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发信人: bage (网事如疯·春心萌动), 信区: AerospaceScience
标 题: SpaceViews -- 2000 December 11(转载)
发信站: 哈工大紫丁香 (2000年12月22日18:55:32 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 2000.50
2000 December 11
http://www.spaceviews.com/2000/1211/
*** News ***
Endeavour Crew Wraps Up Successful Mission to Space Station
NASA Studies Shuttle Booster Problem Following Endeavour's
Launch
Mars Home to Ancient Lakes
Atlas Booster Carries Secret NRO Satellite To Orbit
Russian Rocket Launches Israeli Observation Satellite
U.S. to Pay $84 Million For Use of Iridium Satellites
Russians Suggest Computer Error For QuickBird Failure
Cometcatcher Trims Course for Earth Flyby
SpaceViews Event Horizon
Other News
*** Articles ***
Mir's Deorbit Will Rain Down Wreckage; But Where?
Will NASA's Goldin Continue to Lead the Space Agency in 2001?
Deep Space Network Faces Major Crunch
*** News ***
Endeavour Crew Wraps Up Successful Mission to Space Station
[Editor's Note: The following is a summary of articles filed in the
last week by Todd Halvorson, SPACE.com's Cape Canaveral Bureau Chief.]
The crew of the space shuttle Endeavour completed a successful
mission to the International Space Station last week, installing a
critical set of solar panels for the orbiting facility despite some
early deployment problems.
In a deliberate stop-and-go operation that took two hours,
Endeavour's astronauts inched the second of two delicate arrays out in
fits and starts Monday, trying to avoid the type of whip-cracking wave
that left an identical wing slack after a speedier deployment the day
before.
NASA mission managers delayed the deployment of the second
wing after an identical array bunched up and bounced back and forth
during a 14-minute deployment sequence late Sunday, December 4. The
result: Cables meant to tighten one of the wing's blankets jumped off
their pulleys, leaving the panel just a bit slack. Engineers think
some of the blanket panels stuck together inside their storage box.
The arrays remained folded up within the box for nine months prior to
Endeavour's Nov. 30 launch.
While the first solar wing was generating electricity, NASA
preferred to see it completely taut to make certain the fragile wing
is secure enough to withstand forces put upon it when U.S. shuttles --
as well as Russian crew transport vehicles and cargo carriers -- dock
with the station, thus considered adding repair work to that wing
during the third spacewalk, scheduled for Thursday.
First, through, was a spacewalk Tuesday to wire up the panels
installed on Sunday. During that spacewalk astronauts Joe Tanner and
Carlos Noriega also moved a radio antenna to its permanent position
atop the solar array assembly, hook up coolant lines and work on
radiators designed to shed heat generated by the station's new
electrical system. They also prepared a shuttle docking port for a
move that will take place when the Destiny lab is delivered early next
year.
During that spacewalk the astronauts also surveyed the slack
solar wing, discovering that razor-thin cables designed to tighten one
of the wing's blue-and-gold blankets jumped off their pulleys. "We
think we've got, hopefully, a pretty good handle on it and can
probably fix it," astronaut Jerry Ross told the spacewalkers from
NASA's Mission Control Center in Houston.
Those observations, along with extensive preparations by
engineers and astronauts on the ground, allowed Noriega and Tanner to
quickly fix the wing during Thursday's spacewalk. The two used
utensils similar to large crochet needles to pull two loose blanket
cables up onto reel-and-pulley assemblies housed in the lengthy
storage box that held the slack arrays before they were deployed.
The quick repair work enabled the astronauts to move rapidly
onto the installation of an electrical cable that will give NASA's
next shuttle crew a key television view when the Destiny lab is
attached to the station. The spacewalkers also mounted a new
measuring device designed to determine whether the huge solar wings
present an electrical shock hazard to astronauts working outside the
station.
With the exterior work complete, the STS-97 crew opened the
hatches separating the shuttle with the ISS on Friday, meeting the
three-man crew currently occupying the station.
"On behalf of the crew on Alpha, I'd like commend Endeavour
and its crew for the tremendous technical challenge and the great
achievement of putting [the power plant] together. We really
appreciate it," station commander Bill Shepherd said.
The new solar arrays -- measuring 73 meters (240 feet) from
tip to tip -- will generate 64 kilowatts of direct current (DC) power,
which will enable Shepard and Russian crewmates Yuri Gidzenko and
Sergei Krikalev to use the Unity module, which had been closed off
since their arrival last month because of the lack of power. The
successful installation also clears the way for the next shuttle
mission to the station in January, when astronauts will add the
Destiny lab module to the ISS.
The crews worked together for only a day, transferring
supplies into the station and trash into the shuttle. On Saturday the
shuttle undocked from the station and circled the facility, providing
the best views yet of the newly-expanded station.
"It's an incredible sight - almost unbelievable," Endeavour
pilot Michael Bloomfield said.
"I think Christmas came early for the International Space
Station," said senior NASA project manager Bob Cabana. "The space
station has definitely spread its wings and is flying high on the
success of this last mission."
Endeavour and its five-man crew are scheduled to land at
Kennedy Space Center at 6:04 p.m. Eastern Standard Time (2304 UT)
Monday.
NASA Studies Shuttle Booster Problem Following Endeavour's Launch
By Todd Halvorson
Cape Canaveral Bureau Chief
SPACE.com
Shuttle Endeavour's five astronauts were one failure away from
a potential catastrophe during their thundering Nov. 30 launch to the
International Space Station.
