Дата: 13 марта 1998 (1998-03-13)
От: Alexander Bondugin
Тема: More Evidence Points To Impact As Dinosaur Killer
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Douglas Isbell
Headquarters, Washington, DC March 12, 1998
(Phone: 202/358-1547)
Diane Ainsworth
Jet Propulsion Laboratory, Pasadena, CA
(Phone: 818/354-5011)
RELEASE: 98-42
MORE EVIDENCE POINTS TO IMPACT AS DINOSAUR KILLER
Two new impact crater sites in Belize and Mexico add further
evidence to the hypothesis that an asteroid or comet collided with
Earth about 65 million years ago, subsequently killing off the
dinosaurs and many other species on the planet.
Researchers Adriana Ocampo of NASA's Jet Propulsion
Laboratory (JPL), Pasadena, CA, and Kevin Pope of Geo Eco Arc
Research, La Canada-Flintridge, CA, led an international team that
discovered the two new sites during a recent expedition sponsored
by NASA's Exobiology Program and The Planetary Society, Pasadena, CA.
"We discovered an important new site in Alvaro Obregon,
Mexico, about 140 miles (230 kilometers) from the rim of the
Chicxulub crater. This crater was formed when a 6-to-8-mile
diameter (10-to-14-kilometer diameter) asteroid or comet collided
with Earth," Ocampo said.
"The site contains two layers of material, or ejecta, thrown
out by the impact that flowed across the surface like a thick
fluid, known as fluidized ejecta lobes," added Pope. "This is the
closest surface exposure of ejecta to the Chicxulub crater that
has yet been found and the best example known on Earth from a
really big impact crater."
Centered on the coast of Yucatan, Mexico, the Chicxulub
crater is estimated to be about 120 miles (200 kilometers) in
diameter. The impact 65 million years ago kicked up a global
cloud of dust and sulfur gases that blocked sunlight from
penetrating through the atmosphere and sent Earth into a decade of
near-freezing temperatures. The drop in temperature and related
environmental effects are thought to have brought about the demise
of the dinosaurs and about 75 percent of the other species on Earth.
The Earth orbits the Sun in a swarm of so-called near-Earth
objects, whether they are comets or asteroids, yet the science of
detecting and tracking them is still relatively young. Only a
handful of astronomers around the world search for these objects,
and they estimate that currently only about one-tenth of the
population of near-Earth objects has been detected. Chicxulub is
the only impact event that has been correlated with mass
extinctions to date. The site has been dated geologically to the
boundary between the Cretaceous and Tertiary periods, also known
as the K/T boundary.
Local geologist Brian Holland of Punta Gorda, Belize, guided
the expedition to another new ejecta site about 290 miles (480
kilometers) from the crater rim. This Belize site contains tiny
spheres of altered green glass, called tektites. Tektites are
rocks that have been melted to glass by the severe heat of an
impact. Expedition member Jan Smit of Free University, Amsterdam,
noted that the Belize tektites were similar to those found in
Haiti and northern Mexico. This finding links the stratigraphy of
the Belize sites to the more distant Caribbean and Mexican ejecta sites.
Alfred Fischer of the University of Southern California,
Michael Gibson of the University of Tennessee at Martin, and Jaime
Urrutia and Francisco Vega of the National Autonomous University
of Mexico helped the team collect 900 pounds (400 kilograms) of
samples, including drill cores, for paleomagnetic studies. They
also collected fossils from the site to help date the deposits and
add new pieces to the puzzle of what happened at Chicxulub 65
million years ago.
Impact ejecta is very rare on Earth, but covers much of the
surface of Mars because Mars' surface has remained stable and
unchanged for billions of years, thus preserving debris from these
rare impact events. Also, such fluidized ejecta lobes have never
been observed directly on Earth before and can serve as an
excellent laboratory for studying the ejecta lobes surrounding
many Martian craters.
"The discovery of these new ejecta sites is very exciting,"
said team co-leader Ocampo. "It is like seeing a bit of Mars on Earth."
