The Cosmic Mirror
By Daniel Fischer
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A German companion - only available here!
Current mission news: MGS (latest pictures!) + Cassini + Stardust

Updates from the Mars Rovers and Mars Express
Spirit has found water effects in another rock - and both it and Opportunity have now finished their primary missions and both have been given green light to work until September. NASA Press Release on the mission extension, MER Press Releases of April 15 [JPL], April 8 [JPL] and April 1 [JPL], a JPL Feature on the cameras and coverage of April 27: SD. April 26: S&T, ST. April 24: Dsc. April 22: SD. April 21: AB. April 17: ST. April 16: UPI (other story). April 15: BBC, FT, Heise. April 14: AFP, SC. April 13: AB, New Sci., AP, ST, NZ. April 10: FT. April 9: FT, HC, ST, RP. April 8: SC, Cornell Chronicle. April 7: BBC. April 6: AP, NZ. April 5: Dsc., APOD. April 3: FT. April 2: Ast., ST, NZ. Physics Today. April 1: Dsc, Nat. Geogr., Pasadena * News, SC. March 31: ABC, FT, March 30: AstroBio. Mars Express commissioning almost done - but the MARSIS radar boom has not been deployed yet because of a possible hazard: April 21 and April 8 pictures, March 31 Status and picture and coverage of April 28: BBC, ORF. April 23: New Sci. Mars' methane mystery: AB, Plan. Soc., S&T, SF Gate, UPI, SC. A Mars sample return mission by ESA? EADS/RAS PR. NASA's 2009 rover: SC. Electric dust devils? GSFC Release, SC. Meteorite from Phobos? New Sci. Student 'Mars sensation'? THEMIS Release, Mars Soc. Germany. Dry Mars model: SD.
Update # 276 of Wednesday, April 28, 2004
Gravity Probe B is up! / Bright comet came near Sun, now faint but with fine tail / Sgr A* measured at 7 mm / Lunar A delayed again / Microlensing, transit exoplanet discoveries

After 45 years in the making: Gravity Probe B is in space!

NASA's Gravity Probe B (GP-B) space vehicle roared into space on April 20 from Vandenberg Air Force Base, Calif. Stanford University is the GP-B prime contractor. NASA Marshall Space Flight Center in Huntsville, Ala. manages the program. During its 16-month mission, GP-B will attempt to verify two subtle physical effects predicted by Albert Einstein's General Theory of Relativity, which provides the foundations for understanding the large-scale structure of the Universe. The GP-B space vehicle comprises the spacecraft, built by Lockheed Martin, and its payload. The payload is made up of the dewar, the key structural component around which the GP-B space vehicle was built, and the flight probe, a nine-foot-long cigar-shaped vacuum chamber.

The GP-B experiment will be conducted in an extremely stable environment, free from all outside forces. When the Gravity Probe B experiment begins, the instrument apparatus will measure minute changes in spin axis orientation of four ultra-precise gyroscopes contained within. The gyros will be so free of disturbances that they will provide a nearly perfect space-time reference system. They will measure two predicted effects of Einstein's theory: whether and how space and time are warped by the presence of Earth, and whether and how the rotating Earth drags space-time around with it. This will be by far the most accurate test of any of the predicted effects of Einstein's theory. Small as the two effects measured by Gravity Probe B are, their measurement will provide an important advance by testing previously unproven predictions of Einstein's theory.

Critics had maintained for years that this experiment - first conceived in 1959 and funded by NASA since 1964 - is no longer necessary as numerous astrophysical observations have confirmed key predictions of general relativity. The project has been close to cancellation many times and barely survived the last year. But perhaps it's worth it after all: GP-B's measurements may provide critical clues to modern attempts to unify the four fundamental forces observed in Nature: electromagnetism, gravity, and the so-called strong and weak interactions that govern the behavior of atomic nuclei. Gravity Probe B is one of the few space missions NASA has conducted with relevance to fundamental physics. And if - as hardly anyone expects - its results would turn out to be in disagreement with General Relativity the impact would be enormous.

