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starship-design: FW: SpaceViews -- 1999 August 1
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Sent: Sunday, August 01, 1999 3:22 PM
Subject: SpaceViews -- 1999 August 1
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S P A C E V I E W S
Issue 1999.08.01
1999 August 1
http://www.spaceviews.com/1999/08/
*** News ***
House Slashes NASA Budget
Shuttle Deploys Chandra Telescope
Loose Plug Caused Shuttle Hydrogen Leak
Lunar Prospector Ends Mission with Crash
Deep Space 1 Completes Asteroid Flyby
Mir Cosmonauts Make Final Spacewalks
Turbopump Failure Cause of Proton Crash
Roton Prototype Makes First Flight Test
"Richter Scale" of Asteroid Impact Threats Announced
SpaceViews Event Horizon
Other News
*** Articles ***
Getting Oriented in Weightlessness:
Results of a Space Shuttle Experiment
*** CyberSpace ***
CyberSpace Web Reviews
Editors Note: If you use Netscape Netcenter's "My Netscape" start
page, you can now incorporate SpaceViews headlines into your
start page along with other news, sports, weather, and other
information! To add a SpaceViews box to your page, use the URL:
http://my.netscape.com/addchannel.tmpl?service=net.900
For more information about the My Netscape service, check out
http://home.netscape.com. As always, for the latest SpaceViews
news, visit http://www.spaceviews.com.
- Jeff Foust
Editor, SpaceViews
jeff@spaceviews.com
*** News ***
House Slashes NASA Budget
NASA is facing some of its worst budget cuts in its history
after an appropriations subcommittee of the House of Representatives
voted Monday, July 26, to cut more than $1.3 billion, or nearly 10
percent, from the agency's proposed fiscal year 2000 budget.
Although the full House Appropriations Committee voted
Friday, July 30 to restore $400 million to NASA's FY 2000 budget, the
agency is still facing a cut of more than $900 million from President
Clinton's original request and $1 billion from its 1999 budget.
The original cuts disproportionately affected space science,
accounting for $640 million of the original $1.3 billion, or 29
percent of the original space science budget. If enacted, the cuts
would have canceled the Space Infrared Telescope Facility (SIRTF)
space telescope, the Contour comet mission, future Discovery and
Explorer missions, and Mars missions beyond 2001, as well as research
into future missions to Europa, Pluto, and elsewhere.
The full House Appropriations Committee did vote to restore
$400 million to the space science budget by killing the Americorps
community service program. That funding will be used to restore
SIRTF, Mars exploration, and some technology and research funds.
Also heavily hit was NASA's earth sciences programs, with
$150 million cut into the Earth Observing System as well as
cancellation of the LightSAR radar mission and the Triana
Earth-observing camera.
On the other hand, the space station and space shuttle
programs survived with a combined cut of just $250 million. The
space station budget actually still increases from 1999 to 2000, but
only by $100 million instead of the planned $200 million.
A chorus of protests, from NASA, members of Congress, and
space activists, was heard after the original cuts were announced.
"These cuts would gut space exploration," NASA administrator Dan
Goldin said. "They may force the closure of one to three NASA
centers, and significant layoffs would most certainly follow."
Because the cuts are so tightly focused on Earth and space
sciences, the centers threatened with closure include the Jet
Propulsion Laboratory (JPL) and the Goddard Space Flight Center, two
facilities usually not considered prime targets for closure in the
past.
"If NASA were faced with the reality of having more centers
than it needed, I would certainly expect JPL would be on the list,"
JPL deputy director Larry Dumas told the Pasadena Star-News
newspaper.
Those claims were disputed by Rep. James Sensenbrenner,
chairman of the House Science Committee. "Their claims that NASA will
have to close centers and initiate layoffs... are disingenuous at
best and purposely inflammatory at worst," he claimed. "These are
scare tactics, pure and simple, and should be rejected as such."
NASA's budget has been slowly but steadily declining
throughout Goldin's tenure as NASA administrator, but the proposed
cuts are far sharper than anything the agency has experienced before.
"Up until now, NASA has always stepped up to the budgetary challenge.
This time the NASA team plans to fight," Goldin said. "I won't feel
better until every nickel is restored."
The National Space Society issued an alert asking its members
to contact members of the House Appropriations Committee. "We cannot
stand by and allow the House of Representatives to act so
irresponsibly and play politics with the future of our national space
program," the society said in a statement.
