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发信人: bage (网事如疯·春心萌动), 信区: AerospaceScience
标 题: SpaceViews -- 2000 April 3(转载)
发信站: 哈工大紫丁香 (2000年12月23日18:02:05 星期六), 转信
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【 原文由 hitsma@0451.com 所发表 】
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S P A C E V I E W S
Issue 2000.14
2000 April 3
http://www.spaceviews.com/2000/0403/
*** Special Section: The Mars Reports ***
Premature Engine Cutoff Likely Cause of Mars Polar Lander
Failure
Independent Panel Report Criticizes NASA Mars Program
Management
NASA Cancels 2001 Mars Lander
Goldin Takes Responsibility for Mars Mission Failures
House, Senate Have Mixed Reactions to Mars Report
*** News ***
Shuttle Launch Delayed A Week
Mir Mission Ready for Launch
Software Glitch Implicated in Sea Launch Failure
Astronomers Find Saturn-Sized Extrasolar Planets
X-38 Completes Longest Drop Test Yet
Inaugural Atlas 3 Launch Delayed a Month
SpaceViews Event Horizon
Other News
*** Articles ***
March Storm 2000: Opening the Space Frontier
*** Special Section: The Mars Reports ***
Premature Engine Cutoff Likely Cause of Mars Polar Lander Failure
The premature shutdown of the descent engine on the Mars Polar
Lander (MPL) spacecraft is the mostly likely cause for the failure of
the mission, a NASA report released Tuesday concluded.
The report was released along with an independent panel's
recommendations for changes in NASA's Mars exploration program, as
well as a NASA announcement that a Mars lander scheduled for launch in
2001 has been canceled. [See accompanying articles below.]
An investigation into the loss of MPL concluded that the most
likely cause for the mission failure was the premature shutdown of the
spacecraft's descent engines as the spacecraft's three landing legs
were extended, a conclusion first reported in the media in February.
As the legs locked into their extended position, the
investigators found, they sent spurious signals to the spacecraft's
computer convincing it the legs has touched down on the Martian
surface and thus should turn off the descent engine used to slow the
spacecraft in the final seconds before landing.
The software for the touchdown sensors were enabled at an
altitude of 40 meters (132 feet) above the surface, when the
spacecraft was descending at 13 meters per second (43 feet/second).
The shutdown of the engines at that point, along with acceleration due
to Martian gravity, would have meant that the spacecraft would have
hit the ground at 22 meters per second (72 feet/second), an
unsurvivable impact speed.
A lack of telemetry from the lander during the entry, descent,
and landing phases of the mission means that investigators cannot be
absolutely certain of the cause of the failure, but both the JPL panel
looking into the mission failure as well as the independent panel
studying the overall Mars exploration program are convinced that this
is the most likely cause of the mission failure.
"It's almost certain that if the lander had got to this point
in the mission, this would have caused the failure," said Thomas
Young, chairman of the Mars Program Independent Assessment Team, at a
Tuesday press conference.
The problem was apparently first noticed only in late January
or early February, when Lockheed Martin engineers working on the now-
canceled Mars Surveyor 2001 mission noticed that the extension of that
spacecraft's landing legs triggered a spurious signal that led the
spacecraft's computer to think it had landed. That finding, and its
implications for MPL, were passed on to investigators a week later.
Software on the spacecraft was supposed to filter out such
spurious signals, but was not properly implemented. A "full-up" test
of all spacecraft systems prior to launch also should have caught the
problem, but did not because the landing leg sensors were improperly
wired.
Four tests were performed earlier this year using engineering
models of MPL to look into this possible failure mode. In all four
cases the landing legs triggered the spacecraft's computer to shut
down its engines, convincing investigators this was the most likely
cause.
Several other failure modes were also considered, and while
not considered likely were not ruled out. These included rough
surface conditions that exceeded the spacecraft's design limits, a
loss of control due to a center-of-mass offset or dynamic effects,
heatshield failure because of micrometeoroid impacts, and impact of
the backshell or parachute of the spacecraft with the lander after
touchdown.
Notably missing from the list of possible failure modes is the
failure of the descent engine because of cold temperatures. A UPI
article published a week earlier claimed that NASA engineers knew that
cold temperatures would keep the descent engine from operating as
intended, possibly triggering an explosion.
NASA vociferously denied the allegation, taking the unusual
steps of issuing a press release and demanding a retraction of the
article. NASA's arguments appear to be backed up by the MPL failure
report, which notes that plans implemented in November, less than a
month before the landing, to warm up catalyst beds in the engines
starting several hours before landing appeared to work.
The same panel that investigated the MPL mission failure also
looked into the loss of the two Deep Space Two (DS2) microprobes
carried to Mars along with MPL. With even less data available to them
from the DS2 spacecraft than from MPL, however, investigators were
unable to come up with a single most-likely cause for the failure of
those two spacecraft.
Instead, the JPL team found four equally-likely causes for the
loss of the two probes, which were designed to crash land on the
Martian surface and burrow up to a meter into the soil. Those failure
modes included bounding off the surface upon impact; landing on the
side of the spacecraft, thus hindering performance of the spacecraft's
antenna; battery or electronic failure upon impact; and "ionization
breakdown" of the thin Martian atmosphere caused by voltages at the
tips of the spacecraft's antennas, degrading antenna performance.
Investigators also concluded that the testing program for the
microprobes was so inadequate that "the probes were not ready for
launch," said Young.
Independent Panel Report Criticizes NASA Mars Program Management
A report issued Tuesday by an independent panel criticized
NASA's management of its Mars exploration program and made a number of
recommendations to set the program back on track.
NASA officials appeared to accept the conclusions made by the
Mars Program Independent Assessment Team and announced a number of
immediate changes to the management and funding of its Mars program.