The exact nature of these ejecta lobes on Mars remains a
mystery, Ocampo noted. Some scientists think they were created by
an abundance of water in the Martian crust, which turned the
ejecta into a muddy, molasses-like material. Others suggest the
fluidized ejecta lobes were enabled by a much thicker atmosphere
in Mars' early history. As flying ejecta from an impact event flew
through the Martian atmosphere, it was reduced by friction to a
very dense, turbulent cloud of debris, which also flowed like
water. Study of the Chicxulub fluidized ejecta may help settle
this debate and shed new light on theories that the Martian
surface may once have been more hospitable for life.
Volunteers who assisted The Planetary Society and the
scientists in the field have posted their photographs of the
expedition on The Planetary Society web site at the following URL:
http://planetary.org
Information about and images of newly discovered near-Earth
objects found by JPL's ongoing Near-Earth Asteroid Tracking (NEAT)
program are available at:
http://huey.jpl.nasa.gov/~spravdo/neat.html
Ocampo and Pope's research was funded in part by the
Exobiology Program of NASA's Office of Space Science, Washington,
DC. NASA's Jet Propulsion Laboratory is a division of the
California Institute of Technology, Pasadena, CA.
-end-
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Дата: 13 марта 1998 (1998-03-13)
От: Alexander Bondugin
Тема: Assembly Of NASA's X-Ray Telescope Completed
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Donald Savage
Headquarters, Washington, DC March 12, 1998
(Phone: 202/358-1547)
Dave Drachlis
Marshall Space Flight Center, Huntsville, AL
(Phone: 205/544-0034)
A. Brooks McKinney
TRW Space and Electronics Group, Redondo Beach, CA
(Phone: 310/814-8177)
RELEASE: 98-43
ASSEMBLY OF NASA'S X-RAY TELESCOPE COMPLETED
Assembly of the world's most powerful X-ray telescope, NASA's
Advanced X-ray Astrophysics Facility, was completed last week with
the installation of its power-generating twin solar panels. AXAF
is scheduled for launch aboard Space Shuttle mission STS-93, in
December 1998.
The last major components of the observatory were bolted and
pinned into place March 4 at TRW Space & Electronics Group in
Redondo Beach, CA, and pre-launch testing of the fully assembled
observatory began March 7.
"Completion of the observatory's assembly process is a big
step forward toward launch scheduled for the end of this year,"
said Fred Wojtalik, manager of the Observatory Projects Office at
NASA's Marshall Space Flight Center, Huntsville, AL. "With all
the major components in place, we are now concentrating on a
thorough pre-launch checkout of the observatory."
"We're delighted to reach this major milestone for the
program," said Craig Staresinich, TRW's Advanced X-ray
Astrophysics Facility program manager. "The entire observatory
team has worked hard to get to this point and will continue an
exhaustive test program to ensure mission success. We're looking
forward to delivering a truly magnificent new space capability to
NASA later this summer."
The first pre-launch test of the Advanced X-ray Astrophysics
Facility was an acoustic test, which simulated the sound pressure
environment inside the Space Shuttle cargo bay during launch. A
thorough electrical checkout before and after the acoustic test
verifies that the observatory and its science instruments can
withstand the extreme sound levels and vibrations that accompany
launch.
"With 10 times the resolution and 50-100 times the
sensitivity of any previous X-ray telescope, this observatory will
provide us with a new perspective of our universe," said the
project's chief scientist, Dr. Martin Weisskopf, of Marshall.
"We'll be able to study sources of X-rays throughout the universe,
like colliding galaxies and black holes, many of which are
invisible to us now. We may even see the processes that create
the elements found here on Earth."
Assembly of the observatory began in 1997 with the arrival of
the high resolution mirror assembly at TRW Space and Electronics
Group. In August 1997, the telescope's optical bench was mated
with the mirrors, followed by integration of the telescope with
the spacecraft in October. In February 1998, the observatory's
science instrument module was mated to the top of the telescope.
The complete observatory is 45 feet long, has a solar array wing
span 64 feet wide, and weighs more than 5 tons.
Using glass purchased from Schott Glaswerke, Mainz, Germany,
the telescope's mirrors were built by Raytheon Optical Systems
Inc., Danbury, CT. The mirrors were coated by Optical Coating
Laboratory Inc., Santa Rosa, CA, and assembled by Eastman-Kodak
Co., Rochester, NY. The observatory's charged coupled device
imaging spectrometer was developed by the Pennsylvania State
University at University Park, and the Massachusetts Institute of
Technology (MIT), at Cambridge. One diffraction grating was
developed by MIT, the other by the Space Research Organization
Netherlands, Utrecht, in collaboration with the Max Planck
Institute, Garching, Germany. The high resolution camera
instrument was built by the Smithsonian Astrophysical Observatory.
