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发信人: bage (网事如疯·春心萌动), 信区: AerospaceScience
标  题: SpaceViews -- 2000 June 5(转载)
发信站: 哈工大紫丁香 (2000年12月23日17:51:37 星期六), 转信

【以下文字转载自 bage 的信箱】
【原文由 hitsma@0451.com 所发表】
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                          S P A C E V I E W S
                             Issue 2000.23
                              2000 June 5
                  http://www.spaceviews.com/2000/0605/

*** News ***
         Compton Mission Ends with Safe Reentry
         Compton Leaves a Huge Scientific Legacy
         NASA Enters Multimedia Partnership with Private Company
         Dreamtime May Face Stiff Competition
         NASA: Service Module Depressurization Could Cause Loss of ISS
         More Sharp Mercury Images Released
         Eros May Be a Relic of Early Solar System
         Io More Volcanic Than Once Thought
         Scientists Find the Energy Source for Aurorae
         SpaceViews Event Horizon
         Other News

*** Cyberspace ***
         The Astronomy Workshop
         Failure Is Not An Option
         Brad Gould's Space Links
         Astronautics, Spacecraft Design, and Spacecraft Systems

[Editor's Note: we're publishing this issue a little earlier than
normal because of the editor's travel schedule.  We'll resume our
usual publishing schedule next week.]

                              *** News ***

                 Compton Mission Ends with Safe Reentry

NASA's Compton Gamma Ray Observatory ended its nine-year
mission early Sunday with a successful reentry over the eastern
Pacific Ocean.

NASA engineers fired Compton's thrusters twice in the early
morning hours Sunday, pushing Compton's orbit down into the
atmosphere, where it burned up and scattered debris over a long,
narrow track in an isolated portion of the Pacific southeast of
Hawaii.

Compton fired its thrusters at 12:07 am EDT (0407 UT) for 21
and a half minutes early Sunday in a maneuver that lowered the perigee
of Compton's orbit to 150 km (93 mi.)  That maneuver was followed by a
second, half-hour thruster burn at 1:22 am EDT (0522 UT) that pushed
Compton on its final, fatal trajectory.

The last communications between ground controllers and Compton
took place at about 2:08 am EDT (0608 UT) as the spacecraft hit the
Earth's atmosphere.  The debris from Compton impacted the ocean
approximately ten minutes later, at 2:18 am EDT (0618 UT), according
to tracking data from NORAD.

"We have certainly met our commitment to the science
community, as Compton exceeded our expectations with a nine-year
mission," said Ed Weiler, NASA associate administrator for space
science, at a post-reentry press conference Sunday morning.  "And a
few hours ago, NASA met its commitment to the billions of humans who
live under the Compton orbital path by safely reentering Compton into
the Pacific Ocean."

While officials said that Compton's debris did splashdown
about 3,880 km (2,400 mi.) southeast of Hawaii, in the middle of a
4,100-km (2,540-mi.) predicted track, the exact impact area won't be
known for a couple of days.  "In terms of the exact area, length and
width, of the debris field, right now we can only go with what we
predicted originally," said Tom Quinn, Compton reentry coordinator.

The successful reentry was met with mixed emotions by NASA
officials: a sense of satisfaction and pride that they were able to
bring down Compton as planned, along with sadness about the end of the
mission -- a premature end, some scientists believe.

"This was a bittersweet day for NASA," said Al Diaz, director
of NASA's Goddard Space Flight Center.  "The end of the Compton Gamma
Ray Observatory mission marks the end of a remarkable spacecraft. And
while no one at NASA is ever happy to see the end of a science
mission, prolonging this mission would have posed an unacceptable and
increasing risk to human life."

"The team has done a great job in a very short period of time
and they should all be proud of what they have achieved today," said
Mansoor Ahmed, Compton reentry manager.

NASA decided in March to bring down Compton after one of its
three gyroscopes failed last December.  The agency was concerned that
another gyro failure would lead to an uncontrolled reentry that could
shower up to six tons of debris over populated areas.

After an engineering test burn Sunday night, May 28, the first
in a series of four deorbit burns was conducted Tuesday, May 30 at
9:51 pm EDT (0151 UT).  The 23-minute burn lowered Compton's perigee
from 510 to 364 km (315 to 225 mi.)

The second burn was conducted the following night, on
Wednesday, May 31, at 10:36 pm EDT (0236 UT).  The 26-minute burn
lowered the perigee of Compton's orbit to 250 km (155 mi.).  After
that burn mission managers moved up the times of the final two burns
one orbit to account for a westward shift in Compton's orbit.

While engineers and managers expressed their satisfaction with
the successful reentry, scientists expressed their sadness with the
end of the mission which, despite lasting for nine years, four years
longer than originally planned, was continuing to provide useful data.

