HST Quasar observations pose questions - here's an answer
Much has been made in the media about newly released images of
quasars and their host galaxies by the Hubble Space Telescope (here's
the announcement,
and here are some stories from
Reuters
and Science Now) -
but new these news are not. Already one year ago, at the 2nd Hubble
science conference in Paris, basically the same results have been
presented, part of which had appeared in various journals even earlier
in 1995. The fundamental discovery is that quasars, these extremely
luminous point sources, do not inhabit unusually large galaxies.
Instead they are found in colliding galaxies - or in very normal galaxies
that don't seem to care about the brilliant thing in their center. The
only feature that is always present is a galaxy (most often a gas- and
dust-rich spiral): "Naked quasars" that are
totally isolated do not exist - their "discovery" in 1994 was an
observational error.
How striking is the fact that quasars "live" in different galactic
environments? Perhaps not as breathtaking as the news stories have it:
The preponderance of collisionally damaged galaxies among the quasar
host galaxies points towards collisions as the drivers of quasar
activity - they seem to be required to "feed" the so-called central engine
in the galactic center(s). And what about the seemingly normal galaxies
with quasar cores? It is well possible that they have experienced
collisions millions of years ago, but that the disturbance has reached
their centers only now. Since the angular momentum has to be conserved,
the matter falling into the central engine can do so only by spiralling
through an accretion disk - and that can take many millions of years.
So a collision takes place, the disk gets disturbed, the disturbance
travels inwards while the galaxy reshapes itself into an ordinary
spiral again, and then the - often erratic - quasar activity commences.
Which leaves the question: What is the central engine? Not
necessarily the supermassive Black Hole that is so popular. A completely
different model for the central part of not only quasars but virtually
all galaxies is the so-called Burning Disk, which "can explain all the
phenomena currently attributed to a supermassive Black Hole," according
to its inventor (Kundt, Astrophysics and Space Science235,
319-327 [1996]). Basically it is a flat "star", but one that shines way
above its Eddington limit, i.e. matter flies away from it. Such a
Burning Disk needs feeding, and galactic collisions that greatly disturb
the inner structure of the participants are the perfect feeder. Many
other phenomena of active galaxies, from their amazing jets to faint
shells of matter surrounding them can be explained by this model as well -
the discussion about what sits in the centers of galaxies is far from over.
DF
One year after launch, flood of ISO papers
Exactly one year after the
Infrared
Space Observatory was
launched by ESA, an amazing
collection of scientific papers has appeared in a special issue of the
European astronomy journal Astronomy and Astrophysics - and if
you have unlimited time, you can read them all
online (or download
just their abstracts). The papers cover the pages L27 to L400 of Volume
315 (Nov. (II), 1996) - and a broad range of topics, from the
technical performance of the satellite to astrophysics to the solar system.
Some headlines: "Detection of hot, abundant water toward AFGL 2591",
"The rich spectrum of circumstellar PAHs", "Solid methane toward deeply
embedded protostars", "First detection of the 56-mu rotational line of
HD in Saturn's atmosphere", ... - a brief overview of ISO's early
achievements can also be found in a
conference report. And ISO's view of the famous
Hubble Deep Field
is now available
, too. After so many failures of scientific spacecraft
this year, it's good to read about one that does work! DF
ORFEUS satellite working after troubles; now comes WSF
Everything was a little bit delayed, the launch (but on Nov. 19th almost
on time; only some excess hydrogen caused Columbia to lift off less than
3 minutes late), the deployment of the SPAS and the beginning of its
scientific operations. But after some alignment problems were
solved,
the
ORFEUS payload is now looking into the
UV sky - see also Update #17 for further
details and more links. Unfortunately comet Hale-Bopp has moved rather
close to the sun while ORFEUS sat on the launch pad - it is not clear
whether it can risk a look.