The report was released at the same time that a JPL report
into the loss of Mars Polar Lander was released. That report found
that a spurious signal from the spacecraft's landing legs likely
caused the descent engine to shut down early, leading to a crash
landing that the spacecraft could not have survived.
The independent panel, headed by former Lockheed Martin
executive Thomas Young, found that the Mars Surveyor 1998 missions,
Mars Climate Orbiter and Mars Polar Lander, lacked the necessary
oversight, testing, and independent analysis needed to make ensure
successful missions.
Without this, even a few mistakes can lead to a mission
failure, the panel concluded. "In space, it's a 'one strike and
you're out' business," Young said during a Tuesday press conference.
Both the failures of Mars Polar Lander and Mars Climate
Orbiter, which was lost when a mixup in units between JPL and Lockheed
Martin caused the spacecraft to drift off-course burn up in the
Martian atmosphere last September, could have been prevented with
appropriate testing and oversight, the panel concluded. "Mistakes
were made in areas where we know how to do things correctly," said
Young.
The lack of proper management stemmed from rigorous cost and
schedule limitations on the program. The success of the Mars
Pathfinder mission, which cost approximately $250 million, led NASA to
believe it could then do the two Mars Surveyor 1998 missions for about
the same cost.
"We were pushing beyond the boundary" with those missions,
admitted Ed Weiler, NASA associate administrator for space science,
who estimated that the two missions were underfunded by about 30
percent. "We could have pulled these missions off if we weren't so
cheap."
NASA, JPL, and Lockheed Martin, the prime contractor for the
Mars Surveyor 1998 spacecraft, were all criticized for management
problems which led to the mission failures. "There is an ample amount
of criticism for all participating organizations," said Young.
The independent panel recommended a number of changes in how
future Mars missions are run. Those recommendations ranged from
establishing adequate budget margins for missions so there is reserve
funding in the event of problems, thorough test and verification
programs, experienced project management, and an overriding dictum:
"If not ready--do not launch."
At the Tuesday press conference where those results were
released, Weiler announced a number of changes to the Mars exploration
program stemming from those recommendations. Those changes will be
made in three areas: communications, training, and review and
oversight.
Among those changes is the creation of a "Mars Program
Director" at NASA Headquarters who will be responsible for all aspects
of the Mars program. Scott Hubbard, former project manager for the
Lunar Prospector mission at NASA's Ames Research Center, has been
tapped for that position. A similar position will also be created in
the near future at JPL.
NASA Headquarters will also take over control of overall
program budget reserves, rather than distribute them to various
spacecraft projects. This is designed to encourage project managers
to talk with NASA in the event they run into problems that require
additional funding, Weiler explained.
Weiler stressed the need for those changes, and in the process
shed some new light on the cancellation of another space science
mission last year. Weiler said he found that the proposed Mars sample
return mission, originally scheduled for launch in 2005, was operating
last year with just 10 percent budget reserves, a value Weiler said
was too low. The effort to increase those reserves led to the
cancellation of the Champollion comet lander mission, Weiler said.
Champollion was part of NASA's New Millennium Program of
technology demonstration missions and would have been the first
spacecraft to land on a comet. The cancellation was believed at the
time to be an effort to free up funds for a Hubble Space Telescope
repair mission as well as additional delays in the launch of the
Chandra X-ray Observatory.
While the panel leveled its share of criticism at NASA and
other organizations for the Mars mission failures, it endorsed
continued Mars exploration. "Mars exploration is an important
national goal which should continue," the panel concluded.
The panel also endorsed NASA's "faster better cheaper" (FBC)
mission philosophy, even as that concept has come under increased
attack from the recent Mars mission and other mission failures,
although it said NASA needs to formulate a "crisp" definition of what
FBC means.
One hint of how a chastened NASA might define FBC came from
Weiler. While saying that NASA will continue to do faster and cheaper
missions, "the emphasis will be on the better."
NASA Cancels 2001 Mars Lander
In a move considered all but inevitable, NASA officially
canceled Tuesday a mission to launch a Mars lander mission in 2001 and
announced plans to reconsider its overall Mars exploration program.
The decision to cancel the Mars Surveyor 2001 lander was
announced at the same time both a report into the failures of Mars
Polar Lander and Deep Space Two were released as well as a report from
an independent team on NASA's Mars exploration efforts.
The decision to cancel the lander had been anticipated since
shortly after the failure of the Mars Polar Lander mission in
December, although leading NASA officials refused to rule out the
mission altogether until now.
Ed Weiler, NASA associate administrator for space science,
said at a press conference instruments and other systems for the 2001
lander would be completed, but not flown on that spacecraft. Instead,
those systems would be used on a future mission, such as a 2003
lander.
The 2001 lander carried cameras to provide high-resolution
images of the Martian terrain and spectrometers to study the
composition of rocks and soil. In addition, the lander carried the
"Marie Curie" rover, an upgraded version of the Sojourner rover flown
on Mars Pathfinder.
The lander included a suite of experiments designed to help
characterize conditions important to future human missions, such as
the radiation environment on the surface and any possible soil
toxicity issues. The lander also had an educational component, with a
Martian sundial and a student-designed "nanoexperiment" sponsored by
the Planetary Society.
NASA will go ahead with the Mars Surveyor 2001 orbiter,
however. That spacecraft, similar in design to Mars Climate Orbiter,
will carry instruments to study the composition of the Martian surface
and look for evidence of hydrogen -- and thus possibly water -- just
below the surface.
The search for past and/or present life on Mars will be the
centerpiece a revised Mars exploration program to be developed over
the next several months, an effort that requires that scientists
"follow the water", said Weiler. "You must know where the water was
and where the water is" on Mars, he said.
That revised exploration plan will include a mix of large and
"very small" missions using advanced technologies. NASA plans to
emphasize reconnaissance, navigation, and communications capabilities
in those future missions.
