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发信人: bage (网事如疯·春心萌动), 信区: AerospaceScience
标 题: SpaceViews -- 2000 December 4(转载)
发信站: 哈工大紫丁香 (2000年12月22日18:41:02 星期五), 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 2000.49
2000 December 4
http://www.spaceviews.com/2000/1204/
*** News ***
One Of Two Solar Wings Deployed On Space Station
NASA Leaves Door Ajar For Tito Flight To ISS
Proton Carries Third Sirius Radio Satellite To Orbit
Iridium Satellite Reenters Atmosphere Over Arctic Ocean
Most Distant Object in Universe Not So Far Away
Private Rocket Group Slammed by Environmentalists
New Neighbor May be Closest Known Brown Dwarf
Mysterious Effect May Influence Spacecraft Trajectories
SpaceViews Event Horizon
Other News
*** Articles ***
Search for Another Earth Quietly Underway
Mars Probes Take On Tough Challenges
*** News ***
One Of Two Solar Wings Deployed On Space Station
By Todd Halvorson
Cape Canaveral Bureau Chief
SPACE.com
Shuttle Endeavour's astronauts spread a giant solar wing at
Space Station Alpha late Sunday, taking the first step toward
quintupling the amount of electricity that can be generated at the
power-hungry outpost.
But a bit of slack in the glistening gold-and-blue blanket
prompted NASA to delay deployment of a second power-generating wing
until Monday afternoon at the earliest.
The reason: Engineers want to determine why the first array --
which otherwise is working well and generating electricity -- failed
to stretch out as tightly as expected.
"The wing is not broken. It's a perfectly good power source
and a perfectly good wing," said NASA lead flight director Bill
Reeves. "It's just that the blanket is not completely taut yet."
Agency engineers, as a result, will pour over video of the
massive wing unfurling before giving the shuttle crew a go-ahead to
extend the second panel.
"We're going to do some analysis on the wing that's out, and
when we're convinced we're ready, we'll deploy the second wing,"
Reeves said. "There's no reason to be in a big hurry and deploy the
other blanket until we absolutely understand what we're looking at
right now."
The extended solar wing is one of a pair attached to a $600
million electrical power tower that was mounted atop the International
Space Station during a 7-hour, 33-minute spacewalk Sunday.
Covered with 32,800 shiny solar cells, the panel -- which
converts sunlight into direct-current electricity -- slowly unfurled
like a king-sized accordion in space during a 14-minute deployment
sequence beamed back to Earth and broadcast live on SPACE.com.
"Ah, it looks beautiful," said Endeavour spacewalker Carlos
Noriega, who was watching on from the shuttle's cargo bay at the time.
Added spacewalking partner Joe Tanner: "More power to the
station."
NASA mission managers were just as impressed.
"In one word, it's an awesome sight to see that array out
there as big as it is, and then to imagine what it's going to look
like with the second one out there as well," Reeves said. "It's quite
a sight."
The Alpha crew missed the spectacle. U.S. astronaut Bill
Shepherd and his two Russian colleagues -- cosmonauts Yuri Gidzenko
and Sergei Krikalev -- were in the midst of an eight-hour sleep period
at the time.
Together, the two solar wings -- which are the largest ever to
be hauled into orbit -- are designed to stretch some 73 meters (240
feet) from tip to tip, generating enough electricity to power 30
homes.
That power is critical to the $60 billion station construction
project, which is a joint effort of 16 nations and 100,000 workers on
four continents.
Existing electrical supplies are so sparse that one of the
station's three pressurized work areas remains off limits to the Alpha
crew, which took up residence at the complex in early November.
The extra electrical power also is a must before NASA and its
international partners can expand the station during a series of
almost 40 more U.S. shuttle and Russian rocket missions.
In fact, the station's first science lab -- now set for launch
in mid-January -- would remain grounded if Endeavour's astronauts were
unable to finish wiring the already deployed wing to the station
during a spacewalk later this week.
NASA station flight director John Curry said that the single
deployed panel is expected to generate enough electricity to press
ahead with the lab launch.
"We could support the lab mission, I know that. Obviously
there would be impacts on total power production. But we could survive
with one (array) for a period of time," he said.
The solar wing deployment came after the successful mounting
of the 17-ton power tower atop of the station, a job Canadian
astronaut Marc Garneau deftly did with the shuttle's 15-meter (50-
foot) robot arm.
With the arm acting as a construction crane, Garneau
maneuvered the payload to within 0.9 meters (three feet) of a rooftop
truss mounted to the outpost by a visiting shuttle crew in October.
Decked out in $12 million spacesuits, Tanner and Noriega then
scaled the 13-story station and helped Garneau guide the power tower
into a mechanical claw designed to secure it to the top of the
outpost.
Both were outfitted with helmet-cams that provided
unprecedented glimpses of the international outpost.
Similar to the lipstick-type cameras worn by National Football
League referees and placed inside NASCAR racers, the helmet-cams are
the heart of NASA's new Wireless Video System, or WVS.
The tiny cameras gave both the shuttle crew and NASA TV
viewers close-up looks at work being done by the tool-toting
astronauts, and long-range shots of Endeavour's floodlit cargo bay as
the joined shuttle and station passed around the dark side of Earth.
"I have to tell you guys, this WVS is very cool," shuttle
commander Brent Jett told the spacewalkers.
"I figured it would be," Noriega replied.
Tanner and Noriega will perform two more spacewalks during
Endeavour's stay at the station.
A second sortie is scheduled to begin about 1 p.m. (1800 UT)
Tuesday. The job at hand: Wiring the solar wings to the station and
repositioning a key communications antenna.
The third spacewalk - which is set to begin just after noon
EST (1700 UT) Thursday - will involve mounting a device designed to
determine whether the solar wings might create a shock hazard to
astronauts working outside the station.
Endeavour and its crew -- which also includes pilot Mike
Bloomfield -- are scheduled to land at Kennedy Space Center at 6:19
p.m. EST (2319 UT) Dec. 11.
NASA Leaves Door Ajar For Tito Flight To ISS
By Todd Halvorson
Cape Canaveral Bureau Chief
SPACE.com
The chances of would-be space tourist Dennis Tito flying to
the International Space Station next year might be slim to none, but
NASA -- at least publicly -- isn't completely slamming the door shut
on the controversial idea.
"I think we'd have to wait and see how it all works out,"
former NASA chief astronaut Robert Cabana, now the agency's manager
for international space station operations, told SPACE.com Tuesday
during a news conference at Kennedy Space Center.