That was the word Friday after NASA discovered that a key
detonator used to separate a strut holding Endeavour's left-hand solid
rocket booster to the shuttle's 15-story fuel tank failed to fire in
flight.
A back-up detonator, however, did fire, and the 149-foot
booster separated cleanly from the external fuel tank. But an ongoing
investigation could trigger a delay in plans to move shuttle Atlantis
to its oceanside launch pad Monday.
"Engineers are evaluating the cause of the misfire, and that
evaluation will continue through the weekend," said Kennedy Space
Center spokesman Joel Wells.
A decision on whether to move Atlantis to its pad for the
planned Jan. 18 launch of the station's first science lab -- the bus-
sized U.S. Destiny module -- is expected early Monday.
NASA space shuttles employ two solid-fueled rocket boosters
and three liquid-fueled main engines to make an 8.5-minute climb into
space.
Attached to the shuttle's tank by heavy-duty metal struts, the
boosters fire for the first two minutes of flight before explosive
charges are detonated to separate the solid-fueled rockets from the
ship's external tank.
The segmented rockets then fall into the Atlantic Ocean, where
they are recovered for refurbishment and reuse on future flights.
During post-flight inspections late Thursday, technicians
noticed that an explosive charge associated with Endeavour's left-hand
solid rocket booster failed to fire. Known as a NASA Standard
Initiator, the detonator was one of two located on either end of a
strut that connected the booster to the bottom of the tank.
The firing of either detonator results in the separation of
the booster and the tank.
"The way I understand it -- and I don't have all the details
yet -- is that one initiator didn't fire and the other one did the
job," said NASA flight director Bill Reeves.
Had both detonators failed, though, the booster and the tank
would not have separated cleanly. The likely result would have been
the loss of the vehicle and its crew.
The booster problem was news to the Endeavour astronauts, who
joined the first full-time crew of the international station aboard
the outpost Friday.
Asked about the glitch during a space-to-ground news
conference, shuttle skipper Brent Jett said Mission Control had yet to
tell the crew about the malfunction.
"We haven't been told any of that, so it's difficult for me to
comment on that without seeing all the data," Jett told SPACE.com.
But, he added: "Obviously we have redundancy in critical
systems for a reason, and this is one of the times we relied on that
redundancy -- if the report is correct."
Reeves said a Mission Control didn't receive a report on the
problem until just before the news conference. Consequently, NASA
hadn't had time to transmit the report up to the crew.
The same NASA Standard Initiators have been in use since the
Gemini program in the mid-1960s, and the devices have been very
reliable since then, Reeves said.
"For sure I can tell you we've had no catastrophic failures as
a result of these things," he added.
Engineers, meanwhile, are not certain what caused the
explosive charge to fail. Among possible culprits: Flaws in electrical
circuitry that routes computer commands that initiate booster
separation during flight.
"There will be a thorough examination... to determine why the
one (charge) didn't fire," Reeves said. "But the redundant system did
perform its job."
Endeavour and its crew are due to land at Kennedy Space Center
Monday.
Mars Home to Ancient Lakes
By Robert Roy Britt
Senior Science Writer
and Andrew Bridges
Pasadena Bureau Chief
SPACE.com
New pictures released today show outcroppings on Mars that may
represent sedimentary layers formed by ancient lakes, further adding
to the expectation that Mars was once wet and might have harbored
life.
The images suggest that parts of ancient Mars may have been
riddled with lakes, and that the geology of early Mars was much more
dynamic than previously suspected, said the researchers who produced
the images.
And if life existed on Mars when these features formed, some
4.3 billion to 3.5 billion years ago, the researchers believe that
fossil remnants may be sandwiched between the sedimentary rock layers,
just as they are on Earth.
Examples of layering have been known since the Mariner 9
mission in the early 1970s, said lead researchers Michael Malin and
Kenneth Edgett of Malin Space Science Systems in San Diego,
California. But the layering had not been seen in such detail, nor did
anyone know it was so widespread. Other recent findings have shown
evidence of flowing water and water dribbling from canyon walls on the
Red Planet.
"But this would be the first evidence for widespread standing
water," said Wes Huntress, NASA's former space science chief and now
director of the Geophysical Laboratory, Carnegie Institution of
Washington. "If in fact this holds up under scrutiny from the rest of
the community, there's no doubt it's a fantastic discovery."
Huntress was not involved in the research, but he oversaw the
development of the Mars Global Surveyor, which used its Mars Observer
Camera (MOC) to produce the images. He told SPACE.com that like all
new discoveries, this one "is going to be debated heavily."
The debate began before the images were even released.
Robert Craddock, a geologist with the Smithsonian
Institution's National Air and Space Museum, said he reviewed the
paper for the journal Science and recommended it be rejected.
"In reality, they haven't seen anything we haven't seen
before," Craddock said.
"We've known for three decades about these layered deposits
across the planet," he added. "[The paper] fails to place these new
observations into context and you end up with the impression they're
making new discoveries, when all they're doing is looking at it with
new data."
Others, however, were encouraged that the new images do
represent new information.
"This provides much more compelling evidence for the layering,
although we can still argue about what the mechanism is," said Bruce
Jakosky, a professor of geological sciences at the University of
Colorado.