"This is a sad time," said Compton project scientist Neil
Gehrels during commentary of the reentry carried on NASA television,
moments before contact was lost with the spacecraft for good.

Those who had actively fought to keep Compton in orbit,
arguing that alternative measures would allow for a safe reentry even
if all gyros failed, were sharply critical of NASA's reentry plans.
"We -- me and many scientists -- view this as a dark day for space
science," said Jim Ryan, a coinvestigator on one of Compton's
instruments.

"This is an unfortunate end to an enormously successful
mission -- a mission that revolutionized the nascent field of gamma-
ray astronomy," said Ryan.

                Compton Leaves a Huge Scientific Legacy

When the Compton Gamma Ray Observatory spacecraft reentered
the Earth's atmosphere early Sunday morning, it ended a nine-year
mission that provided scientists with their best look yet at some of
the most energetic processes in the universe.

Compton, the second in NASA's series of Great Observatories
spacecraft that includes Hubble and the Chandra X-Ray Observatory,
generated a wealth of data that has given astrophysicists new insights
into everything from the Sun to distant, powerful gamma-ray bursts.

"Compton left a legacy of outstanding science and
revolutionized our knowledge of the gamma-ray sky," said Al Diaz,
director of NASA's Goddard Space Flight Center, said early Sunday.

"New discoveries made by Compton changed our view of the
universe in fundamental ways," said Alan Bunner, head of NASA's
"Structure and Evolution of the Universe" science program, back in
March.

One of the key discoveries made by Compton dealt with the
source of mysterious, powerful gamma-ray bursts (GRBs), brief, intense
emissions of gamma rays from a localized source.  While some
scientists believed that GRBs originated within our own galaxy,
Compton data showed that the distribution of GRBs was isotropic, or
evenly spread across the sky.  Thus, astronomers now think GRBs come
from outside our galaxy, and thus must be even more powerful than
originally believed.

Compton also discovered "blazars", a class of quasars with
jets of gamma rays aimed directly at the Earth, and found evidence for
antimatter in the center of our own galaxy.

Just this March, scientists pouring over data from Compton
found that about half of the 170 unidentified gamma-ray sources
discovered by Compton were located in the Gould Belt, an expanding
region of gas about 2,000 light-years across and relatively near the
Earth that is thought to be the remnant of a supernova explosion tens
of millions of years ago.

"These are objects we've never seen before," Neil Gehrels,
project scientist for Compton, said at the time the Gould Belt
findings were published in the journal Nature. "We can't make out what
they are yet, but we know they're strange and, boy, there's a lot of
them."

Because of these steady stream of discoveries, scientists had
hoped to keep Compton operating well into this decade before a gyro
failure last December led NASA to terminate this mission.  That
decision was greeted with disappointment, and even protest, in the
scientific community.

"This is an unfortunate end to an enormously successful
mission -- a mission that revolutionized the nascent field of gamma-
ray astronomy," said Jim Ryan, a physics professor at the University
of New Hampshire and one of the coinvestigators on COMPTEL, one of
Compton's four instruments.

Had Compton remained in orbit, scientists would have used it
in part to study the Sun as it passed through the peak of its 11-year
activity cycle this year and next.  Studying gamma-ray emissions from
solar storms was one of the primary goals of the Compton mission.

The loss of Compton will now deprive astronomers from high-
quality gamma-ray observations for the near term, although a flotilla
of upcoming missions will help fill the gap later this decade.

The first of those missions will come in April 2002, when the
European Space Agency launches Integral, a gamma-ray observatory based
on the XMM-Newton x-ray observatory launched last December.  Integral
will include a gamma-ray imager and spectrometer, as well as X-ray and
visible-light camera to help identify gamma-ray sources.

In 2003 NASA will launch Swift, a small mission devoted to
studying GRBs.  Swift will be able to identify a gamma-ray burst and
determine its position to an accuracy of 1-4 arcminutes (1/15th to
1/60th of a degree) within 15 seconds, enabling other instruments on
the spacecraft, as well as other ground- and space-based instruments,
to quickly observe the burst before it fades from view.

Swift will be followed in 2005 by the Gamma-Ray Large Area
Space Telescope (GLAST).  GLAST promises to be 30 times more sensitive
to gamma rays than corresponding instruments on Compton, and observe
ten times as many active galactic nuclei and black holes than
previously seen.  Instruments for GLAST were selected by NASA earlier
this year.

However, until 2002 gamma-ray astronomers will be without a
key instrument for studying these exotic, energetic objects, a topic
of considerable disappointment for astronomers.

"Compton opened up a whole new window to the universe," said
Ryan, "from powerful explosions taking place on the Sun, to
understanding the radioactive materials in our galaxy to explosions of
incomprehensible magnitude taking place in distant galaxies."