The full House of Representatives is expected to take up the
appropriations bill this week. The Senate has yet to act on
appropriations legislation for the space agency, and may not do so
until after the August recess. President Clinton has also promised
in the past to veto any appropriations bill that did not include
funding for his Americorps program, a potential stumbling block for
NASA funding. The long legislative process ahead means there is still
time for funding to be restored, or additional cuts to be made.
"This is only the beginning of the process," Rep. James Walsh
(R-NY), chair of the appropriations subcommittee that made the
initial devastating cuts, told the Associated Press. "We're at about
the bottom of the third in a nine-inning ball game."
Shuttle Deploys Chandra Telescope
Despite some problems during launch, the shuttle Columbia
successfully completed its mission last month to deploy the Chandra
X-Ray Telescope.
Columbia lifted on on mission STS-93 at 12:31 am EDT (0431
UT) Friday, July 23. The launch had been delayed one day by
thunderstorms, and two days before that when a sensor erroneously
detected a buildup of hydrogen in an engine compartment seven second
before liftoff.
The crew, commanded by Eileen Collins, the first woman to
command a shuttle mission, completed its primary task seven hours
after launch when it deployed the Chandra X-Ray Telescope. The
telescope's Inertial Upper Stage (IUS) fired perfectly one hour
later, placing the telescope in an elliptical orbit. The telescope's
onboard thrusters have been tweaking the orbit into its final
version, between 10,000 and 140,000 km (6,200 and 87,000 mi.) above
the Earth.
After the telescope was deployed, the five-person crew turned
their attention to a suite of secondary experiments, ranging from a
small ultraviolet telescope mounted in the shuttle to a test of a new
hinge for deploying solar arrays to biological tests on the effects
of microgravity.
While much of the attention during the early phase of the
mission focused on Chandra and on Collins, later on in the mission
the focus changed to a series of problems that took place during the
launch. A short circuit five seconds after launch disabled the
controllers for two of the three main engines. Backup controllers
took over, but additional malfunctions would have shut down at least
one of the engines, requiring an abort and emergency landing.
At a post-flight press conference, Collins said she
originally thought the warning lights that appeared when the
controllers failed were more ordinary lights she had seen on previous
launches, then reconsidered when mission controllers advised her and
pilot Jeff Ashby to shut down other systems in an effort to keep them
from being taken out by the short.
"I thought, 'This isn't right, this isn't what I was
expecting,'" Collins said. "The next thoughts that are going through
my mind are, 'What's our abort capability? If we lose an engine,
where are we going to go?'"
At the end of the launch, the main engines shut down a
split-second early, placing the shuttle in an orbit 11 km (7 mi.)
lower than planned. The early shutdown was traced to a leak of
hydrogen coolant from one of the main engine nozzles during launch
(see accompanying article below.)
The launch problems had no effect on the landing, which took
place at 11:20 pm EDT July 27 (0320 UT July 28) at the Kennedy Space
Center.
Loose Plug Caused Shuttle Hydrogen Leak
A loose plug fell through an engine nozzle, puncturing three
coolant tubes and causing the hydrogen leak noticed during the STS-93
shuttle mission, NASA investigators said Friday, July 30.
According to investigators, the plug, used to seal a liquid
oxygen injector tube, fell off as the main engines on the shuttle
Columbia were ignited six seconds before liftoff. The engine thrust
accelerated the tiny plug, no larger than a small nail, to supersonic
speeds as it crashed into the size of the nozzle, weakening the tubes
and causing them to rupture.
The ruptured tubes allowed liquid hydrogen, used to cool the
engine nozzles before being consumed as fuel by the engines
themselves, to leak from the shuttle. More than 1,000 kg (2,200
lbs.) of hydrogen leaked out during the ascent into orbit.
The leak caused the engine to run up to 55 degrees Celsius
(100 degrees Fahrenheit) warmer than normal, in turn consuming an
additional 1,800 kg (4,000 lbs.) of liquid oxygen. That led to the
shutdown of the main engines a split-second early, placing the
shuttle in an orbit 11 km (7 mi.) lower than planned.
Shuttle officials said that the leak could not have caused an
explosion, and did not immediately endanger the shuttle. However, if
the leak had been larger, the engine temperature would have increased
to the point where the engine shut down, forcing an emergency landing
either back at the Kennedy Space Center or the transatlantic abort
site in Africa.