"What we're seeing is a couple of things: One, [the layering
is] much more widespread than people had thought. The second is that
the evidence is incontrovertible," Jakosky said.
The Martian outcrops, in some cases a few miles (kilometers)
thick, appear to be made of fine-grained materials deposited in
horizontal layers, the hallmark of sedimentary rock. These outcrops
are found inside and between craters, and within chasms, said Malin
and Edgett.
A lake is not required to make sedimentary deposits. Wind,
volcanic activity and even an asteroid impact could have similar
effects. But the prevalence of the Martian sedimentary outcrops within
basin-like features suggests that they were deposited by water,
perhaps in lakes that formed within the craters and chasms, the
researchers said.
Under this scenario, sediments may have been transported into
the lakes in regular, swift pulses, building up thin layers. Larger
blocks of sediment may have been deposited when a lake became stagnant
or deep enough to cause sediments to sift down through the water over
longer intervals.
"Some of the MOC images of these outcrops show hundreds and
hundreds of identically thick layers, which is almost impossible to
have without water," Malin said.
If researchers can prove that Mars was once wet, it could be a
significant boost for future Mars missions, with the ultimate goal
being the search for signs of life, past or present.
"I think most of us have been convinced that [there was once
water on Mars] just from the photographs that show erosion that could
only have been done by water," said Morris Aizenman, senior science
associate in the National Science Foundation's Mathematical and
Physical Science Directorate. "This just adds another point to that
very convincing argument."
And Aizenman points out that water is widely viewed as a
necessary ingredient for life as we know it. "With the existence of
water is the possibility that there was once life on Mars," he said.
Malin and Edgett identified three main outcrop types: layered
units, massive units and thin mesa units.
Layered units consist of rock beds only a few yards (meters)
or less thick, stacked on top of one another in distinct groups.
Massive units appear as one bulky rock layer with no clearly defined
horizontal bedding. In a few cases, these types appear together, with
the massive unit always perched on top of the bedded unit.
Thin mesa units, with surfaces ranging from smooth to pitted,
to ridged and grooved, are almost always found on top of eroded
massive or layered sedimentary rock.
A paper on the images will appear in this Friday's issue of
the journal Science. The findings were to be reported at a NASA news
conference Thursday, after an embargo on the information lifted. That
embargo was lifted today, after other news organizations published
accounts of the study.
The sedimentary units show no telltale signs of wind
deposition, and the researchers concluded that explosive volcanic
eruptions and impact cratering probably could not have produced enough
sediment to create the large-scale and geographically widespread
outcrops seen on the Martian surface.
Although Malin and Edgett favor water as the sedimentary
suspect, they also offer an alternative model that involves changes in
atmospheric pressure on early Mars. They suggest that periods of
relatively high atmospheric pressure -- caused by fluctuations in the
amount of solid carbon dioxide on the planet's surface --could have
increased the atmosphere's ability to carry dust produced by heavy
cratering.
To confuse matters, the researchers don't know where the
original sediments came from, or how they were transported to their
final resting places, since there are no traces of gullies or streams
or other channels associated with the outcrops. They think that
erosion may have wiped out both the source of the sediments and their
travel routes.
In some cases, sedimentary rock has eroded out of the crater
in which it formed, also vanishing without a geologic clue.
To Malin, the history of Martian geology looks like a jigsaw
puzzle.
"In the center of the puzzle, we have these layered rocks,
which are good evidence of an extremely dynamic environment. On either
side of this well-developed puzzle piece, we have mysteries." In any
case, Mars' sedimentary rocks suggest a very active early history for
the planet.
"This makes Mars more complicated and more exciting. This
record is going to tell us a lot about what early Mars was like, and
maybe the early Earth as well, since we don't have a lot of rocks on
our own planet from this time period," said Edgett.
Global Surveyor was launched in 1996 to make a detailed map of
Mars from an orbital vantage point. It carries a suite of instruments
designed to provide new details about the planet's surface.
Atlas Booster Carries Secret NRO Satellite To Orbit
By Jim Banke
Senior Producer, Cape Canaveral Bureau
SPACE.com
Blasting off with a clandestine satellite onboard, an Atlas
2AS rocket successfully ended Cape Canaveral's 2000 launch season on
Tuesday with a light show of fire and smoke that could be seen for
miles along Florida's Atlantic coast.
A very public mission for the usually secretive National
Reconnaissance Office (NRO) began at 9:47 p.m. Eastern Standard Time
(02:47 Wednesday GMT) with the ignition of the Atlas rocket's first
stage main engines and two of four solid rocket boosters.
The Lockheed Martin-built Atlas launch vehicle slowly climbed
into a star-filled sky, ignited its remaining two boosters and then
quickly picked up speed as the rocket turned downrange while thousands
of local residents, tourists and holiday shoppers looked on.
Appearing for a short time as the brightest star in the east,
the Atlas soon disappeared from view on its way to deliver the NRO-
designed satellite into its intended orbit. Spacecraft separation from
the Centaur upper stage occurred 29 minutes after liftoff from Launch
Complex 36.
NRO officials would not comment on the Atlas' cargo, but
industry observers agree the spacecraft is a sophisticated data relay
communications satellite, capable of receiving and passing on signals
from other NRO spy satellites in Earth orbit.
Although no clever code name has surfaced for this particular
payload, the spacecraft is believed to be a slimmed down version of a
Satellite Data System spacecraft that was originally designed to fly
-- and did -- on NASA Space Shuttles and Air Force Titan 4's.
