Astronomy (and other Space Sciences)

As mentioned in class, an impact of a small asteroid packs a lot of power and can create a rather larger
crater. An impact from a large asteroid can have a devastating effect on a large scale; we now think that
the impact of a large asteroid is responsible for the extinction of the dinosaurs. The idea of asteroid
impacts has fascinated us for a long time and shows up in many places in popular culture, including
movies such as Armageddon and Deep Impact.
NASA currently is attempting to find and attract asteroids that are large enough to pose a threat to Earth
but it remains a question as to what to do if a large asteroid is found to be on an impact course with the
Earth. For this project, you will read two short papers talking about the dangers that asteroids pose, the
odds of a collision, and a possible way to protect Earth from a threatening asteroid (these papers can be
found in the “Asteroid Writing Project” folder in the “Assignments” area of Blackboard). After you read
these papers, you need to decide if it is worth spending tax dollars to try and protect us from possible
asteroid impacts. You will then write a paper stating your position and defending your position with
facts from the papers; you may also use additional resources for information. Your paper should be a
maximum of two pages, not including references, and must include in-text citations in proper MLA
format.
As was the case with the previous writing project, if you submit the paper early, I will provide feedback
and you will have the chance to resubmit for a higher score.
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Diagram: How to Off An Asteroid
The Threat is Out There
More than 100,000 asteroids hurtle past our planet. But only one—that we know of—may hit us in the next 30
years.
By David Noland
Published in the December 2006 issue.
Scientists at Arizona’s Kitt Peak National
Observatory first spotted the Apophis asteroid in June 2004. (Photo: Bryan Allen)
Friday the 13th of April 2029 could be a very unlucky day for planet Earth. At 4:36 am Greenwich Mean Time, a
25-million-ton, 820-ft.-wide asteroid called 99942 Apophis will slice across the orbit of the moon and barrel toward
Earth at more than 28,000 mph. The huge pockmarked rock, two-thirds the size of Devils Tower in Wyoming, will
pack the energy of 65,000 Hiroshima bombs—enough to wipe out a small country or kick up an 800-ft. tsunami.
On this day, however, Apophis is not expected to live up to its namesake, the ancient Egyptian god of darkness
and destruction. Scientists are 99.7 percent certain it will pass at a distance of 18,800 to 20,800 miles. In
astronomical terms, 20,000 miles is a mere stone’s throw, shorter than a round-trip flight from New York to
Melbourne, Australia, and well inside the orbits of Earth’s many geosynchronous communications satellites. For a
couple of hours after dusk, people in Europe, Africa and western Asia will see what looks like a medium-bright star
creeping westward through the constellation of Cancer, making Apophis the first asteroid in human history to be
clearly visible to the naked eye. And then it will be gone, having vanished into the dark vastness of space. We will
have dodged a cosmic bullet.
Maybe. Scientists calculate that if Apophis passes at a distance of exactly 18,893 miles, it will go through a
“gravitational keyhole.” This small region in space—only about a half mile wide, or twice the diameter of the asteroid
itself—is where Earth’s gravity would perturb Apophis in just the wrong way, causing it to enter an orbit
seven-sixths as long as Earth’s. In other words, the planet will be squarely in the crosshairs for a potentially
catastrophic asteroid impact precisely seven years later, on April 13, 2036.
Radar and optical tracking during Apophis’s fly-by last summer put the odds of the asteroid passing through the
keyhole at about 45,000-to-1. “People have a hard time reasoning with low-probability/high-consequence risks,”
says Michael DeKay of the Center for Risk Perception and Communication at Carnegie Mellon University. “Some
people say, ‘Why bother, it’s not really going to happen.’ But others say that when the potential consequences are
so serious, even a tiny risk is unacceptable.”
Former astronaut Rusty Schweickart, now 71, knows a thing or two about objects flying through space, having been
one himself during a spacewalk on the Apollo 9 mission in 1969. Through the B612 Foundation, which he co-founded
in 2001, Schweickart has been prodding NASA to do something about Apophis—and soon. “We need to act,” he
says. “If we blow this, it’ll be criminal.”
