   [ top ]
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