And while this freeflyer is still out (not due
for retrieval until 2 weeks later) the crew of Columbia is preparing the
deployment of a 2nd freeflyer, the Wake Shield Facility:
Never before
have there been two freeflyer around a shuttle orbiter before. The
WSF should be retrieved by Monday; two spacewalks are planned for the
coming week, too. STS-80 is the first shuttle mission managed by the
United Space Alliance,
by the way. Meanwhile a new - and much delayed -
Progress supply
ship has reached Mir today. And an Atlas rocket has carried the Eutelsat
Hot Bird 2 satellite to its proper orbit yesterday: Europe's Ku band
satellite TV fans can prepare for even more TV channels... (Florida
Today and other sources)
Briefly noted:
The Mars Global Surveyor has achieved the first trajectory correction,
but the solar array is still misaligned: Follow the developments at the
Flight Status Report
page of the project: Apparently there will be an attempt to shake the
array free during the 2nd correction firing. Certain rumors have
reached The Cosmic Mirror that the mission of the MGS is in grave danger
if the array problem cannot be resolved, but this has not been confirmed.
Meanwhile the Russian flight controllers suspect that
Mars'96 itself, not the Proton, are to blame for the wrong 2nd
firing of the "Block D" upper stage - it was probably initiated by wrong
commands from the spacecraft. (Science Now Nov. 20, 1996)
Mars meteorite auction a failure: The bidding stopped at $ 1.1m -
not high enough for the seller of a rare collection of all three major
types of Martian meteorites who had wanted $ 1.5 to 2m. Now the precious
stones will be sold through different channels. The prices collectors
were willing to pay for Martian meteorites had skyrocketed after August
7th, but apparently there is a limit for what people are willing to pay.
(
CNN Online Nov. 21, 1996)
Direct images of an accretion disk around a protostar have been
obtained with 0.2" resolution by an adaptive optics system in Hawaii:
The scientific paper will only be published next April, but it can be
read - with illustrations in color -
online. This
are the highest resolution images ever achieved of HL Tauri with its
amazing circumstellar environment.
Biosphere 2 a biological Hubble? Now that the controversial
facility
in Arizona is under a new and real
scientific management,
its reputation
among scientists is growing - and there are even scientific results on
closed ecosystems coming out of its fancy past when human 'Biospherians'
lived inside it. Just like with the Hubble Space Telescope, which produced
some good science despite its flawed main mirror, but really took off
after the problem was fixed, lots of valuable results are
expected in the future. (Science Nov. 15, 1996, p. 1150-1151)
Update #19 of Nov. 20, 1996, at 16:30 UTC
Loss of Mars'96 shakes European space science
The
failure of the Russian Mars'96 spacecraft to leave Earth orbit
and its fast plunge into the Pacific is more than just one of the
three 1996 Mars launches gone wrong: It marks the end of an era in
the 40 year history of space exploration. Mars'96 had been the sole
survivor of the incredibly ambitious Soviet planetary exploration program
that had seen a number of failures but also a serious of spectacular
successes: Many firsts at Venus were achieved by Soviet Venera
spacecraft, including the only images from the surface, the first
radar maps, the only balloons in the atmosphere. The latter had been
deployed by the VeGa spacecraft on the way to Halley's comet where
they were successful, too. The VeGa missions also broke new ground for
the Soviet space program because there were literally tons of foreign,
including Western, instruments aboard.
Mars, on the other hand, had always given the Soviets trouble. Bold
attempts to soft-land in the early 70's failed to return useful images,
miniature rovers that one tried to deploy failed as well. But some
orbiters had worked and sent back good images of the surface (which in
the West, unfortunately, were totally overshadowed by the Mariner and
later Viking orbiter pictures). Then the target was the Martian moon
Phobos, and again the payload was international. Even before the two
spacecraft were launched, the Soviet Union announced during 1987 that
Venus was history for them and Mars would take centerstage from now on:
Starting in 1992, in each launch window two big (6-7 metric tons)
spacecraft would go, with orbiters, landers, rovers, ballons, even a
sample return rocket. After the good VeGa experience more foreign
space agencies came aboard than ever before - especially France and
Germany invested heavily; Germany,
for example, provided both cameras.