Bill Gerstenmaier, shuttle program manager, told Florida
Today that 20 to 40 coolant lines would have had to rupture to
overheat and shut down the engine.
The plug that damaged the coolant lines was one of two
installed to plug a small injector tube, one of several hundred that
feed liquid oxygen into the main engine. The tube had become damaged
and was plugged to prevent oxygen from leaking and inadvertently
mixing with liquid hydrogen. The other plug held, NASA officials
said.
An investigation into the coolant leak and the exact series
of events that caused it is ongoing. Also still under investigation
is an electrical short five seconds after launch that disabled two of
the six computers that serve as engine controllers. Technicians are
expected to take some time to check Columbia's wiring to find the
exact location of the short circuit.
It's not currently known if either problem will push back the
next shuttle launch, Endeavour's mid-September launch on STS-99, a
radar mapping mission.
Lunar Prospector Ends Mission with Crash
The Lunar Prospector spacecraft ended its highly-successful
18-month mission with a deliberate crash into a crater near the lunar
south pole July 31 in a search for water.
Prospector crashed near the lunar south pole at 5:52 am EDT
(0952 UT) July 31, project officials reported. The impact took place
a minute later that previously planned because a thruster burn early
Friday that placed the spacecraft in an elliptical orbit to prepare
for the impact was slightly stronger than planned.
Neither amateurs nor professionals reported seeing a plume of
dust that some thought the spacecraft's impact would raise. The fact
that no impact plume was seen, NASA officials said, actually
increases the likelihood that Prospector hit its desired impact site
deep within a shaded crater near the lunar south pole.
Observations by a large group of terrestrial telescopes,
including the Keck Observatory and telescopes in Arizona and Texas,
as well as the Hubble Space Telescope and the Submillimeter Wave
Astronomy Satellite (SWAS), were made in a search for water that
would have been thrown up by the impact. Analysis of the data is
expected to take up to several months.
"Once again, Prospector has done everything we have asked of
it," said Alan Binder, principal investigator for Lunar Prospector.
"This mission provided ten times better data than we expected. The
spacecraft performed flawlessly to its very end."
In its final days, the spacecraft had to survive a partial
lunar eclipse July 28 that kept the spacecraft out of the Sun for
several hours. To conserve the limited battery power on the
spacecraft non-essential systems, including most of the scientific
instruments, were turned off. Project officials said the spacecraft
made it through the eclipse with no problems.
Prospector was crashed into the Moon at the end of its
18-month mission in an effort to directly detect any water ice that
is believed to be hidden in permanently-shadowed craters near the
lunar poles. Prospector was targeted to impact in one such shadowed
area of a 50-km (30-mi.) crater near the lunar south pole, although
the exact site of impact was not known.
Scientists cautioned that the odds of success for this impact
were small, no more than 10 percent, according to David Goldstein,
the University of Texas scientist who proposed the crash. If water
was detected, however, it would lay to rest nearly all doubts that
ice exists at the lunar poles.
Two Stanford University scientists earlier in July cautioned,
though, that any water near the lunar poles could be locked up in
hydrated minerals similar to concrete. The impact, they believed
could librate water from those minerals that does not exist in free
form on or near the lunar surface.
The crash also deposited on the Moon the ashes of the late
geologist Eugene Shoemaker, a pioneer in lunar research in the 1960s
who was killed in an auto accident in Australia two years ago. A
sample of his cremated ashes were included on the Lunar Prospector
spacecraft, fulfilling a desire he had to travel to the Moon.
Deep Space 1 Completes Asteroid Flyby
NASA's Deep Space 1 spacecraft capped off its
technology-development mission with a successful flyby of a small
asteroid July 29, although a mispointed camera may mean no close-up
images of the asteroid.
DS1 passed within about 15 kilometers (9 miles) of asteroid
9969 Braille, formerly known as 1992 KD, at 12:46 am EDT (0446 UT)
July 29. Mission officials initially reported the flyby was a
success, returning images and other data about the small asteroid.
However, mission scientists reported Thursday afternoon, July
29, that DS1's camera was misaimed during the closest portion of the
flyby and did not return any closeups of the asteroid.
The spacecraft used an onboard navigation system called
AutoNav to guide itself past the asteroid safely. AutoNav was one of
a dozen technologies tested by the spacecraft during the mission.
