Friday27 August 20043:39pm MDT2004-08-27 UTC 2139 last
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The Asteroid/Comet Connection's
daily news journal about
asteroids, comets, and meteors

Today's issue status: done

IndexyesterdayContentstomorrow
The IAU Astronomical Headlines page is showing today C/2004 Q2, “The tenth visual comet discovery by Don E. Machholz, Jr.” The NEOCP puts the comet at “R.A. = 04 17, Decl. = -22.4, m1 = 11.3.”

Cover: Francesco Manca at Sormano Observatory in Italy caught 2004 QV16 last night at magnitude 19.3 moving 4.12"/min. in this three-minute exposure. Today the one impact solution for this object was removed (see below).

Nuts & bolts – panel 1/1 Major News for 27 August 2004 previous
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Nuts & bolts   by Marco Langbroek

Contrary to a widely circulated wire story, the meteoric fireball seen over eastern Australia at 1330 UTC on 25 August (11:30 pm local time) was not likely to have been man-made space junk (news). Instead, it quite probably was a true meteor, an interplanetary particle entering our atmosphere.

First, let us clear up a misunderstanding. “Nuts and bolts” do not create large fireballs. They are too small and slow for this. Man-made space junk typically re-enters at a speed of ~7.5 km/s, about 50% of the speed of even the slowest meteoroid. At that speed, they need to be significantly larger than a normal meteoroid in order to cause a fireball.

Bright fireballs can be caused only by pieces of space junk larger than about one meter in diameter. For example, June sightings of the re-entry of a meter-size Russian rocket motor over the U.S. resulted in a group of fireballs of magnitude -3, about as bright as the planet Venus (news). Smaller objects (nuts and bolts) will be much dimmer.

USSTRATCOM (formerly NORAD) routinely tracks debris in low Earth orbit from 10cm (4") size upward. A piece of debris large enough to cause the Australian fireball would certainly be large enough to be cataloged. But a check with the NASA Orbital Information Group (OIG) revealed there

“What many people believe to be shooting stars are actually stray nuts and bolts burning up on re-entry”

— Australian AP story quote from a Mount Stromlo Observatory astronomer about the 26 Aug. 2004 eastern Australia bolide

A big ball of fire in last night's sky over Cowley County was more than likely space junk falling to earth and not a meteor

— Arkansas City Traveler article lead from a Wichita State University astronomer about the 8 July 2004 south-central U.S. bolide

were no suitable decay candidates to explain the Australian sighting. The only object near decay around this time was a rocket booster of the 2001 Navstar 50 launch (SSC catalogue nr. 26692; COSPAR ID 2001-04C) with a diameter of about 2.5 meters. It, however, was over China at the time of the Australian sighting, did not pass over Australia for several hours after the sighting, and, finally, the orbital updates show it was still in orbit and tracked several hours after the fireball (last known orbit when checked by the author at 26 August 0815 UTC was for epoch 26 August 0530 UTC).

In reality, the decay of man-made space junk is a relatively rare event, and meteoric fireballs happen more often. The probability that a fireball you witnessed was a true meteor is by far larger than the chance that it was space junk.

News briefs – panel 1/1 Major News for 27 August 2004 previous
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News briefs

Main Belt news:  After a period of confusion yesterday about whether Robert Hutsebaut had made his first asteroid discovery, it was cleared up that he had indeed been credited with discovering Main Belter 2004 QX16 Wednesday morning, which was linked with his Monday morning attempt at recovering a long lost NEO. He confirmed the new object yesterday morning along with Peter Birtwhistle, who commented about the confusion that he had gone two months without realizing he had been credited with his first discovery. This is the second asteroid discovery made with Rent-a-scope equipment at New Mexico Skies. The first was by Ulrich Wolff (“Main Belt news” thread, discovery story). Robert Hutsebaut recently told about how he got started in this work.