Tito, a multimillionaire investment manager from California,
had hoped to become the world's first space tourist with a flight to
the aging Russian space station Mir early next year.
A former NASA engineer, Tito already has made partial payment
on a $20 million ticket sold by the private company MirCorp and RKK
Energia, the Russian company that operates Mir.
The flight to Mir, however, appears to be "no-go" for launch.
The Russian Aviation and Space Agency (Rosaviakosmos) said
earlier this month that Mir will be sent on a destructive plunge
through the atmosphere -- and into the Pacific Ocean -- a week after
the station's 15th anniversary in February.
In a November 16 interview with SPACE.com, Tito said he was
working on a deal to launch aboard a Russian Soyuz spacecraft for a
six-day stay at the new international station in late April.
Both NASA and Rosaviakosmos officials at the time said the
deal was news to them.
Cabana, however, left the door slightly ajar.
The topic, he said, is one that NASA officials are not
currently negotiating with their counterparts at Rosaviakosmos. He
added that Rosaviakosmos officials have said publicly that they have
received no request from MirCorp or RKK Energia to fly Tito.
At the same time, though, Cabana noted that NASA and its
international partners still are in the early stages of a daunting
string of critical missions aimed at building a 480-ton station -- a
job many considering the most complex engineering project of all time.
"I think right now, at this point in the (station) assembly
sequence, we have a tremendous job up there, and we want to have
professional astronauts doing it," the veteran shuttle mission
commander said.
Still unclear: Whether NASA ultimately would take issue with
any Russian move to fly Tito during the crucial early stages of
station construction.
"Whether or not we'd object or not, I can't say at this time,"
Cabana said. "I'd have to wait and see what gets presented. We'll
evaluate it at the proper time when the Russians come to us and say
this is something they want to do, and this is what they have worked
out."
Proton Carries Third Sirius Radio Satellite To Orbit
By Jim Banke
Senior Producer, Cape Canaveral Bureau
SPACE.com
Driving to work next year will become a more pleasurable
experience thanks to a satellite launched from Central Asia on
Thursday.
The spacecraft sent into orbit by a Russian rocket was the
third of three needed by Sirius Satellite Radio of New York City in
order for the company to begin offering commercial-free, CD-quality
radio programming to commuters and drivers across the United States
next year.
The first and second Sirius radio satellites were launched on
Protons earlier this year and together the constellation makes it
possible for a radio unit in a car or truck to receive the digital
programming no matter where you're driving in the continental U.S.
When the service is declared operational, a long-haul truck
driver can tune in one of 50 channels of commercial free music -- or
one of 50 channels of traditional news and entertainment programming
-- and not have to touch the dial during a journey from Boston to San
Diego or Minneapolis to Orlando.
Rollout of the service will be gradual so that Sirius
engineers can test quality and performance at every step as more and
more receivers are used throughout the nation, company spokeswoman
Mindy Kramer told SPACE.com on Thursday.
"We're not going to make radios widely available until we can
assure high quality service," Kramer said.
The company will not release any numbers on projected sales
but Kramer did say they expect the greatest volume to come later in
2001 as consumers shop during next year's holiday season.
Sirius already has established alliances to install three-band
radios in new Ford, Chrysler, BMW, Mercedes, Mazda, Jaguar and Volvo
vehicles as well as Freightliner and Sterling heavy trucks. That means
that in addition to receiving satellite programs, you'll be able to
hear local AM and FM stations as well.
The company also is setting up deals with electronics
retailers so that consumers can purchase and install receivers and
adapters in their current vehicles.
Initial price for the satellite signal receiving hardware is
expected to be between $300 and $400, but the price is expected to
drop following a more-or-less normal consumer electronics pattern,
officials said.
Subscription charges for the service is expected to be $9.95
per month.
Although you can't sign up for the service yet, Sirius is
compiling an e-mail list at its corporate Web site so it can inform
customers who are intersted in becoming charter at the proper time.
Thursday's launch from the Baikonur Cosmodrome took place at
2:59 p.m. EST (1959 UT) when a workhorse, four-stage Proton rocket lit
up the cold desert, hauling its payload toward space on a brilliant
plume of fire and smoke.
The mission -- marketed and managed by International Launch
Services -- officially ended some two-and-a-half hours after liftoff
when the the Space Systems Loral-built satellite separated from the
Block DM upper stage.
All three Sirius satellites were flown on ILS Proton boosters
in only five months.
A fourth satellite, built as a ground spare, is to be
delivered by Space Systems Loral to Sirius for storage in August 2001.
The satellite was damaged during its manufacture, delaying its
delivery and briefly sparking concerns among investors in Sirius.
Although not recovered from its 52-week high of $69 and seven-
sixteenths, shares of Sirius stock closed Thursday at $32 and one-
eighth -- up $2 or 6.64 percent from Wednesday -- with 1.2 million
shares traded during the day.
Iridium Satellite Reenters Atmosphere Over Arctic Ocean
By Andrew Bridges
Pasadena Bureau Chief
SPACE.com
The first Iridium telecommunications satellite to reenter the
atmosphere broke up over the Arctic Ocean early Wednesday.
The non-operational satellite reentered at 4:44 a.m. Eastern
Standard Time (0944 UT), said Master Sgt. Larry Lincoln, of the United
States Space Command, which tracks about 8,000 artificial objects
orbiting the Earth, including spacecraft, satellites, rocket bodies
and debris.
"The satellite was not designed to survive reentry intact and
was expected to mostly burn up in the atmosphere," Lincoln said.
The satellite was launched September 8, 1998, but failed and
was reported tumbling out of control just two months later.
A second Iridium satellite is expected to reenter the
atmosphere no later than December 17.
As for the Chicken Littles of the world, they need not worry.
A study of the Iridium satellite reentries, show they are
within a NASA and U.S. government standard of acceptable risk, said
Nicholas Johnson, chief scientist and program manager for NASA's
orbital debris office at the Johnson Space Center in Houston, Texas.
That is, there is a one-in-10,000 chance of anybody being hurt on the
ground by a falling Iridium spacecraft, he told SPACE.com.
Although the Iridium constellation will lose a few more
satellites that are tumbling in orbit, the roughly 70 remaining
operational birds have found their savior.
Last month the U.S. Bankruptcy Court for the Southern District
of New York approved Iridium Satellite LLC's bargain-basement $25
million bid to purchase the operating assets of Iridium LLC and its
subsidiaries.