That revised schedule of missions is expected to be completed
by mid-summer. Without releasing any details, NASA officials made it
clear that the goal of returning samples from Mars would be pushed
back from its original 2008 date. "I'm not telling them 'You must
bring a rock back in 2008,'" Weiler said. "This is going to be a
decade-long program."
Goldin Takes Responsibility for Mars Mission Failures
In his first public comments since the release of an
independent report sharply critical of NASA's Mars exploration
program, space agency administrator Dan Goldin accepted responsibility
Wednesday for the recent mission failures and promised to work with
employees to make improvements.
"As the head of NASA, I accept responsibility" for the recent
failures of Mars Climate Orbiter and Mars Polar Lander, Goldin said
Wednesday, March 29, in a speech to employees at JPL.
"In an effort to empower people, I pushed too hard," he
explained. "It may have made some failures inevitable."
The relatively short speech by Goldin, who did not take any
questions from the audience of employees at JPL's Von Karman
Auditorium, was his first public statement in the wake of Tuesday's
release of a report by the Mars Program Independent Assessment Team
that was critical of NASA's management of the two failed missions.
Goldin's visit to JPL was intended to shore up sagging morale
at the center, which ran the two failed Mars 98 missions. Goldin said
he met with the leaders of the team that ran those missions the night
before, not the criticize them but to praise them.
"I salute that team's courage and conviction," Goldin said.
"They need not apologize to anyone. They did not fail alone. If
anything, the system failed them."
Goldin also used the talk to brush aside rumors that NASA
would be moving control of Mars or other deep-space missions from JPL
to another NASA center. "Don't believe what you read in press," he
warned. "JPL is and will continue to be the center of excellence for
America in deep-space missions."
Saying that "even the best must do better," Goldin to call on
employees to continue to embrace NASA's "faster better cheaper"
philosophy, but to speak up -- and to listen -- when problems develop
during a project. "I'm not inferring that anyone is bad," Goldin
said. "I'm just saying that we need a stronger process of listening."
"Simply put, our mission to explore the frontier of space and
to enrich life here on Earth is simply too exciting, too inspiring,
too important to do anything else."
House, Senate Have Mixed Reactions to Mars Report
Members of the U.S. House of Representatives and Senate had
mixed reactions to Tuesday's release of an independent panel's report
on NASA's Mars exploration program, with some Senators extremely
critical of the space agency.
The release of the report by the Mars Program Independent
Assessment Team, headed by former Lockheed Martin executive Thomas
Young, garnered strong reactions from leading Senators, who now want
NASA to release additional information about the investigation into
the failure of the Mars Polar Lander (MPL) mission.
"My initial review of the Young report on the Mars Polar
Lander and Deep Space 2 Missions confirms my belief that NASA senior
management is missing in action," said Sen. John McCain (R-AZ),
chairman of the Senate Committee on Commerce, Science, and
Transportation, the committee that oversees NASA. "This report is an
embarrassment to the agency."
McCain and several other leading Senators from the committee,
both Republican and Democrat, requested copies from NASA of all tests
performed on the engine systems on MPL. "In light of recent news
accounts that NASA test results may have been altered, we, on the
Senate Commerce Committee, must be able to review the best numbers
available on the reliability of Mars Polar Lander," said Sen. John
Breaux (D-LA), ranking minority member of the Science, Technology, and
Space Subcommittee of the Commerce Committee.
That request was apparently prompted by a UPI report earlier
in March that claimed that NASA middle management knew that a problem
with the descent engine would have prevented MPL from safely landing,
but covered up those test results. NASA strongly denied those claims,
and the engine system was largely exonerated of blame by the JPL panel
investigating the mission failure, who instead believe a problem with
software on the lander prematurely shut down the engine when the
landing legs were extended prior to touchdown.
"I think a thorough review of Mars Polar Lander documents is
not just in order, but is imperative," said McCain. "We owe it to the
American taxpayer. I believe it抯 important that this Committee
exercises more rigorous oversight of NASA from this point forward."
McCain's criticism of NASA is not surprising. McCain, who
suspended his campaign for the Republican Presidential nomination in
early March, voiced his criticism of NASA management practices on
several occasions on the campaign trail as well as on his Web site.
"We still support NASA," he said on NBC TV's Today show last December,
but added, "I think we've got to look at what they've been doing and
how we can ensure the best use of the American taxpayers' dollars.
Members of the House of Representatives were not as strongly
critical as their Senate colleagues about NASA management, although
they still made their displeasure known.
"During the past few months, some have argued that NASA抯
'faster, better, cheaper' philosophy was the underlying cause," said
Rep. James Sensenbrenner (R-WI), chairman of the House Science
Committee. "However, it's important to recognize the Young Report
points not to the 'faster, better, cheaper' philosophy, but rather to
an overly aggressive interpretation of 'faster, better, cheaper'."
"Given the Young Report抯 finding that these Mars missions
were underfunded by 30 percent, I am concerned NASA may have misjudged
the minimum resources needed to successfully complete these missions
under the 'faster, better, cheaper' philosophy," Sensenbrenner added.
"This approach has resulted in some exhilarating achievements and some
incredible failures. The failures are more exasperating because they
were caused by such seemingly simple mistakes."
Some members of Congress, though, struck something of a
conciliatory note. "While these failures have been a heavy blow to
our Mars exploration program, NASA must be supported through this time
of evaluation and correction," said Rep. Dave Weldon (R-FL), vice-
chairman of the space subcommittee of the House Science Committee.
However, he added, "NASA management must ensure that NASA's other
objectives, namely the human space flight program, are beyond
reproach."
Sensenbrenner has tentatively scheduled a hearing of the House
Science Committee on April 12 that will feature Young and other
officials to discuss the contents of the report.