"It is difficult to capture in a few words the extent of
knowledge that Compton brought to us," he added,  "and it is
unfortunate that it ends so prematurely, with so much new science
unstudied."

        NASA Enters Multimedia Partnership with Private Company

NASA and a Silicon Valley startup company have joined forces
to provide "the very best in multimedia" from NASA's past and future
missions under an unprecedented partnership announced Friday.

The partnership between NASA and Dreamtime Holdings, Inc. will
result in everything from an online archive of existing NASA photos
and videos to high-definition television (HDTV) broadcasts from the
shuttle and International Space Station.

Although details about the agreement had been leaked earlier
in the week, the partnership was officially unveiled Friday at a press
conference at NASA's Ames Research Center in Silicon Valley, a 90-
minute presentation that featured everyone from two astronauts to a
member of Congress to an Oscar-winning director.

"We are going to have the very best in multimedia," said NASA
administrator Dan Goldin.  "We are going to touch every heart and
every soul."

Initially, Dreamtime will digitize NASA's extensive archives
of photos, videos, blueprints, and other materials dating back to the
early days of NASA's predecessor, the National Advisory Committee for
Aeronautics (NACA).  These materials will be made available through a
web portal site the company expects to have up and running in six
months.

Later, Dreamtime will provide NASA with HDTV cameras for use
on shuttle missions and the International Space Station.  NASA will be
able to use the imagery from these camera to monitor experiments and
check the spacecraft for any problems, while Dreamtime will be able to
sell the footage commercially.

No money changes hands between NASA and Dreamtime under this
partnership: the company will digitize NASA's archives and provide the
space agency with the HDTV cameras, an investment of $100 million;
NASA will fly the cameras and provide some technical support.
However, officials from both organizations said the two would share in
any "upside" -- profit -- generated by Dreamtime, which NASA would
reinvest to support future commercial ventures.  The nonexclusive
agreement lasts for seven years with a five-year option.

Dreamtime plans to make money in three lines of business.  The
first will be selling "professional resolution" versions of NASA
photos and videos from its archives.  The second will be through its
portal site, which will include not only multimedia but educational
features, news, and interactive features.  A third line of business
will the production of documentaries and television content, using the
company's HDTV cameras.

NASA and Dreamtime officials emphasized that NASA will
continue to offer as least as many photos and videos for free as it
has in the past, and that the partnership will make even more
materials available.  "The public will get more than it ever got
before for free," said Peggy Wilhide, NASA associate administrator for
public affairs.

Much of the focus of the press conference was not on the
economics of the agreement but on its wide ranging impact: a "win-win-
win-win situation", said Joe Rothenberg, NASA associate administrator
for space flight, referring to NASA, researchers, Dreamtime, and the
taxpayers.

Researchers will benefit from having HDTV cameras on ISS and
shuttle missions to allow them to better monitor experiments, giving
them a "virtual presence" on missions not possible today, said
Rothenberg.  The HDTV cameras will also be able to monitor the
exterior of ISS, looking at possible problems and helping NASA
determine if a repair spacewalk is in order.

Those same camera also have commercial applications that have
excited companies and individuals.  "The next step will be to get a
director up there and really tell the story," said director Jim
Cameron, who phoned in to the press conference.  Cameron, who is
working on a number of Mars-related film projects, half-jokingly
volunteered to be that director on ISS.

Dreamtime executives stressed the educational aspects of the
partnership.  "To us, space is the great adventure, and this is the
perfect marriage of high tech and high emotion," said Bill Foster,
chairman and CEO of Dreamtime.  "The opportunity to educate and excite
is at the heart of this venture."

Dreamtime was founded by Foster and Carleton Ruthling, both
formerly of Excite@Home, a broadband Internet access provider and web
portal company.  Excite@Home is one of the backers of Dreamtime, along
with Lockheed Martin, Sumitomo Bank, marketing firm Omnicom, and
Hollywood talent agency Endeavor.

The partnership was made under a provision of the Commercial
Space Act of 1998 that allows the space agency to make commercial
partnerships with private companies.  NASA solicited offers for a
multimedia collaboration late last year, and selected Dreamtime from a
dozen offers submitted.

"I would have been happy if they just painted the [shuttle's]
external tank into a Coke bottle," quipped Rep. Dana Rohrabacher (R-
CA), chairman of the space subcommittee of the House Science Committee
and a leading proponent of the Commercial Space Act.  As the country
moves into space, he said, "it is fitting America should do so at a
profit."

Goldin sees Dreamtime as a first step to get NASA back on the
path towards exploration, including a return to the Moon and missions
to Mars.  "NASA has been locked into Earth orbit since the 1960s," he
said, "and the only way to break out is to turn it over to
entrepreneurs."