Budget conscience NRO officials now procure their launch
vehicles from the commercial marketplace and have turned to
International Launch Services' (ILS) family of Atlas 2 and Atlas 3
rockets to fly several missions. Tuesday's launch fulfilled the second
NRO contract for ILS.
The mission itself, however, was nicknamed "The Great Bear" in
honor of the late Don Potter -- a former Central Intelligence Agency
employee assigned to the NRO as an engineer -- who was a strong
supporter of an NRO community effort called the Cub Run Partners in
Education Program, volunteering at Cub Run Elementary School in
Centreville, Va.
A bear logo was painted on the rocket's nose cone, designed in
a contest that generated 700 entries and won by 13-year-old Samantha
Wingo of Stone Middle School in Centreville, Va., who was present at
Cape Canaveral Air Force Station for the launch.
According to a statement about the dedication from ILS: "The
Ursa Major constellation, the Great Bear, was selected as the theme
for the design because it complemented Cub Run's mascot, the bear cub,
and symbolized Dan's love and support for the students and the
Partners in Education Program."
The Atlas launch team also dedicated the mission to the late
Jennifer Bertuzzi, a flight software engineer who had worked on this
particular mission for five years, said launch commentator Don
Spencer.
Tuesday's launch from the Cape was the last scheduled shot
from the Space Coast for the year 2000. In all there were 19 launches
from the Cape, a number that includes the five shuttle missions flown
from the Kennedy Space Center.
The next rocket to fly from the Cape is scheduled to blast off
on January 18 when shuttle Atlantis is to bring the Destiny science
module up to the International Space Station. That will be followed 12
days later by an Air Force Delta 2 carrying a Navstar Global
Positioning System satellite.
The next Atlas targeted to fly is in May.
Russian Rocket Launches Israeli Observation Satellite
by the Associated Press
for SPACE.com
A Start 1 rocket on Tuesday successfully launched an Israeli
observation satellite into orbit from Russia's Far East, the Strategic
Missile Forces said.
The Eros A1 satellite is Israel's first civilian photography
satellite, and it can take pictures of objects as small as 1.8 meters
(5.9 feet), according to Russian and Israeli media.
It was launched from the Svobodny Cosmodrome in the Amur
region of the Russian Far East, about 5,500 kilometers (3,400 miles)
east of Moscow and entered its orbit, said Lt. Maxim Fedin, a missile
forces spokesman. The rocket used to launch it was converted from a
Topol intercontinental ballistic missile.
The 250-kilogram (550-pound) satellite was built by ImageSat,
Ltd., a joint venture including Israel Aircraft Industries and El-Op
Electro-Optics Industries of Israel, as well as European and American
investors. It is based on an Israeli spy satellite, the Ofeq 3.
Foreign companies routinely use Russian space facilities to
launch commercial satellites. The Russian rockets are usually
considered reliable and a good bargain compared with European and
American competitors.
U.S. to Pay $84 Million For Use of Iridium Satellites
By Jeremy Singer
Spacenews.com Staff Writer
The U.S. Defense Department will pay $3 million per month over
the next two years for unlimited use of the Iridium mobile satellite
telecommunications system, according to a senior Pentagon official.
The Pentagon will spend another $6 million per year to operate
its Iridium gateway station in Hawaii, said Dave Oliver, principal
deputy undersecretary of defense for acquisition, technology and
logistics.
Motorola Inc. of Schaumburg, Ill., the lead investor in
Iridium, has been operating the 66-satellite system since a company
formed for that purpose, Iridium LLC of Washington, went bankrupt last
year.
Motorola's proposed sale of the Iridium assets to a group of
venture capitalists has been approved by the bankruptcy court for the
southern district of New York, according to a document distributed by
Oliver at a Pentagon briefing Dec. 6. The investors have formed a new
company, Iridium Satellite LLC. Boeing Co. of Seattle has agreed to
operate the satellites under contract to Iridium Satellite.
Motorola's approval of the deal was contingent on a Pentagon
agreement to indemnify the company against liabilities associated with
the design, operation and eventual atmospheric reentry of the Iridium
satellites, the document said. Oliver said the Pentagon has agreed to
provide the desired indemnification, which covers liabilities in
excess of Motorola's existing insurance policies.
The military needs the Iridium telecommunications service for
ships at sea, small-unit operations in areas without satellite
coverage, and communications at the Earth's poles, Oliver said.
The Pentagon decided to make only a two-year commitment to the
service to preserve its option to look at comparable services that may
materialize in the near future, Oliver said.
Russians Suggest Computer Error For QuickBird Failure
By Yuri Karash
Moscow Contributing Correspondent
SPACE.com
Russian investigators looking into the November 28 failure of
a Cosmos 3M booster do not think the rocket was at fault, according to
an official with the Russian State Interdepartmental Commission.
Instead, they suggest a computer error inside the satellite
may have caused the U.S.-built spacecraft to unfurl its electricity
generating solar arrays while the rocket was still climbing through
the atmosphere.
Initial reports had blamed a failure of the Comos 3M rocket's
second stage for not placing the satellite into orbit.
"If the failure was caused by an absence of a second burn of
the second stage, we would have noticed the anomaly during the first
burn of this stage already," a member of the commission said in an
interview with the Russian Kommersant newspaper, speaking on condition
of anonymity.