The long-term effects of the hearings and investigations
remains to be seen, but it's unlikely that it would result in less
Congressional support for space exploration in general. "The members
of this Committee understand that space exploration is inherently
risky," said Sen. Ernest Hollings (D-SC), ranking minority member of
the Senate Commerce Committee. "We want to be confident that risks
being taken are in pursuit of scientific breakthroughs, and are not as
a result of errors on the ground."
*** News ***
Shuttle Launch Delayed A Week
The launch of the shuttle Atlantis has been delayed a week to
allow the a sprained ankle suffered by the mission commander enough
time to heal, NASA announced Wednesday.
The launch of Atlantis on mission STS-101 is now scheduled for
Friday, April 24, at 4:15 pm EDT (2015 UT), from pad 39A at the
Kennedy Space Center, Florida. That launch date is a week later than
previous plans.
NASA made the decision to delay the launch to allow extra
training time for shuttle commander James Halsell. Halsell suffered
what NASA termed a "moderate sprain" to an ankle while climbing out of
a simulator at the Johnson Space Center March 15.
While the ankle is healing well, Halsell has not been able to
keep up with training, including T-38 and Shuttle Training Aircraft
flights. The week's delay should give Halsell the time needed to
complete those training flights once his ankle heals.
The delay had been anticipated by shuttle officials. On March
24 NASA delayed the Terminal Countdown Demonstration Test, a dress
rehearsal for the launch, a week from March 30-31 to April 6-7,
because of Halsell's ankle injury.
The delay will also give the rest of the crew additional
training time. This should prove especially useful for the three
newest members of the STS-101 crew, Susan Helms, James Voss, and Yuri
Usachev. They were added to the crew in February to replace three
other crew members who were transferred to another shuttle mission,
STS-106.
That transfer was prompted by a change in mission plans for
STS-101. The mission was originally scheduled for launch only after
Russia launched the Zvezda service module to the International Space
Station so that the station could be outfitted for its first permanent
crew. However, with the service module launch delayed until July, and
the need to perform maintenance on the two ISS modules currently in
orbit, NASA split the original STS-101 mission into two parts.
The new STS-101 mission will work on the Zarya and Unity
modules, including replacing a faulty battery in Zarya. STS-106,
tentatively scheduled for launch in August, will perform the remainder
of the tasks originally scheduled for STS-101. The first ISS crew of
one American and two Russians would then be launched on a Soyuz by
late this year.
Mir Mission Ready for Launch
A pair of cosmonauts are ready to launch early Tuesday on not
only the first mission to the Mir space station since it was abandoned
last August, but the first commercial human space flight.
Soyuz-TM30 is scheduled for launch at 1:01 am EDT (0501 UT)
Tuesday, April 4, from Baikonur, Kazakhstan. The spacecraft and its
two person crew, Alexander Kaleri and Sergei Zaletin, will dock with
the space station two days later.
The mission is the first human space flight supported solely
by commercial and not government funding. MirCorp, a Netherlands-
based company, is funding the mission to check out the station for
future commercial uses.
"The April 6 docking will fulfill MirCorp's promise to
reactivate Mir -- preparing it for commercial operations that are
expected to range from industrial production and scientific
experimentation to space tourism and in-orbit advertising," said
Jeffrey Manber, the American president of MirCorp.
Kaleri and Zaletin will spend about 45 days on Mir,
reactivating systems on the station and fixing any problems. High on
their list of activities will be identifying the source of a small but
persistent air leak on the station first noticed shortly before the
last crew left the station in August 1999.
Already some systems on Mir have been reactivated after months
of inactivity. On March 24 station controllers successfully
reactivated the station's main computer and gyrodynes, which maintain
the station in the proper attitude.
If the cosmonauts can successfully restore Mir to good working
condition, it will open the way for future commercial use of the
station. "Mir's successful reactivation will enable the current
investors to continue their backing for the project, and will allow
MirCorp to seek additional funding on the capital market for long-term
commercial operations on Mir," said Chirinjeev Kathuria, an
entrepreneur who is one of the investors in MirCorp.
In a speech last month Manber said MirCorp is planning the
next mission to Mir in September. That mission could fly with the
world's first paying space tourist, he said, as several qualified
individuals are reportedly seriously interested in the flight.
The two cosmonauts on this mission were originally going to be
joined by a third person, Russian actor Vladimir Steklov. Steklov was
to film portions of a movie called "The Last Journey" about a
cosmonaut who refuses to abandon Mir. However, he was bumped from the
mission last month when the movie's producers failed to pay the
undisclosed fee for flying Steklov to Mir, estimated to be on the
order of $10 million based on past deals.
Manber also said last month that MirCorp would consider an
initial public offering (IPO) of stock in the company next year that
could raise several hundred million dollars more for Mir. Some of
that would go into a renovation of the station. "There's nothing
wrong with the Mir station that money can't cure," he said.
A successful reactivation and subsequent commercial use of Mir
would be a major victory for the Space Frontier Foundation, a space
activist organization that has fought efforts to deorbit Mir over the
last few years with a "Keep Mir Alive" campaign.
That campaign will soon reach a successful conclusion when the
new Mir crew docks with the station. "At that time or shortly
thereafter, we will be declaring victory in our Keep Mir Alive
Campaign, [and] closing the formal Web site," wrote foundation
president Rick Tumlinson in a recent email message.
The foundation will then turn its attention to other matters,
according to Tumlinson: "beginning the next phase of our battle to
create Alpha Town -- the first human community in space -- the hand
off of the ISS [International Space Station] from NASA to the private
sector."
Software Glitch Implicated in Sea Launch Failure
Investigators believe that a problem with ground software, and
not a hardware failure, caused the March 12 failure of a Sea Launch
rocket, company officials said Wednesday.