"Houston," said Foster, "we have an opportunity here."

                  Dreamtime May Face Stiff Competition

Despite its partnership with NASA, startup company Dreamtime
may find itself in a pitched battle with several other companies to
market images and other multimedia products from space.

The Silicon Valley-based startup announced Friday it had
entered into a partnership with NASA to provide high-quality
multimedia products from both NASA's archives and future shuttle and
International Space Station missions.  Although no money changes hands
between Dreamtime and NASA under the Commercial Space Act agreement,
both will share in the profits from the venture.

However, the agreement between NASA and Dreamtime is not
exclusive; NASA has the right to sign contracts with other companies
to provide additional multimedia services if it so desires.
"Entrepreneurs don't want exclusivity, they want openness," claimed
NASa administrator Dan Goldin.

Even if NASA sticks with Dreamtime, though, there are a number
of competitors in the wings who promise similar services.  Dreamtime's
closest competitor will likely be existing aerospace company SPACEHAB,
which announced plans last December to partner with a Russian company
to build a module for ISS.

The Enterprise module, as it will be called, will serve in
part as a broadcast studio in orbit.  "Among our new businesses will
be the first independent commercial television and Internet Web site
broadcasts from space," said SPACEHAB chairman Shelley Harrison last
December.

The module, which replaces the Docking and Stowage Module
planned for the Russian section of the station, will be built by
Russian company Energia at a cost of $100 million, which will be split
by the two companies.  An firm date for the module's launch has not
been set, although in the current space station assembly plan the
Docking and Stowage Module is scheduled for launch in 2004.

In April SPACEHAB created a wholly-owned subsidiary, Space
Media Inc., which will create content from the Enterprise module for
broadcast and Internet uses under an exclusive contract.  In addition,
SPACEHAB said it has obtained exclusive rights to the archives of the
Russian and former Soviet space programs, although later reports made
it unclear whether SPACEHAB had those rights or was still in
negotiation to obtain them.

"We have all dreamed about 'someday' when we would finally be
able to routinely access and share the adventure and excitement of
space exploration," said John Getter, an Emmy-award winning journalist
and senior vice president of Space Media, in April.  "Well, 憇omeday�
is today."

Competition also comes from outside ISS.  MirCorp, the Western
firm that is leasing the Mir space station from Energia, has said in
the past it intends to create an Internet portal site on Mir in the
near future, but has been sketchy on additional details.

That portal site would carry "data content" as well as live
images of the Earth, MirCorp investor Chirinjeev Kathuria said in
April.  Kathuria believes that the site could prove extremely valuable
to the company: "We have built successful Internet companies in Europe
and Japan that have valuations in the billions of dollars, and we feel
our first ever Internet space portal on Mir will have a high value as
well."

Several other companies are also looking at the multimedia
possibilities of commercial missions to the Moon.  LunaCorp, a company
developing plans for rover missions on the Moon for the better part of
a decade, is expected to announce later this month a substantial
investment from a major company.

LunaCorp's IceBreaker mission would set a rover down near the
lunar poles to look for evidence of water ice.  When not being used
for scientific work, users on Earth will be able to control the rovers
or experience a simulation of the rover's journey through the 360-
degree video returned by the rover.

Two other companies, Applied Space Resources and TransOrbital,
plan to provide high-resolution photos and videos from their planned
orbiter and lander missions to the Moon in the next several years.

     NASA: Service Module Depressurization Could Cause Loss of ISS

The International Space Station could be lost if its Russian-
built service module loses pressure during the first 18 months after
launch, NASA documents released last week revealed.

A NASA "ISS Safety Noncompliance Report" and accompanying
change request, dated May 18, say that if the station's Zvezda service
module depressurizes, key equipment in the module could fail that
could lead to the loss of the station.  The documents were published
on the independent NASA Watch web site June 1.

"Critical Functions necessary for maintaining the station on-
orbit are not verifiable after a depressurization prior to ISS Flight
8A," the documents note.  "As a result, depressurization of the SM
[service module] may result in loss of station."

The problem deals with the ability of the equipment inside
Zvezda to work after a loss of atmosphere.  "Much of the equipment
necessary for maintaining ISS on-orbit, in the SM, is air-cooled
and/or not vacuum-compatible, and will therefor eventually fail after
a depressurization," the safety noncompliance report noted.  Those
critical functions include attitude control, reboost, communications,
and power.

Backup American systems will be installed on the station that
would handle most of these problems, but they are not scheduled to be
launched until ISS assembly flight 8A, a shuttle mission currently
scheduled for launch in January 2002.

Zvezda, meanwhile, is still on track for a launch between July
8-14, a NASA status report issued Thursday noted.  An exact launch
date for ISS assembly flight 1R, as it is officially known, will be
determined at a general designer's review in Moscow June 22-23.