But then the Phobos missions largely failed, and the ambitious Mars
program began its long road to oblivion: Schedules started to slip,
and the number of spacecraft dwindled - in the end there was only
Mars'96 left (the same project that initially was to go in 1992). With
its loss, Russia has no planetary program left. Even the successor
of Mars'96, Mars'98, had been cancelled recently, and all the hope to
rescue some of the experience of Russia's engineers would be with a
revived "Mars Together" project: Russian technology flying on an American
spacecraft. Such a mission had been very tentatively planned
before the Mars'96 disaster struck. And for the international partners
of Mars'96 the search for other "carriers" of the instruments has begun -
many of them would be way to heavy for the new 'lean'
U.S. Surveyor
spacecraft, unfortunately. But the energy invested into the development
programs is certainly not lost: The smaller of the German Mars cameras,
I've heard, had already been adapted for terrestrial use in airplanes.
DF
Briefly noted:
Leonid meteor rates were up: The prospects for a great display
of the Leonid meteor shower may have increased as even in Europe
Zenithal Hourly Rates of up to 100 were observed in the hours before
sunrise on November 17th. (IMO Reports)
Hipparcos data products for sale! An order form for the
printed and CD-based ultimate star catalogues is now
available from ESA: The Hipparcos catalogue (118 218 star positions
with extreme accuracy) and the Tycho catalogue (1 058 332 star positions
and magnitudes with excellent accuracy) cost $ 100 for CD only or
$ 400 with all 16 printed volumes. Volumes 14-16 are the "Millennium
Star Atlas" generated from these catalogs; they will be sold separately
by Sky Publishing.
Replacement of all four Cluster spacecraft recommended: The
Space Science Advisory Committee of ESA is calling for an almost
full replacement of the four space physics satellites lost in the
Ariane 501 launch failure in June, and the Science Programme Committee,
which makes the decisions, usually follows these recommendations. While
the 4 spacecraft will be rebuilt (significantly cheaper than the
original ones), not all the scientific instruments can be replaced:
They are in the responsibility of individual institutes, most of which
have severe budget problems... (Space News Nov. 11, 1996)
Update #18 of Nov. 14, 1996, at 19:20 UTC
Upcoming Leonid meteor shower no hit for Europe
When will the famous meteor shower of the Leonids peak this year -
and who's gonna be able to watch it? For the turn of the century major
displays (of "storm" strength) are expected, but last year the rates
were only moderately up from older values. If the Leonids are up this
year, the prospects for a major show (though probably not as wild as
the one from 1966) are good; observations are therefore strongly
encouraged.
But when to look? If the maximum would take place at the same place
along the Earth's orbit around the sun as last year, it would fall
into the afternoon hours (UTC) on Nov. 17th. But experts consider it
more likely that the maximum is shiftig closer to the closest approach
of Earth to the actual position of the responsible dust cloud left
behind by the parent comet 55P/Temple-Tuttle. If so, the maximum
is on Nov. 17th already around 7:00 UTC.
This is bad news for Europe: During the night 16/17 Nov. zenithal
rates of not more than 30 meteors are to be expected in the morning
hours, and in the coming night the rates will already be down again.
Fortunately meteor observers are well
organized
all over the world,
so we will learn about the peak rate - and thus the future prospects
of the Leonids - early next week. (Mitteilungen des AKM21
[Oct. 1996] p. 151)
Briefly noted:
The launch of Columbia has slipped, as expected (see previous
Update), to Tuesday Nov. 19th; the launch window opens at 19:53 UTC and
lasts for 2.5 hrs. The reason for the delay were high winds and the
waiting Atlas Rocket with
Eutelsat's
Hot Bird 2: It can try to launch all weekend. There has to be a 48 hr
period between an ELV launch and a shuttle mission; thus Columbia can
try on Tuesday the earliest. Meanwhile the launch of Mars'96
seems to stay on coming Saturday Nov. 16. (Florida Today)
All what's new in Jupiter's atmosphere can now be read on the
Web as well, in the first HTMLized
International Jupiter Watch
Newsletter - including detailled amateur observations, not just
Galileo stuff. This must mean something...