Homepage + Launch picture gallery (including a view of the deployed s/c) + Science@NASA of April 26 and April 19 + a portrait of GP-B's lead scientist.
NASA (launch update), Stanford, MSFC, LockMart and Boeing Press Releases [earlier], the status on April 23 and a launch log.
Coverage by S&T, PhysWeb, SN, SciAm, BBC, AFP, New Sci., SC, ST (earlier), NZ (früher).
Advance press releases by NASA, CfA, UA, LockMart and MSFC.
Previews by Science News, NSU, ABC, BBC, CSM, MercNews, Guard., SpaceRev, FT (earlier), New Sci., SF Gate, SN, ST, NZ, Welt (früher).

Bradfield faint in Northern morning skies - but with photogenic dust tail

When it came close to the Sun, comet C/2004 F4 briefly rose to -3 mag. in SOHO's pictures, but when Bradfield reappeared in the morning sky around April 22, it had faded to a mere 4th magnitude (about 4.7 mag. on April 27). Nonetheless it was still possible to pick out a broad dust tail, especially with photography or some electronic help (such as adding up video images). Visually, Alan Hale described the comet as "a relatively impressive sight" in a 20-cm telescope on April 23, while for SpaceWeather "by all accounts Comet Bradfield is a beautiful sight through binoculars, its long tail stretching 10 degrees above the rosy glow of the rising sun."

Posted on April 18

Glorious Bradfield in SOHO's view!

Newly discovered comet Bradfield is now closest to the Sun, in full view of SOHO's coronagraph LASCO C3: it has developped a mighty dust tail, and the head has become so bright that it 'blooms' out on the CCD chip. What a pity that the solar eclipse on April 19 is only a partial one, everywhere on Earth ... So SOHO is the choice: Check the C3 latest image every few hours, until about April 20!

Posted on April 13

Bradfield finds another comet, will get bright, but only for SOHO

William A. Bradfield of Yankalilla, South Australia, has discovered a comet in the constellation Cetus: He first spotted it low in the western evening sky with his 10-inch reflector on March 23rd and 24th, then lost sight of it until April 8th. According to the first orbit calculation the comet will move even closer to the Sun, both in space and as seen from Earth, until the third week of April, and reaches perihelion on the 17th, when it will be a scant 0.17 astronomical unit (about 25 mio. km) from the Sun, well inside Mercury's orbit. Even though perhaps brightening to 2nd magnitude, it will be totally impossible to observe for a week or more for anyone on Earth - but it should be a fine sight in SOHO images, primarily from the LASCO C3 instrument.

C/2004 F4 (Bradfield) should enter the C3 coronagraph field on April 16 and leave it on April 20; it passes 2.6 degrees from the Sun's center on April 18th. The elongation then rapidly increases and mid-Northern observers should be able to pick it up as a 4th magnitude object in the morning twilight on April 23. Bradfield remains a binocular object in the morning sky until June, passing through Pisces and Andromeda and is close to M31 in the second week of May. The first orbit suggests that C/2004 F4 should have been a relatively bright object during the winter and well placed in northern skies, so it is a little surprising that no-one picked it up. Perhaps it will be found in archival images, which should lead to an immediate improvement in the orbit.

Alternatively the comet may have undergone an outburst, in which case its future behaviour becomes uncertain. It may well be worth getting up early at the end of the month as there may be three comets on view! 2003 T3 (Tabur) lies 5° below Bradfield's comet, whilst 2002 T7 (LINEAR) is on the eastern horizon. Indefatigable comet hunter Bradfield, now age 76, is credited with numerous other discoveries dating back to 1972: All 18 of these comets bear his name alone, which means he spotted and reported them well ahead of any other observer. But it's been nine years since his last discovery, C/1995 Q1. Born in New Zealand, Bradfield worked many years for the Aussie government as a research scientist on rocket-propulsion systems before retiring in the late 1980s. (Based on an S&T AstroAlert and an SPA Special Electronic News Bulletin of April 12)