The NASA report downplayed the dangers of a depressurization
incident in the service module.  "Based on the information in this NCR
[noncompliance report], the risk of having a depressurization in the
1R-8A timeframe is low probability," the report stated.

Moreover, the report said that Russian officials have noted
"limited uncertified capabilities" that would permit the survival and
rescue of the station in the event of a depressurization incident.

If NASA decided that Zvezda needed be in full compliance in
safety regulations, the NASA report said that a "major redesign" of
the station would be necessary, delaying its launch one to two years.
Because of these factors, the NASA change request recommended that the
agency "accept risk and approve NCR."

Not clear from the reports is why this issue with the service
module's capabilities became an issue so close to launch.  Russian
flight hardware has generally been designed to operate in a
pressurized environment throughout the history of the Russian and
Soviet space programs.

                   More Sharp Mercury Images Released

Images of a previously-unseen region of the planet Mercury
released last month by Boston University astronomers may not be the
first nor the best look at the planet, SpaceViews has learned.

In the same issue of the Astronomical Journal that published
groundbased images of Mercury that showed a region of the planet never
before seen, another group, using the same data, published images
which they argue are even better.

The other group, led by Ron Dantowitz of the Museum of Science
in Boston, took data simultaneously with the Boston University (BU)
group, using the 1.5-meter (60-inch) telescope atop Mount Wilson,
California, in late August 1998.

However, Dantowitz and colleagues used a subtly different set
of procedures that resulted in what he believes to be a higher
resolution image of Mercury.  Dantowitz recorded his data onto
broadcast-quality video tape, rather than storing them digitally as
the BU did.  "Analog is sometimes better than digital," Dantowitz
said.

Both groups used a technique that selects the sharpest handful
of images from more than 200,000 taken during the course of the 90-
minute observation.  However, Dantowitz said he selected his images by
eye, manually finding the best views of the planet, rather than
relying on a computer algorithm, as the BU team did.

The result is an image that appears similar to the BU team's
image, particularly with large-scale features such as a large, dark
basin in the planet's northern hemisphere.  However, Dantowitz's image
does appear to show more details at smaller resolutions, and has a
more realistic terminator -- the shadow line between day and night --
than the BU image.

Another advantage of the Museum of Science's technique is its
low cost.  Dantowitz said the whole system for taking the Mercury
images cost less than $400.  By comparison, he claims BU spent more
than $10,000 for their system.

The Boston University astronomers who were originally
publicized last week for their Mercury images were unavailable for
comment because of a conference.

Dantowitz developed the technique in recent years using a
smaller telescope at the museum.  That smaller system has been able to
resolve in considerable the detail the space shuttle in orbit as it
made daytime passes over the museum, among other objects.

While both groups collected their data at the same time and
both were published in the same issue of the same journal, Dantowitz
can claim to be the first to generate the high-resolution images of
Mercury: he submitted his paper to the Astronomical Journal last June,
while the BU group did not submit theirs until just after the first of
this year.

Dantowitz said that -- if he can find new funding -- he would
like to take additional high-resolution images of Mercury at different
wavelengths.  This would allow the creation of a mineralogical map of
the planet that would show scientists the composition of the planet's
surface.

Dantowitz and the museum also plan to develop this imaging
system into a low-cost instrument that would allow schools, museums,
and other institutions to do cutting-edge science on a budget.

               Eros May Be a Relic of Early Solar System

New data from NASA's NEAR Shoemaker mission shows that the
near-Earth asteroid Eros may be a relic left over from the formation
of the solar system, planetary scientists announced Tuesday.

Scientists used data from NEAR Shoemaker's X-ray/Gamma-ray
Spectrometer (XGRS) to study the composition of a region of the
surface of the asteroid.  The instrument recorded x-rays emitted by
the surface in the wake of a solar flare on May 4 that bombarded the
asteroid with x-rays.

The XGRS data revealed that this particular region of the
surface contained silicon, magnesium, and aluminum in the same ratios
as seen in the Sun and in a class of meteorites known as chondrites:
evidence, scientists say, that Eros is very old and has not been
subjected to heating or other processes that would cause these
elements to differentiate from the rest of the elements that make up
the asteroid.

"In Eros we are seeing the ratios of silicon, magnesium and
aluminum -- produced from the cloud of gas from which planets
condensed -- all basically preserved as they were in the solar nebula,
and nothing much has happened since the changes," said Cornell
University's Steven Squyres, one of the members of the XGRS science
team.  "So we are seeing into the very distant past here."

The results could be a key step in linking a common class of
asteroids with a common variety of meteorites.  Eros is a member of
the S-class of asteroids, the most common type.  Squyres believes the
NEAR Shoemaker data could be "a key piece of information suggesting
that many other S asteroids also might show this primitive
characteristic."

