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Astronomy Picture of the Day |
APOD: 2002 March 3 - The
Regolith of Asteroid Eros
Explanation: From fifty kilometers
above asteroid Eros, the surface inside one of its largest craters appears
covered with an unusual substance: regolith.
The thickness and composition of the surface dust that is regolith
remains a topic of much research. Much of the regolith on 433 Eros was probably created by
numerous small impacts during its long history. In this
representative-color view taken by the robot spacecraft NEAR-SHOEMAKER
that orbited Eros in 2000
and 2001, brown areas indicate regolith that has been
chemically altered by exposure to the solar wind during micrometeorite
impacts. White areas are thought to have undergone relatively less exposure. The
boulders visible
inside the crater appear brown, indicating either that they are old enough to
have a surface itself tanned by the solar wind, or
that they have somehow become covered with some dark surface regolith.
APOD: 2001 October 9 -
The Past of Asteroid Eros
Explanation: How did large rocks come
to be scattered on the surface of asteroid Eros? Eros
stands out not only because of its proximity
to Earth but also because it was visited recently by NASA's NEAR-Shoemaker spacecraft. After
arriving at Eros in
2000 February, the robot probe was maneuvered to a controlled
landing earlier this year. Although NEAR-Shoemaker is no longer
active, scientists are still poring over the images and data, finding
new mysteries, and drawing new hypotheses about the ancient tumbling space
mountain. For example, analyzing the locations of rocks has led to the hypothesis
that many of them originated in a single large collision that occurred possibly
about a billion years ago. Still unknown, however, includes why Eros has unusual ponds of blue
dust.
APOD: 2001 August 24 -
NEAR at Eros: Before Touchdown
Explanation: On 12 February, 2001,
the NEAR-Shoemaker
spacecraft gently
touched-down on the the surface of Eros -- the first ever landing on an asteroid.
During the descent, the spacecraft's camera recorded successive images of
the diminutive
world's surface, revealing fractured boulders, dust filled craters, and a
mysterious collapsed channel. The last frame, seen
in the above montage at the far left, was taken at a range of 128 meters.
Expanded in the inset, it shows surface features a few centimeters across. Stereo
experimenter Patrick Vantuyne, constructed this montage from the final
images in the landing sequence, carefully identifying the overlapping areas in
successive frames. Frames which overlap were taken by the spacecraft from
slightly different viewpoints, allowing
Vantuyne to construct close-up stereo
images of the surface of asteroid 433 Eros.
APOD: 2001 June 5 -
Asteroid Eros Reconstructed
Explanation: Orbiting the Sun between Mars and Earth,
asteroid 433 Eros was visited by the robot spacecraft NEAR-Shoemaker
in 2000 February. High-resolution surface measurements made by NEAR's Laser Rangefinder (NLR) have been
combined into the above
visualization based on the derived 3D model of the tumbling space rock.
NEAR allowed scientists to discover that
Eros is a single solid body, that its composition is nearly uniform, and
that it formed during the early years of our Solar System. Mysteries
remain, however, including why some rocks on the surface have disintegrated. On
2001 February 12, the NEAR mission drew to a dramatic close as it was crash landed onto the
asteroid's surface,
surviving well
enough to return an analysis of the composition of the
surface regolith.
Unless re-awakened by NASA, NEAR will likely
remain on the asteroid for billions
of years as a monument to human ingenuity at the turn of the third millennium.
APOD: 2001 March 5 -
Survivor: NEAR Shoemaker On Asteroid Eros
Explanation: Not part
of a television game series, the NEAR Shoemaker spacecraft
survived its unprecedented landing on an asteroid last month. As
suggested in the illustration inset
above, the car-sized probe likely rests gently on the tips of its solar
panels having touched down under the influence of asteroid Eros' feeble gravity.