Ephemeris, a detailled map and the IAUC # 8320.
Get observing reports for current comets from C. Morris! And FG Kometen News has updates, too.
Post-perihelion pictures of April 27 by Holloway (USA), Rudz & al. (Poland), Westlake (USA) and Lakomiak (USA; with ISS trail), April 26 by Westlake (USA), April 25 by Lüthen (Germany, summed Mintron pix), Pacholka (USA), Brinkmann (Germany), Cook (USA) and Cantin (Canada), April 24 by Whittaker (in an airplane!) and Endo (Japan) and April 22 by Jäger (Austria) - and the (unfortunately only partial) eclipse of April 19 as seen by Pasachoff in South Africa.
Coverage on April 22: SOHO Pick of the Week, SC. April 20: BBC. April 19: APOD. April 16: S&T, SC. April 15: SOHO Pick of Week. April 13: ACC, SC. April 12: ACC.

HST can't find "Sedna's" expected moon

Also the diameter of 2003 VB12 could not be measured directly: NASA and HST Releases, Science@NASA, S&T, BBC, New Sci., SC, ST, BdW, MW, NZ. Did Sedna form out there?! A paper by Stern. The discoverers' view: a new paper by Brown & al.
Water ice grains found in comet C/2002 T7 (LINEAR) with Subaru: NAOJ PR.
SOHO sees 750th comet, another amateur discovery: ESA News [SD].

NEO hunt begins in the Southern hemisphere

A joint collaboration between the UA LPL and the ANU, funded by NASA, is now searching for Near Earth Objects with two telescopes in Australia: UA Press Release, The Age. Astronauts call for NEO deflection experiments: NEO News, BBC, SC. Impact consequences: Nat'l Geogr., BBC, SC.
The origin of the Park Forest meteorites that fell near Chicago in 2003: UC Press Release [SN], SC. New mineral found in lunar meteorite: BBC, AP, BdW, RP. How asteroids were heated in the early solar system, to sometimes more than 1100 °C: PSRD.

Intrinsic size of Sgr A* measured - radio emission close to Schwarzschild radius

Radio astronomers using the VLBA have detected the intrinsic size of Sagittarius A*, the Galactic Center radio source associated by most theorists with a supermassive black hole, showing that the short-wavelength radio emission arises from very near the event horizon of such a black hole. Radio observations with the Very Long Baseline Array show that the source has a size of 24±2 Schwarzschild radii at 7 mm wavelength. In one of eight 7-mm epochs an increase in the intrinsic size of some 60% was also noted. These observations place a lower limit to the mass density of Sgr A* of 14,000 solar masses per cubic astronomical unit.

The bright, radio-emitting object would fit neatly just inside the path of the Earth's orbit around the Sun, the astronomers said. The black hole itself, they calculate, is about 14 million miles across, and would fit easily inside the orbit of Mercury. To make their measurement, the astronomers had to go to painstaking lengths tor circumvent the scattering effect of the plasma "fog" between Sgr A* and Earth. By making many observations, only keeping the highest-quality data, and mathematically removing the scattering effect of the plasma, the scientists succeeded in making the first-ever measurement of Sagittarius A*'s size.

A paper by Bower & al., an NRAO Press Release, various Sgr A* pics and coverage by CSM, SC, Welt. Sgr A* discovered 30 years ago: AP.

How M31 'ate' numerous smaller galaxies

is documented by a wealth of structure in the Andromeda galaxy's halo: RAS Press Release, SC. Numerous stellar black hole candidates in M 31: RAS Press Release, SC, BdW.
Dozens of ultra-compact dwarf galaxies in the Fornax cluster have been found during a survey with the AAT (see also Update # 256 small items) - they look almost like stars: RAS Press Release, Ast., AFP, SC.