Thus, S-type asteroids could be the parent body for chondrite
meteorites, the most common meteorites found on Earth, although past
spectroscopic studies of both the asteroids and meteorites have not
conclusively linked the two.

"If our future observations confirm this data, we can go to
our meteorites and find those with the exact same elemental ratios,"
said Squyres.  "It vastly narrows down the range of possibilities of
what meteorites could be representative of."

Planetary scientists caution, though, that the data comes from
a region only 6 kilometers (3.7 mi.) across, and thus may not be
representative of the asteroid as a whole, or of other asteroids.

"It's possible that other areas on Eros were exposed to some
melting and differentiation, or that the surface composition has been
altered by the constant hail of micrometeorites in space," said Jacob
Trombka, head of the XGRS instrument team at NASA's Goddard Space
Flight Center. "As we get closer and take more data, we will gradually
unveil Eros' character."

"One should extrapolate from Eros to the rest of the S
asteroids with great caution," added Squyres.

If the data is confirmed, it could greatly aid scientists in
their understanding of how the solar system formed 4.5 billion years
ago.  "If more data confirm Eros is primordial, Eros will be a link
between the chondrite meteorites found on Earth and the history of the
solar system's formation," said Tim McCoy, a scientist with the
Smithsonian Institution's National Museum of Natural History.  "With
Eros, we could be looking at the structure of the solar system during
a time no longer recorded on Earth."

That data should come later this summer, as XGRS and other
instruments on the NEAR Shoemaker spacecraft collect data from its
current orbit 50 km (31 mi.) above the asteroid's surface.  Starting
July 7 the spacecraft will move even closer -- 35 km (22 mi.) --
giving scientists even better data as the map the composition of the
asteroid's surface.

If the link between Eros and chondrite meteorites is
confirmed, scientists may not need to look far for samples of the
asteroid.  "It will be like holding a piece of Eros in our hands," he
said of the chondrites on Earth. "In fact, we may be holding a piece
of Eros."

                   Io More Volcanic Than Once Thought

The latest images from NASA's Galileo spacecraft show that the
Jovian moon Io may have many more volcanoes than once believed,
planetary scientists reported last week.

Images from Galileo's February 22 flyby of Io, its third and
closest flyby yet of the volcanic inner large moon of Jupiter, has
revealed an abundance of volcanoes and caught some of those volcanoes
in the act of erupting.  The images were released Wednesday during the
spring meeting of the American Geophysical Union in Washington, DC.

Galileo images of a region of the moon's surface about the
size of Texas -- five percent of the total surface of Io -- revealed
the existence of 14 volcanoes.  That region was previously believed to
have only four volcanoes.

By extrapolation, scientists believe that Io may have many
more than 81 volcanoes currently known to exist.  "Since the
distribution of active volcanoes on Io appears to be uniform, we can
expect Io to have some 300 active volcanoes, most of which have not
been discovered," said Rosaly Lopes-Gautier of JPL.

Comparison of the February images with data from the previous
two flybys in October and November of last year show volcanoes of
different sizes appear to behave differently.  Small volcanoes turn on
and off over the course of a few weeks, while larger volcanoes may
remain active for years or even decades at a time.

The February flyby took place as one of Io's large volcanoes,
Loki, was completing one of its periodic major eruptions that began
during the first flybys.  The images from the flybys show major
changes in the appearance of the volcano's caldera.

"Most of the surface of its caldera, a region of more than
10,000 square kilometers (about 4,000 square miles) or half the size
of Massachusetts, seems to have been covered by hot lava in the
intervening four and a half months," said John Spencer of Lowell
Observatory.

Images of another volcanic caldera, Chaac Patera, showed walls
that are 2.8 km (1.7 mi.) high with an incredibly steep slope of 70
degrees.  "The wall rocks must be very strong to support this
topography," said Alfred McEwen of the University of Arizona.

One of the reasons scientists have shown an interest in Io is
to understand what is involved with large-scale volcanic processes,
with an eye towards how they might apply to the Earth's past, when it
was more volcanic.  However, scientists acknowledge that some of the
unusual features they see on Io may not be applicable to any other
world in the solar system.

"There are processes on Io for which we have no terrestrial
experience," said McEwen. "Strange new observations like these will
provide fodder to current and future scientists for understanding the
processes that have shaped this fascinating world."

             Scientists Find the Energy Source for Aurorae

Connections between the magnetic fields of the Earth and Sun
permit the energy that powers aurorae and other "space weather"
disturbances to reach the Earth, scientists reported Thursday.

Speaking at a meeting of the American Geophysical Union in
Washington, scientists said that such "magnetic reconnections" create
gaps in the Earth's magnetic field that allow energy from the solar
wind to flow into the space around the Earth, answering a 50-year
debate about how solar energy generated space weather.