Fortunately, the spacecraft's solar panels were bathed in sunlight and able to
power NEAR's
gamma-ray spectrometer. Perched on the asteroid, this instrument can
determine the composition of Eros to a depth of about 10 centimeters with
unanticipated accuracy by measuring the gamma-ray
signatures of the atomic nuclei present. The data returned from the
surface of Eros are plotted above and show clearly features corresponding to
Iron, Oxygen, Silicon, and Potassium in the asteroid's regolith. Also briefly
operating on Eros, NEAR's
magnetometer has indicated that no surface magnetic field
is discernible. Now
turned off, NEAR Shoemaker could remain preserved in its present location,
the vicinity of the huge, saddle-shaped feature dubbed Himeros, for billions
of years. But, as the asteroid
orbits, the spacecraft's solar panels will be repeatedly turned toward the
Sun ... offering the possibility of reawakening this survivor.
APOD: 2001 February 13 -
NEAR Spacecraft Survives Landing on Asteroid Eros
Explanation:
Yesterday NEAR-Shoemaker became the first
spacecraft to land on an asteroid and send signals back from its surface.
Since the robot
spacecraft was not designed for such a contingency, the
success of the landing on asteroid 433 Eros was not
assured. Shown
above is the last picture taken by NEAR-Shoemaker before its touchdown. The
streaking on the lower part of the image was caused by the loss of telemetry as
the satellite impacted the surface. The image was
taken 130 meters above the surface and spans 6 meters across. Rocks as small as
a human hand are visible. As engineers continue to try to
communicate with the beached car-sized spacecraft, scientists will work to
understand features visible in the highest resolution
photographs ever taken of an asteroid.
APOD: 2001 February 12 -
Approaching Asteroid Eros
Explanation: Today, at about 3 pm EST,
the first human-made
spacecraft is scheduled to touchdown on an asteroid. At an impact
speed of 8 kilometers per hour, it is most probable that the robot spacecraft NEAR-Shoemaker
will not survive its planned collision
with 433 Eros. A primary
reason for the descent, diagrammed above,
will be to take images during the four hours on the way down. If all goes well,
some of those pictures will show surface features as
small as 10 centimeters across. Scientists hope to learn more about this unusual
Manhattan-sized
rock that is, quite possibly, older than the Earth.
APOD: 2001 February 11 -
NEAR Shoemaker Views Eros
Explanation: Orbiting asteroid 433
Eros, 145 million miles from Earth, NASA's NEAR spacecraft has been returning stunning views as its
year long mission of exploration nears completion. A mosaic
of NEAR images
recorded at a range of about 127 miles, this picture
illustrates some of the amazing contrasts which apparently exist within the
domain of this diminutive world. Features as small as 65 feet are visible here,
while long shadows
emphasize the differences in the cratered regions at the left and smooth grooved
terrain at right. Up
close, the undulating surface seems flecked with bright deposits and
peppered with enormous boulders. Last year,
NASA changed the spacecraft name from NEAR to NEAR-Shoemaker in honor of the
late Dr. Eugene M.
Shoemaker, legendary geologist, comet hunter, and
inspirational pioneer in the field of interplanetary science. Tomorrow, NEAR-Shoemaker will complete its scheduled
mission as it will be commanded to descend to the
surface of the ancient asteroid.
APOD: 2001 February 6 -
Touchdown Site on Asteroid Eros
Explanation: The first controlled
descent of a spacecraft onto an asteroid is scheduled to occur next
week. The robot spacecraft
NEAR-Shoemaker has been orbiting asteroid Eros for nearly one year On
February 12, before maneuvering fuel wanes, NASA will command the craft to descend right down onto
the surface. Although the spacecraft is not expected to survive the impact,
it is hoped that it can transmit photographs showing surface details as
small as 10 centimeters during the descent. The touchdown site, shown above by
the yellow circle, is on the edge of the large saddle shaped feature known as Himeros, and near the
boundary between two distinct types of surface terrain.
APOD: 2001 January 22 - A
Two Toned Crater on Asteroid Eros
Explanation: What lies beneath
the surface of asteroid Eros? This image taken
two weeks ago by the robot NEAR
spacecraft orbiting the dark asteroid shows a kilometer-wide crater where some type
of light material lies beneath some of the darker surface regolith.