A logic failure in ground support system software caused a
valve in a second-stage pneumatic system on the Zenit 3SL booster to
remain open when it should have been closed prior to launch,
investigators believe. As a result, the pneumatic system lost
pressure before and after liftoff.
The pneumatic system is used to control a variety of systems
on the booster, including the operation and actuation of a steering
engine on the second stage. By the time the second stage was started,
the pneumatic system had lost more than half of its pressure, reducing
the performance of the steering engine. This led to the booster
drifting off course to the point where an automated self-destruct
system on the booster was triggered.
The Zenit 3SL was launched early March 12 from Sea Launch's
mobile, floating platform, stationed on the Equator in the Pacific
Ocean southeast of Hawaii. The booster was to place into orbit ICO F-
1, the first satellite in a planned 12-satellite constellation for
satellite phone company ICO.
The software glitch was discovered by engineers from Yuzhnoye,
the Ukrainian company that provides the Zenit booster used by Sea
Launch; and Energia, the Russian company that provides the Blok-DM
upper stage for the Zenit. Officials with Boeing, the American
company that is the managing partner of the Sea Launch consortium,
said that telemetry from the booster supports this conclusion.
Earlier in March Yuzhnoye and Energia were publicly arguing
over the cause of the Zenit failure. At the time Yuzhnoye said a
failure with an Energia-provided guidance computer caused a failure,
an explanation Energia rejected. It's unknown if the "guidance
computer" explanation is related to the software error uncovered by
the two companies.
All four companies involved with Sea Launch -- Boeing,
Energia, Yuzhnoye, and Norwegian shipbuilder Kvaerner Group -- are
conducting independent investigations into the cause of the failure,
the first in three Sea Launch flights. A separate failure review
oversight board, established March 23, will start work in April to
review this failure as well as make sure no similar problems exist
elsewhere.
Sea Launch officials believe the review board's investigation
will be completed by mid-May, allowing Sea Launch to resume launch
operations sometime this summer.
Astronomers Find Saturn-Sized Extrasolar Planets
A team of veteran planet hunters has for the first time
discovered extrasolar planets with masses less than that of Saturn, an
"extremely important step" towards the discovery of distant Earth-like
worlds.
Astronomers Geoff Marcy, Paul Butler, and Steven Vogt
announced Wednesday the discovery of a pair of extrasolar planets
orbiting Sun-like stars, each with a minimum mass less than that of
Saturn.
Orbiting the star HD46375, a Sun-like star 109 light-years
away, the astronomers found a planet 80 percent as massive as Saturn
orbiting the star at a distance of just 6.1 million kilometers (3.8
million miles). With that tight an orbit, the planet completes one
revolution around the star in just 3.5 days.
Around another Sun-like star, 79 Ceti, located 117 light-years
away, astronomers found an even lighter planet, with just 70 percent
of the mass of Saturn. It is orbiting the star in an elliptical orbit
with an average distance of 52.5 million km (32.5 million mi.),
approximately the same distance from the star that Mercury is from the
Sun, and takes 75 days to complete an orbit.
The two new planets are the least massive extrasolar planets
ever discovered and the first with minimum masses less than the mass
of Saturn. The previous lightest extrasolar planet was one discovered
last year by Swiss astronomer Michel Mayor and colleagues. That world,
orbiting the star HD75289, has a minimum mass 1.4 times that of
Saturn.
Marcy, Butler, and Vogt made the discovery by carefully
measuring shifts in the wavelength of spectral lines from these stars,
a technique known as the radial velocity method. The "wobble" induced
in the star by a planet as it rotates around the star causes the
wavelength of the spectral lines to shift because of the Doppler
effect. Measuring the magnitude and period of the shifts allows
astronomers to determine the mass, period, and orbital distance of the
perturbing planets.
A drawback of the radial velocity method is that without
knowledge of the inclination of the planet's orbit as seen from Earth,
the exact mass of the planet cannot be determined. A planet whose
orbit is nearly face-on to the Earth would have to be very massive to
generate the same wobble as one in an edge-on orbit. Thus, the mass
determined by the radial velocity method is usually just a minimum
mass, leading some critics to wonder if the objects being detected are
not, in fact, much more massive brown dwarfs, or "failed stars."
The discovery of these worlds with even smaller minimum masses
should go a long way towards convincing astronomers that these are
planets and not brown dwarfs. "Now we are confident we are seeing a
distinctly different population of bodies that formed out of dust
disks like the disks Hubble Space Telescope has imaged around stars,"
said Marcy.
Another key aspect of this discovery is that the wobble
velocity of these stars is about 11 meters per second (24.5 mph), less
than the wobble velocity of our own star generated by Jupiter. This
makes it possible for astronomers to eventually discover "Jupiter
analogues", extrasolar planets the mass of Jupiter orbiting in
distant, circular orbits, rather than the very close or eccentric
orbits in which extrasolar planets to date have been discovered.
Such Jupiter analogues are the "Holy Grail" of planet
searches, said Alan Boss of the Carnegie Institution of Washington.
Stars with Jupiter-like worlds in Jupiter-like orbits would be good
places to look for even smaller Earth-like planets in orbits that
could support life.
"The important news today is that the discovery of Saturn-like
planets is an extremely important step towards the discovery of
terrestrial planets," added Heidi Hammel, an astronomer with the Space
Science Institute.
Such discoveries, though, remain beyond the scope of current
instruments and techniques. Just being able to find Saturn-like
planets involved two years' of work using a $5-million spectrograph
designed by Vogt and installed on one of the twin Keck Observatory
telescopes in Hawaii, the largest in the world.
Marcy believes that further work would allow them to discover
planets as small as Neptune, a planet with only five percent the mass
of Jupiter. However, limits on technology and the size of terrestrial
telescopes will prevent them from finding smaller worlds. "We'll be
out of business in ten years," quipped Marcy.