"Reconnection is the fundamental process for transferring and
exchanging energy in the Sun-Earth system," said Japanese researcher
Atsuhiro Nishida.

During magnetic reconnection, fields moving in opposite
directions -- and thus with opposite polarities -- break and connect
with each other.  When this happens between the Earth's and Sun's
magnetic fields, it creates "tears" in the Earth's magnetosphere.
Although these tears can sometimes be as small as one kilometer (0.62
miles) long, they are large enough to allow the solar wind to flow
through into the space around the Earth.

"The magnetosphere acts like a great magnetic cocoon around
the Earth," said Jack Scudder of the University of Iowa, principal
investigator on an instrument on NASA's Polar spacecraft that observed
the reconnection events.  "There are often times when the solar wind
creates tears in this cocoon, allowing charged particles and energy
from the Sun to enter the space around Earth. This tearing --
reconnection -- is what we directly observed with Polar."

Such reconnection events appear to be critical to powering
space weather events such as aurorae that create brilliant light shows
in the Earth's atmosphere and can disrupt electronics on orbiting
satellites.

"Reconnection on the day side of Earth is critical for
allowing solar wind energy to come into the magnetosphere," said
Nishida.  "Night-side reconnection is critical for the transfer of
that energy down to the atmosphere."

"When the solar wind and magnetospheric fields reconnect, it
opens a valve or faucet that lets the solar wind energy cross the
magnetopause and pour into the magnetosphere," said Jeffrey Hughes of
Boston University. "Without reconnection, the magnetosphere would be a
very benign place."

A common misconception is that the solar wind provides the
electrically-charged particles that generate space weather phenomena.
Instead, scientists say, the energy from the solar wind excites
existing particles trapped within the Earth's magnetic fields.

Scientists are still struggling to understand why the
reconnection events take place.  "The $64 question is what makes the
tears possible," said Scudder.  "We'd like to see some more of them to
know whether those already detected represent a general or an unusual
picture of the switch."

These results were made through the International Solar-
Terrestrial Physics (ISTP) program, a joint effort involving NASA,
ESA, the Japanese space agency ISAS, and others, using spacecraft from
the three space agencies.

The newest spacecraft for the ISTP program, the Imager for
Magnetopause to Aurora Global Exploration (IMAGE), has returned its
first images, including the first-ever images of the cloud of
electrified gas surrounding the Earth, scientists reported at the
meeting.

IMAGE, launched in March, is designed to monitor the effects
of space weather on the Earth's atmosphere and magnetosphere.  "IMAGE
is the first weather satellite for space storms," said James Burch,
principal investigator for IMAGE.  "This revolutionary spacecraft
makes these invisible storms visible."

And while spacecraft operators might dread an active period of
solar activity, scientist are looking forward to the new data from
IMAGE and other space science missions.  "We eagerly anticipate the
arrival of severe solar weather associated with solar maximum," said
Burch.

                        SpaceViews Event Horizon

June 5          Proton launch of the Gorizont 45 communications
                  satellite and Breeze-M upper stage from Baikonur,
                  Kazakhstan at 10:59 pm EDT (0259 UT June 6)

June 6          Pegasus XL launch of the TSX-5 military experimental
                  satellite off the coast from Vandenberg Air Force
                  Base, California at 8:57 am EDT (1257 UT)

June 10         Silicon Valley Space Enterprise Symposium,
                  San Jose, CA

June 21         Delta 2 launch of the GPS 2R-5 satellite from Cape
                  Canaveral, Florida at 6:59 am EDT (1059 UT)

June 22         Proton launch of the Express 3A communications
                  satellite from Baikonur, Kazakhstan

June 26         "Going Public 2000" space tourism symposium,
                  Washington DC

                               Other News

Taking Pluto's Temperature:  European astronomers have for the first
time measured variations in the temperature of Pluto's surface,
matching up those variations with changes in the distant planet's
brightness, the European Space Agency said Monday.  Using data from
the now-defunct Infrared Space Observatory, astronomers found that
regions of the planet's surface varied in temperature between 35 and
65 kelvins (-238 to -208 degrees Celsius, -396 to -342 degrees
Fahrenheit.)  The warmest regions roughly correspond with the darkest
regions of the planet, and the coldest line up with the brightest, as
expected.

SETI Telescope Repairs:  The Planetary Society said last month it has
raised enough funds to begin repairs of a Massachusetts radio
telescope used in the search for extraterrestrial intelligence (SETI).
Work will begin soon on the 26-meter (84-foot) Oak Ridge antenna west
of Boston that was damaged during a freak windstorm in March 1999.
The telescope has been used for the Billion-Channel Extraterrestrial
Assay (BETA), a privately-funded effort to detect radio signals from
an extraterrestrial intelligence by scanning 240 million radio
channels at a time.  The cost of the repairs to the antenna's dish and
gearbox is estimated to be approximately $100,000.