This light substance, seen on other photographs, may
be relatively fresh material not yet well exposed to a darkening solar wind and micrometeorite impacts. As
fuel wanes, NASA plans to
end the NEAR spacecraft mission on February 12 with a spectacular controlled
descent to the asteroid's surface.
Although not designed to survive a landing, it is hoped that NEAR will be able
to record and relay high-resolution
pictures on its way down.
APOD: 2000 October 27 -
Close To Eros
Explanation: Scroll right and fly close over asteroid Eros! This long mosaic was
constructed of images returned yesterday by the NEAR Shoemaker spacecraft as it orbited
to within 6.4 kilometers of a spot in the southern hemisphere of the rotating
asteroid's surface. That distance (about 21,000 feet) is less than the cruising
altitude of most commercial airline flights. The digital images show that while
many regions appear smooth with craters filled in by an accumulation of loose regolith, much of
Eros' surface is littered with rocks and boulders. The large boulder glinting in
the sunlight at the far left, just above the center of the mosaic, spans
approximately 25 meters. In the high-resolution view, the smallest rocks visible are
roughly human-sized at
about 1.4 meters (5 feet) across. The car-sized Near
Shoemaker spacecraft is now on its way to a
higher, more stable orbit about 200 kilometers above asteroid Eros.
APOD: 2000 October 26 -
The Map Of Eros
Explanation: This map of Eros was
constructed from a mosaic of images recorded by the NEAR Shoemaker spacecraft,
currently orbiting the 40 x 14 x 14 kilometer asteroid. A simple cylindrical
projection of an irregularly shaped world,
the map's individual images don't always match up at the edges. Shown here,
place names have been proposed
to describe the geography of Eros with a fitting
theme, though. They are based on romantic figures in the history and literature
of the cultures of planet Earth. The largest feature, Himeros, is a
depression about 10 kilometers wide. In Greek mythology, Himeros
was an attendant of Eros and the personification of the longing of love. Today,
after safely surveying
Eros for the past eight months, NEAR Shoemaker is scheduled to make a daring close approach to
the asteroid, briefly flying to within about 6 kilometers of its surface. Images returned from that distance are
expected to show features less than 1 meter across.
APOD: 2000 August 29 -
The Regolith of Asteroid Eros
Explanation: From fifty kilometers
above asteroid Eros, the surface inside one of its largest craters appears
covered with an unusual substance: regolith.
The thickness and composition of the surface dust that is regolith
remains a topic of much research. Much of the regolith on 433 Eros was probably created by
numerous small impacts during its long history. In this
representative-color view taken by the robot spacecraft NEAR-SHOEMAKER
currently orbiting Eros,
brown areas indicate regolith
that has been chemically altered by exposure to the solar wind during micrometeorite
impacts. White areas are thought to have undergone relatively less exposure. The
boulders visible
inside the crater appear brown, indicating either that they are old enough to
have a surface itself tanned by the solar wind, or
that they have somehow become covered with some dark surface regolith.
APOD: 2000 August 24 -
Eros At Sunset
Explanation: Gleaming in the rays of the setting
sun, boulders litter the rugged surface of asteroid 433 Eros. The brightest
boulder, at the edge of the large, shadowy crater near this picture's bottom
center, is about 30 meters (100 feet) across. In orbit around Eros since
February 2000, the NEAR Shoemaker
spacecraft's camera recorded the dramatic view
earlier this month from an altitude of about 50 kilometers. Eros itself orbits
the Sun with a perihelion
of 1.13 Astronomical
Units (AU) and aphelion
of 1.78 AU. Part of a class of near-Earth asteroids, it spends much
of its time between the orbits of Mars (at 1.5 AU) and Earth (at 1 AU) ... but
it wasn't always that way. Eros and other near-Earth asteroids
originally orbited in the main
asteroid belt, between Jupiter and Mars.