The Cosmos 3M rocket is a version of a former Soviet-era
nuclear missile now modified to serve as a small commercial space
launcher from the Plesetsk Cosmodrome in Northern Russia. Marketed in
the West by United Start Corp. of Huntsville, Alabama, the Cosmos
hardware has a success record of 238 out of 240 launches since 1986
for a 99.2-percent success rate.
A computer error may have resulted from a hold in the launch,
which was delayed one-hour because a Norwegian tracking station was
not ready to monitor the satellite. Russian officials propose someone
forgot to reset the satellite computer to account for the new launch
time.
As result, according to the theory, the spacecraft's flight
command sequence began at the original launch time and, following its
preprogrammed time line, attempted to deploy the satellite's solar
panels while it was still attached to the rocket during the early
phase of the flight.
If this happened, it would have resulted in the destruction of
the satellite and possibly the loss of the rocket.
Data that may help clear this up has not yet been provided to
Russian officials, the commission source said.
Cometcatcher Trims Course for Earth Flyby
By Andrew Bridges
Pasadena Bureau Chief
and Leonard David
Senior Space Writer
SPACE,com
NASA's Stardust is on track for a Jan. 15 flyby of Earth after
flight engineers trimmed the comet-chasing spacecraft's trajectory
this week.
Stardust will swoop to within about 3,700 miles (6,000
kilometers) of the eastern coast of Africa during the early afternoon
local time flyby, a maneuver designed to give it a gravity boost that
will increase its relative velocity and place it in a wider orbit
around the Sun.
The flyby is expected to take place with little fanfare,
unlike the protests that greeted Cassini when it swung past the Earth
in 1999 with its 72-pound (32-kilogram) plutonium fuel source in tow.
"We're solar powered, so I don't think anyone knows we're
coming," said Tom Duxbury, the Stardust project manager at NASA's Jet
Propulsion Laboratory (JPL).
Engineers commanded the probe to fire it rockets on Tuesday to
change its velocity by 2.8 meters (9.2 feet) per second. An earlier
brush with a solar flare -- which temporarily blinded the robotic
spacecraft -- delayed the rocket-firing maneuver. The spacecraft will
perform a similar maneuver on Jan. 5, just 10 days before its Earth
encounter.
After the January flyby, the period of time it takes Stardust
to orbit the Sun will increase by six months, to 2.5 years. That will
place the probe on course to swing past the comet Wild 2 in January
2004 and then back by Earth again two years later.
In 2006, Stardust will jettison to Earth samples of dust and
volatiles it has gathered during its flight past Wild 2, as well as
minute quantities of interstellar dust collected at various other
stages of the mission.
The rocket-firing delay gave flight engineers the opportunity
to double up the trajectory correction maneuver with a second bit of
spacecraft ballet geared to maximizing the scientific value of the
Wild 2 encounter.
Engineers had Stardust turn toward the Sun for approximately
20 minutes on Tuesday, allowing its warming rays to heat a portion of
the probe's navigation camera.
For more than a year, contaminants have gummed up the camera,
obscuring its view and vexing engineers. By heating the camera's
components, the mission team hopes to boil off the contaminant.
For more than a week now, and for another few weeks yet, the
probe has kept two separate camera heaters on in an effort to drive
off more of the frosty contaminant.
"This is the warmest they have been and the warmest we expect
they will ever be," Duxbury said of the combined heating and
sunbathing effort.
The mission expects to receive star images taken by the camera
in late December that will reveal how much the situation has improved.
The camera smudging may vanish completely.
"If we're lucky," said Donald Brownlee, Stardust's principal
investigator at the University of Washington in Seattle. "If we're not
so lucky, it'll stay similar to what we have."
Barely a month later, Stardust will also have a chance to snap
some up-close images of the Moon, which should give an indication of
any improvement to the camera's spatial resolution. In the images, the
Moon's disk should fill about half of the camera's field of view, or
the same as will Wild 2.
Originally, mission members had hoped Stardust would capture
images of Wild 2's nucleus that were 10 times as detailed as those
made by the Giotto spacecraft of Comet Halley in 1986. The Giotto
images marked the first and only time a spacecraft has spied a comet's
nucleus.
However, if the present situation holds, Stardust will return
images with a resolution perhaps only twice as good as those from
Giotto.
"We think we can do the mission okay with the camera as it is.
We can do the comet flyby even without the camera. So it's never a
life-or-death situation. On the other hand, we'd like to take the best
pictures of the comet that we can," Brownlee said.
Following the January flyby, Stardust will then enter a
prolonged cruise period, lapping the Sun until its 2004 meeting with
Wild 2. However, mission planners still hold out the opportunity that
they could encounter Asteroid 5535 Annefrank in November 2002.
The encounter would require the spacecraft to turn its solar
panels away from the Sun and rely on battery power. While risky, the
encounter would allow spacecraft controllers to hone the skills they
will need to help steer the probe to within 90 miles (150 kilometers)
of Wild 2 two years later.
SpaceViews Event Horizon
Note: You can now add these events to your Palm handheld by clicking
on, or copying and pasting into a Web browswer, the URL below each
event. Visit Coola's Web site at http://www.coola.com/ for more
information about this free service.