Motorola, builder and initial operator of the $7 billion
constellation of Iridium satellites will provide subscriber equipment
for users of the worldwide satellite network. The Boeing Co. will
operate and maintain the satellites.
Most Distant Object in Universe Not So Far Away
By Robin Lloyd
Science Editor
SPACE.com
The race to observe the beginning of time and the edge of the
universe suffered a slight setback Thursday as astronomers announced
that the most distant object ever found is not quite so far away.
An image of the object, a faint galaxy called STIS
123627+621755 but referred to informally as "Sharon," was taken with
NASA's Hubble Space Telescope and reported last year by a team as
being 12.5 billion light-years away (a light-year is about 6 trillion
miles). That distance is equivalent to looking back in time to about
600 million years after the Big Bang, when the universe was only 5
percent of its current age.
In a classic case of the scientific method, a team of
astronomers led by Daniel Stern of NASA's Jet Propulsion Laboratory in
Pasadena, California now reports that Sharon is a lot closer -- likely
about 10 billion light-years away, corresponding to 3.3.billion years
after the Big Bang. That's about 25 percent of the current age of the
universe.
"I thought we should make this known," said Stern's JPL
colleague Peter Eisenhardt. "We don't know what's going on out on the
edge. That's why we're interested. We'll have to wait a little longer
to reach out that far. The horizon of where we can get to is not quite
out there."
A report by Stern, Eisenhardt and others on the new distance
is published in the latest issue of the journal Nature, along with
similar findings from Hsiao-Wen Chen, whose team made last year's
estimate of the distance when she was at SUNY Stony Brook.
The upshot is that a quasar called SDSSp J104433.04-012502.2
and announced in April by the Sloan Digital Sky Survey now reigns
supreme as the farthest known object at 10 billion light-years away.
Redshift reduction
Stern and his colleagues showed that the redshift of Sharon
was different than had been originally reported. Redshift, the
standard distance measurement used by astronomers, measures how fast
an object is moving away from us as the universe expands. The faster
it is moving away, the more its light shifts to the red end of the
spectrum (toward longer wavelengths). In the 1920s, Edwin Hubble
discovered that the faster an object appears to move, the farther away
it is.
"The identification of galaxies at extreme distances provides
our most direct information on the earliest phases of galaxy
formation," said Stern, whose team made the new observations using
images obtained at the Keck Observatory, Mauna Kea, Hawaii.
Stern said the great distances of objects like Sharon makes
them difficult to study. "It's hard for scientists to interpret faint
observations of distant galaxies, and occasional misidentifications
will occur," he said.
Time and distance
The effort to find the most distant object in the universe is
much more than a battle for a superlative. For one, because light from
the edge of the universe travels across unimaginable distances to
reach us, the light we see represents activity that occurred very long
ago, on the heels of the universe's beginnings -- presumed by most
scientists to be the Big Bang.
"You're observing the history of the formation of massive
objects by reaching further back in time," Eisenhardt said. "You're
seeing baby picture and early childhood pictures of massive galaxies."
Beyond the impressively young age of distant objects,
astronomers also want to study the state of the universe at that time.
For instance, the presence of either one or another of two states of
hydrogen gas (neutral, independent atoms versus ionized hydrogen atoms
stripped of their single electron) is a marker of transitions between
the universe when it was a few hundreds of thousands years old and the
present.
"It's like the difference between steam and liquid water,"
said Eisenhardt. "It's a really basic difference and we'd like to pin
that down."
Astronomers study light of various wavelengths from objects to
discern the nature of hydrogen gas there. It will be easier to make
that measurement on the Sloan quasar than it would have been on the
Hubble faint galaxy, Eisenhardt said.
"It would've taken a really heroic observation to measure
state of universe around that (Sharon)," Eisenhardt said. "So now we
know it's worth effort on this object (the Sloan quasar)."
Megapixel IR detectors
Improvements in detectors that measure infrared light will
make it easier to find even more distant objects in a matter of a few
years, Eisenhardt said.
The expansion of the universe carries light beyond the visible
to the infrared (IR) range so the search for distant objects must be
made in the infrared part of the spectrum, he said. The improved
distance measurement on Sharon was made using a 65K (65,000) pixel
detector on a telescope at the Keck Observatory.
"We are just now getting megapixel IR detectors," Eisenhardt
said. "You can put those on big scopes we have now."
"I have no doubt we'll be reaching out to red shifts of 6 and
7. That's about 12.5 billion versus 12.6 billion years ago... I think
we can get back to 5 percent of the age of universe within the next
couple of years."
Private Rocket Group Slammed by Environmentalists
By Leonard David
Senior Space Writer
SPACE.com
A private rocket group aiming to become the world's first
fully reusable launcher with liftoffs from the American Southwest has
come under fire by a leading environmental group.
The challenge is seen as a warning flare to those advocating
the spread of commercial spaceports around the United States and
abroad.
In an investigative cover story, Earth Island Journal's Winter
2000-2001 issue questions the Kistler Aerospace Corporation's private-
sector intention to launch its K-1 rocket from area 18 at the Nevada
Test Site, 60 miles (96 kilometers) northwest of Las Vegas, Nevada.
The magazine article focuses on Kistler's two K-1 launch
corridors emanating from an inland Nevada spaceport. It claims that
the rocket project constitutes "a significant risk to thousands of
rural and city residents."
Gar Smith, Earth Island Journal's editor-in-chief, co-authored
the Kistler story with Vernon Brechin, an environmental consultant and
writer.
Smith said there is great probability for error with Kistler
launches, problems that could mean collateral damage on the ground.
"I don't see any reason to expose people in North America to
that kind of potential," Smith told SPACE.com.
The journal was founded in the late 1980s and is a publication
of the Earth Island Institute. Based in San Francisco, California, the
institute was founded by environmental activist David Brower.
Kistler responds
Contacted by SPACE.com, Debra Facktor Lepore, Kistler's
director of marketing in Kirkland, Washington, declined to directly
respond to the magazine's viewpoints.
Rather, Lepore said that "efforts are continuing" to secure
the final round of financing needed to bring the K-1 rocket through a
flight test phase. "We're hoping to gear up sooner rather than later,"
she said.
To date, Kistler has raised over $500 million in private
capital, Lepore said.
Engineering on the K-1 is 85 percent complete, Lepore said.
Some 75 percent of the hardware for the first vehicle has been
manufactured, and qualification testing is underway, she said.
Kistler expects to start flight tests of the K-1 one year
after completion of full financing, Lepore said.
