Thursday27 May 20041:46am MDT 28 May2004-05-28 UTC 0746 back top next  
Asteroid 4 Vesta on 19 April & 3 May 
1992 by Marco Langbroek

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Cover: From there to here. On 19 April and 3 May 1992 Marco Langbroek photographed 4 Vesta with a simple camera with an ordinary 50mm f/1.8 lens and ISO 400 film. And he has in his collection this slice from a piece of the 1960 Australian Millbillillie meteorite fall, which is well documented as probably being a piece of Vesta itself.

Cover story – panel 1/1 Major News for 27 May 2004 back top next  

Cover story   by Marco Langbroek

The two "vintage" pictures used to make today's cover animation show asteroid 4 Vesta, and also show that you do not need large, expensive equipment if you just want to photograph an asteroid. Some larger Main Belt asteroids can be caught with an ordinary camera lens.

The two frames are from 19 April and 3 May 1992, made with a very simple Practika f/1.8 50mm reflex camera and Fujichrome 400 ISO film with an exposure of 1.5 minutes. The camera was mounted piggyback on my 4.5" Newton, which is on an equatorial mount and which I completely hand-guided on a star during the exposures. The starry field is in Leo, and the frames show only part of the original slides. They were shot from Voorschoten, a village close to The Hague in the Netherlands.

4 Vesta is believed to be the parent body of the HED (howardite, eucrite, and diogenite) type of meteorites. On the cover you see an example from my own collection, a 5.7-gram, 41mm-wide slice of the Millbillillie eucrite from Australia. It is an example

of an extraterrestrial basalt. That is, a piece of a surface basalt flow from volcanism on early Vesta some 4.5 to 4.6 billion years ago.

The brecciated character of the slice, with coarse grained clasts in a fine grained, darker gray matrix, shows that, after it formed, impacts plowed the basalt surface of Vesta. Yamaguchi et al. characterize Millbillillie as a granulitic breccia in an impact melt. Thus this meteorite probably once formed part of the impact breccia at the bottom of an impact crater created between 4.4 and 3.6 billion years ago. Millbillillie, including this particular slice, also contains thin glassy melt veins due to one or more later impacts, which probably occurred around 3.5 billion years ago.

another eucrite: The Pasamonte fall >>


Yamaguchi, et al., Textural variations and impact history of the Millbillillie eucrite, Meteoritics 29 (1994), 237-245 [ADS 1994Metic..29..237Y].

The Pasamonte fall – panel 1/2 Major News for 27 May 2004 back top next  
The Pasamonte fall

By Marco Langbroek

Science News from its March 27th issue had an item showing its 24 March 1934 cover (at right) with "the only photograph that ever caught the head of any meteorite in its flight" and its "first general publication" from what was then exactly a year earlier. We asked Marco Langbroek about what is thought today about that photograph, and whether it might be a fake.–Ed.

This is a very famous picture, shot at the time of the Pasamonte meteorite fall. It is probably not fake, yet it probably also does not show what many claim it shows. Please note that this is still disputed and not everybody will agree with what I write here.

The Pasamonte fall produced a brilliant fireball of several seconds, with a persistent train. A ranch foreman, Charles M. Brown, was inside when the fireball lit up the sky. He happened to be an enthusiastic amateur photographer, using a Kodak

Science News cover, 24 March 1934

©2004 Copyright Science Service, all rights reserved, used with permission

"box" camera. He had it at hand in the room and he snapped it up, ran outside, and (note!) opened the shutter while running some ten yards to a spot with a clear view and then pointed his camera.

While the picture was originally presented as of the fireball itself, several people over the years have noted that it rather must be a picture of the persistent train visible after the fireball had disappeared, and that

continued >>

The Pasamonte fall – panel 2/2 Major News for 27 May 2004 back top next  

<< continued from panel 1

it is motion blurred. Brown was pointing a camera with the shutter open and took the picture not from a tripod, but with the camera in his hands.

A second issue was whether the Pasamonte fireball moved straight or "corkscrewed," as some have claimed, using the Brown picture as an argument. I believe this idea probably originated with people observing the fireball's "persistent train." A persistent train starts to show "corkscrews" very soon after formation, due to high altitude winds. This may have led people to erroneously think that the fireball itself must have corkscrewed. But not everybody will agree with me. The "corkscrewing Pasamonte fireball" and Brown's picture are among those cherished legends of meteoritic folklore that somehow people don't want to give up.

The Pasamonte meteorites are eucrites, an achondrite of a type believed to originate from Main Belt asteroid 4 Vesta. See above for more about that.

Marco Langbroek is a professional archaeologist and an amateur meteor astronomer active with the Dutch Meteor Society. He is published on topics as diverse as Neanderthals and comet dust trails, and has helped inform A/CC readers about European fireballs, small object risks, and calculating object sizes from their brightness (Index).