Over time, the gravitational influence of Jupiter and other planets perturbed
their orbits sending them on trajectories closer to
Earth.
APOD: 2000 August 03 - 22
Miles From Eros
Explanation: Last month the NEAR Shoemaker
spacecraft swooped closer
to Eros, orbiting only 22 miles (36 kilometers) from the center of the
asteroid. These two images taken on July 19 (left)
and July 24
(right) reveal the diminutive world's
pocked and mottled surface in amazing detail, showing features as small as 19
feet (6 meters) across. Eros is thought to be a primordial,
undifferentiated asteroid
based on X-ray
and gamma-ray studies of its surface composition. In the left picture, its
surface layer or regolith is seen
to be laced with bright and dark regions while in the right hand image dark regolith appears
to have filled in some crater floors. The left and right images span an area
about 2,600 feet (800 meters) and 3,000 ft (900 meters) wide respectively. On
July 31, NEAR Shoemaker returned to its
familiar 31 mile (50 kilometer) orbit, circling Eros
serenely at about 6 miles per hour.
APOD: 2000 July 21 - Eros
Craters And Boulders
Explanation: From a delicate
orbit around asteroid 433 Eros, the NEAR Shoemaker spacecraft's camera has now
imaged the entire surface of the small oddly-shaped world at
least once. Recorded on July 7th from a distance of 50 kilometers, this dramatic
view is about 1.8 kilometers across. It shows the walls and rims of two
large overlapping impact craters on the
horizon. Massive boulders which may be debris from the impacts are perched along
the crater edges. The prominent boulder on the horizon
near picture center is about 40 meters long. In fact, the NEAR mission to Eros has shown
that along with craters and boulders, grooves and ridges are
also common on the asteroid's
surface. While the craters are clearly of impact origin, puzzles
about the other surface features still remain. On July 13, controllers fired
the spacecraft thrusters and moved NEAR
Shoemaker to an even closer 35 kilometer orbit
to enable higher resolution surface studies.
APOD: 2000 May 25 - Eros
Horizon View
Explanation: Since April 30, the
robotic NEAR-Shoemaker spacecraft has been
orbiting only 31 miles from asteroid Eros. Cruising over
the asteroid's
north and south poles at a leisurely 7 miles per hour, the spacecraft completes
an orbit
once every 1.2 earth days. This dramatic
horizon view recorded by the spacecraft's camera on May 18 spans about 0.8 miles
and reveals features as small as 13 feet across. Emphasized by long, harsh shadows produced by
the low sun angle, the rolling surface of Eros is seen to be strewn with
boulders and craters with a range of sizes. The jagged-looking boulder near the
picture center is over 190 feet tall. While gathering sharp pictures of Eros'
surface, experimenters will
also take advantage of the close
orbit to explore the asteroid's surface composition and internal structure,
and search for a magnetic field.
APOD: 2000 April 17 -
Flying Over Asteroid Eros West End
Explanation: The robot
spacecraft NEAR Shoemaker continues to orbit asteroid Eros. This condensed 40-minute long
time-lapse sequence taken last month shows what it looks like to pass within
200 kilometers of Eros' west
end. The north pole of the rotating mountain is
toward the bottom of the picture. This month NEAR-Shoemaker closes to within 100
kilometers, and by the end of this month will orbit only 50 kilometers from the
center of this 33-kilometer long asteroid.
One reason for moving in so close is to determine if 433 Eros has a
magnetic field. NEAR Shoemaker, launched in 1996, is run by a computer similar to a
PC released 15 years ago (12 MHz, 256K).
APOD: 2000 March 27 -
Flying Over Asteroid Eros
Explanation: What would it look like to
fly over an asteroid? Spacecraft
NEAR Shoemaker in orbit around asteroid 433 Eros found out
earlier this month when it recorded its first fly-over sequence. The saddle region of the
Sun-orbiting space-mountain appears to zip past the camera in this condensed hour-long
time-lapse sequence. The spacecraft was orbiting about 200 kilometers above
the asteroid.