Pretty pictures of the Sun haven been put together on the
SOHO homepage, and
amazing pictures of spacecraft in orbit, taken with amateur means
are shown by the Boston Museum
of Science - yours truly has seen the system they were taken with in
action. By cleverly adding up parts(!) of single TV frames, Ron
Dantowitz often attains a resolution of less than 1/2 arc second (and
this from Boston!). Next target: the planet Mars!
Update #17 of Nov. 12, 1996, at 18:00 UTC
Last posting from the U.S. - The Cosmic Mirror returns to Germany
Columbia's launch set for coming Friday!
Boosters not a risk - but weather could spell Trouble
Late yesterday NASA managers finally cleared the space shuttle Columbia
for the launch of its ambitious 16 day mission
STS-80. Exhaustive analysis of the nozzle insulation in the
booster rockets had shown that the mysterious 60 grooves found in the
thermal insulation of Atlantis' boosters after its September mission had
been caused by a processing problem and other related factors. The launch
window now opens at 19:51 UTC on Friday, Nov. 15th, and lasts for 2 1/2
hours. The weather prospects for this time (as well as for an Atlas
rocket with a European TV satellite due to launch tomorrow), however,
are quite poor: High winds reduce the chance of acceptable conditions
for both launches to 20% at this time.
Mission STS-80 is unique in that two free-flying satellites will be
deployed and retrieved again, requiring some unusual maneuvering of
the orbiter. Of most interest for reader of The Cosmic Mirror is
ORFEUS,
of course, the Orbiting and Retrievable Far and Extreme UV Spectrometer.
Together with another telescope and six add-on experiments, ORFEUS sits
on SPAS, the Shuttle Pallet Satellite. Two spectrometers, a German and
an American one, share the same big UV telescope. The studies concentrate
on the interstellar medium which is probed by the narrow absorption
lines it causes in the spectra of stars. The sensitivy of the instrumentation
(which was improved after ORFEUS' first flight, as were the optics) should
allow ISM probing across the whole galaxy. The other telescope on SPAS,
IMAPS, achieves much higher spectral resolution, but only with the
few UV-brightest stars in the sky. For the first time, the German space
agency DARA (which ironically will cease to exist soon) is providing a
homepage for the mission - as do the
German scientists
involved with ORFEUS, of course.
The other free-flyer on STS-80 is the
Wake Shield Facility, which,
on its 3rd flight, will finally produce composite semiconductors that will
actually be used in experimental electronic devices. The first two WSF
missions, through marred by heavy glitches, had demonstrated that this
giant flying disk can produce an enormously good vacuum behind it when
rushing through Low Earth Orbit - and that the
epitaxial growth of
semiconductors works better under these conditions indeed than in any
lab on the ground. If WSF-3 is a success (2 good wafers would be needed),
subsequent missions could start semiconductor mass production -
and finally make money! STS-80 will feature several other experiments
besides the free-flyers, including two more EVAs in preparation of
Space Station work and the first
flight of the Space Experiment
Module for space experiments of students. (Florida Today +
CNN Nov. 11 + NASA Pre-Launch Press Conferences Oct. 31, 1996)
Update #16 of Nov. 8, 1996, at 23:45 UTC
Posted from Cambridge, MA, U.S.A.
Space Interferometer, Sample Return, Seismometers on Mars:
New "Themes" for New Millennium Missions
The mission concepts for the next five spacecraft under NASA's
"New Millennium" program for
innovative space technology experiments are even bolder than the
first three. While "Deep Space 1" will fly by an asteroid and a comet
(see Update #3) and Deep Space 2 will consist of very small Martian
penetrators hitchhiking on the Mars Surveyor Lander 1998 (and there will
also be an advanced Earth imaging mission), the subsequent Deep Space
missions with launches in 2000 til 2002 will try out totally new
scenarios. Firm decisions on which technology goes on which mission have
yet to be made, but the following list gives some idea what to expect:
Deep Space 3 could be a mission to try out linking separated
spacecraft - and to construct a unique optical interferometer of
free-flying telescopes! It is unclear (at least to me :-) whether this
would be just a technical proof of concept or whether the satellite
constellation would actually be able to generate astronomical images
with extremely high resolution (see also my article on optical
interferometry in the November
Sky & Telescope). It is generally believed that the first
astronomical interferometers in space would consist of several
telescopes on one satellite, with a rather short baseline of
not more than tens of meters. Only for the distant future interferometers
distributed onto several spacecraft were anticipated.