Discovery of terrestrial worlds will have to wait for future
spacecraft missions, like the Space Interferometry Mission. That
spacecraft, scheduled for launch in 2006, will combine light from two
or more widely-separated telescopes to create a large "virtual" mirror
that may be able to resolve smaller worlds around other stars.
Another future mission, the Terrestrial Planet Finder (TPF),
would fly several large telescopes in interplanetary space that would
be able to take pictures and spectra of terrestrial worlds, allowing
astronomers to determine which worlds might be able to support life.
Earlier in March JPL awarded study contracts for the TPF
mission to several companies, including Lockheed Martin, Ball
Aerospace, and TRW, although the mission itself is still far in the
future: NASA doesn't expect TPF to fly until at least 2012.
Until then, though, astronomers will stick with current search
techniques to look for more Jupiters and Saturns around Sun-like
stars. Butler said they plan to look at least 1,100, and potentially
up to 2,000, Sun-like stars within several hundred light-years of the
Earth before they conclude their research.
X-38 Completes Longest Drop Test Yet
The X-38, an experimental prototype of a future "lifeboat" for
the International Space Station, completed its longest drop test yet
from an aircraft Thursday, NASA reported.
The unpowered X-38 was released from a B-52 aircraft at an
altitude of 11,900 meters (39,000 feet) above Edwards Air Force Base,
California. After flying free for 44 seconds and reaching speeds of
over 800 kmph (500 mph), the X-38 deployed a drogue parachute that
slowed the vehicle down to 113 kmph (70 mph).
The X-38 then deployed a 510-square-meter (5,500-square-foot)
parafoil that allowed the vehicle to glide gently for 11 1/2 minutes
before landing on the dry lake bed at Edwards. The landing was
reported to be smooth even though one of three landing skids on the X-
38 failed to deploy as planned.
Thursday's test, originally scheduled for February but delayed
because of a technical problem with the vehicle, was the fifth for the
X-38 program dating back to March 1998, and the third for this X-38
vehicle, designated V-132. The X-38 was dropped from the highest
altitude and achieved the highest speed yet during the test.
More importantly, this test for the first time simulated the
conditions that a real spacecraft based on the X-38 would experience
as it returned to Earth. The drogue chute was designed to deploy at
the same speed and altitude during this drop test as it would for a
spacecraft returning from orbit.
"By intercepting the spaceflight return profile, we verified
the X-38's operation in a phase of flight it will encounter as a
station lifeboat," said X-38 program manager John Muratore. "We
traveled a road for the first time today that we will soon follow all
the way home from space."
The flight also successfully tested new automated flight
control software as well as a new, more stable parafoil design. "We
now understand the dynamics of parafoil deployment and some of the
separation operations of the vehicle," said project manager Bob Baron.
NASA plans to conduct additional, more complex tests through
2001 as engineers drop the vehicle from higher altitudes to better
simulate the flight conditions a spacecraft returning from space would
experience. The X-38 tests will culminate in 2002 when an X-38,
carried into orbit by the space shuttle, will fly back to Earth.
The X-38 is intended to be a prototype for a crew return
vehicle (CRV), or "lifeboat" that would be attached to the space
station to allow the crew to evacuate in the event of an emergency.
While a lifeboat is considered mandatory for ISS, there is
some degree of uncertainty whether it will be based on the X-38.
Space News reported in its March 20 issue that NASA has delayed until
2002 a decision on what kind of CRV to use for the station.
Voices outside of NASA have been encouraging the agency to
look at other alternatives to the CRV, including a Crew Transfer
Vehicle (CTV) that could carry crews to and from ISS. Right now only
the shuttle and the Russian Soyuz vehicle are slated to carry crews to
the station, but concerns about shuttle reliability and Russia's
ability to support its share of ISS work have provided an impetus to
alternative plans.
Space News reported that NASA plans to fund a series of trade
studies this year to see if a CRV or CTV is the best solution for the
space station. If NASA were to choose a CTV design, it could mean
scrapping the X-38, although there has been some interest,
particularly by the European Space Agency, in modifying the X-38 to
serve as a CTV launched on an Ariane 5.
Inaugural Atlas 3 Launch Delayed a Month
The long-delayed first launch of Lockheed Martin's Atlas 3
booster will be pushed back another month, this time because of
problems with its satellite payload, company officials said last week.
An Atlas 3A was scheduled to launch around April 14 from Cape
Canaveral on its inaugural flight and place into orbit the Eutelsat W4
communications satellite, which will be used by the European satellite
broadcasting company to provide television and Internet service to
portions of Russia and Africa.
However, Eutelsat requested a delay in the launch to
investigate potential problems with the propulsion system on the W4
spacecraft, built by Alcatel Space of France. That investigation is
expected to push back the launch about a month, International Launch
Services (ILS), the international consortium that markets Atlas and
Russian Proton launches, said in a March 29 statement.
The delay is the latest setback for the next generation of the
venerable Atlas family of launch vehicles. The inaugural Atlas 3
launch was originally scheduled for mid 1999, but was delayed in the
aftermath of a Delta 3 failure in May. The upper stage of the Delta
3, which was the cause of the failure, uses a variant of the Pratt and
Whitney RL-10 engine used in the Atlas 3's Centaur upper stage.
While the Atlas 3 remained grounded, its original payload, the
Telstar 7 communications satellite, canceled its launch contract.
Loral Space and Communications decided to use an Ariane 4 booster,
which successfully launched Telstar 7 in September. The Atlas 3A
launch was then put on indefinite hold until ILS signed a launch
contract with Eutelsat in early February for the W4 spacecraft.