A Savior for Iridium?  Investment firm Castle Harlan is reportedly in
talks to purchase the assets of failed satellite communications
company Iridium, Wired News reported last week.  Iridium has requested
that a U.S. bankruptcy court give Castle Harlan permission to buy the
company's assets, including its constellation of over 70 satellites
and a worldwide network of ground stations.  Iridium filed for
bankruptcy protection last August and announced in March it was
ceasing operations when no buyer for the company could be found,
although Iridium's investors, such as Motorola, have been looking for
a buyer since then.  There was no word what Castle Harlan would do
with the assets, for which it would pay $50 million plus $900,000 a
month in maintenance costs.  According to its Web site, the company
invests "at sensible prices in companies that offer the opportunity
for solid, achievable growth" -- qualities not previously attributed
to Iridium.

China, Japan Plan New Launchers:  Both China and Japan are investing
in efforts to develop a new generation of small launch vehicles.
SpaceDaily reported that China plans to develop a solid-propellent
launch vehicle, SLV-1, that would be based on existing ICBM designs.
The booster would be able to launch a satellite from a mobile launch
site in as little as 12 hours, and place payloads weighing up to 300
kg (660 lbs.) into low-Earth orbit (LEO).  Several Japanese companies
plus American firms Lockheed Martin and Aerojet are in talks to revive
the J-1 rocket, a small launch vehicle the Japanese space agency NASDA
studied several years ago.  The liquid-propellent two-stage vehicle
could place up to three tons in LEO by 2004.

Accreditation at Last:  Keith Cowing's long-running battle with NASA's
bureaucracy to obtain press credentials came to a successful end last
week.  "It was all rather painless -- no shots were fired or insults
hurled," Cowing noted on his web site, NASA Watch, of his visit to
NASA headquarters to fill out accreditation paperwork.  Cowing had
tried for years to obtain press credentials to cover NASA press
conferences and other events, only to be rebuffed by officials
claiming he wasn't a journalist.  The growth of the Internet-based
news services, along with concerns Cowing was being barred because of
his often-critical stances towards NASA policies, generated
Congressional scrutiny of NASA's accreditation policies, an
investigation by NASA's Inspector General, and resulting changes in
NASA press policies.  SpaceViews hasn't experienced similar problems
when requesting press credentials, but that is at least in part
because Keith has been banging on the door for so long, making sure
Internet-based publications get the same respect as their print and
broadcast counterparts.  Thanks, Keith.

                           *** CyberSpace ***

                         The Astronomy Workshop

While the school year may be winding down in many places, it's never
too late to take in a fun lesson or two about astronomy.  Learn a
little more about astronomy with The Astronomy Workshop, an online,
interactive set of lessons and demonstrations about various aspects of
astronomy, and science and math in general.  Of particular interest: a
section where you can virtually clobber the Earth or another world
with an asteroid or comet, and learn about the effects of such a
collision, and a generator that allows a user to create a new solar
system -- and see if it's stable.

http://janus.astro.umd.edu/

                        Failure Is Not An Option

Longtime mission control flight director Gene Kranz, perhaps best
known for his leadership during the Apollo 13 mission, is the author
of a new book, Failure Is Not An Option, that recounts his career at
NASA.  You can learn more about him and his book at this Web site,
which follows a mission control theme: an "anomaly log" provides
corrections to the book, while a "flightplan update" includes
information that didn't make it into the book.  This sites is a useful
resource for people interested in the book as well as those who have
already read it.

http://www.genekranz.com/

                        Brad Gould's Space Links

This site provides a nice collection of links to various space-related
resources online, all organized into a number of categories and listed
in a convenient set of drop-down menus.  Whether you're looking for
the Romanian Space Agency (look under "Government & Military") or the
New Zealand Space Agency (look under "Space Humor"), this is a good
starting place for your own cyberspace exploration.

http://www.orbitworld.net/blgould/spacelnk.html

        Astronautics, Spacecraft Design, and Spacecraft Systems

As you might imagine, virtually every space-related project that isn't
classified has its own Web site.  Where do you go, though, to find the
sites of some of the lesser-known ones?  Visit "Astronautics,
Spacecraft Design, and Spacecraft Systems", a site created by USC
aerospace engineer professor Mike Gruntman.  The site has an extensive
list of links to Web sites about spacecraft, launch vehicles, launch
sites, and related resources.  The site also links to a separate page
by Gruntman that features a comprehensive bibliography on spacecraft
design.

http://ae-www.usc.edu/bio/mikeg/spacecra/spaccrft.html

========
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