Deep Space 4 could be a testbed for technology to aquire
samples from the surface of a small body (such as an asteroid or a
comet nucleus) and to bring them to Earth. There is some maneuvering
inside JPL at the moment to turn the cancelled
Champollion comet lander of Rosetta (see Update #2)
into Deep Space 4 - and thus be
on the target years before Rosetta and its remaining
RoLand
lander...
Deep Space 5 finally could try out the technologies
needed for long-lived microprobe-type seismic stations as an
add-on for a a Mars mission. Or it could be a lunar far-side
sample return. In total as many as 20 new technolgies will be the
objectives of the three new Deep Space as well as two new Earth Orbiting
probes, and 10 to 20 new partners will be involved, in addition to the
24 groups involved in the first three New Millennium missions.
(Space News Oct. 28, 1996)
Life on Earth 3.85 billion years old?
The problem resembles the
analysis of the Martian meteorites: Is it life or just inorganic chemistry
that left its traces in sediments from Greenland which are almost 3.9
billion years old? The oldest clear-cut fossilized cells are
3.5 billion years old; all evidence preceding that time is - and stays -
purely geochemical. But a new analysis of the Greenland sediments has
increased the likelyhood that life is involved: the carbon isotope ratios
and their mineralogical environment would fit.
Living cells almost 4
billion years ago would be quite something: The Late Heavy Bombardement
by the Earth-Moon system from planetesimals (left over from the formation
of the solar system) had just ended at that time. Did life arise
almost at the moment it had the chance to do so - or was it around even
during the violent youth of the Earth? The continued existence of weird
archaebacteria, some of them fanatic heat-lovers, could indicate that.
(NASA News #230 of Nov. 6, 1996, and many other sources)
Briefly noted:
MGS Solar Array problem called minor: NASA engineers say the problem
with the misaligned solar array of the Mars Global Surveyor (see last
Update) is minor and that the spacecraft can be
righted in time for a crucial Nov. 22 thruster firing, the first of
four that will fine-tune its flight path to the Red Planet. One of the
solar panels on the spacecraft failed to open completely about an
hour after a launch: the panel remained tilted about 20 degrees from its
proper position and was causing the spacecraft to wobble
slightly in flight. Engineers, however, must stabilize the craft before a
thruster firing for the first trajectory correction can be carried out
later this month. Star sensors that serve as key
guidance and navigation devices will not work properly if the spacecraft
is wobbling. (Florida Today Nov. 8, 1996)
Cassini not endangered by Saturn's rings: Data from previous
space missions and groundbased and Hubble observations of the ring plane
crossings of 1995 plus derived computer models about the dust
environment of Saturn show that the probability of a fatal hit by a ring
particle is less than 1% during the four years that
Cassini will spend in orbit.
(Space News Oct. 28, 1996)
Green Light for Columbia expected: A group of NASA experts has
concluded that shuttle Columbia's booster rockets are safe to fly,
which might clear the ship for launch late next week.
The engineers from NASA's Marshall Space Flight Center in Huntsville, Ala., will
present their findings Monday to top agency managers, who will then decide
whether to allow Columbia to liftoff on a 16-day mission. (Florida Today
Nov. 8, 1996)
Update #15 of Nov. 7, 1996, at 23:00 UTC
Posted from Cambridge, MA, U.S.A.
Mars Global Surveyor on the Way to Mars!