December 11 Ariane 4 launch of the Eurasiasat 1 satellite from
Kourou, French Guiana at 5:04 pm EST (2204 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
6:04 pm EST (2304 UT)
http://www.coola.com/cgi-bin/addinfo.cgi?pid=10003&rid=975887834&type=D
December 21 Ariane 5 launch of the Astra 2D and GE-8
communications satellites from Kourou, French Guiana
http://www.coola.com/cgi-bin/addinfo.cgi?pid=10003&rid=976492478&type=D
Other News
More Saturn Moons Discovered: Astronomers announced last week the
discovery of four more moons orbiting Saturn, bringing to ten the
number of moons discovered around the planet since October. The four
moons were first spotted in September by astronomers Brett Gladman of
France's Observatoire de la Cote d'Azur and JJ Kavelaars of McMaster
University in Canada, and confirmed by additional observations in
November. Gladman, Kavelaars, and others also discovered four moons
announced in October and two more reported last month, bringing to 28
the total number of moons orbiting the planet. Like the onces
announced in recent months, these moons are believed to be small
bodies, perhaps no more than a few kilometers in diameter, in distant
orbits. Such moons did not likely form at the same time as Saturn but
were captured later by Saturn's gravity, perhaps from the Centaur
family of small icy bodies that orbit the Sun between Saturn and
Uranus.
Pioneer 6 Contacted: NASA successfully contacted Pioneer 6 on Friday,
nearly 35 years to the day after the space agency's oldest working
spacecraft was launched into solar orbit on what was to have been a
six-month mission. NASA used its 70-meter (231-foot) dish antenna in
Goldstone, California, to lock onto a signal from the spacecraft's 8-
watt transmitter at 7 p.m. EST. The first -- and sole survivor -- of
a series of four identical spacecraft, Pioneer 6 was designed for a
fleeting six-month mission to study the solar wind, magnetic field and
cosmic rays. "It's a record for a NASA spacecraft, in longevity,"
said Dave Lozier, the Pioneer flight director. NASA no longer
contacts the spacecraft on a regular basis, but project officials said
they'll try contacting the spacecraft in the future whenever telescope
time can be scrounged.
*** Articles ***
Mir's Deorbit Will Rain Down Wreckage; But Where?
By Leonard David
Senior Science Writer
SPACE.com
Russia is on track to crash its history-making Mir space
station into a huge, desolate zone of South Pacific waters in late
February. The deliberate ditching of the Russian outpost will produce
a sizeable shower of hardware that will reach Earth's surface.
Yuri Koptev, head of the Russian Aviation and Space Agency
(Rosaviacosmos), stated last month that Mir's deorbit would take place
in the February 26-28 time period.
Mir has been a long time fixture in space. The central core of
the Russian station was hurled into orbit on February 20, 1986.
But now, just a little more than 15 years to the day, it will
be lights out for the complex of large docked modules, sets of solar
panels, antennas and various pieces of attached equipment.
If all goes as planned, over 130 tons (118,182 kilograms) of
space hardware will be carefully nudged out of orbit and sent
screaming through Earth's atmosphere.
Space debris experts project that as much as 50 tons (45,455
kilograms) of Mir leftovers are likely to smack into the ocean after
surviving the fiery fall from grace.
Goodbye salute
For NASA's chief, Daniel Goldin, it's goodbye to Mir, hello
safety.
"As far as we are concerned, we salute the decision that the
Russian government made. It's a very reasonable decision," Goldin told
SPACE.com.
Goldin said that at NASA, safety is of the utmost priority.
Protecting the general public first, then the astronauts, followed by
workers on the ground and, finally, the assets.
"They are going right to the priorities we set. Protect the
general public. That is more important than anything else -- I salute
their decision," Goldin said.
Abandon in place
Congressman James Sensenbrenner (R-Wisconsin), chairman of the
science committee in the House of Representatives, believes it's high
time to lower the boom on keeping Mir alive.
"I had hoped the Mir would have been brought down a couple of
years ago. That's when it was obviously used up. The Russian's
actually abandoned it and its modules were slowly depressurizing. Then
it became a political issue in Russia, and an issue of national pride,
" Sensenbrenner told SPACE.com.
The U.S. lawmaker said one of the things hurrying the demise
of Mir is the fact that two other technological marvels -- Russia's
submarine, the Kursk, and the giant television tower in Moscow --
ended up having accidents within a few weeks of each other last
summer.
"I think that if something like that happened to Mir, and a
bunch of people were killed, that would be another blow to Russia's
national pride, one that the Russian government and their president
would not want to have to explain," Sensenbrenner said.
Real rocket science
Russia's disposal of Mir early next year will get an
electronic helping hand courtesy of the U.S. military's global space
surveillance tracking network. In addition, aircraft and mariner alert
notices are to be issued via both U.S. and Russian channels.
But in some government circles, there is concern about too
much American involvement. In the event that Mir's reentry goes awry,
perhaps careening into a populated area, would the United States be
held partly accountable for a botched job?
"Mir's health is pretty good. So I don't see any reason why
they can't do it successfully," said Joseph Loftus, assistant director
for engineering in space and life sciences at NASA's Johnson Space
Center in Houston, Texas.
"Clearly, this is a Russian responsibility. They've
acknowledged that it is their responsibility," Loftus said. "Keep in
mind, these guys are good. They have been doing reentry exercises for
years. This is not some arcane art. It is rocket science, but it's
understandable," he said.