Movies such as this are scientifically useful
for discerning between regions that are naturally dark and regions that have
their brightness dominated by shadows. The week before, a bright X-ray
burst from the Sun allowed NEAR's X-ray spectrometer to detect the presence of
several elements on Eros' surface
by their X-ray fluorescent
signatures.
APOD: 2000 March 16 -
NEAR Shoemaker Views Eros
Explanation: Orbiting asteroid 433
Eros, 145 million miles from Earth, NASA's NEAR spacecraft has been returning
stunning views as its year long mission of exploration gets underway. A mosaic of
recent NEAR images
recorded at a range of about 127 miles, this picture
illustrates some of the amazing contrasts which apparently exist within the
domain of this diminutive world. Features as small as 65 feet are visible here,
while long shadows
emphasize the differences in the cratered regions at the left and smooth groved
terrain at right. Up
close, the undulating surface seems flecked with bright deposits and
peppered with enormous boulders. As NEAR is poised to
investigate mysteries of the formation of asteroids
and the origins of the solar system from this unprecedented vantage
point, NASA has renamed the spacecraft NEAR Shoemaker in honor of
the late Dr. Eugene M.
Shoemaker, legendary geologist, comet hunter, and
inspirational pioneer in the field of interplanetary science.
APOD: 2000 March 8 -
Nearer To Asteroid Eros
Explanation: As the robot spacecraft NEAR lowers
itself toward asteroid 433 Eros, more
surface details are becoming visible. Last week's maneuvers
brought NEAR to within 204
kilometers of the floating mountain's surface. With
increased resolution, NEAR's camera then
documented Eros'
unusual shape, craters large and
small, boulders,
and mysterious grooves similar to asteroid Gaspra and Martian moon Phobos.
If you could stand on Eros,
you would still be too small to be visible on this recent
image, which shows features as small as 20 meters across. However, you would
feel gravity only
1/1000 that on Earth, so that you could easily jump over even this large 5
kilometer wide crater.
APOD: 2000 February 24 -
Stereo Eros
Explanation: Get out your red/blue glasses and
float next to asteroid 433
Eros, 260 million kilometers away! Orbiting the Sun once every 1.8
earth-years, asteroid Eros is
a diminutive 40 x 14 x 14 kilometer world of undulating horizons, craters, boulders and
valleys. Its unsettling scale and bizarre shape are emphasized in this picture - a
mosaic of recent images from the NEAR spacecraft processed to yield a stereo anaglyphic view. Along
with dramatic chiaroscuro,
NEAR's 3-D imaging provides important measurements of the asteroid's landforms
and structures, and hopefully clues to the origin of this
city-sized chunk of solar system. The
smallest features visible here are about 30 meters across.
APOD: 2000 February 21 -
A Giant Gouge on Asteroid Eros
Explanation: Asteroid 433 Eros is
posing several riddles. NASA's robot spacecraft NEAR
began orbiting the 30-kilometer space rock last week, and new pictures are now
being beamed back to Earth regularly. As usual in science, when you arrive at a place you've never been before, you
see things you don't
immediately understand. Scientists are contemplating, for
example, the cause of the above-pictured
giant gouge in the middle of Eros. Intriguing internal features include groves
oriented parallel to the asteroid's
length and the relative paucity of craters. These indicate that the gouge formed
well after the asteroid
itself. One question answered by the shape and density is that, unlike asteroid
253 Mathilde, Eros
is not a pile
of rocks but one big rock. Astronomers are hopeful that data taken over the
coming year might indicate the nature and origin of the baffling bright patches.