"This is a dramatic finale to an amazingly successful
mission," said Marc Rayman, deputy mission manager. "With AutoNav's
successful piloting of the spacecraft, we've completed the testing
and validation of the 12 new technologies onboard and possibly
acquired important science data, including photos."
Mission officials later told the Associated Press that the
camera lost the asteroid about 20 minutes before closest approach,
when the spacecraft was still more than 16,000 km (10,000 mi.) from
the asteroid.
"This is analogous to mispointing a camera and getting a
blank field of view," project scientist Robert Nelson told the AP.
Data from other instruments initially appeared to be okay, however.
Later reports indicated that some infrared images were
obtained fairly close to, but not at, the time of closest approach.
No images have yet been released, but a press conference has been
scheduled for August 3 to report on the quantity and quality of the
science data returned during the flyby.
The flyby was not without problems. About 16 hours before
closest approach a software glitch triggered a "safing event", when
the spacecraft shut down nonessential systems and waited for
instructions from Earth. The problem was corrected about six hours
later.
"This has been by far the most challenging, dramatic and
stressful day on the project," said Rayman. "The last 16 hours before
the flyby were really, really exciting. We had the safing event, we
recovered from it and we managed to squeeze in a trajectory
correction maneuver to update Deep Space 1's flight path."
Any scientific results will be considered an added bonus for
the mission, whose primary purpose is technology development. Since
its launch in October, DS1 tested technologies ranging from an ion
engine to advanced solar panels to an autonomous control system.
The mission is officially scheduled to end in September.
There has been past discussion of an extended mission, which would
include two comet flybys in 2001, but the precarious nature of NASA's
space sciences budget make the probability of obtaining such funding
unlikely.
The asteroid received its new name just a few days before the
flyby. The name was selected by the discoverers of the asteroid,
Eleanor Helin and David Lawrence, from a set of finalists chosen by a
Planetary Society panel as part of a competition run by the
organization.
Mir Cosmonauts Make Final Spacewalks
Two Russian cosmonauts made two spacewalks late last month
that are likely to be the final spacewalks performed outside the Mir
space station.
Cosmonauts Viktor Afanasyev and Sergei Avdeyev spent six
hours outside Mir on July 23 in a largely unsuccessful effort. They
attempted to deploy a large Russian-Georgian antenna designed to
communicate with other satellites, but were unable to open the
antenna after an extended effort.
They also attempted to search the exterior of part of the
station in a search for an air leak first noticed several weeks ago,
but were unable to locate the source of the leak.
Afanasyev and Avdeyev performed a second spacewalk July 28.
During that five-hour, 22-minute spacewalk, they were finally able to
fully deploy the communications antenna. They also also installed
equipment to study the effects of electric and magnetic fields on the
station, as well as equipment which the Russian Interfax news agency
described as being able to detect air leaks from the station,
although the two did not resume their search for an existing leak
from the station that they attempted in their previous spacewalk.
During both spacewalks the third member of the Mir crew,
French cosmonaut Jean-Pierre Haignere, remained in the station and
monitored the progress of the spacewalkers.
Russian officials downplayed any mention of the leak, saying
it was not serious to the current crew. However, officials said a
week earlier that if the leak was not fixed, the station would be
uninhabitable within three months.
That shouldn't pose a problem for the current crew, which is
now scheduled to depart the station August 28. The station will be
left unoccupied after that, with the possible exception of a
short-term visit to Mir in December that Russian officials discussed
earlier this year.
Unless private funding can be found, Russia will deorbit Mir
in early 2000 over the Pacific Ocean.
Turbopump Failure Cause of Proton Crash
A fire in the turbopump of one of the engines in the second
stage of a Proton booster caused it to crash several minutes after
launch July 5, Russian officials revealed this week.
In an interview with the Russian Izvestia news service July
27, Anatoli Kiselev, Director-General of Khrunichev State Research,
said that a faulty weld in the turbopump triggered a fire which
destroyed the second stage and caused the rest of the booster to
crash downrange from its Baikonur, Kazakhstan launch site.
"The fire was started by a stray aluminum particle in a seam
between the cover and the apparatus as a result of a defect in a
weld," Kiselev told Izvestia. Such stray particles can be blown in
by a turbopump or enter though the fueling equipment as a result of
personnel neglect.