ISS etc. Update

ESA Press Releases on the docking and launch of Soyuz TMA-4, a NASA Statement on extended ISS stays, a NASA OIG PR on CAIB costs, an interview with an Exp. 9 astronaut, Science@NASA on ISS fluid FX, a RAS Press Release on why one should go to the Moon and Mars, a House PR on the Moon's uncertain resources, the Science Def. Team report on JIMO, the Exped. 9 Status and coverage of April 28: AFP, NZ, RP. April 27: SC. April 26: FT (other story), SpaceRev, UPI, SC (other story). April 24: FT, Welt. April 23: FT, HC, Dsc., AFP, New Sci., SR, ST, RP. April 22: SN, HC, FT (other story), SR, SD, SC, ST, NZ. April 21: SN (other story), FT, BBC, UPI, AFP, SC, ST, NZ, RP. April 20: Dsc., AFP, New Sci., ST.
April 19: Space News, AFP, New Sci., Guard., SC (other story), ST, NZ. April 18: SN, FT, HC (other story). April 17: HC, FT (other story), AP. April 16: New Sci., FT, AP, SD, SC (other and another story). April 15: ST. April 14: UPI. April 13: NY Books, FT, HC, AP, SC. April 12: Space News, Dsc., SpaceRev (other story). April 11: BBC. April 10: FT, ST. April 9: HC, BBC, AP, SC, ST, RP. April 8: S&T, SR, UPI, BBC. April 6: NSU, UPI, ST, RP. April 5: SciAm, SpaceRev, BBC (Q&A), CENAP. April 4: AP. April 3: FT, ST. April 2: HC, FT (OpEd), AFP, AP, ST. April 1: CSM, ST. March 31: HC, AFP, AP, SC, ST. March 30: SC.
The HST crisis - a RAS Press Release on why the UV is important and coverage of April 27: Dsc., HC. April 26: Space News, UPI, NZ. April 23: S&T, BBC, Welt. April 22: AW&ST. April 17: DailyCam. April 16: SC. April 15: SC. April 12: HC. April 9: S&T. April 6: SC, April 5: SC. April 2: SD.

Lunar-A launch delayed

JAXA has delayed the launch of a lunar mission that had been scheduled to lift off this summer because valves in the spacecraft's thrusters have been recalled by their American manufacturer: Japan Today, ST.

Shape of Hayabusa's target asteroid determined with the radio telescope at the Arecibo Observatory in Puerto Rico: a paper by Ostro & al., SD.

ESA looks for a 'Cosmic Vision 2015-25'

to continue its long-term planning for the science program: Call for Themes [SR]. ESA undergoes major reorganization - the heads of manned spaceflight and earth observation directorates will be replaced, ESA is disbanding three other offices, and two new directorates have been created: ST.

SMART-1's ion drive has run for a total of 2000 hours, and its behaviour is understood pretty well now: ESA Science News (earlier).

No variation seen in fine structure constant

from new quasar observations with the VLT - perhaps it's a constant after all: ESO Press Release, SciNow, New Sci., BdW. Before the Big Bang: SciAm. Horn-shaped topology of space? New Sci., Guard., ST, BdW.

Star formation peaked later than thought, analysis of SDSS galaxy sample suggests: S&T, SC, NZ. Big black holes growing in star clusters? Chandra PR, more, S&T, New Sci., SciAm, BBC, SC, ST, BdW.

Spatial motions of 14,000 Milky Way stars measured

in 1000+ nights spread over 15 years - now the changing dynamics of the Milky Way since its birth can be studied in detail: ESO Press Release, SD, Ast., SciAm, SC, MW.

AO images of Titan from the VLT

with the NACO system are supporting the Cassini/Huygens mission: ESO Press Release (earlier [SN]), MPG PM, BBC, SC, BdW, MW. Similar pics from Keck: Berkeley Release [SR], details. "Shipping forecast" for Titan's - potential - ocean: RAS and ESA Press Releases, BBC, New Sci., SC, MW.

Titan crossed the Crab Nebula last year and was tracked by Chandra in X-rays - the diameter of Titan's shadow was found to be larger than the known diameter of its solid surface: Chandra Release, Ast., MW. Japetus studied with Arecibo radar: SC, BdW.