Maiden voyage: a Nevada no-show
Kistler documents state that when the first K-1 takes to the
sky, it will not depart from Nevada.
The private group will initially conduct launch operations
from a dedicated site outside of Woomera, Australia.
Only after successful demonstration of K-1 flight operations
in Australia would launch site construction begin in Nevada.
Earlier this year, the Federal Aviation Administration issued
a draft assessment of Kistler's plans to use the Nevada Test Site.
Their preliminary look-see found that K-1 rockets would have little
impact on the environment.
The K-1 flight profile from both Australia and Nevada dictate
launch and landing over land. Kistler documents state that "this is
achievable most safely from a remote area with low population density
and with the necessary available infrastructure."
Kistler has recently broadened its prospective customer base
by developing a K-1 ability to dispense payloads beyond low Earth
orbit.
Also, the company is wrapping up a NASA-awarded contract to
study how the K-1 can meet contingency resupply needs for the
International Space Station, Lepore said.
Flight path fallout
The article notes that Kistler boosters eventually would
streak over eight states: Nevada, Washington, Idaho, Montana, Utah,
Wyoming, North Dakota and California, as well as British Columbia. At
least 98 major U.S. cities and native reservations would fall under
the flight path of Kistler K-1 rockets lifting off from Nevada.
Tagging it unproven "fly back technology," the magazine finds
fault with Kistler's projected flight plan that calls for the K-1
upper stage -- after it places cargo into orbit -- to plunge back to
Earth and cross over a host of California cities, en route to a
touchdown at the Nevada spaceport.
Use of the two-stage Kistler booster to routinely hurl
satellites into space, the article declares, exposes U.S. cities to
"potential rocket mishaps".
First-stage or second-stage failures of the rocket could mean
out-of-control hardware falling from the sky into populated areas, the
magazine claims.
Hear the inland roar
The environmental magazine also waves a red flag regarding
prospective spaceports elsewhere.
"I appreciate reusable rockets from an engineering standpoint.
They are ingenious, but also an unproven technology. The major concern
is a generic question of whether there should be inland-based space
launch sites," Smith said.
Permitting the Kistler K-1 to roar out of Nevada "would set a
precedent that could unleash an era of commercial satellite launches
over inhabited inland portions of the U.S.," the magazine cautions.
The article cites proposed inland spaceports in New Mexico,
Montana, Utah, and one suggested launch zone in Texas. From that site,
the magazine adds, commercial rockets would be sent "blasting over a
national seashore inhabited by white pelicans and endangered sea
turtles."
Also, developing the Nevada site -- already designated as a
test area for nuclear bombs -- would remove wildlife habitat and
destroy desert vegetation. Launches there, the article adds, would
generate a sonic boom swath that "temporarily" deafen birds and
wildlife.
A confident industry
Environmental issues of inland spaceports shouldn't be a big
deal, said rocket expert, Marshall Kaplan, chairman of Satellite On
Demand, Inc., of Potomac, Maryland.
"Current spaceports have the same problems. The fact that they
are on a coast doesn't really matter. There are still environmental
concerns. The environmental concerns from inland ports are not any
more severe, for the most part. So I don't think that's an issue that
will stop anything," Kaplan told SPACE.com.
However, Kaplan does raise an eyebrow regarding safety and
liability issues of operating private Kistler rockets from Nevada. The
change from launching vehicles over water to over land is going to be
hard to do, especially with a private sector vehicle, he said.
"The FAA is not going to give them a license until they've
proven they can operate their rocket safely from Nevada. That won't be
for a long time. That's why they went to Australia," he said.
Kaplan said that controlled reentry has long been proven by
the space shuttle.
"The Kistler vehicle being unpiloted is inherently less safe
in terms of its own ability to reenter properly. So there is an issue
there in that it's not crew-rated. It's a question of liability and
safety. How safe is the Kistler vehicle versus something like the
shuttle?" he said.
"Australian outback has a lot more room in it than does
California and Nevada," Kaplan said. "If it were me, personally, I
probably would not allow any Kistler overflight of populated areas."
Final roundup of funds
According to Kistler documents available on the firm's web
site, a fleet of five K-1 vehicles and two dedicated launch sites can
provide true launch-on-demand capability, and a high launch capacity.
K-1 launch rates of one per week are projected. Each rocket
would be capable of quick turnaround between flights and reuse up to
100 times.
But as for the premier flight of the K-1, no date has been
set. "We're not saying anything about schedule. As soon as we finish
the financing, then we will have something to say," Lepore said.
The Iridium specter
K-1 rockets would be used to put constellations of
communications satellites around the planet, Smith said. "That's how
they're trying to make a buck. And we know from past experience that
these things, like the Iridium system, are not guaranteed financial
successes," he said.
"We raise that question in the article. Who is responsible for
all that orbiting abandoned space communication gear up there?" Smith
said.
Kistler is a commercial trucking company, Smith said. "This is
not space exploration ... not the glorious romance of exploring the
outer parameters of space."
New Neighbor May be Closest Known Brown Dwarf
By Robert Roy Britt
Senior Science Writer
SPACE.com
A team of astronomers has discovered a dim object 60-90 times
as massive as Jupiter roughly 13 light-years from Earth, practically
in our back yard. The object may be our closest known brown dwarf,
bolstering the belief that there are many celestial treasures left to
find, even in our own cosmic neighborhood.
More research is needed to determine if the object is in fact
a brown dwarf -- essentially a small, failed star -- or if it is a
real star that is relatively small and dim. The object sits alone in
space, not part of any star system or cluster.
The nearest confirmed brown dwarf is 16 light-years away. The
nearest known star is Proxima Centauri, at 4.2 light-years away. A
light year is the distance light travels in one year, about 5.88
trillion miles.
So what is it?
The object was found by Thierry Forveille of the Canada-
France-Hawaii Telescope Corporation and French astronomer Xavier
Delfosse. Eduardo Martin of the University of Hawaii analyzed the
object with the Keck I Observatory, looking for evidence of lithium, a
signature of all but the largest brown dwarfs. He found none.
"If this object is a brown dwarf, then it is the closest one,
but we are not sure," said Martin. "It failed the lithium test, so it
could be a very low-mass star [75-90 Jupiter masses] or a high-mass
brown dwarf [60-75 Jupiter masses]."
Martin told SPACE.com that there might be several unknown
brown dwarfs even closer, but they would be cooler, fainter and even
tougher to spot.
"Determining how many brown dwarfs exist will tell us about
where these objects come from and what is their contribution to the
overall chemical and dynamical budget of the Milky Way," Martin said.
