The search for Near Earth Objects (NEO) - Microplanets (comets, asteroids and meteoroids) that share our region of the solar system. Inspired by the work of Gene Shoemaker and a memorial lecture by Ken Russell from the Anglo Australian Observatory. The term Spaceguard was coined by Arthur C Clarke in his 1973 science fiction novel Rendezvous with Rama. The introduction has an uncanny September 11 coincidence. (Extract)
Tip: These pages are in plain HTML. Try
Ctrl-F to "Find" any text you are interested in. Why so plain?
- this page was started in 1997.
"No one wants to look back and regret
actions not taken" - Dr David Suzuki, The Nature of Things.
'Many might say "But we know of no one
that has ever died from an asteroid impact." That's true [in
recent times], but then who has ever died from a
thermonuclear explosion? Surely no one would claim that they
are not dangerous?' - Arthur C Clarke, Foreword to Rogue
Asteroids and Doomesday Comets by Duncan Steel.
"No one has ever been killed by a meteorite in the presence of a meteoritist and a medical doctor!" - John Lewis
Recent items are near the top (posting date shown).
For more news see Spaceguard UK's
News page, Spaceviews,
NASA's
Asteroid/Comet
Impact Hazard news page and NEO Office News Page
(NNN), The
Planetary Society NEO News, The Cosmic
Mirror , Cambridge
Conference Network(CC), SpaceDaily, Tumbling
Stone (SGF/NEODys),SpaceWeather.com
(has a list of forthcoming close approaches), Asteroid/Comet
Connection, Universe
Today (UT- space news from around the Internet, updated
every weekday)
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of page 
1972: Rock samples collected by Apollo
17 (the last manned mission to the Moon) show that the age of
the 85km diameter Tycho
Crater is about 100 million years. An asteroid or comet
about 4km across would be needed to make a crater this size. On
average the Earth is struck by a microplanet this size every 10
million years. The impact rate on the smaller Moon is about one
tenth of that on Earth so Tycho is within expectations (but see
this note
about impacts randomly distributed in time).That is why this is an unofficial web-site - there is no Spaceguard Survey in Australia at the present time. The web site has been started to support the re-establishment of the Australian Spaceguard Survey and to provide links to other Spaceguard-related sites.
It is evident that the Australian
Government is only interested in short term issues and
is unlikely to support a project which might not benefit
mankind for decades, or even centuries. One problem is that
the bureaucracy does not have a "pigeon hole" for this topic -
it is not pure "science" and there is no tangible enemy to
make it a "defence" matter. Therefore the Australian
Spaceguard Survey will probably need the support of
individuals, corporations and societies.
We are not asking for money, but an indication of support - and to determine whether the web site is a suitable way to generate this support. See also the Guestbook.
1 April 1997 Canberra Times: "Asteroid watch might resume" - Sky watching for "killer rocks" in Australia could be resurrected after intervention by Prime Minister John Howard...Science Minister Peter McGauran said Mr Howard recently asked him, Education Minister Vanstane and Defeence Minister McLachlan to examine whether asteroid spotting should continue..."we're treating it as a case where individuals can fall between portfolios becuase they don't fit neatly in one or the other"...
Update March 1999: A glimmer of hope about Australian funding for Spaceguard: The Coordination Committee on Science and Technology (CCST) is a high level committee set up by the Government of the Commonwealth of Australia, comprising representatives of departments with an interest in or responsibility for science, technology and innovation matters. It lists "Near Earth Asteroids" under "Matters receiving attention in the current financial year"! . Copy here (for the record!)
Update 10 September 1999: After a
three year break a professional search for Earth-threatening
asteroids will soon begin again in Australia. The project is a
collaboration between astronomers at the University of Arizona
and the Australian National
University. It involves refurbishing a telescope at Siding
Spring in New South Wales and providing a verysensitive
electronic detector array, computer pointing control and
automatic detection software.