Perfect launch - perfect trajectory - almost perfect health
It was one of the most spectacular Delta 2 launches ever, and the first
one with a planetary destination: At precisely the right centi-second
the journey of the Mars Global Surveyor began at the Kennedy Space
Center. At 17:00:49.996 UTC (or 4 milliseconds early :-) the engines
fired, and the Delta rose into a blue sky; the jettisoning of first 6 and
then another 3 boosters was well visible.
Here
lots of outstanding high-resolution pictures are available!
All the crucial
events in the subsequent
50 minutes took place on time as well, from the jettisoning of the 1st
stage and the 2 burns of the second to the burn of the 3rd and the
yoyo-despinning - then, at 17:51 UT, the Mars Global Surveyor was on its own.
Ground stations on several continents and a plane over the Indian Ocean
had monitored the telemetry, and viewers in the U.S. could watch on
NASA Select TV how flight engineers were eagerly monitoring the
most satisfying data coming in.
At a news conference at 19:30 UTC a panel of NASA managers had further
good news: communication with the spacecraft on its way to Mars had been
established through the Deep Space Network as planned, the downlink as well
as the uplink (i.e. commands to the MGS) worked, and the spacecraft had
unfolded its solar arrays. However, one of the four panels had stopped short
20 degrees from the nominal position. This was described as a minor problem
that might correct itself - or if not, could be compensated by the gimballing
mechanism of the arrays. At the moment the arrays are delivering 670 Watts,
much more than needed, but once operations in Mars orbit are under way
(the mapping will run from Apr. 1998 til April 2000), there'll be need for
all the power the MGS can get. (NASA Select live coverage) Finally
a reminder for radio hams:
you
can be part of the MGS mission, too!
Notes from a very special Comet Conference in Cambridge, MA
On Nov. 5th one of the most famous astronomers of this century - and
probably the most famous planetary scientist of our time -
celebrated his 90th birthday:
Fred Whipple. On this occasion his home institute for many
decades, the
Harvard-Smithsonian Center for Astrophysics
here in Cambridge, Massachussets
(recently the topic of OMNI's
Live Science) hosted a small conference on the present knowledge about
comets, one of the many interests of Fred Whipple, and the topic that
had made him world-famous. Fred, of course, was the scientist who in 1950
had figured out what comet nuclei are like - his 'dirty-snowball model'
(he preferrs the term 'icy-conglomerate') was finally proven right by the
Halley spacecraft in 1986. Here are some of the many interesting points that
were made at the conference.
Comet nuclei are no dirty snow- but icy dirtballs: Many findings
from esp. the
Giotto
spacecraft lead to the conclusion that refractory
material dominates the structure of a typical comet nucleus and not icy,
volatile material. Nuclei have a strength in itself: That became clear
from the analysis of Halley's nucleus with its large 'mountain' at the
terminator or the extended 'duck tail' on the dark side. And tthe dusty
crust that is growing on ageing nuclei is cohesively connected to the
boulders making up the nucleus itself.
"Galactic Tides" are the most important disturbers of the Oort cloud:
The distribution of the orbits of long-period comets coming in from the
vast reservoir of dormant nuclei, the
Oort Cloud, contains a lot of
information about what made those comets cross into the inner solar system.
Apparently stars plowing through the cloud and knocking nuclei off their
circular orbits do only play a minor role. Instead it seems to be the
up and down movement of our Sun through the galactic plane that disturbs
the orbits in the Oort cloud,
Are we experiencing a comet shower? This provocative statement
comes from tedious crater counting on the Moon and the
Earth: If we
understand the cratering history of both bodies correctly, the rate of
impacts from celestial bodies has about doubled in the last
billion years, compared to the 2 billion years before. The argument
can be made that this increase is due to an increasing "influx" of
comets - which would make sense in the Galactic Tide model mentioned
above. Every 31 million years the Sun is crossing the galactic plane;
it did so 65 million years ago (ask the dinosaurs what happened), it
happened 32 million years ago (again major impacts shook the Earth), and
it's happening right now. Maybe the Sun got into this dangerous oscillation
state close to the galactic plane only "recently", perhaps after a close
encounter with a molecular cloud...