Brown dwarfs are thought to form when an interstellar cloud of
gas and dust collapses under the weight of gravity. This is also how
real stars, like our Sun, are born. Planets, on the other hand, are
generally thought to form out of the leftovers of such a process.
Scientists are currently grappling with the confusing overlaps in
definitions.
100 billion brown dwarfs?
Other brown dwarfs have been discovered recently, but their
distances have not yet been determined, according to Tom Geballe of
the Gemini Observatory.
"I think it is likely that of the 20 or so cool brown dwarfs
now discovered, one or two will be found to be this close or closer,"
said Geballe, who was not involved in the new study but does research
the strange objects.
Geballe told SPACE.com that surveys done so far indicate brown
dwarfs may be as prevalent as stars.
"If the [prevalence] of brown dwarfs and stars are about the
same then there are over 100 billion brown dwarfs in our galaxy,"
Geballe said, adding that it would then be logical to assume that at
least one would be found at around 4.2 light-years away, the distance
to the closest star.
In recent years, some scientists had suspected that brown
dwarfs might account for unseen "dark matter" that is presumed to
pervade the universe.
"This now appears to be ruled out," Geballe says. "There would
need to be about 100 times more brown dwarfs than are being found to
account for all of the dark matter."
Old images, new discovery
At the Observatory of Paris, Jean Guibert and Francoise Crifo
dug up three old pictures of the newly discovered object, and found
that it had moved considerably between 1975 and 1999 [see adjacent
animation] indicating that the object is closer than other stars in
the images.
Guibert and Crifo made the distance estimate of 13 light-years
by relying on comparisons with objects that have similar
characteristics. For that reason, the distance figure could change as
more is learned about the object. The object was named DENIS-P
J104814.7-395606.1 and will be reported in an upcoming issue of the
journal Astronomy and Astrophysics Letters.
The 5 dwarfs
Brown dwarfs aren't massive enough to trigger the
thermonuclear reactions that power real stars. But, most researchers
say, they are more massive than planets.
Researchers are working to develop new classifications for
different types of brown dwarfs. In addition there are also four other
known "colors" of dwarfs, two of which are real stars:
White dwarfs: Burned-out stars that no longer shine through
nuclear fusion, and have collapsed to Earth-sized objects. Their
surface temperature rises as they collapse, making them white-hot.
Yellow dwarfs: Normal stars with our Sun's temperature and
mass.
Red dwarfs: Real stars that are small, cooler and dimmer than
our Sun. The cooler a star the redder it is, just as a dying ember
fades from yellow-orange to cherry-red.
Black dwarfs: A theorized later stage of a white dwarfs that
cools to nearly absolute zero. The universe isn't old enough yet for
black dwarfs to exist, scientists say.
Mysterious Effect May Influence Spacecraft Trajectories
By Leonard David
Senior Space Writer
SPACE.com
Space probes using Earth to slingshot their way outward into
the solar system appear to have received an extra boost by a
mysterious force - perhaps an unknown component of gravity.
Scientists hope to confirm the unusual effect as the Stardust
spacecraft whips by Earth this coming January.
Analysis by radio scientists of the post-Earth flyby
trajectories of three spacecraft have shown each craft to have picked
up an unexpected increase in speed: The Galileo spacecraft in December
1990; the Near Earth Asteroid Rendezvous (NEAR) probe in January 1998;
and the Saturn-bound Cassini spacecraft in August 1999.
The Galileo spacecraft slipped by Earth a second time in
December 1992. But the vehicle dipped too close to Earth making the
measurement of any "flyby effect" unusable.
Doin' the Doppler shift
"This problem has been with us for about 10 years, and we
haven't found a solution," said John Anderson, a senior research
scientist and member of the Stardust science team at the Jet
Propulsion Laboratory (JPL) in Pasadena, California.
"We're looking forward to the Stardust flyby. That would be
our fourth measurement of this anomalous effect," Anderson told
SPACE.com.
Using JPL's Deep Space Network of radio telescopes, the
velocity of Stardust is measured by analyzing its Doppler shift. In
this case, a change in frequency or wavelength of sound due to the
relative motion between the emitting source, Stardust's radio
transmitter, and ground receiving equipment.
Stardust is expected to show a bump up in velocity as it flies
by, Anderson said. "We can't find any source or any mechanism that
would do that," he said.
"Cassini, NEAR, Galileo...they all show it. If it follows the
pattern that we've seen in the other three, it should be clearly
measurable," Anderson said. "That's why we're so anxious to get the
Stardust data," he said.
X-band rated
The Stardust spacecraft will zoom past Earth on January 15,
2001, at the end of its first elongated orbit of the Sun, said Donald
Brownlee, Stardust's principal investigator of the University of
Washington, Seattle.
Launched in February 1999, Stardust is on a long-and-winding
road to comet Wild-2. In 2004 the probe will snag cometary material,
then return the samples to Earth in 2006.
Stardust is equipped with an x-band transponder (radio
transmitter/receiver), allowing radio scientists on Earth to precisely
track the spacecraft, Brownlee said.
As Stardust slips by Earth to attain a flight path change, it
will pass 6,000 kilometers (4,000 miles) above Africa, Brownlee said.
There is a prediction of where the spacecraft should be, one that
takes into account the flyby effect, he said.
"Those past spacecraft, after the flyby...they are leaving
with slightly more energy than expected. Each one had a consistent
anomaly. It's quite intriguing," Brownlee said.
"It is possible, I guess, it's some new factor that hasn't
been taken into account. But the most interesting possibility is it's
a previously undiscovered component of gravity," Brownlee said.
Head scratching science
Just what the effect might be remains a puzzle, Anderson said.
"It could be fundamental physics...it might not be. I view it
as a mysterious anomaly. To be speculative, it could be revealing
something new in physics," he said.
Anderson said he could not discount that some systematic
navigation error, yet to be identified, has been uncovered.
"Either way, it is important to pin it down, hopefully after
we get the Stardust flyby," Anderson said. Stardust radio data
collected during the January swingby could be fully analyzed by his
four-person team at month's end, or later in February, he said.
"If the force was with us, basically, this would be a
phenomenal discovery," Brownlee told SPACE.com.
What's the charge?
Anderson said colleagues have ventured guesses as to what
might explain the effect, if it is a true phenomenon in the first
place.