The Atlas 3A is an upgraded version of the Atlas 2 that has
been in service for many years. The Atlas 3A features the Russian RD-
180 engine for its single-stage main engine, a lengthened main stage,
and a single-engine Centaur upper stage. Another version, the Atlas
3B, is similar but uses a dual-engine stretched Centaur upper stage.
SpaceViews Event Horizon
April 3-6 16th National Space Symposium, Colorado Springs, CO
April 4 Soyuz launch of a Soyuz-TM spacecraft carrying two
cosmonauts to the Mir space station from Baikonur,
Kazakhstan at 1:01 am EDT (0501 UT).
April 18 Ariane 4 launch of the Galaxy 4R communications
satellite from Kourou, French Guiana
April 21 Delta 2 launch of a GPS satellite from Cape Canaveral,
Florida
April 24 Launch of shuttle Atlantis on mission STS-101 from
Kennedy Space Center, Florida at 4:15 pm EDT
(2015 UT)
April 27-29 Space Access 2000 conference, Scottsdale, AZ
Other News
Amateur Launch Effort Falls Short: An effort by a California group
late last month to be the first amateurs to launch a rocket into space
was stymied by a number of technical glitches. JP Aerospace had hoped
to launch a rocket from a set of balloons at an altitude of 30.5 km
(100,000 feet) March 25, but the loss of several of the helium-filled
weather balloons kept the launch platform from reaching the desired
altitude. The team tried to fire the rocket from a lower altitude,
but the ignition system failed, so the group was forced to parachute
the rocket back to Earth. John Powell, head of JP Aerospace, vowed
last week to determine the problem and try to launch again, although
this launch attempt "zeroed out" the team's bank account. JP
Aerospace hopes to eventually fly a rocket that travels to an altitude
of 200 km (125 mi.) and capture the $250,000 Cheap Access To Space
(CATS) Prize.
New Black Hole Images: Astronomers have combined images from two
cameras on the Hubble Space Telescope to provide the first close look
at spirals of dust in the center of galaxies that may feed black
holes. Ohio State astronomers used images from visible and infrared
cameras to reveal dust formations that appeared to be spiraling into
supermassive black holes in the center of 20 active galaxies. The
existence of such spirals of dust may be the key difference between
active galaxies and "normal" ones, like the Milky Way, which have
black holes but do not emit the large amount of energy that active
galaxies do. "Before black holes become active, you have to feed
them," said astronomer Richard Pogge.
A Solar Heartbeat: The discovery of a 16-month "heartbeat" within the
interior of the Sun may be an important step towards understanding the
Sun's 11-year activity cycle, scientists said last week. In a paper
published in the March 31 issue of the journal Science, a team of
solar scientists reported the discovery of two parallel layers of gas
deep within the Sun that speed up and slow down in synchronicity: as
one speeds up, the other slows down. The layers are located on either
side of the tachocline, a region of the solar interior thought to
drive the Sun's magnetic fields and thus activity such as solar flares
and storms, which vary on an 11-year cycle. "For the interior to
change speed every 11 years would make sense," said Jesper Schou of
Stanford University. "But a 1.3-year period was unexpected. We don't
know what it means, but isn't it interesting!"
Scientists Get Access to XMM: The European Space Agency's X-Ray Multi
Mirror (XMM) observatory, now named XMM-Newton, was turned over to
scientists last month after completing an initial set of on-orbit
checks. XMM-Newton will now begin over two months' worth of instrument
calibrations as that spacecraft engineers are satisfied that the
orbiting observatory is working as intended. "Our part of the job,
which for some of us started way back in the late 80s, is done," said
XMM-Newton project manager Robert Laine. "It is now up to the science
teams to fine-tune the instruments for the start of full science
operations this summer." Scientists will now precisely calibrate the
instruments by observing well-known X-ray sources in the universe
before regular science observations begin in June.
Weather Satellites Turn 40: Saturday marked the fortieth anniversary
of the launch of the first weather satellite, a tool that has since
become indispensable to meteorologists worldwide. TIROS-1 was
launched into low-Earth orbit April 1, 1960 on a Thor-Able rocket from
Cape Canaveral. During its 78-day operational life the spacecraft
returned over 20,000 images of the Earth, which showed for the first
time that coherent cloud formations could stretch for thousands of
kilometers, and that those formations were closely correlated with
warm and cold fronts.
Briefly: You would think in the wake of the recent spate of reports
criticizing NASA that the space agency's workforce would be
demoralized. In fact, a study released Friday showed that NASA
employees enjoy a greater level of job satisfaction than most other
federal workers. The National Partnership for Reinventing Government
(NPR) Employee Survey showed NASA employees gave the agency the
highest favorable ratings in 14 out of 32 categories... The failure of
Iridium is proof that "big, shiny space rockets aren't the coolest
things in the universe," claimed science fiction author Bruce Sterling
in an essay published in the online magazine Feed last week. Rockets
are "incredibly cool" only if you're strapped inside one, he writes,
"Then, yeah, they're really amazing, but that's never gonna happen to
you." Hmmm... maybe someone should book Sterling a reservation with
one of the nascent space tourism companies?
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*** Articles ***
March Storm 2000: Opening the Space Frontier
by Jeff Foust
Once again, dozens of space activists descended on Washington,
DC last month for March Storm 2000, the sixth annual grassroots space
lobbying effort organized by ProSpace, in an effort to promote
programs and policies that promise to open the space frontier.
Several dozen people -- one of the largest turnouts ever --
visited the offices of well over 200 Congressmen and Senators during
the week of March 13-17. This year's event was functionally similar
to past years' events: a training session on Sunday followed by five
days of briefings with Congressional staffers. (For personal
perspectives on the past two March Storms, read "In the Eye of March
Storm" [http://www.spaceviews.com/1998/04/article2a.html] from the
April 1, 1998 issue and "March Storm Redux" [http:
//www.spaceviews.com/1999/04/article2a.html] from the April 8, 1999
issue.)