The project will help to fill a huge gap in our ability to
detect asteroids which might collide with the Earth. Until now
the only professional searches were in the Northern Hemisphere
- the southern half of the sky was not covered. Early
detection of a potentially threatening asteroids is essential
if mankind is to have sufficient time
to mitigate the threat. Even the moderate rocket power we have
available today would be sufficient to deflect an asteroid
away from a collision, provided that the action can be taken
over decades and the asteroid is
given a little nudge during each orbit around the Sun.
Although the ANU/UA project is a welcome development renewed
government funding for an additional telescope will be
required if the goals of the international Spaceguard Survey
are to be achieved. That goal is to
discover, within a decade, 90% of Earth-approaching asteroids
with a diameter of 1 km or more. A collision by an asteroid of
this size would be a grave threat to our civilisation and the
death toll would likely be
in the hundreds of millions.
NASA NEO News - copy of
ANU/UA Press Release
18 Mar 02 OPINION - There was good coverage of the Spaceguard issue on Australian TV yesterday. Science Minister Peter McGauran tried to accuse NEO researchers of "fear-mongering" and being "self-indulgent" - a sure sign of an uncomfortable politician. In fact none of the 91 scientists from 17 countries who signed the letter to the Federal Government earlier this year would benefit in any way from an Australian decision to fund Spaceguard - other than the knowledge that a blind spot in the south would be eliminated. However, the reaction to the programs was overwhelmingly supportive and I think Mr McGauran should discuss this issue with his colleagues. He suggested Spaceguard would take 5% out of the $18 million budget for astronomy in Australia - a sneaky way to try and eliminate support for Spaceguard from other astronomers. We are saying it is not strictly science research and it would be more appropriate to fund it from the huge defence budget. If you agree please tell your local member of federal parliament.
1 Feb 02: In a remarkable show of
global solidarity more than 90 scientists from 17 countries
have signed a letter to Australian
Prime Minister John Howard, calling
for a major Australian contribution to Spaceguard
- the international effort to detect asteroids that might
collide with the Earth. The signatories to the letter come
from Australia, Canary Islands, Croatia, Czech Republic,
Denmark, Germany, Greece, Israel, Italy, Poland, Romania,
Russia, Spain, Sweden, Ukraine, United Kingdom and
United States of America. They include leading asteroid
researchers such as David Levy and Carolyn Shoemaker - famous
for discovering Comet Shoemaker Levy 9
that collided with Jupiter in 1994. The letter was organised
by Jay Tate from the Spaceguard
Centre in the UK and Dr Benny Peiser from Liverpool John
Moores University, UK. Michael Paine from the Planetary
Society Australian Volunteers assisted them. A PDF copy of the
letter and press release can be viewed at http://www4.tpg.com.au/users/tps-seti/pr_oz_sg.pdf.
Updates: Space.com World's
Asteroid
Hunters Make Political Plea to Save Earth. Recipient
list added to PDF
document. 5 Feb 02 Canberra Times: Australia
fails
world on asteroids: scientists.
The Risk and Consequences of Asteroid/Comet Impact
The following table is based on data from the NEO weblinks and you are encouraged to follow those links for a more complete picture. There are some inconsistancies between these links due, in part, to a lack of observational information (which would be corrected by a full Spaceguard survey). Therefore the table is very approximate but it will give some idea of the threat posed by asteroid and comet impacts.