One possibility being aired, Anderson said, is that spacecraft
become charged as they whisk through the Earth's magnetic field. This
electromagnetic charge then interacts with the Earth's gravity,
creating the anomalous motion in the spacecraft as it cruises by
Earth, he said.
Anderson also said the effect could be some outcome of string
theory prediction.
String theory is a supposition that space is imbued with
electromagnetic, weak and strong nuclear interactions, as well as
gravity forces, that form curled-up dimensions, in addition to the
observable dimensions of length, height, and width.
But putting such speculation aside, Anderson said, obtaining
matter-of-fact data in January is important.
"Assuming that we see it again on Stardust...we should be able
to start seeing a pattern to this," Anderson said. "Nobody has
suggested that we shouldn't pursue this. There might be something to
this. It's very hard to question our results. We just don't know what
it is," he said.
SpaceViews Event Horizon
December 5 Start-1 launch of the Israeli Earth Remote Observation
Satellite EROS A1 from Svobodny, Russia
http://www.coola.com/cgi-bin/addinfo.cgi?pid=10003&rid=975284072&type=D
December 5 Atlas 2AS launch of a classified NRO satellite from
Cape Canaveral, Florida at 8:14 pm EST (0114 UT
December 6)
http://www.coola.com/cgi-bin/addinfo.cgi?pid=10003&rid=975284294&type=D
December 7 Roundtable on Space Issues Facing Next Congress,
Dirksen Senate Office Building, Washington, DC
http://www.coola.com/cgi-bin/addinfo.cgi?pid=10003&rid=975895305&type=D
December 8 Ariane 4 launch of the Eurasiasat 1 satellite from
Kourou, French Guiana at 5:03 pm EST (2203 UT)
http://www.coola.com/cgi-bin/addinfo.cgi?pid=10003&rid=975284379&type=D
December 11 Landing of the space shuttle Endeavour to end mission
STS-97 at the Kennedy Space Center, Florida at
6:19 pm EST (2319 UT)
http://www.coola.com/cgi-bin/addinfo.cgi?pid=10003&rid=975887834&type=D
Other News
Seabeds on Mars? NASA announced Friday that is has scheduled a press
conference for Thursday at 1 pm EST to discuss a "major" Mars
discovery. The press conference features scientists Michael Malin and
Ken Edgett, who announced in June the discovery of geological features
consistent with the existence of liquid water at or near the surface
of present-day Mars. While NASA has not released the exact details of
their discovery, the Sunday Times of London reported that the
scientists had discovered evidence of ancient sea beds on the planet.
That report also said that Britain's Beagle 2 spacecraft, a spacecraft
that will land on the planet in late 2003, may be directed to one of
those regions. While NASA called Malin and Edgett's work "their most
significant discovery yet," the agency said it would not broadcast the
press conference live on NASA TV -- as is normally the case with even
routine press conferences -- in order to avoid preempting live
coverage of the STS-97 shuttle mission.
H-2A Delay: The Japanese space agency NASDA is reportedly considering
delaying the maiden launch of its new H-2A booster by half a year,
Reuters reported last week. That launch, scheduled for February of
next year, may be pushed back until the summer because of problems
with the booster's engines, ranging from traces of erosion in seals to
a liquid hydrogen leak during a test firing back in July. The H-2
program has been in disarray since the failure last year of an H-2,
forcing NASDA to shelve the troubled, expensive booster in favor of
the H-2A, which NASDA hopes will offer improved performance at a lower
cost.
Giant KBO Discovered: Astronomers announced Friday that they had
discovered a Kuiper Belt Object (KBO) that potentially could be larger
than Ceres, the biggest asteroid. The object, 2000 WR106, is in an
orbit about 43 AU (6.45 billion kilometers, 4 billion miles) from the
Sun, with n apparent magnitude of 20. While the object's size is not
yet known, estimates based on its magnitude and estimates of its
albedo, or reflectivity, mean the object could be between 530 and 1210
km (330 to 750 mi.) in diameter. By comparison, Ceres, the largest
asteroid, is 920 km (570 mi.) across, while Pluto is 2375 km (1470
mi.) in diameter. If 2000 WR106's large size is confirmed, it could
reopen questions about Pluto's classification as a planet rather than
a KBO, since it could be at little as twice the size of the largest
KBO.
Space and Politics: Space policy issues that will be taken up by the
Congress next year will be the subject of a roundtable Thursday,
December 7, sponsored by ProSpace, the Space Frontier Foundation, and
the Space Transportation Association. The event, which will feature
panelists from government, the private sector, and nongovernmental
organizations, will be held from 8:30 am to 10:30 am in Room 538 of
the Dirksen Senate Office Building... You know that the brouhaha over
the presidential election has gone too far when it appears to
interject itself into a shuttle launch. Florida governor Jeb Bush,
brother of Republican candidate George W. Bush, was in attendance at a
pre-launch dinner at the Kennedy Space Center and viewed the launch
with NASA administrator Dan Goldin. Not to be outdone, Al Gore, the
Democratic candidate, sent a letter in his capacity as Vice President
to Goldin congratulating the administrator for his long tenure at the
agency; that letter was presented to Goldin at the dinner by a Gore
aide. And after the launch, as CNN returned to its coverage of the
ongoing legal battles for the presidency, political analyst Jeff
Greenfield said, "You'll note that Endeavour was launched in Florida
but was being controlled in Texas. Perhaps there's a political message
there."
*** Articles ***
Search for Another Earth Quietly Underway
By Robert Roy Britt
Senior Science Writer
SPACE.com
After a five-year search that has turned up more than 40
giant, inhospitable planets around other stars, the hunt is quietly
underway to discover another place like home. And while no scientist
can say for sure that any such planet exists, optimism is high that
another Earth will be found within the decade, possibly much sooner.
It would be a discovery of sizeable historic proportion, akin
to learning that our solar system was not the center of the universe
and recharging the growing expectation that we are not alone.
And it could galvanize and accelerate efforts to explore space
to a degree not seen since the U.S.-Soviet space race.
The sheer volume and variety of extrasolar planets found so
far fuels a strong expectation among those involved in the search that
there must be other Earth-sized planets orbiting other stars at
distances suitable for supporting life.
"There are about 200 billion stars in our galaxy," said Paul
Butler of the Carnegie Institution of Washington. "I would guess that
Earth-like planets must exist."
Butler and a colleague, Geoffrey Marcy, pioneered the hunt for
extrasolar planets, or exoplanets. They lead teams that detect small
wobbles in stars caused by the gravitational pull of an orbiting
planet. Along with their colleagues, they have found the majority of
confirmed other worlds.