If the dice do land the wrong way in 2029, Apophis would have to be deflected by some 5000 miles to miss the
Earth in 2036. Hollywood notwithstanding, that’s a feat far beyond any current human technology. The fanciful
mission in the 1998 movie Armageddon—to drill a hole more than 800 ft. into an asteroid and detonate a nuclear
bomb inside it—is about as technically feasible as time travel. In reality, after April 13, 2029, there would be little
we could do but plot the precise impact point and start evacuating people.
According to projections, an Apophis impact would occur
somewhere along a curving 30-mile-wide swath stretching
across Russia, the Pacific Ocean, Central America and
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Click to enlarge
Fortunately, Apophis needs to be nudged only about a mile to
avoid a gravitational “keyhole” in space—a region that would
send the asteroid on a collision course with Earth. Otherwise, it
would have to be diverted 5000 miles for it to miss our planet.
This reduces the energy required to deflect Apophis by a factor of
about 10,000—making it theoretically possible using current
technology. A number of methods have been proposed to do the
job.
Apollo astronaut Rusty Schweickart holds a
model of the asteroid 1998 KY26.
on into the Atlantic. Managua, Nicaragua; San José,
Costa Rica; and Caracas, Venezuela, all would be in line
for near-direct hits and complete destruction. The most
likely target, though, is several thousand miles off the
West Coast, where Apophis would create a 5-mile-wide,
9000-ft.-deep “crater” in the water. The collapse of that
transient water crater would trigger tsunamis that would
hammer California with an hour-long fusillade of 50-ft.
waves.
BUT DON’T EVACUATE just yet. Although we can’t force
Apophis to miss the Earth after 2029, we have the
technology to nudge it slightly off course well before then,
causing it to miss the keyhole in the first place.
According to NASA, a simple 1-ton “kinetic energy
impactor” spacecraft thumping into Apophis at 5000 mph
would do the trick. We already have a template for such a
mission: NASA’s Deep Impact space probe—named after
another 1998 cosmic-collision movie—slammed into the
comet Tempel 1 in 2005 to gather data about the
composition of its surface. Alternatively, an
ion-drive-powered “gravity tractor” spacecraft could hover
above Apophis and use its own tiny gravity to gently pull
the asteroid off course.
In 2005, Schweickart urged NASA administrator Michael
Griffin to start planning a mission to land a radio
transponder on Apophis. Tracking data from the device would almost certainly confirm that the asteroid won’t hit the
keyhole in 2029, allowing everyone on Earth to breathe a collective sigh of relief. But if it didn’t, there still would be
time to design and launch a deflection mission, a project that Schweickart estimates could take as long as 12
years. It would need to be completed by about 2026 to allow enough time for a spacecraft’s tiny nudge to take
effect.
NASA, however, is taking a wait-and-see attitude. An analysis by Steven Chesley of the Near Earth Object program
at the Jet Propulsion Laboratory (JPL) in Pasadena, Calif., concludes that we can safely sit tight until 2013. That’s
when Apophis swings by Earth in prime position for tracking by the 1000-ft.-dia. radio telescope in Arecibo, Puerto
Rico. This data could also rule out a keyhole hit in 2029. But if it doesn’t, the transponder mission and, if
necessary, a last-resort deflection mission could still be launched in time, according to Chesley. “There’s no rush
right now,” he says. “But if it’s still serious by 2014, we need to start designing real missions.”
IN 1998, CONGRESS mandated NASA to find and track near-Earth asteroids
at least 1 kilometer in diameter. The resulting Spaceguard Survey has
detected, at last count, about 75 percent of the 1100 estimated to be out
there. (Although Apophis was nearly 2500 ft. short of the size criterion, it was
found serendipitously during the search process.) Thankfully, none of the
giants so far discovered is a threat to Earth. “But any one of those couple of
hundred we haven’t found yet could be headed toward us right now,” says
former astronaut Tom Jones, an asteroid-search consultant for NASA and a
Popular Mechanics editorial adviser. The space agency plans to expand
Spaceguard to include asteroids down to 140 meters in diameter—less than
half the size of Apophis, but still big enough to do serious damage. It has
already detected more than 4000 of these; NASA estimates approximately
100,000 exist.