Cassini sees storms merging on Saturn, spots the F ring shepherding moons: PhotoJournal (earlier), Cassini Release (earlier [SR]), BBC (earlier), BdW. Four filter views of April 3: PhotoJournal [SN]. Saturn from 56 million kilometers: PhotoJournal [SR], ESA Science News, BBC, New Sci. ISS shoots by Saturn & its moons: Edelmann movie!

Disappearance of Jovian storms predicted

Most of the large storms in Jupiter's atmosphere will disappear over the next several years, a model says, as a 70-year climate cycle comes to an end, causing the temperature of the atmosphere to change as much as 10°C: Berkeley PR, Ast., SC, ST, BdW.

Modern technology sharpens images from Soviet missions - imagery produced by several of the Soviet Venera series of craft have undergone reprocessing by an imagery specialist: SC.

Exoplanet discovery by microlensing?

This has been claimed several times before, now the confidence is much greater: a paper by Bond & al., JPL and NASA Releases, S&T, AD, New Sci., Dsc., BBC (earlier), SC, ST, BdW and RP stories.

Two new confirmed exoplanet discoveries with the transit method have been made by the OGLE project: papers by Bouchy & al. and Konacki & al. SuperWASP hunting for exoplanets in transit: PPARC Release [SR], BBC. Comet falling into young star? Penn State PR [SR], Ast., BBC. Complex protoplanetary disk around AB Aur: Subaru PR.

Are habitable 'Earths' frequent? Every second one could harbor Earth-type planets in the HZ, simulations suggest: RAS Press Release, BBC, AFP, MW. Europa's chances for life - C. Chyba interviewed by AB.

Genesis mission almost over

On April 1 the solar wind collector was stowed: JPL Feature, Press Release and invitation, New Sci., CSM, Wired.

Aura satellite delivered to launch site, liftoff planned for June: NASA Release [JPL].

China launches two smallsats

A Chinese rocket launched two small technology demonstration satellites on April 18 - the larger of the two, named Experiment Satellite 1, weighs 204 kg and carries a camera capable of taking stereo images of the Earth's surface, while the 25-kg Nano-satellite 1 will be used for unspecified experiments: Xinhua, AFP, ST.

X-43A test declared full success - the scramjet really worked: NASA Release. What could come next? AD. First aerospike engine flight test successful: DFRF Press Release, SN.

New VLTI instrument in operation

The new AMBER instrument of the VLT Interferometer has been tested in March with the light from two telescopes - but soon three beams will be combined, making imaging possible: ESO, MPIfR and and MPG Press Releases. 5-year anniversary of the VLT - what was achieved: ESO Press Release. Triple galaxy imaged: ESO Photo.

The first 8.4 m mirror is in the LBT! First light will follow later this year: UA Press Release.

Ultra-stable performance of an underground-based laser interferometer for gravitational waves

has been reported from Japan - going underground reduces seismic effects a great deal: a paper by Sato & al., BdW.

Seven-pixel detector installed at Arecibo radio telescope - ALFA (the Arecibo L-Band Feed Array) was built in Australia: Cornell Press Release [SR].

  • Spitzer unveils one of the most violent regions of star birth in our galaxy, DR21: Spitzer PR [JPL], Ast., BBC.
  • HST resolves the stars in galaxy NGC 300, with 6.5 million light-years distance one of our closer neighbors: STScI Release, Ast. HST views ring galaxy AM 0644-741: HST and ESA Releases, Ast., BBC, SC.
  • Chandra view of SNR 0540-69.3 shows two aspects of the enormous power released when a massive star explodes: Chandra Release.
  • Venus next to the Plejades in early April: APOD.
  • FAA issues launch licenses for X Prize contestants Scaled Composites and XCOR: FAA, XCOR Press Releases, ST (earlier), SC, RP. SS1's 2nd powered flight: SC. X Prize race: UPI, SC.
  • The history of McNeil's Nebula and its outbursts - we may be witnessing an FU Ori event on its way to maximum: a paper by Briceno & al.
  • The astronomical orientation of ancient buildings - now also claimed for Menorca: RAS Press Release, BBC, New Sci., SC, BdW. A related book review: BMCR.

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Compiled and written by Daniel Fischer