Loftus said that a formal and final government declaration to
dump the Mir is forthcoming. "They treat these kinds of things like we
treat base closings. So there's a commission卆nd going through their
protocol," he said.
The fact that the Mir space base is being downed -- with its
core segment having been in orbit around 15 years -- is of special
meaning to Russian engineers, Loftus said. Those segment's longevity
is the criteria by which engineers measure hardware for use on the
International Space Station, he said.
Slam dunk
Tracking data shows that Mir can remain in orbit until at
least the beginning of March.
The Russian plan as it is now sketched out is to loft in late
January a Progress M1 craft, brimming with propellant. It will join a
Progress 243 vehicle already docked to Mir.
Over several days, "phasing burns" of Progress engines will
position the Mir for the final last blast.
On deorbit day, starting somewhere over Africa, Progress
rocket motors are to ignite and burn for some 800 seconds. Mir ground
controllers will be tracking the doomed station as it flies over
Russia one last time.
As the critical firing ends off the east coast of Russia, Mir
will be on a descending trajectory that will lob it well clear of
Australia, New Zealand, the Marquesas Islands and other populated
oceanic terra firma.
The splashdown zone for Mir is huge -- about 3,726 miles (6,
000 kilometers) long and 124 miles (200 kilometers) wide.
"By the time things start hitting the ocean, they'll be
essentially south of everything. It's as good a place as you are going
to find. There are no islands, no air or ship traffic," NASA's Loftus
said.
Russian roulette
Odds are good that things will go smoothly for Mir's swan
dive.
On the other hand, it might not be all smooth sailing. "I
think the major uncertainty is how Mir itself is going to respond.
It's an old system and [has] been up there a long time," said William
Ailor, director of The Aerospace Corporation's Center for Orbital and
Reentry Debris Studies in El Segundo, California.
Given the complicated structure of Mir, there is no telling
how the orbiting lab might respond during its breakup, Ailor said.
Another uncertainty, Ailor said, is just how turbulent Earth's
atmosphere might be on deorbiting day. Solar activity could mean
larger aerodynamic forces acting on Mir, causing the station to become
unstable.
If so, then Mir takes on a fate that mirrors the old adage:
"What does a 500-pound gorilla do? Anything it wants to."
"If Mir goes unstable, then it's a random process after that.
It will come down where ever it wants to," Ailor said.
But not too worry. No need to run out and buy anti-space
debris hard hats.
"Even if the Russians can't control Mir, there's a lot of
water down below. Three-quarters of the Earth is covered by water. So
chances are it'll hit in the water, and [there's] one-chance-in-four
Mir will hit land," Ailor said.
"There's plenty of open space," Ailor said. "That's why we've
not had anybody actually get hurt, even though we have about 100
reentries a year of major items," he said.
Will NASA's Goldin Continue to Lead the Space Agency in 2001?
By Alan Ladwig
Special to SPACE.com
While Washington caterers wonder if they'll be billing the
Republicans or Democrats for hors d'oeuvres at inaugural balls,
Capitol Beltway space geeks wonder who will be running the show at
NASA. Will Daniel S. Goldin serve under yet another Bush
administration, or will someone new be tapped to lead the space
odyssey in 2001?
A recent memorandum to cabinet and agency heads from White
House Chief of Staff John Podesta has some 3,000 presidential
appointees scurrying to update their resumes. The November 29 memo
asks appointees to submit letters of resignation by December 15 and
indicate a departure no later than noon, Inauguration Day, January 20,
2001.
According to Podesta, this is being done "to give the next
president maximum flexibility in assembling his new administration."
The action affects cabinet secretaries and heads of independent
agencies, including NASA and other Senate-confirmed appointees.
Resignations have not been requested from Inspector Generals or from
term-appointees such as the director of the National Science
Foundation or certain regulatory agencies.
Compared to other agencies, NASA's 18 appointed positions
barely register on the White House personnel radar screen. In addition
to the administrator, only three other positions require Senate
confirmation. These include the deputy administrator, the chief
financial officer and the inspector general. Senior and staff level
personnel in offices dealing with policy, legislation and public
affairs fill most of the remaining positions.
The Podesta memorandum also asked each cabinet secretary and
agency head to identify one Senate-confirmed presidential appointee by
January 12, 2001 "to remain in place." This individual will serve as a
liaison until the incoming president has appointed "at least one
official who is able to assume legal responsibility for the agency."
The list of who is eligible to "remain in place" at NASA is
extremely short. Since the Clinton administration never appointed
anyone to serve as the deputy administrator, only Goldin or Chief
Financial Officer Arnold Holz meet Podesta's criteria.
Goldin, 60, was appointed to the job on April 1, 1992 by
President George Bush. When Bill Clinton defeated Bush in the election
that fall, Goldin elected not to follow tradition and did not submit
his resignation. Instead, he volunteered to remain at NASA until the
Clinton administration was able to appoint a replacement. Eight years
later, he remains in office.
The White House Office of Personnel was unable to locate any
documentation signed by Clinton that reaffirmed Goldin's appointment.
A spokesperson at the White House noted that the NASA administrator is
a "POP" position, meaning he serves at the "pleasure of the
president." Since Goldin never resigned, there was no need for Clinton
to take personnel action so the records list his appointment date as
April 1, 1992.
Goldin could end up being around longer than many people
think, or longer than some people hope.