Predicting asteroid orbits can be a messy business, as the history of tracking Apophis in its 323-day orbit
demonstrates. Astronomers at Arizona’s Kitt Peak National Observatory discovered the asteroid in June 2004. It
was six months before additional sightings—many made by amateurs using backyard telescopes—triggered alarm
bells at JPL, home to the Sentry asteroid-impact monitoring system, a computer that predicts the orbits of
near-Earth asteroids based on astronomical observations. Sentry’s impact predictions then grew more ominous by
the day. On Dec. 27, 2004, the odds of a 2029 impact reached 2.7 percent—a figure that stirred great excitement
in the small world of asteroid chasers. Apophis vaulted to an unprecedented rating of 4 on the Torino Impact Hazard
Scale, a 10-step, color-coded index of asteroid and comet threat levels.
But the commotion was short-lived. When previously overlooked observations were fed into the computer, it spit out
reassuring news: Apophis would not hit the Earth in 2029 after all, though it wouldn’t miss by much. Oh, and there
was one other thing: that troublesome keyhole.
The small size of the gravitational keyhole—just 2000 ft. in diameter—is both a blessing and a curse. On the one
hand, it wouldn’t take much to nudge Apophis outside it. Calculations suggest that if we change Apophis’s velocity
by a mere 0.0001 mph—about 31 in. per day—in three years its orbit would be deflected by more than a mile, a
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50 THOUSAND YEARS AGO
BARRINGER CRATER
Arizona
Diameter: 4100 ft.
Cause: 150-ft.-wide meteorite
Claim to fame: Also called “Meteor Crater” (above),
this is the first impact crater ever identified on Earth,
as well as the best preserved one. In the 1960s,
astronauts went there to practice sampling techniques
for the Apollo program.
35.7 MILLION YEARS AGO
POPIGAI CRATER
Siberia, Russia
piddling amount, but enough to miss the keyhole. That’s easily within the capabilities of a gravity tractor or kinetic
energy impactor. On the other hand, with a target so minuscule, predicting precisely where Apophis will pass in
relation to the keyhole becomes, well, a hit-or-miss proposition. Current orbit projections for 2029 have a margin of
error—orbital scientists call it the error ellipse—of about 2000 miles. As data rolls in, the error ellipse will shrink
considerably. But if the keyhole stubbornly stays within it, NASA may have to reduce the ellipse to a mile or less
before it knows for sure whether Apophis will hit the bull’s-eye. Otherwise, a mission risks inadvertently nudging
Apophis into the keyhole instead of away from it.
Can we predict Apophis’s orbit to the submile level far enough in advance to launch a deflection mission? That level
of forecasting accuracy would require, in addition to a transponder, a vastly more complex orbital calculation model
than the one used today. It would have to include calculations for such minute effects as solar radiation, relativity
and the gravitational pulls of small nearby asteroids, none of which are fully accounted for in the current model.
And then there’s the wild card of asteroid orbital calculations: the Yarkovsky Effect. This small but steady force
occurs when an asteroid radiates more heat from one side than the other. As an asteroid rotates away from the
sun, the heat that has accumulated on its surface is shed into space, giving it a slight push in the other direction.
An asteroid called 6489 Golevka, twice the size of Apophis, has been pushed about 10 miles off course by this
effect in the past 15 years. How Apophis will be influenced over the next 23 years is anybody’s guess. At the
moment we have no clue about its spin direction or axis, or even its shape—all necessary parameters for
estimating the effect.
IF APOPHIS IS INDEED headed for the gravitational keyhole, ground observations won’t be able to confirm it until
at least 2021. By that time, it may be too late to do anything about it. Considering what’s at stake—Chesley
estimates that an Apophis-size asteroid impact would cost $400 billion in infrastructure damage alone—it seems
prudent to start taking steps to deal with Apophis long before we know whether those steps will eventually prove
necessary. When do we start? Or, alternatively, at what point do we just cross our fingers and hope it misses?
