MESSAGE
| DATE | 2010-01-23 |
| FROM | Ruben Safir
|
| SUBJECT | Subject: [NYLXS - HANGOUT] Killer Asteroids...
|
The most likely way human civilization will come to an end would be by
an Asteroid hit. If your not certain of this, read the research...
however... this report out of nasa is just befuddling. How can
Telescopes attack Asteroids?
http://www.networkworld.com/cgi-bin/mailto/x.cgi?pagetosend=/news/2010/012210-layer8-nasa-asteroid-comet-protection.html&pagename=/news/2010/012210-layer8-nasa-asteroid-comet-protection.html&pageurl=http://www.networkworld.com/news/2010/012210-layer8-nasa-asteroid-comet-protection.html&site=printpage
How will NASA defend Earth against killer asteroids and comets?
Report outlines NASA’s option in discovering, defending against
hazards from space
By Michael Cooney, Network World
January 22, 2010 06:01 PM ET
Sponsored by:
Combinations of space- and ground-based telescopes may be the most
economically palpable defenses NASA can mount against asteroids and
comets heading toward Earth, but there are more advanced defenses
involving spacecraft and nuclear explosions that might be plausible in
the future.
Those were just some of the conclusions included in a report,
“Defending Planet Earth: Near-Earth Object Surveys and Hazard
Mitigation Strategies,†issued today from scientists at the National
Research Council on what options NASA has to detect more near-Earth
objects (NEOs) -- asteroids and comets that could pose a hazard to
Earth.
NASA telescopes watch cosmic violence, mysteries unravel
The same council issued a preliminary report in August saying imminent
impacts (such as those with very short warning times of hours or weeks)
require better current discovery capabilities. Existing surveys are not
designed for this purpose; they are designed to discover more-distant
NEOs and to provide years of advance notice for possible impacts. In the
past, objects with short warning times have been discovered
serendipitously as part of surveys having different objectives. Search
strategies for discovering imminent impacts need to be considered, and
current surveys may need to be changed.
No matter what though, the report says the $4 million the US currently
spends annually to search for comets and asteroids is insufficient to
meet a congressionally mandated requirement on NASA to detect NEOs that
could threaten Earth.
The report states that while impacts by large comets or asteroids are
rare, “a single impact could inflict extreme damage, raising the
classic problem of how to confront a possibility that is both very rare
and very important. Far more likely are those impacts that cause only
moderate damage and few fatalities.â€
An asteroid or comet about 10 kilometers in diameter struck the Yucatan
peninsula 65 million years ago and caused global devastation, probably
wiping out large numbers of plant and animal species including the
dinosaurs, the report states.
Objects as large as that strike Earth only about once every 100 million
years on average, the report notes. NASA has been highly successful at
detecting and tracking objects 1 kilometer in diameter or larger, and
continues to search for these large objects. The report notes that NASA
has managed to accomplish some of the killer asteroids mandate with
existing telescopes but with over 6,000 known objects and countless
others the task is relentless.
Objects down to sizes of about 140 meters in diameter -- which NASA has
been mandated to survey for -- would cause regional damage; such impacts
happen on average every 30,000 years, the report says.
The report recommends that NASA monitor for smaller objects -- those
down to 30 to 50 meters in diameter -- which the report says recent
research suggests can be highly destructive.
The report states that detailed studies of ways to mitigate collisions
are best viewed as a form of insurance. How much to spend on these
insurance premiums is a decision that must be made by the nation’s
policymakers.
The report goes on to say that with sufficient warning four types of
mitigation could meet the threat from all NEOs, except what it called
the most energetic ones:
• Civil defense (evacuation, sheltering in place, providing emergency
• infrastructure) is a cost-effective mitigation measure for saving
lives from the smallest comet or asteroid hit and is a necessary part of
mitigation for larger events.
• “Slow push†or “slow pull†methods use a spacecraft
to exert force on the target object to gradually change its orbit to
avoid collision with the Earth. This technique is practical only for
small NEOs (tens of meters to roughly 100 meters in diameter) or
possibly for medium-sized objects (hundreds of meters), but would likely
require decades of warning. Of the slow push/pull techniques, the
gravity tractor appears to be by far the closest to technological
readiness.
• Kinetic methods, which fly a spacecraft into the NEO to change its
orbit, could defend against moderately sized objects (many hundreds of
meters to 1 kilometer in diameter), but also may require decades of
warning time.
• Nuclear explosions are the only current, practical means for
dealing with large objects (comets or asteroids with diameters greater
than 1 kilometer) or as a backup for smaller ones if other methods were
to fail.
“Although all of these methods are conceptually valid, none is now
ready to implement on short notice, the report says. Civil defense and
kinetic impactors are probably the closest to readiness, but even these
require additional study prior to reliance on them,†the report
stated.
NASA has been increasing its ability to track dangerous comets and
asteroids. For example, part of the space agency’s recently launched
Wide-field Infrared Survey Explorer spacecraft to uncover objects never
seen before, including the coolest stars, the universe's most luminous
galaxies and some of the darkest near-Earth asteroids and comets.
In addition, NASA's Jet Propulsion Laboratory recently launched the
Asteroid Watch Web site to act as a centralized source for information
on objects hurtling at Earth.
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