Using "super advanced U.S. equipment" to simulate the
accident, Kiselev said a particle weighing as little as 0.2 grams is
sufficient to start a fire, and that a weld as little as 25 percent
below the norm can harbor such particles.
Telemetry returned by the rocket showed that the first four
minutes and 37 seconds of its July 5th flight were normal. At that
point, however, the number three engine of the second stage destroyed
itself in a fire, also taking out portions of the rear of the stage
and the bottom of the second stage fuel tank. Within a half-second
the fuel and oxidizer tanks of the stage depressurized, destroying
the stage.
The third stage and the Breeze-M upper stage, making its
inaugural flight, survived the destruction of the second stage but
did not have enough velocity to reach orbit. Aerodynamic and heat
loads destroyed these stages at an altitude of 30 km (18 mi.),
scattering debris over portions of Siberia and Kazakhstan.
Kiselev said the Russian State Commission investigating the
launch failure will recommend that the turbopump design be upgraded,
and a filter be added that can catch spurious particles that can
start such fires. The fueling equipment may also be upgraded.
"We were planning to perform all these upgrades in 2000
anyway, but this failure presses us to do it earlier than we
expected," Kiselev said.
"An important thing is that this failure is of a singular
manufacturing nature," he added. "The failure has not lowered our
estimate of Proton reliability beyond the reference level," which is
a success rate of 96 percent.
The timeframe for these upgrades, and the return to flight of
the Proton, is unknown. Kiselev said he believes an additional four
Western payloads can be launched on Protons by the end of the year.
This would require Kazakhstan to lift its ban on Proton launches
which it put into place after the crash. Negotiations between
Russian and Kazakhstan on the Proton ban are ongoing.
A Proton will also be used late this year to launch the
Zvezda service module for the International Space Station.
International Launch Services, the joint venture between
Lockheed Martin, Khrunichev, and Energia, said the Russian State
Commission will likely release their formal report on the launch
accident in the first or second week in August. They released the
Izvestia report as they cannot share technical information with
Khrunichev until the U.S. federal government approves a license for
them to do so.
Roton Prototype Makes First Flight Test
A prototype of Rotary Rocket Company's Roton reusable launch
vehicle made its first test flight Friday, July 23, hovering a few
meters off the ground for several minutes.
The Roton Atmospheric Test Vehicle (ATV) successfully
performed three takeoff and landing maneuvers during the flight test,
which lasted 4 minutes and 40 seconds, just under the planned
5-minute duration. The Roton ATV hovered at an altitude of about 2.4
meters (8 feet) during the test, within the planned range of 1.5 to 3
meters (5 to 10 feet).
"It is this demonstrated performance that provides
creditability to Rotary Rocket's aims of achieving low-cost space
flight," said Rotary Rocket president and CEO Gary Hudson.
The flight test was performed with a crew of two onboard:
pilot Dr. Marti Sarigul-Klijn, a retired Navy commander and Roton
Chief Engineer, with Brian Binnie, also a retired Navy commander and
Roton Flight Test Director, as copilot. Both are experienced test
pilots.
The test flight took place Friday morning, July 23, at Rotary
Rocket's facilities in Mojave, California, but was not reported until
Wednesday, July 28. Rotary officials had declined comment on the
test flight until Wednesday's announcement.
The Roton ATV is a full-scale prototype designed to test the
flight characteristics of the Roton launch vehicle in the atmosphere,
particularly during approach and landing. The vehicle has no rocket
engines but does have a helicopter-like rotor, with small thrusters
on the tips of the blades, that is used to propel the vehicle in the
atmosphere.
The ATV will eventually be used on longer flights from
altitudes of over 1,000 meters (3,300 feet) to test the approach and
landing characteristics of the vehicle. No timeline for those tests
were given by Rotary officials.
A future test vehicle, the Roton PTV, will be used to test
the launch characteristics of the vehicle. That version will
incorporate a rocket engine based on NASA's Fastrac engine under
development. The company selected the Fastrac over its own RocketJet
engine design during a reorganization in June.
The company plans to have the full version of the Roton
single-stage reusable launch vehicle enter commercial service in
2001, funding permitting.
"Richter Scale" of Asteroid Impact Threats Announced
The International Astronomical Union has officially endorsed
Thursday, July 22, a new system of communicating the threat of
potential collisions by near-Earth asteroids.