BREAKING NEWS - Update #14 of Nov. 6, 1996, at 18:30 UTC - BREAKING NEWS
Posted from Cambridge, MA, U.S.A.
Clouds, wind force delay of MGS launch - next attempts Thursday
Heavy clouds and then upper level winds along with threatening clouds
and rain have forced NASA to forego both launch windows of
the Mars Global Surveyor today; tomorrow's two launch windows will be at
17:00:50 and 18:05:56 UTC. Like today, weather officials say there is
an 80% chance of acceptable conditions. You can follow the progress
of the launch campaign (or lack thereof) through frequent
reports by a CBS
reporter at the Cape, or by periodically reloading the grabbed
video image from NASA Select TV: Is the Delta rocket
still at the launch pad or not?
Once it's up, it will be a while before the MGS is actually on the
way to its destination: Here is the
timeline. To find
out more about the mission, read the
brochure,
where also links to the homepages of the 6 science instruments
aboard MGS can be found. The
Thermal Emission Spectrometer
team has put particular effort into its public relations work and is
even publishing its own newsletter! And at the site of the MGS
Camera you can find out all about the (in)famous
"Face on Mars"... What the Russians are doing in the meantime is
documented on this pretty
colorful homepage. (With Florida Today)
Update #13 of Nov. 6, 1996 at 16:00 UTC
Posted from Cambridge, MA, U.S.A.
Launch of Mars Global Surveyor imminent!
At 17:11 and again 18:15 UTC two short launch windows open today for the
Mars Global Surveyor spacecraft
(quick
summary), and as of yesterday afternoon no problems with the spacecraft,
the Delta rocket or the weather at Cape Canaveral were in sight. And there
are many more launch opportunities in the coming three weeks; only the
arrival date in Mars orbit would slip one day for every two days of launch
delay. Currently it is Sept. 11, 1997. Click here for
live
pictures from the cape, updated every 90 seconds!!!
Starting on that date, the Global Surveyor would first "aerobrake" itself
from a highly elliptical into a more circular orbit; then the most
comprehensive investigation of Mars as a whole. The "MGS" is carrying
duplicates of most of the instruments that were on the Mars Observer, lost
on arrival in 1993. Of most interest for the public will be the
camera,
of course, and NASA has promised to make its images available within days.
Some will have a resilution of 1.4 meters!
The launch of the MGS will be an important milestone for NASA, because
it is not just another planetary spacecraft. Instead, this launch will be
the beginning of the first concerted effort to understand Mars, with launches
coming up in every window way into the 21st century. And for NASA, a successful
mission would be proof that "faster" and "cheaper" can be "better",
too: The decision to start the Mars Surveyor program came just a few months
(!) after the Mars Observer was given up, in February, 1994. Many other
innovations are also
implemented in the MGS - good luck! (D.F., with a NASA News Conference
of Nov. 5, 1996)
Delay for Mars'96: Apparently the launch of the next Mars mission,
the Russian-international Mars'96, which was scheduled for Nov. 16, has been
delayed by about 4 days due to processing problems with its Proton rocket in
Baykonur. At least that's what was announced inofficially at the NASA
News Conference mentioned above.
Both astrophysics satellites are probably dead, that were on the
ill-fated Pegasus launch two days ago: According to
Jonathan's Space Report, "HETE is carried inside the Dual Payload
Attach Fixture on which
SAC-B is mounted, so it's trapped and was unable to deploy its solar
panels. The satellite is now defunct. SAC-B was able to deploy its solar
panels, but the tumbling spacecraft was unable to remain in sunlight
enough to recharge the batteries and it appears that SAC-B too is now
lost."
Satellites don't separate from Pegasus - only SAC-B partially useful
The first double launch of two science satellites on a winged
Pegasus rocket has ended in a disaster: The satellites (see Update #8,
where also lots of links can be found)
failed to separate from the rocket, and while they reached the proper
orbit, they are largely useless. Only the Argentine SAC-B might be
able to perform part of its mission; HETE, however, is buried underneath
it and cannot do anything. Without solar power it is probably already
dead when you read this. Analysis of the Pegasus malfunction - the
2nd one in the last 5 launches! - is underway in various places,
and because a lot of telemetry was downlinked, the problem should be
located soon. The kind of malfunction observed now is new.