Ball Aerospace & Technologies Corporation of Boulder, CO,
developed the science instrument module.
The Advanced X-ray Astrophysics Facility program is managed
by Marshall for the Office of Space Science, NASA Headquarters,
Washington, DC. The Smithsonian Astrophysical Observatory,
Cambridge, MA, will operate the observatory for NASA.
- end -
Hа сегодня все, пока!
=SANA=
Дата: 13 марта 1998 (1998-03-13)
От: Alexander Bondugin
Тема: X-38 Atmospheric Vehicle Completes First Unpiloted Flight Test
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Michael Braukus
Headquarters, Washington, DC March 12, 1998
(Phone: 202/358-1979)
James Hartsfield
Johnson Space Center, Houston, TX
(Phone: 281/483-5111)
Fred Brown
Dryden Flight Research Center, Edwards, CA
(Phone: 805/258-2663)
RELEASE: 98-44
X-38 ATMOSPHERIC VEHICLE COMPLETES FIRST UNPILOTED FLIGHT TEST
Development of the X-38, an innovative new spacecraft
design planned for use as a future International Space Station
emergency crew return "lifeboat," passed a major milestone
today with a successful first unpiloted flight test.
The first X-38 atmospheric test vehicle was dropped from
under the wing of NASA's B-52 aircraft at the Dryden Flight
Research Center, Edwards, CA, at 11:30 a.m. EST and completed a
descent from a 23,000 foot altitude at 11:38 a.m. EST. The
test focused on the use of the X-38's parafoil parachute, which
deployed as planned within seconds after the vehicle's release
from the B-52 and guided the test craft to landing.
"This was a real experimental flight test and the
culmination of two years of hard work by a team from the
Johnson Space Center and the Dryden Flight Research Center," X-
38 project manager John Muratore said. "We had done everything
we could to minimize the unknowns. But the real proof of the
concept is a successful flight. We got one of those today, and
we plan to do this about 20 more times over the next two years
to prove we're ready to fly from space."
Atmospheric drop tests of the X-38 will continue for the
next two years using three increasingly complex test vehicles.
The drop tests will increase in altitude to a height of 50,000
feet and include longer flight times for the test craft prior
to deployment of the parafoil. In 2000, an unpiloted space test
vehicle is planned to be deployed from a Space Shuttle and
descend to a landing. The X-38 crew return vehicle is targeted
to begin operations aboard the International Space Station in 2003.
"With Johnson and Dryden employees working as a team, we
were able to design, outfit and test the vehicle," said Bob
Baron, Dryden X-38 project manager. "Using existing NASA
infrastructure, such as the Johnson and Dryden control rooms
and the B-52 mothership, has provided considerable cost and
schedule savings in the development of this prototype X-38 vehicle."
Once operational, the X-38 will become the first new human
spacecraft designed to return humans from orbit in more than 20
years, and it is being developed at a fraction of the cost of
past human space vehicles. The primary application of the new
spacecraft would be as an International Space Station
"lifeboat," but the project also aims at developing a design
that could be easily modified for other uses, such as a
possible joint U.S. and international human spacecraft that
could be launched on expendable rockets as well as the Space
Shuttle. The European Space Agency is cooperating with NASA in
the current development work, supplying several components for
the planned space test vehicle.
The X-38 is being developed with an unprecedented eye
toward efficiency, taking advantage of available equipment and
already-developed technology for as much as 80 percent of the
spacecraft's design. The design uses a lifting body concept
originally developed by the Air Force X-24A project in the mid-
1970s. Following the jettison of a deorbit engine module, the
X-38 would glide from orbit unpowered like the Space Shuttle
and then use the steerable parafoil parachute for its final
descent to landing.
In the early years of the International Space Station, a
Russian Soyuz spacecraft will be attached to the station as a
crew return vehicle. But, as the size of the station crew
increases, a return vehicle like the X-38, that can accommodate
up to seven passengers, will be needed.
-end-
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