But the wobble method so far spots mostly very large planets
that orbit extremely close to their host stars -- many are closer than
Mercury is to our Sun -- not a place you'd want to live. And
scientists have yet to see these planets directly.
Now, new methods and a handful of missions on the horizon are
close to bringing another Earth within our optical reach.
Earth-sized planet discovery imminent
In recent interviews, three leading planet hunters told
SPACE.com that a potentially habitable Earth-like planet might well be
found within 10 years. And extrasolar planets in the "terrestrial"
range -- no more than 2.5 times the size of Earth -- could be found
within five years, possibly even during 2001.
Discovering one of these so-called "terrestrials" could well
spur the funding, decisions and brainstorming needed to support
missions that would root out truly habitable planets, scientists say.
Hans J. Deeg, a planet hunter involved in multiple searches,
says if either of two planned missions gets off the drawing boards in
a timely manner -- the ESA's Eddington mission or NASA's Kepler
mission -- then a truly Earth-sized planet should be found in about 10
years.
Meanwhile, Deeg is currently working on COROT, a European
space-based telescope due to launch in 2004.
"The COROT mission should find planets about twice Earth's
diameter within five years -- if they exist," Deeg said.
Small target, small telescope
Deeg and a colleague, Laurance Doyle of the SETI Institute,
aren't waiting for a costly or complicated space mission. They're
using a worldwide network of relatively small (1-meter, or 3 foot)
ground telescopes to look for planets between 1.8 and 2.5 times the
size of Earth -- the high end of what's considered potentially
habitable.
Using a new search method, Deeg and Doyle watch for slight
dips in starlight as a planet crosses in front of a star. (Astronomers
have long used this technique to study Venus and Mercury as they cross
in front of the Sun.)
This transit method, as it is called, can only spot planets
whose orbits bring them in front of their host star as seen from
Earth. Its first success came last November, but so far it has only
been viable for spotting large planets closer to their host stars --
situations that generate large enough fluctuations in starlight to be
detected from Earth.
So Deeg and Doyle have refined the method to find smaller
planets using a smaller telescope. They take several readings over
many days and add them together, boosting otherwise imperceptible
signals to detectable levels. They've also confined their hunt to
relatively small stars, where a planet's signal would be more obvious
in relation to the total starlight.
The two researchers have compiled reams of data on a star
system called CM Draconis, 54 light-years away. A total of nine
possible planets were identified in the data. Further observations
showed that seven of these were not planets.
But Doyle is optimistic about the remaining two possibilities,
putting the odds at 50-50 that one of them will be a planet less than
2.5 times the size of Earth.
Doyle says that regardless of whether or not they find an
Earth-like planet around CM Draconis, their method shows that
terrestrials can be detected using today's technology.
"We're saying that if you use these techniques, you can do the
job," Doyle said. "It's not easy, but we don't have to wait for the
next decade [to find] terrestrials."
Good morning, good morning
The first extrasolar Earth-like planet discovered might be a
strange world, one where dawn is marked by a double sunrise. Why?
Because Deeg and Doyle have so far confined their search to star
systems called eclipsing binaries. These pairs of stars orbit each
other in a plane that is parallel to our line of site -- meaning that
they pass in front of each other.
A planet around a binary system would also most likely orbit
in this same plane, which means the transit method could find it.
(Using the transit method, Deeg and Doyle would actually see
two dips in the starlight as the planet passed in front of each star.)
Doyle says they have also begun collecting data on crowded
star fields. One picture contains more than 100 eclipsing binaries and
more than 10,000 single stars.
So while Doyle says a satellite-based telescope could spot a
terrestrial within a decade, he also makes it clear that such a
discovery could happen much, much sooner, though he refused to offer a
specific prediction.
"The answer could be forthcoming," he says.
But will there be life?
While an Earth-like planet might be the top prize for
exoplanet hunters, the ultimate goal for many researchers is to find
extraterrestrial life. For that, an exoplanet must be found in a so-
called "habitable zone."
And a habitable planet needs water. So it can't be too close
to its host star, or the water will boil away. Venus, for example, is
scorching hot and dry. Too far, and the planet becomes a block of ice.
Witness Pluto, or even frigid Mars.
Habitability depends on a number of other factors, Deeg
explains, including the size and temperature of the host star. And the
planet must have a stable long-term climate with the right chemical
ingredients, and there must be a magnetic field to protect against
deadly radiation coming from the star and elsewhere in the cosmos.
Mars is an example of a planet with a weak magnetic field that
offers little protection from deadly energetic particles. Earth, on
the other hand, is well protected from daily doses of space weather.
Butler, of the Carnegie Institution, throws another wrench
into the habitability problem. For an Earth-sized planet to sustain
life, it might need a big brother to clear the way. For us, Jupiter
serves this role.
"By virtue of being the largest planet, Jupiter acts as a
gravitational vacuum cleaner," Butler explains. "Jupiter ended the
period of 'heavy bombardment' in the early solar system in the same
way that it dealt with comet Shoemaker-Levy." What Butler means is
that Jupiter swallowed space rocks, sparing Earth the bulk of the
potentially life-destroying collisions. "It is only after the period
of heavy bombardment that life could gain a toehold on Earth," he
says.
Jupiter's circular orbit also keeps Earth in a calm, circular
orbit, Butler says. If Jupiter's orbit were not circular, it would
throw Earth into an eccentric orbit, which would cause extreme climate
variations as the planet moved close to the Sun and then farther away.
Fancy sleuthing ahead
Even if an Earth-sized planet is discovered in a seemingly
favorable orbit, it will take some fancy sleuthing to figure out if
the new world is habitable, something a 1-meter (39-inch) terrestrial
scope can't do. It would require the launch of a large space
telescope, such as the ESA's Darwin telescope array or NASA's
Terrestrial Planet Finder (TPF) -- two missions that are currently
only in the thinking stages.
In spite of tremendous cost and technical hurdles, "the
pressure on NASA and ESA to launch Darwin/TPF will be overwhelming,"
said Andrew Collier Cameron, a planet hunter at University of St.
Andrews.
Cameron also thinks a potentially habitable planet could be
discovered within a decade, but said it might be another five to 10
years before we know if that planet is actually capable of supporting
life.
But Doyle, of the SETI Institute, said the discovery of an
Earth-like planet would change everything. He wouldn't be surprised if
his SETI colleagues decided to "sit on it for awhile," pointing their
radio telescopes in the direction of the planet to listen for possible
alien broadcasts.