Preliminary analysis of today's launch of the SAC-B and
HETE spacecraft indicates that the Orbital Sciences
Corporation's Pegasus XL third stage failed to separate
properly, according to NASA. Both spacecraft are still attached to the third
stage in low Earth orbit. Project officials believe up to four of the five
scientific instruments aboard SAC-B may still be able to
return scientific data.The HETE spacecraft was unable to
deploy its solar arrays and battery failure is expected today. No probmes
had occured prior to launch, and the preparations had actually run
ahead of schedule.
The Pegasus launch from the carrier plane
had occured at approximately 12:09 p.m.
EST offshore from NASA's Wallops Flight Facility in Virginia.
The Pegasus vehicle achieved the desired orbit of 265 nautical
miles by 297 nautical miles at an inclination of 38 degrees.
NASA attempted to acquire a signal from the spacecraft
through the Goldstone tracking station in California, and
successfully sent commands and received data from SAC-B
through the Wallops tracking station at the end of the first orbit.
(NASA News # 227 + Florida Today + Breaking News in Space,
Nov. 4, 1996)
Update #11 of Nov. 4, 1996 19:00 UTC
Posted from Cambridge, MA, U.S.A.
Shuttle Launch Delayed by at least a Week
NASA needs at least another week to find out more about the
strange erosion events in the boosters that took place during the
last launch. And there is also an Atlas launch coming up on Nov. 13th:
Should it slip, the launch of
STS-80, which could take place on
Nov. 15 or 16, would slip with it. (Florida Today Nov. 4, 1996 -
the fastest source on
the developping situation...)
And so the German UV astronomy freeflyer
ORFEUS-SPAS, a joint DARA/NASA
mission,
which was quite
successful
during the first flight, will have to wait a little longer, as has
Wake Shield Facility.
Briefly noted:
The closest approach of Galileo to Callisto took place
this morning
(or during the day, for readers in Europe, Africa and Asia): No
spacecraft had ever come to within 1118 km of this Jovian moon's
surface before! As usual it will take several weeks before the
first images taken during the flyby will
appear on the Net -
not because NASA wants to hide something from the public as many
space enthusiasts often
presume, but because the images come in little pieces through
the slow downlink from Jupiter and have to be reassembled first.
Hale-Bopp brighter than 4th magnitude?! Many observers are
estimating the brightness of this comet around 4.8 mag right now,
but Hale-Bopp is already low on the horizon for many sites. If one
corrects the estimates properly for the extinction, the real
magnitude could be as high as 3.8 mag! So Hale-Bopp can do
it after all ... I told you so, in Update #6 and 8. Watch the progress
of Hale-Bopp's magnitude before it slips behind the sun next month
through the "ICQ" and "JPL" links on my home page.
No fragments will ever be found from the Tunguska impactor:
That's the conclusion of detailled Russian calculations of the most
dramatic
impact event of the century. Small bodies entering the
atmosphere get braked high up: They produce brilliant meteors at times,
but substantial meteorits of decimeters to meters in size can sometimes
reach the ground. Not so if the impactor is big, like the Tunguska
meteoroid was (most likely a stony asteroid of some 60 meters in
diameter). Objects like these speed through the atmosphere and explode
low (at 9 km altitude in this case) - all that remains are widely
scattered fragments less than 10 cm in size. And the Russian
calculations now show that the heat of the explosion's fireball was
so immense that the solid fragments must have been destroyed
alltogether! So it's no wonder that
no Tunguska meteorites have ever been identified with certainty.
(Svetsov, Nature Oct. 24, 1996, p. 697-699)
This page and my home page have been
visited times since Halloween 1996.
Go to the preceding issues. Other
historical issues can be found in the Archive.
Compiled and written by
Daniel Fischer (send me a
mail to
[email protected]!),
Skyweek