Some references and photos of samples:


News briefs – panel 1/3 Major News for 27 May 2004 back top next  
News briefs

Shoemaker Grants:  A fund raising letter from Planetary Society Executive Director Louis Friedman has been posted at SpaceRef.com today about “Help Us Find and Track Dangerous Asteroids and Comets!” It starts, “This past January, those of us in the asteroid-detection business were on the edge of our seats [about] asteroid AL00667” (2004 AS1, see Index). And it finishes with “The Gene Shoemaker NEO Grant Fund is stretched to the breaking point, and with every day of delay, good projects somewhere in the world die for want of financial backing.” The society's NEO Page says “the next round of grant applications” will be announced “soon.” Grants were previously awarded in the years 2002, 2000, 1998, and 1997, mainly in small amounts to experienced amateur NEO observers. The application guidelines presently state that “The Society is not accepting applications at this time.”

Just noticed at the Planetary Society site is a wrap-up of the MUSES-C "Hayabusa" mission to date, posted after its Earth flyby last week.

El Paso mag. -7.2 fireball 
21 May 2004 MDT 5:16am 
caught by Jim Gamble

Meteor news:  At right is a third U.S. southwestern meteor from the night of 20-21 May, this one caught at dawn by Jim Gamble's El Paso, Texas fisheye all-sky camera on its northern horizon at 5:16am MDT May 21st at magnitude -7.2, lasting 3.2 seconds.

The biggest event that morning was a meteor that exploded over Montrose, Colorado at a reported apparent magnitude of around magnitude -13.4, “two to three times brighter than the full Moon” according to Chris Peterson's report. He has updated that report to note that, “This fireball exploded unusually high [suggesting] that the parent body was particularly fragile, possibly cometary debris or a carbonaceous chondrite.” New analysis indicates that, if any pieces survived, the strewn field likely is “about 12 miles to the northeast” of Montrose, “between Montrose and

Meteor news continued >>

News briefs – panel 2/3 Major News for 27 May 2004 back top next  

<< Meteor news continued from panel 1

Crawford.” See more about this story yesterday and May 22nd. The latter tells also about the first of that night's meteors caught by southwestern all-sky cameras (11:12pm, 2:44am, and 5:16am), this one from Sandia National Lab's all-sky camera in Albuquerque, New Mexico.

Sandia has posted a bright-meteor movie from 12:59am MDT today (422Kb) showing a brief unmoving flash overhead.

Astronomy.com has an article from yesterday, “Anatomy of a bolide,” about the March 2003 Park Forest, Illinois event (see A/CC's report then and more recent Index). It has links to two videos that caught the event, and tells about the conclusion by Peter Brown et al. that the object went from “12.5 tons (11 metric tons)” to “40 pounds (18 kilograms) of meteorites recovered,” beginning with a “main fragmentation event . . . at a height of 44 miles (70 km) . . . quickly followed by two smaller detonations at 22 and 16 miles (36 and 26 km).”

Spitzer news:  The Spitzer Space Telescope has a news release today, “Raw Ingredients for Life Detected in Planetary Construction Zones,” about finding “icy dust particles coated with water, methanol and carbon dioxide [which] may help explain the origin of icy planetoids like comets. . .  Previous studies identified similar organic materials in space, but this is the first time they were seen unambiguously in the dust making up planet-forming discs.”

Hayabusa news:  The Institute of Space and Astronautical Science of the Japan Aerospace Exploration Agency has a news item dated May 25th, “Current Status and Future Plan of Hayabusa” and another about optical and radar observation of destination 25143 Itokawa (1998 SF36). The former notes that the spacecraft shut down its ion engines on March 31st and used a chemical rocket to "provide larger momentary power . . . to tune precisely its orbit," and that it had to go to battery power for the first time during the flyby gravity assist maneuver. There's also a better Earth image from May 18th.

more news briefs >>

News briefs – panel 3/3 Major News for 27 May 2004 back top next  

<< continued from panel 2

Bits & pieces:  The IAU CBAT/MPC Astronomical Headlines today page announces C/2004 H6 (SWAN) as “found on SOHO/SWAN images, later confirmed by ground-based observers.” Update:  The Central Bureau for Astronomical Telegrams has publicly posted IAUC 8347 with an ephemeris and a preliminary orbit calculation that puts C/2004 H6 perihelion at 0.776 AU on May 12th on a parabolic retrograde (i=107.7°) path.

The Thursday Daily Orbit Update MPEC shows that Arecibo in Puerto Rico imaged 2000 JS66 on May 21st, the first day of eight scheduled for radar observation of this asteroid.

The Spacewatch FMO Project has told its online volunteers that an object reported May 24th to the Minor Planet Center as a possible discovery, and that was rejected as probably artificial, may be the European Space Agency SMART-1 spacecraft that is gradually making its way to lunar orbit by ion propulsion and gravity maneuvering.

Risk monitoring - panel 1/1 Major News for 27 May 2004 back top next  
Risk monitoring 27 May

(There was no risk monitoring news to report today.)

Summary Risk Table - sources checked at 2359 UTC, 27 May

Object

Assessment

Years

VI
PS
cum
PS
max
T
S
Arc 
days
 2004 HZJPL 5/182023-20231-5.27-5.27018.114
NEODyS 5/14R E M O V E D
VI = count of "virtual impactors" (impact solutions)
See A/CC's Consolidated Risk Tables for more and maybe
  newer details, and check the monitors' links for latest info.
Note that only objects recently in view are shown here.
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