When the odds are 10-to-1 against it? A thousand-to-1? A million?
When NASA does discover a potentially threatening asteroid like Apophis, it has no mandate to decide whether,
when or how to take action. “We’re not in the mitigation business,” Chesley says. A workshop to discuss general
asteroid-defense options last June was NASA’s first official baby step in that direction.
If NASA eventually does get the nod—and more important, the budget—from Congress, the obvious first move
would be a reconnaissance mission to Apophis. Schweickart estimates that “even gold-plated at JPL,” a
transponder-equipped gravity tractor could be launched for $250 million. Ironically, that’s almost precisely the cost
of making the cosmic-collision movies Armageddon and Deep Impact. If Hollywood can pony up a quarter of a billion
in the name of defending our planet, why can’t Congress?
Earth’s Greatest Hits
About 100 tons of interplanetary material drifts to the
Earth’s surface on a daily basis. Occasionally, an object
hurtles with enough force to leave a mark.
ASTEROIDS are large rocky or metal bodies that originate
in the relatively warm inner solar system, in the region
between the orbits of Mars and Jupiter.
COMETS are composed mostly of water ice and rock, and
form in the cold outer solar system beyond the planets’
orbits. Scientists believe comets may have delivered the
first organic compounds to Earth billions of years ago.
METEOROIDS are either pieces of asteroids that collided
in space, or debris released by vaporizing comets. When
meteoroids enter Earth’s atmosphere, they are called
meteors, and when they reach its surface they are called meteorites. So far, the remnants of more than 160
impact craters have been identified on Earth. Here are six of the most notable:
35 MILLION YEARS AGO
CHESAPEAKE BAY CRATER
Maryland
Diameter: 53 miles
Cause: 1- to 2-mile-wide meteorite
Claim to fame: Though long ago filled in by soil and
water, this is the largest impact crater in the U.S. The
event that caused it fractured bedrock more than a mile
deep, creating a saltwater reservoir that still affects the
region’s groundwater.
65 MILLION YEARS AGO
CHICXULUB BASIN
Yucatán Peninsula, Mexico
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Diameter: 62 miles
Cause: 3-mile-wide asteroid
Claim to fame: The crater is flecked with
industrial-grade diamonds created by shock pressure
on graphite. A recent theory posits that this asteroid
and the Chesapeake Bay meteorite originated from
one asteroid. 1.85 BILLION YEARS AGO
SUDBURY CRATER
Ontario, Canada
Diameter: 155 miles
Cause: 6-mile-wide comet
Claim to fame: On the crater floor, heat from the
impact and cometary water fed a system of hot
springs possibly capable of supporting life. The rim of
the crater also holds one of the world’s largest
supplies of nickel and copper ore.
Diameter: 110 miles
Cause: 6-mile-wide asteroid
Claim to fame: This impact triggered enormous tsunamis
and magnitude 10 earthquakes. Scientists believe it led
to the extinction of dinosaurs and of 75 percent of all
species, effectively ending the Cretaceous Period.
2 BILLION YEARS AGO
VREDEFORT DOME
South Africa
Diameter: 236 miles
Cause: 6-mile-wide comet
Claim to fame: Though now the most eroded, Vredefort is the oldest and (at impact) the largest such crater on
Earth. It was created by the world’s greatest known energy release, which may have altered the evolution of
single-cell organisms
Chapter 2: Hazard of Cosmic Impacts

Identify a group of historical/endangered materials to be digitized/reproduced from one or several local information organizations, libraries, museums, archives, or individuals in Jamaica.

i have already started this essay with draft you can use that as the guide the location as to be national library of Jamaica they have a web site where can get the information from and can use other site to use as guide

please identify each question that is answered i have answered question 1 to 2. scholarly should be articles used if not you can place the links