APOD: 2000 February 16 -
Eros From Orbit
Explanation: On February 14th, the NEAR spacecraft became the first
artificial moon of an
asteroid. Captured by the gentle gravity of a 20 mile long slipper-shaped
mountain of rock, NEAR recorded this premier
image while orbiting asteroid 433 Eros at a distance of about 200 miles. The
image shows features as small as 100 feet across in a view dominated by a 3 mile
wide crater near Eros' narrow waist. Enticing
layers and grooves are visible within the crater rim along with an enormous 170
foot boulder lying on the crater floor (near picture center). Although Eros is a
large
S-type near-earth asteroid, it is still not massive enough for its own
gravity to have shaped it into a planet-like spherical
form. By
comparison, Eros has less than a thousandth Earth's gravity, so a 100 pound
object on Earth would weigh about 1 ounce on Eros. A baseball thrown at
22 miles per hour would completely escape into space. The weak gravity and
irregular shape make orbiting Eros a delicate challenge for NEAR's controllers who
plan a year long exploration program with possible close approaches to the asteroid's
surface.
APOD: 2000 February 14 -
An Unexpected Asteroid Valentine
Explanation: Maybe the Moon owns our hearts, but this won't
stop the occasional asteroid from sending
us a valentine.
Friday, to the surprise of many, the NEAR mission on approach
to asteroid 433
EROS photographed what appears to be a heart-shaped
depression. After NEAR reaches the asteroid today, NASA plans a series of
maneuvers to make the robot spacecraft the first ever to orbit an asteroid.
More detailed pictures will soon
be taken of the 33 kilometer long asteroid EROS and this 5
kilometer long depression. Most likely, fortuitous lighting and viewing angles
accentuate the apparent heart
shape -- but don't tell the Moon.
APOD: 2000 February 10 -
Eros Encounter Nears
Explanation: After an unanticipated extra
trip around the Sun, the NEAR spacecraft
is now politely
approaching asteroid 433, Eros, at a respectful relative
speed of about 20 miles per hour. Still nearly 2,000 miles distant, NEAR will close to within
approximately 200 miles by February 14th - Valentine's Day. If all goes well,
the spacecraft will then be captured by the gentle attraction of Eros' gravity, becoming the
first artificial moon
of an asteroid. While Eros is not
round it is certainly not
heart-shaped either as seen in this series of frames
showing the roughly 20 x 8 x 8 mile asteroid during its 5.27 hour rotation
period. Different
perspectives clearly show a gouge or saddle and a large impact crater with a
raised rim near
the asteroid's narrow waist. The frames were recorded by the NEAR
spacecraft's multi-spectral
imager on February 4th from a range of 4,600 miles.
APOD: 2000 February 5 -
NEAR to Asteroid Eros
Explanation: On December 23, 1998 the Near Earth Asteroid Rendezvous (NEAR)
spacecraft flew by asteroid 433 Eros. The
robotic spacecraft
was intended to brake and orbit Eros, but an unexpected shutdown
of its main engine caused this plan to be aborted. Now closing with the
asteroid again, NEAR will make another attempt to enter Eros' orbit on February 14th
... Valentine's Day, of course! A successful encounter would make NEAR the first
spacecraft ever to orbit an
asteroid. This image sequence was
taken as NEAR approached Eros in 1998. The rotation of the asteroid
is visible in the successive frames. While cruising through the solar system,
NEAR has also been hunting for gamma-ray
bursts as part of the operational Interplanetary Network.
APOD: December 28, 1998 -
NEAR to Asteroid Eros
Explanation: On December 23, the NEAR spacecraft flew by asteroid 433 Eros. NEAR was
originally scheduled to brake and orbit Eros, but an unexpected shutdown
of its main engine caused this plan to be aborted. NEAR will now be reset
and attempt to return to orbit Eros in early 2000. The above
image sequence
was taken as NEAR approached Eros. The rotation of the asteroid
is visible in the successive frames. When NEAR is fully operational,
it will likely provoke the world's largest
telescopes to point not toward asteroid Eros but to positions indicated by
another of NEAR's instruments: its gamma-ray burst (GRB)
detector. NEAR's distant GRB detector happens
now to be in a unique position to
contribute information crucial to the rapid acquisition of
accurate GRB positions.