He already holds the record as the longest single-term head of
the agency, but he could soon become the longest serving administrator
in NASA's history. If he appoints himself as the liaison to the next
administration, and if he remains on the job until March 5, 2001, he
will surpass Dr. James Fletcher's record of eight years, 11 months
during two separate terms.
There is one Fletcher record, however, that not even Goldin is
likely to break. Dr. Fletcher worked for four separate presidents:
Richard Nixon, Gerald Ford, Ronald Reagan and George Bush. Goldin will
most likely serve under three Presidents: George Bush, Bill Clinton
and either president-elect, George W. Bush or Al Gore.
Historically, the appointment of a NASA administrator has not
been a high priority for new presidents. A traditionally bipartisan
agency engaged in risky business, NASA offers little political capital
to White House politicians. Nor does NASA's bank account offer much
enticement to those who measure worth by the size of an agency's
budget. At roughly $14 billion, NASA accounts for less than 1 percent
of a $1.8 trillion Federal budget.
Ronald Reagan didn't get around to nominating James M. Beggs
as administrator until six months after the inauguration. The
confirmation process took another month and Beggs wasn't sworn in
until July 10, 1981. The process was no speedier under George Bush
when he succeeded Reagan in 1988. Bush announced the selection of Rear
Admiral Richard H. Truly on April 13, 1989, but it took another three
months to be confirmed.
There is little reason to believe that NASA will receive more
expeditious attention from a George W. Bush administration. Space was
not a prominent issue for either candidate during the campaign. In six
years as governor of Texas, Bush never visited the Johnson Space
Center in Houston.
One Republican space policy expert who asked not to be
identified doubted that issues related to NASA in general, or
candidates for administrator in particular, will be discussed by the
Bush transition team any time soon.
The only buzz that a member of the Bush family has caused
among space advocates came last week in at the Kennedy Space Center in
Florida. Florida Governor Jeb Bush took a break from the vote recount
controversy and showed up at the VIP site to view the launch of STS-
97.
Deep Space Network Faces Major Crunch
By Andrew Bridges
Pasadena Bureau Chief
SPACE.com
The worldwide array of antennas NASA uses to communicate with
its interplanetary spacecraft faces a looming crisis in late 2003,
when nearly a dozen different missions will require as much as three
times the network support the giant dishes can handle.
The antennas in the United States, Spain and Australia that
provide radio communications for NASA and other spacecraft are
typically always overbooked, with demand steadily outstripping the
sheer number of hours of coverage the giant dishes, some 70 meters
(231 feet) across, can provide.
But in late 2003 and stretching into early 2004, the crunch
will grow far, far worse.
During that time, a regular fleet of American, European and
Japanese spacecraft will all be performing critical maneuvers, placing
an unprecedented burden on the Deep Space Network (DSN) of antennas.
As a result, demand could peak at upward of 300 percent of the
network's capacity, said Gael Squibb, director of the
telecommunications and mission operations directorate at NASA's Jet
Propulsion Laboratory (JPL) that oversees the DSN.
"This is a time where we've seen more loading than we have
typically seen," Squibb said.
Indeed, during that window, within a period of just a few
short months:
* Deep Impact launches;
* CONTOUR flies by the comet Encke;
* Two Mars Exploration Rovers land on Mars;
* Europe's Mars Express enters Mars Orbit;
* Britain's Beagle 2 lands on Mars;
* Japan's Nozomi enters Mars Orbit;
* Stardust encounters the comet Wild 2;
* Cassini performs gravity wave experiments;
* Space Infrared Telescope Facility is in prime of mission;
* 2001 Mars Odyssey is in prime of mission.
"There's a traffic jam at Mars and the antennas are
overcommitted," said Thomas Gavin, director of the space science
flight projects directorate at NASA's JPL.
Although the jam lies years in the future, NASA is already
working to relieve the pressure.
"Three years ahead of the fact there is this recognition of
what is going to happen and 慜h my God, what can we do about it?'"
said Peter Theisinger, the project manager for the twin 2003 Mars
rovers. The rovers, dubbed "A" and "B" for the time being, land on
Mars on January 4 and February 8, 2004, with a 55-day overlap on the
surface.
No one is panicking yet, though. Network planners have
requested that individual missions winnow down the number of hours
they might need.
"We've asked missions to nail down their coverage, what
they'll use and how critical it is," Squibb said.
NASA may also add one or two antennas to augment the giant
dishes already at work in Goldstone, California; Canberra, Australia
and Madrid, Spain.
But at roughly $30 million a pop, 34-meter (112-foot) beam
wave-guide (BWG) antennas don't come cheap. Several European and
Japanese antennas will likely also pitch in with the effort.
"There need to be more ears," Gavin said.
As for rescheduling missions to avoid the winter pileup,
that's just not an option, since it's the heavens -- not NASA --
calling the shots.
"The celestial mechanics are pretty unforgiving," Theisinger
said.
NASA scientists expect to have a plan in place by February.
"There is a lot of action going on and we are just taking an
early look at what this implies so we don't get caught without any
options," Squibb said.
Gavin said the problem is in many ways a badge of pride for
NASA.
"That's a good thing. It's saying we're launching so many
missions that there's a traffic jam," he said.
Even though missions will have to horse trade some time on the
network to make it all work, no one mission will get short shrift,
Theisinger predicted.
"The system operates under the 'they're all my children'
approach," he said. "Everyone is treated as an equal."
========
This has been the December 11, 2000, issue of SpaceViews.
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