Since March Storm was started in 1995 ordinary citizens,
traveling to Washington at their own expense, have had a considerable
impact on space policy, raising the awareness of commercial space
among members of Congress and playing an instrumental role in securing
the passage of the Commercial Space Act in 1998. There is still a lot
of work to be done, though, based on the busy agenda this year's March
Stormers had.
The Agenda
The 2000 March Storm agenda included a number of items, split
between legislation designed to support the commercial use of space
and technology and other investments that would also help open the
space frontier.
One piece of legislation in the agenda, the ProSpace
Commercial Space Transportation Investment Incentives Act of 2000,
would provide tax credits to those who invest money in companies
developing new launch systems that promise to reduce space access
costs "significantly below current levels." The legislation was
drafted by ProSpace but has yet to be introduced by any member of
Congress: the purpose of the Congressional visits was to find
potential sponsors and supporters of the bill.
Two other pieces of legislation already introduced were also
included in the agenda. The Spaceport Investment Act (S.1239 in the
Senate and H.R.2289 in the House) would adjust tax legislation to
treat commercial spaceports in the same way as airports, allowing
local and state governments to issue tax-exempt municipal bonds to
fund their development. The Zero Gravity, Zero Tax Act of 2000 (H.R.
3898), introduced just days before March Storm by Rep. Dana
Rohrabacher (R-CA), would provide a 25-year tax moratorium on profits
derived from new space-based profits and services. "Mature" space-
based industries, such as communications and remote sensing, would be
excluded from the bill.
ProSpace also included in this year's agenda a request that
Congress establish a commission that would study the various
privatization options for the International Space Station. This
commission would choose the most promising course for ISS
privatization and create a timetable for that privatization after the
station is fully assembled.
The agenda also included requests for modest funding increases
for several programs: $40 million for the military spaceplane, based
on the X-37 being developed by NASA and Boeing; $30 million for space
solar power studies; and $40 million more for "Alternative Access" to
the International Space Station, an effort to fund other means of
supplying the station than the shuttle. NASA's fiscal year 2001
budget request already included $40 million for alternative access;
ProSpace recommended that this amount be doubled to show NASA's
commitment to use alternative, commercial means of supplying the
station and making it easier for those companies to demonstrate that a
market exists for their services and thus raise funds.
One difference from previous years is that the additional
funding requested was not offset with suggested cuts in other
programs. In the past ProSpace has recommended that funding for other
programs deemed unnecessary, ranging from shuttle upgrades to the
Triana Earth-observing satellite, be trimmed to offset the increases
elsewhere in the budget. Given the current era of large budget
surpluses, the impact of a small amount of "plus ups" (Congressional
jargon for funding increases) is offset by being able to provide a
positive message.
A Visit from MirCorp
One of the highlights of this year's March Storm, while not
directly related to the Congressional lobbying itself, took place
during the Sunday training session when Jeffrey Manber, president of
MirCorp, stopped by to give a short talk. He provided a vision of
what commercial space might soon be like if his company is able to
turn the Mir space station into an orbiting commercial outpost.
Manber emphasized that while the agreement earlier this year
to lease Mir to MirCorp was a big victory for commercial space, the
company still has a number of hurdles to overcome. First among them
is this month's mission to Mir, where a pair of cosmonauts will check
on the status of the station and work to restore it to normal
operations -- assuming that nothing irreparably bad has happened to
the station since it was abandoned last August.
MirCorp then needs to raise "tens of millions of dollars" by
June, according to Manber. MirCorp is looking at a number of funding
sources, including other space agencies interested in flying
experiments on Mir while waiting for ISS, as well as other "non-
traditional" sources.
If those and future rounds of funding work out, Manber said
MirCorp would likely perform an initial public offering (IPO) of stock
in 2001, raising several hundred million dollars for the company.
About $200 million of that would go into a renovation of the station,
which Manber estimates to be worth $2-4 billion. "There's nothing
wrong with Mir that money can't fix," he said.
MirCorp hopes to transform Mir into the "consumer symbol of
this age," Manber said. "There is no better symbol of this age than a
commercial, international project."
This Year's Results
So how did this year's March Storm agenda go over with
staffers? Apparently quite well. "Most Congressional offices were
openly friendly to our agenda this year," said Dale Gray, a frontier
historian who participated in his third March Storm this year. "Most
remembered us from past years and many seemed eager to hear what we
were about."
"I am consistently amazed by the progress ProSpace has made,"
said Marc Schlather, Vice President for Communications for ProSpace.
"Because of the dedication of our members in coming to Washington year
after year, and because of the new people we are able to attract each
March, we have made real, measurable progress."
Investments in commercial launch vehicles and spaceports were
of particular interest to Congress. "I think we found a real
understanding of the need to build our domestic launch infrastructure,
from new space transportation to finding ways to update our
spaceports," said Schlather. "I think the Spaceport Investment Act
has a solid chance of being part of any tax bill that passes this
year."
He also added that feedback from the Congressional visits as
well as conversations with industry is allowing ProSpace to modify its
investment tax credits legislation "in a way that might give it a real
chance as well."
Since March Storm ProSpace has made a more public push for the
Alternative Access program, calling on people to contact their
Senators and urge them to support increased funding for it when the
VA-HUD Appropriations subcommittee begins initial discussions of the
budget figures in the near future. "Using the information provided by
the March Storm participants, we are now talking to a number of House
and Senate offices about securing that increase," said Schlather.
While getting the March Storm agenda passed is still something
of an uphill battle, it -- as well as the ultimate goal of opening the
space frontier -- is a real possibility. "This is not a lost cause,"
ProSpace President Ransom Wuller told March Storm participants. "It
is eminently possible."
========
This has been the April 3, 2000, issue of SpaceViews.
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