The Torino Scale, endorsed by the IAU at the United Nations
UNISPACE III meeting in Vienna, is a 0-10 scale designed to easily
express the danger posed by a near-Earth asteroid collision. The
scale is named after the Italian city where it was adopted by an IAU
working group in June.
The scale is analogous to the Richter Scale used to measure
the intensity of earthquakes as well as similar scales to gauge the
strength of hurricanes and tornadoes. However, the Torino scale
takes into account both the potential damage an asteroid could do as
well as the probability of a collision.
On the Torino scale, an asteroid measuring 0 would have no
chance of hitting Earth, or would be unable to do reach the ground if
it encountered the Earth. An asteroid measuring 10 would be certain
to hit the Earth and cause global damage.
An 8, 9 or 10 on the Torino scale would correspond to a
certain collision of varying magnitudes. Lower numbers would be used
to describe less certain impacts of varying strengths.
Currently all known asteroids measure a 0 on the Torino
scale. Some asteroids, such as 1999 AN10, at one time measured a 1
on the scale, meaning that they had about an equal probability of
striking the Earth as a random, undiscovered object of similar size.
These asteroid have been downgraded, though, after new observations
led to refined orbits that reduced or eliminated any impact
probability.
The scale was developed by Richard Binzel, a planetary
astronomy professor at MIT, as a way to better communicate the real
dangers -- or lack of danger -- posed by near-Earth asteroids.
"Scientists haven't done a very good job of communicating to the
public the relative danger of collision with an asteroid," he said.
"The Torino scale should help us clearly inform but not confuse the
public."
An asteroid impact, Binzel said, "is a case of a
high-consequence but low-probability event. It's difficult in human
nature to figure out what level of anxiety we should assign to an
approaching asteroid."
The adoption of the Torino scale comes at a time when the
rate of near-Earth asteroid discoveries has sharply increased, thanks
to sophisticated detection systems like the LINEAR project at MIT's
Lincoln Laboratory and long-term searches like Spacewatch in Arizona.
The increased discovery rate has led to impact "scares" like
1999 AN10 this year and 1997 XF11 last year, when newly-discovered
asteroids were found to have small but non-zero impact probabilities
in the coming decades. Those probabilities decreased after new
observations led to refined orbits.
"What I find especially important about the Torino impact
scale is that it comes in time to meet future needs as the rate of
discoveries of near-Earth objects continues to increase," said Hans
Rickman, IAU Assistant General Secretary.
Binzel hopes that the Torino scale will make as easy to
communicate the threat of an asteroid collision as the Richter scale
does to describe the intensity of an earthquake. "If you tell a
Californian that an earthquake registering one on the Richter scale
was going to hit tomorrow, he would say, 'So what?'" he said. "If you
were talking about a six, that would be different."
SpaceViews Event Horizon
August 4 Ariane 4 launch of the Indonesian Telekom-1
communications satellite from Kourou, French Guiana
at 6:48 pm EDT (2248 UT)
August 12-15 Mars Society 1999 Conference, Boulder, CO
August 14 Galileo flyby of the Jovian moon Callisto
August 15 Delta 2 launch of four Globlastar satellites from
Cape Canaveral, Florida at 1:09 am EDT (0509 UT)
August 18 Cassini flyby of Earth
September 23-26 Space Frontier Conference 8, Los Angeles, CA
Other News
Delta 2 Launch: A Delta 2 successfully launched four more Globalstar
communication satellites early Sunday, July 25. The Delta 2 lifted
off from pad 17A at Cape Canaveral at 3:46 am EDT (0746 UT), at the
beginning of the first of two available launch windows. The launch
was the third Delta 2 launch of Globalstar satellites in a six-week
period, after launches on June 10 and July 10. A fourth launch, the
last in this cluster of launches, is planned for mid-August, after
the Cape Canaveral launch facilities are reopened after range
modernization work. With the July 25 launch, 32 Globalstar
satellites are now in orbit, 20 from four Delta 2 launches and 12
from three Soyuz launches. Three more Soyuz and one more Delta 2 will
be used this fall to complete the 48-satellite constellation plus fly
four on-orbit spares.
Atlas 3 Loses Payload: The first launch of Lockheed Martin's new
Atlas 3 booster will likely be delayed after it lost its first
payload to Ariane July 26. Loral Space and Communications announced
that it would launch its Telstar 7 communications satellite on an
Ariane 4 in September, and not on the first flight of the Atlas 3A as
originally planned. The launch of the Atlas 3A, an upgraded version
of the Atlas 2 using Russian-designed RD-180 main engines and a
Centaur upper stage, has been delayed while an investigation
continued into the failure of an RL-10 engine on a Delta 3 launch in
May similar to the engine used by the Centaur.