| Very approx size of object * | Equiv. Megatons of TNT ("Bravo" H bomb=15Mt) |
Odds in 50 years # | Consequences @ |
| 10 metres | 20 kilotons | Annual | "Fireballs" burn up in atmosphere. Local hazard from debris and shockwaves. Possible trigger for nuclear warning systems. Smaller objects in much greater numbers pose a threat to spacecraft |
| 100m | 75 megatons | Earth:1 in 20 Inhabit:1 in 160 |
Meteor crater, Wolfe Crater, Tunguska. Local direct destruction (eg 50km radius). Around 1 million fatalities. |
| 500m | 10,000 | Earth:1 in 800 Inhabit:1 in 3,600 |
Regional destruction. Short-term global climate (and economic) effects. Tsunami (tidal waves) devastate coastal areas. Around 35 million fatalities. |
| 1km | 100,000 | Earth:1 in 2,000 Inhabit:1 in 6,000 |
Medium-term global climate effects. Around 63 million fatalities. |
| 2 km | 1 million | Earth: 1 in 20,000 Inhabit: 1 in 30,000 |
Global catastrophe threshold. Severe long-term climate effects. Collapse of agriculture. Around 1500 million fatalities. |
| 10km | 100million | Earth:1 in 2 million Inhabit:same! |
K-T impact. Mass extinction (eg dinosaurs) |
These values are based on the estimated NEO population. Care should be taken when comparing the "odds in 50 years" with actual evidence of impacts with the Earth. See Poisson Distributions.
Update 25 Nov 04 Icarus (abstract):
Bias-corrected
population,
size distribution, and impact hazard for the near-Earth
objects - Globally
destructive collisions (~1021 J) of asteroids 1 km or larger
strike the Earth once every 0.60±0.1 Myr on average.
Regionally destructive collisions with impact energy greater
than 4×1018 J (~200 m diameter) strike the Earth every
56,000±6000 yr. Collisions in the range of the Tunguska
event (4-8×1016 J) occur every 2000-3000 yr. This
latest analysis suggests that the odds shown in the above
table improve by about 5 times for 1km objects and less.
Another way of looking at the risk posed by asteroid/comet impact is to compare the chances of dying from selected causes. This table is based mostly on a paper by Clark Chapman and David Morrison and is for residents of the USA:
| Cause of death | Chances |
| Motor vehicle accident | 1 in 100 |
| Homicide | 1 in 300 |
| Melanoma (a skin cancer*) | 1 in 300 |
| Fire | 1 in 800 |
| Firearms accident | 1 in 2,500 |
| Electrocution | 1 in 5,000 |
| Asteroid/comet impact | 1 in 20,000# |
| Passenger aircraft crash | 1 in 20,000 |
| Flood | 1 in 30,000 |
| Tornado | 1 in 60,000 |
| Venomous bite or sting | 1 in 100,000 |
| Food poisioning by botulism | 1 in 3 million |
In other words, a US resident is 200 times more likely to die
in car crash than from a NEO impact and 5 times more
likely to die from a NEO impact than a venemous bite or sting.
Note that although an asteroid/comet impact is a very rare event, the number of people likely to be killed is greatly in excess of the other causes in the table. Compare the national US expenditure on "prevention" for all of these causes and it is evident that asteroid/comet detection is grossly under-funded.
For people living in low-lying coastal areas on the shoreline of deep oceans the risk could be several times greater due to the extra risk of tsunami.
.![[asteroid]](ast1-5km.jpg)
Note: I have cheated with this picture - it is actually asteroid Ida which is 50km across - you will have to imagine it is only 1km (in fact the small dot to the right is a 1km companion asteroid "Dactyl"). Thank you to Dr. Christian Gritzner from EUROSPACE GmbH for pointing this out!
NEO Web Links has moved (getting too large for this page!)
The worldwide Spaceguard program should be able to detect several thousand "candidate" asteroids/comets over a fifteen year period for less than US$10 million per year. Compared with worldwide defence expenditure, and space exploration budgets, this is very cheap "insurance" for mankind!
Media Contacts
Since there is no Australian Spaceguard Survey at present
general media inquiries in Australia should be directed to
research organisations such as the Anglo-Australian
Observatory (phone Sydney 02 93724800) or Mt Stromlo(Canberra 02
6249 0230) or the links at ASTRONOMICAL
SOCIETY
OF AUSTRALIA. We will, however, try and answer email enquiries about
matters covered on this web site.
Update May 2013: Astronomer and author Duncan Steel now has a
website.
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