APOD: February 4, 1998 -
A Passing Spaceship Views Earth
Explanation: This is how Earth
appeared to the passing spacecraft NEAR. The Near Earth Asteroid
Rendezvous (NEAR) spacecraft was launched from
Florida, USA, planet Earth in 1996. After a quick flyby of asteroid Mathilde in
June last year, NEAR passed the Earth two
weeks ago on its way to asteroid 433 Eros. Visible on the above
representative-color picture is the western part of Earth's Southern
Hemisphere. Prominent features include the white snow-covered Antarctica and
swirling and extended cloud systems. Oceans
appear blue and part of South America is visible on the right.
APOD: January 29, 1998 -
The Earth-Moon System
Explanation: This
evocative mosaic image of the Earth-Moon system was recorded by NASA's Near Earth Asteroid Rendezvous (NEAR)
spacecraft earlier this month. The relative sizes shown are appropriate for
viewing both the
Earth and Moon
from a distance of about 250,000 miles, although the apparent brightness of the
Moon has been increased by about a factor of five for the sake of appearances.
This space-based perspective is a unique one, the bland and somber Lunar Southern
Hemisphere contrasting strongly with blue oceans, swirling clouds, and the
bright icy white continent of Antarctica on planet Earth.
Though its lack of atmosphere and oceans make it relatively dull
looking, the Earth's moon is one of the largest moons in
the solar system - even larger than the planet Pluto. During this recent flyby of the
Earth-Moon system, the NEAR spacecraft used Earth's gravity to deflect it
towards its ultimate destination, the Asteroid 433 Eros.
It is scheduled to arrive at Eros in January 1999.
APOD: January 26, 1998 -
Interplanetary Spaceship Passes Earth
Explanation: Last Thursday
an interplanetary spacecraft flew right past the Earth. The above images show
sunlight momentarily reflected from this spacecraft's solar panels. No aliens
were involved - the Near
Earth Asteroid Rendezvous (NEAR) mission actually originated from Earth.
Launched in 1996, NEAR
zipped past the asteroid 253 Mathilde last
June. This Earth
flyby gravitationally deflects NEAR onto a trajectory passing the asteroid
433 Eros next year. Above, NEAR appears to move through the constellation of Perseus, as clouds created a
changing diffuse white glow. NEAR was only visible for about 2 minutes from San Jose, California, where these
image-intensified video camera observations were taken.
APOD: June 30, 1997 -
NEAR Mathilde
Explanation: Hey Earth, look what I found! On the
way to visiting the asteroid
433 Eros in February 1999, the Near Earth
Asteroid Rendezvous (NEAR) spacecraft flew right by another asteroid: 253
Mathilde last Friday. Shown above is one
picture from the encounter. Mathilde is a large chunk of
rock roughly 60 kilometers across that orbits the Sun between Mars and Jupiter in
the main asteroid
belt. Mathilde's surface is very dark and heavily cratered. The NEAR pictures of
Mathilde received so far indicate that the asteroid has undergone
spectacular collisions, one of which created the huge impact basin in the
center, which is estimated to be about 10 kilometers deep.
APOD: February 15, 1996 -
NEAR to an Asteroid
Explanation: Excitement mounts as NASA's Near Earth Asteroid Rendezvous (NEAR)
spacecraft nears launch
- currently scheduled for 3:53 ET on February 16. NEAR's mission is to
become the first spacecraft to rendezvous with and orbit an
asteroid, the asteroid designated 433 Eros.
After achieving Eros orbit in 1999, project plans are to explore the asteroid
for 1 year from this premiere vantage point, perhaps approaching to within 15
miles of the surface. For comparison, above is an image
of the limb of asteroid
Ida made by the Galileo spacecraft from a distance of about 1,500 miles, the
highest resolution image of an asteroid
surface - so far. It is hoped that NEAR will go far towards answering
questions about the nature and origin of near Earth asteroids. These
objects are thought to contain clues to the formation of the inner planets and
influence the evolution of the atmosphere and life on Earth. Are asteroids and
meteorites related? Do
asteroids ever strike the Earth?