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The
Smithsonian Institution contributes to national aerospace goals through
the activities of the Smithsonian Astrophysical Observatory (SAO) in Cambridge,
Massachusetts, and the National Air and Space Museum (NASM) in Washington,
D.C. SAO conducts a broad program of research in astronomy, astrophysics,
Earth and space sciences, and science education. NASM, in addition to
offering extensive research and education programs, serves as the primary
repository for the archives and artifacts of space exploration and discovery.
Successfully deployed from the Space Shuttle in July 1999, the Chandra
X-ray Observatory has been orbiting Earth and sending back a steady stream
of spectacular x-ray images. Images of objects obtained by Chandra's detectors,
including the High Resolution Camera designed by SAO, are received at
the Operations Control Center operated for NASA by SAO in Cambridge. SAO
is also the site of the Chandra Observatory Science Center, which coordinates
research of the space observatory and receives and archives its data for
the world astronomical community.
By
observing the transits of a suspected planet in front of the star HD209458,
SAO astronomers have taken a giant step toward learning about the nature
of planets outside our solar systemtheir size, mass, and density.
These observations, made initially by a graduate student advisee of an
SAO scientist, marked the first time that astronomers had directly detected
an extrasolar planet, in this case by watching its shadow cross the disk
of a Sun-like star. The precise observations allowed astronomers to determine
that the suspected planet is a "gas giant," with a density somewhat less
than that of Saturn in our own solar system and a size about one-third
greater than Jupiter's.
The
popular image of nascent planetary systems as thin, spinning pancakes
of cosmic dust and debris may be changed by a new computer model that
shows how that disk of debris is transformed into a very distinct ring
once Pluto-like bodies start to form. By analyzing Hubble Space Telescope
images of a suspected young planetary system recently discovered around
the star HR 4796A, SAO scientists and their colleagues produced a computer
model that suggests the ring around that object probably is a common feature
of all planetary systems. Indeed, the well-known Kuiper Belt of asteroids
in our own solar system may even be the residual remains of such a ring.
Launched
from a Pegasus-XL vehicle on December 5, 1998, the SAO-designed Submillimeter
Wave Astronomy Satellite (SWAS) is the first spaceborne observatory to
operate at submillimeter wavelengths and has been giving astronomers new
clues to some old cosmic mysteries, including how starsand their
accompanying planetsare born. For example, SWAS discovered that
large amounts of water seem to pervade the interstellar medium, with particularly
copious amounts in the huge molecular clouds thought to be the incubators
of newborn stars. By contrast, SWAS has so far failed to detect molecular
oxygen in those same interstellar clouds. However, in this case, no news
may be perceived as good news, because the apparent absence of molecular
oxygen, a byproduct of slow chemical "aging processes" in these clouds,
may actually help astronomers to determine their ages.
For
nearly four decades, solar scientists have been puzzled by the fact that
the high-speed portion of the solar wind travels twice as fast as predicted
by theory, with some particles reaching velocities of 2 million miles
per hour as they stream out of the Sun and wash over the entire solar
system. Now, observations made with instruments built by SAO and flown
aboard NASA's Spartan 201 spacecraft and the international Solar and Heliospheric
Observatory (SOHO) have revealed a surprising explanation for this mystery:
magnetic waves propel the particles through the corona like surfboarders
riding the crests of a cosmic sea. The Sun's outermost atmosphere, or
corona, is an extremely tenuous, electrically charged gas that is seen
from Earth only during a total eclipse of the Sun by the Moon, when it
appears as a shimmering white veil surrounding the black lunar disk. Using
ultraviolet coronagraph spectrometers on Spartan and SOHO to create artificial
eclipses, SAO scientists detected rapidly vibrating magnetic fields within
the corona that form magnetic waves that, in turn, seem to accelerate
the solar wind. The electrical charges of the solar wind particles, or
ions, force them to spiral around the invisible magnetic lines. When the
lines vibrate, as they do in a magnetic wave, the spiraling ions are accelerated
out and away from the Sun. Indeed, SAO scientists believe there are magnetic
waves in the corona with many different "wiggling periods," or frequencies.
Thus, these waves can accelerate various solar wind particles at different
rates. For example, SAO researchers found, surprisingly, that the heavier
oxygen ions actually move faster than the lighter hydrogen ions.
On
July 20, 1999, Vice President Al Gore presented the Smithsonian Institution's
Langley Medal to the Apollo 11 astronauts in commemoration of the 30th
anniversary of their lunar landing, at a ceremony in NASM's "Milestones
of Flight" gallery, next to the Apollo 11 command module Columbia and
near the Wright Flyer. Special educational activities related to the Moon
landing and other space explorations were offered to thousands of NASM
visitors on that same day, as well as later during the "Geography from
Space" program given as part of National Geography Awareness Week.
"Reflections
on Earth," supported in part through a donation by the Honda Corporation,
developed a teaching poster distributed to 40,000 middle schools nationwide
in an effort to help students understand the use of space technology in
the study of Earth and its environment. In addition, NASM held a teacher
workshop on forest biodiversity and remote sensing, supported a variety
of field studies, and developed a Web page to disseminate results from
this program.
"Earth
Today: A Digital View of our Dynamic Planet" is the first exhibit to display
near-real-time, global-scale Earth science data sets collected daily by
NASA, NOAA, the U.S. Navy, and the U.S. Geological Survey. The NASM program
includes daily updates to changing global views of Earth's atmosphere,
oceans, and land masses.
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