Titan's Hydrocarbon Oceans: New images from the Keck Observatory
released July 28 have provided the best view yet of Titan's surface
and show evidence of possible oceans of ethane, methane, or other
hydrocarbons. The images, taken at infrared wavelengths that can
peer through the moon's thick smog, show evidence of bright and dark
regions on the surface that scientists interpret as areas of land and
ocean, respectively. The images are not the first view of the
surface of the moon: The Hubble Space Telescope provided similar
views at near-infrared wavelengths in 1994. However, the Keck images
are sharper, thanks to a process known as "speckle interferometry"
that combines a large number of short snapshots are processed
together to remove the blurring effects of Earth's turbulent
atmosphere.
Keeping Track of Near-Earth Asteroids: Despite several new search
efforts and a decrease in the estimated overall population, most of
the near-Earth asteroids (NEAs) that pose the greatest threat to the
Earth have yet to be discovered, astronomers reported at a conference
Tuesday, July 27. While new observations have led some astronomers
to believe that there are only 500-1000 NEAs 1 km (0.6-mi.) or larger
in diameter, only 15-20% of these NEAs have been discovered. At
current discovery rates the rest will be found in 20 to 40 years,
although quadrupling the discovery rate should allow 90% of these
NEAs to be discovered in the next 10 years, the goal of the proposed
Spaceguard program.
Interesting NEAs: Some NEAs that have already been discovered have
proven to be interesting objects. Images and other data collected by
the Near-Earth Asteroid Rendezvous (NEAR) spacecraft's flyby of Eros
show the asteroid is likely a solid body, and not a rubble pile like
other asteroids. Two papers published in the July 23 issue of
Science show that Eros more closely resembles the main-belt asteroid
Ida rather than Mathilde, a rubble-pile asteroid NEAR flew by in
1997. A much smaller NEA, 1998 KY26, is also likely a solid body, in
part because its 10-minute rotation period makes it the most
rapidly-rotating solar system body yet discovered. A compositional
analysis of the asteroid, based on telescopic observations in June,
show that the asteroid is a carbonaceous chondrite, rich with water.
"This asteroid is quite literally an oasis for future space
explorers," said JPL's Steve Ostro.
Indemnification, Russia Legislation: The House Science Committee's
space subcommittee passed bills Thursday, July 29 that would extend
commercial launch indemnification and would tie any NASA funding of
Russia's space program to missile nonproliferation efforts. HR 2607,
the Commercial Space Transportation Competitiveness Act of 1999,
would extend for five years the indemnification on catastrophic
launch accidents that is currently set to expire at the end of 1999.
HR 1883, Iran Non-Proliferation Act of 1999., would prevent NASA from
sending any money to the Russian Space Agency in the event that the
administration determined that Russia was helping Iran develop
long-range ballistic missiles. The subcommittee passed two
amendments that would allow funding for safety reasons, or to
complete and build the space station's service module, even if a ban
was in effect.
*** Articles ***
Getting Oriented in Weightlessness:
Results of a Space Shuttle Experiment
by Dr. Charles M. Oman
"What's up?" is not a trivial question for astronauts in
weightlessness. Gravitational "down" cues are missing, so they must
depend on vision to maintain their spatial orientation. Many
astronauts seem to maintain a local "subjective" vertical frame of
reference, which accounts for their occasional reports of inversion
illusions, visual reorientation illusions, and fear of falling during
space walks, all of which can sometimes trigger space motion
sickness. Previous Spacelab studies using rolling dotted cylinder
displays showed increased susceptibility to roll circular vection (a
visually induced motion illusion) during the first week in space.
However, information on linear vection susceptibility, and perceptual
responses to structured visual scenes remained important pieces of
the scientific puzzle which were missing prior to Neurolab.
The availability of the Neurolab Virtual Environment
Generator on the STS-90 shuttle mission in April 1998 allowed us to
employ a wider repertoire of stimuli, including not only dotted
cylinders, but also moving corridors, and tilted or rolling
spacecraft interiors. This was the first use of virtual reality
techniques in space. We studied both circular and linear vection,
visual reorientation illusions, and subjective reference frame
effects on figure recognition and shading interpretation.