"I think it might spark a lot of ingenuity to see if it is
habitable or not," Doyle said.
Morris Aizenman, senior science associate in the National
Science Foundation's Mathematical and Physical Science Directorate, is
not a planet hunter. But he knows all about the current searches, and
while his expectations for a discovery of a habitable planet anytime
soon are reserved, he too expects they exist.
"It would be very unusual if there were no other habitable
planets in our galaxy," Aizenman said. "But we're only looking at a
small part of our galaxy with the instruments we currently have."
And searching only in one corner of the Milky Way Galaxy, of
course, excludes the entire rest of the universe.
Aizenman agrees with Doyle and others that finding an Earth-
like planet would be the ultimate impetus for developing better
instruments, so a newly found sister world could be studied in detail
and the search for other Earths could expand.
"The bottom line is that we just don't know what the
probabilities are for finding a planet about the size of Earth in an
essentially circular orbit at a distance from the star that such
conditions would be habitable," Aizenman says. "Nevertheless, the hunt
is a great adventure."
Mars Probes Take On Tough Challenges
By Leonard David
Senior Space Writer
SPACE.com
If engineers at this NASA center have their way, the agency's
armada of future Mars spacecraft will seem to arrive at the Red Planet
by materializing out of thin air.
Their plan involves using the lean and mean Martian atmosphere
to brake spacecraft into orbit around Mars. But getting a lander down
to a select spot on the fourth planet from the Sun, while avoiding
harsh, rough-and-tumble terrain, is an exacting science.
For that reason, atmospheric, materials and high-speed
specialists at NASA'a Langley Research Center in Hampton, Virginia are
revving up their computers and wind tunnels to help shape Mars
exploration plans over the next decade and beyond.
Confidence builders
Langley is focused on several upcoming Mars missions,
specifically, Mars '01, '03 and '07 spacecraft, said Mary Kae
Lockwood, team leader for planetary exploration in the center's
vehicle analysis branch.
She said that researchers are simulating aerocapture and
aerobraking techniques for safely swinging payloads into Mars orbit.
Mars aerocapture is a fuel-saving technique whereby a
spacecraft dives deep into the Martian atmosphere, slowing itself down
to attain an orbit around the planet. Aerobraking is when a spacecraft
gradually dips into the planet's upper atmosphere to reach a final
Mars orbit over a number of days.
Work is also ongoing to mimic how spacecraft can take a fiery
plunge through Mars' atmosphere, then autonomously maneuver across the
Martian sky to a precise landing area, Lockwood said.
"Being able to demonstrate and mature new technologies more
gradually in several upcoming missions will help us prepare for the
Mars return sample mission," Lockwood told SPACE.com.
A recent revamp of NASA's Mars plans has pushed returning
samples from the Red Planet to a launch in 2014. Originally, it was
hoped such a venture could be underway much sooner. But the sample-
return mission has proven costly, as well as technologically
challenging.
Langley's work on Mars missions now underway can hasten the
day of the sample-return project, Lockwood said.
Prasun Desai, an aerospace engineer at Langley, pointed out
why returning to Earth precious scoops of Martian soil and rock is a
tough task. "To this point, we've only done half the mission. We go
there and stop. That second leg of coming all the way back requires a
lot more infrastructure," he said.
Putting on the aerobrakes
The next aerobraking adventure for NASA comes with the 2001
Mars Odyssey spacecraft set for launch on April 7, 2001.
Langley experts are helping script the months of delicate
maneuvering required to place Odyssey into orbit around Mars.
Arriving at Mars in late October, the new orbiter will begin
skimming about the planet's atmosphere and do so for upwards of 70
days, said Richard Powell, a Langley senior research engineer.
"It will take some 300 orbits over those 70 days to get down
into the orbit we want," Powell said. When exactly the Odyssey will
drop into the final two-hour Mars orbit depends on how volatile the
Martian atmosphere becomes, which can be stirred up by massive dust
storms.
"If the atmosphere is exactly the same every pass, we would be
there really quick. If the atmosphere is giving us some difficulty, we
obviously take a more conservative approach, Powell said.
Sensors mounted on Odyssey will assure that the probe and its
large solar array don't take too much of a heat load as the spacecraft
repeatedly skims through the Martian upper atmosphere, Powell said.
Experience gained in aerobraking the Mars Global Surveyor --
now carrying out science duties while circling the planet -- has been
a bonus, Powell said. However, the yet-to-be-lofted Mars orbiter will
be aerobraking in a different part of the atmosphere than its
predecessor, he said.
Wrap around airbags
Langley also is busy defining the entry, descent and landing
profiles for the twin Mars exploration rovers to be rocketed spaceward
in June 2003, Desai said. Reaching Mars in early 2004, each rover will
be wrapped in airbags akin to those used in 1997 to cushion the bouncy
touchdown of Mars Pathfinder and the Sojourner mini-crawler.
Safely depositing the two rovers on Mars in 2004, however,
won't be a mirror image of the earlier Mars Pathfinder landing, Desai
said. The mass and incoming flight angles of the vehicles are
different, he said.
As they plummet toward Mars' surface, each of the rover-
carrying spacecraft, said Desai, will transmit data on their
condition.
"They will have a more detailed dictionary, better than
Pathfinder, allowing us to isolate particular events during the entry,
descent and landing," Desai said.
Out maneuvering
NASA proposes to build and launch to Mars in 2007 a
sophisticated long-range, long-duration mobile science laboratory.
A Langley team is busy defining a "smart lander" -- a
spacecraft shell that holds the robotic lander as it aerobrakes and
maneuvers itself through the thin Martian atmosphere.
"It's an exciting mission from the technology standpoint, as
well as the possibility for science," Lockwood said.
Plopping heavy robotic hardware onto Mars requires use of a
smart lander that not only plows through Mars' atmosphere, but thinks
for itself as it glides and banks toward a pre-selected landing zone.
Langley engineers are studying different spacecraft shapes,
called aeroshells, capable of "aero-maneuvering" at Mars. The hope is
to shrink a Mars landing zone from the usual 62-mile to 124-mile (100-
kilometer to 200-kilometer) footprint down to a mere 2 miles (3
kilometers). It would be the most unique Mars entry ever attempted,
Lockwood said.
"This would be a significant increase in capability.
Scientists can select more interesting landing sites," she said. "We
are aiming at offering the most capability possible with the
technology we'll have."
========
This has been the December 4, 2000, issue of SpaceViews.
SpaceViews is also available on the Web at:
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