Bits & pieces:  The Deep Impact comet mission has posted its August newsletter with back-to-school features such as interviews with Summer interns, the story behind the mission's spacecraft paper models that you can build yourself, mission-related math challenges, and a revised “Designing Craters” science activity.

Astronomy.com has an article from yesterday about meteors providing a life supply of phosphorous (see also the University of Arizona's August 24th news release). And

Call for observations:  An E-mail from Don Yeomans at JPL to professional astronomers yesterday was forwarded to the Minor Planet Mailing list (MPML) today, then to A/CC:

The Genesis spacecraft executed a mid-course correction on August 9 and since that time, we have only data from Mauna Kea and Powell observatories on Aug. 16. There will be 8 hour spacecraft correction burns centered on 1200 UTC on both August 29 and September 6. Hence, in order to provide orbit solutions in burn-free time intervals, we would need a few additional observations prior to Aug. 29 or between August 29 and Sept. 6. During the latter interval the spacecraft should brighten considerably. 

See “Impactor practice” August 17th, for more info and where to find ephemerides, and related “Sample returns” news.

Time magazine posted a column yesterday, “Strange Doings on Tunguska” (see also a Space.com report August 12th).

Scripps Howard News Service today circulated yesterday's Albuquerque Tribune story about “an asteroid's close encounter with Earth last week.” It actually happened March 31st and was made public this past Sunday — see yesterday's “2004 FU162 update.”

Risk monitoring - panel 1/2 Major News for 27 August 2004 previous
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Risk monitoring 27 August

The Friday Daily Orbit Update MPEC (DOU) reports observation of 2004 QV16 last night by Sormano Observatory in Italy (see “cover” image above). And today NEODyS removed its one impact solution for this object, which is estimated at more than a half kilometer wide.

The DOU has a triplet for 2004 PP97 from the Australian National University 1m telescope in New South Wales on Tuesday. JPL apparently received this data ahead of the DOU and removed its impact solutions yesterday, and NEODyS removed its solutions today. This object is estimated to be on the order of 900 meters/yards wide.

2004 QJ7 is reported from Wednesday from Mt. John Observatory in New Zealand. Today NEODyS removed all of its 71 impact solutions (the first less than three years away) and JPL removed all of its 107 solutions for this object, which is estimated to be about the same size as 2004 PP97.

And from LINEAR in New Mexico, the DOU has eight observations of 2004 QF14 spanning an hour yesterday morning. Today JPL removed its one impact solution for this small object. All four objects dropped from risk listings today had their one to 107 impact solutions removed after the first observations became available since

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

Object

Assessment

Years

VI
PS
cum
PS
max
T
S
Arc 
days
 2004 QZ2 NEODyS 8/252068-20792-6.65-6.8304.644
JPL 8/252068-20681-6.17-6.1704.644
 2004 QV16NEODyS 8/27R E M O V E D
 2004 QJ7JPL 8/27R E M O V E D
NEODyS 8/27R E M O V E D
 2004 QF14JPL 8/27R E M O V E D
 2004 QD14 NEODyS 8/262028-20708-4.63-4.9601.297
JPL 8/262018-2098122-3.24-3.7501.297
 2004 QB17 NEODyS 8/272021-20515-5.24-5.4101.007
JPL 8/272013-209929-4.31-4.9201.007
 2004 PP97NEODyS 8/27R E M O V E D
JPL 8/26R E M O V E D
 2004 FU162JPL 8/242006-2104824-5.38-6.3700.031
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.

discovery confirmation. All it took in each case was the participation of just one observing facility.

Also reported in today's DOU is observation of 2004 QB17 from Sandlot Observatory in Kansas

continued >>

Risk monitoring - panel 2/2 Major News for 27 August 2004 previous
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<< continued from panel 1

yesterday morning. Today JPL slightly raised its low risk assessment for QB17, which is estimated at roughly 600 meters wide.


Update:  NEODyS has posted 2004 QB17.

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