We found that susceptibility to both linear as well as
circular vection illusion was increased in weightlessness for three
test subjects. Both vection measures were consistently reduced in
flight when the subject wore a harness which held them "down" to the
deck. We also tested the effects of stationary spacecraft interior
scenes tilted at various angles on the perceived vertical -- a 0-G
extension of classic tilted room experiments. Responses of three
subjects did not change in orbit. All of them were either strongly
dependent or strongly independent on visual scene tilt in preflight
tests. However, one moderately visually independent subject -- as
evidenced by sensitivity to scene content and body orientation --
shifted to strong visual dependence in flight, and gradually returned
to independence during the first week post flight. No subjects became
more visually independent during or after flight.
Our tumbling room tests confirmed a consistent increase in
circular vection in orbit. Visual reorientation illusion frequency
in supine testing preflight and in flight were similar for most
subjects. The distribution of scene angles at VRI onset showed
statistically significant modal tendencies, but were unchanged in 2
of 3 subjects. We had hypothesized that complex figure recognition
and interpretation of shape from shading would show effects when the
direction of the subjective vertical was manipulated, as it does on
Earth, even though gravity is absent. Most subjects had response
biases or performed the task inconsistently, which may have masked
the effect. However, one subject was able to demonstrate both types
of effects consistently, showing that choice of subjective reference
frame can have important perceptual consequences for astronauts.
Our experiment has been tentatively selected for reflight on
the International Space Station, to see how our measures of astronaut
spatial orientation change over months, rather than days in. Our
Neurolab scientific results, virtual reality methods, and analysis
techniques are proving useful in the current research of the National
Space Biomedical Research Institute, aimed at developing preflight
spatial orientation training as a countermeasure, and understanding
how sense of direction is coded in 3 dimensions in the hippocampus.
Our findings also broaden our understanding of how elderly people and
patients with diseases of the inner ear or hippocampus use visual
cues, and why some find certain situations in daily life disorienting
-- for example walking or driving at night, in subway stations or
supermarket corridors, or in wide screen movie theaters.
Dr. Charles M. Oman is director of the Man Vehicle Laboratory at the
Massachusetts Institute of Technology. This article was adapted from
a final report submitted by Oman and colleagues Ian P. Howard, Ted
Carpenter-Smith, Andrew C. Beall, Alan Natapoff, James E. Zacher, and
Heather Jenkin.
*** CyberSpace ***
NASA Apollo 11 30th Anniversary
This site, created by the NASA History Office, could be considered
the "official" site for the 30th anniversary of this historic
mission. It's also one of the most comprehensive, with transcripts
of interviews with the Apollo 11 crew, biographies of the crew and
mission managers, images and movies from the mission, and a list of
events to commemorate the 30th anniversary. This site should be one
of the first places to turn to for more information about Apollo 11.
http://www.hq.nasa.gov/office/pao/History/ap11ann/eagle.html
Where Were You July 20, 1969?
The title of this site succinctly expresses its purpose: where were
you on July 20, 1969, when Apollo 11 landed on the Moon? This site
collects the stories of ordinary people from around the world who
provide their recollections of this historic event. From those
serving in Vietnam -- and those protesting the war at home -- to
children and others, this site provides real stories, both funny and
touching, from this historic day.
http://www.wherewereyou.com/
The N-1 Moon Rocket
The N-1 rocket was the Soviet Union's answer to the Saturn 5: a giant
booster powerful enough to send cosmonauts on a lunar landing
mission. The rocket was never successfully launched, and its
development was shrouded in mystery in the West for many years. This
site sheds some light on the history of the N-1, including a list of
attempted launches, technical details about the booster, and one of
the best photos available of the N-1 on the launch pad.
http://hometown.aol.com/nodin/N1pages/N1index1.html
XRayTelescope.com
The Chandra X-Ray Telescope (formerly AXAF), the latest in NASA's
series of "Great Observatories", has recently gone into orbit. This
site, created by the "Science@NASA" team at NASA Marshall, provides
some background information about the telescope, latest news about
its launch, and a gallery of images and video of the telescope. If
you ever wanted to know details about Chandra and the science it will
perform, this is the place to go.
http://xraytelescope.com/
========
This has been the August 1, 1999, issue of SpaceViews.
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