| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 699.1 | PVO Update - January 25 | ADVAX::KLAES | All the Universe, or nothing! | Mon Jan 28 1991 15:09 | 34 |
| From: [email protected] (Ron Baalke)
Newsgroups: sci.space,sci.astro
Subject: Pioneer Venus Update - 01/25/91
Date: 25 Jan 91 23:23:14 GMT
Sender: [email protected]
Organization: Jet Propulsion Laboratory, Pasadena, CA.
PIONEER VENUS STATUS REPORT
January 25, 1991
A 25-pulse precession maneuver was successfully executed on
January 19 by the Pioneer Venus spacecraft. An HGA (High Gain
Antenna) adjustment was not required because the precession moved the
antenna in the desired direction.
On January 18, a scheduled 34 meter track in Spain was cancelled
due to station antenna problems. This prevented the loading of the
spacecraft with the commands to turn the downlink on for a subsequent
Goldstone 34 meter track on the same day. As a result, data from both
tracks were lost, as well as the periapsis data for orbit 4427.
On January 19, several antenna problems at the 70 meter station
at Australia, caused a 1 hour and 30 minute loss of telemetry data,
and a 2 hour and 20 minute loss of command capability. On January 20,
a power failure at the same station caused a 1 hour and 30 minute loss
of data. This was post-periapsis data for orbit 4429.
___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | [email protected]
| | | | __ \ /| | | | Jet Propulsion Lab |
___| | | | |__) |/ | | |___ M/S 301-355 | It's 10PM, do you know
/___| | | | ___/ | |/__ /| Pasadena, CA 91109 | where your spacecraft is?
|_____|/ |_|/ |_____|/ | We do!
|
| 699.2 | PVO Update - February 1 | ADVAX::KLAES | All the Universe, or nothing! | Mon Feb 04 1991 11:57 | 43 |
| From: [email protected] (Ron Baalke)
Newsgroups: sci.space,sci.astro
Subject: Pioneer Venus Update - 02/01/91
Date: 4 Feb 91 04:23:30 GMT
Sender: [email protected]
Organization: Jet Propulsion Laboratory, Pasadena, CA.
PIONEER VENUS STATUS REPORT
February 1, 1991
The Project will request a "short loop" configuration at the
DSS's (Deep Space Stations) prior to critical commanding of the
Pioneer Venus spacecraft. This was done to avoid the frequent CPA
(Command Processor Assembly) failures which have affected the commanding.
On January 24, the spin period was adjusted from 12.95 seconds to
13.15 seconds. During 70 meter supports, the bit rate will be raised
to 2048 bps. Long eclipse season #20 begins on February 12 and will
last through February 20.
Pioneer Venus-1 (sometimes referred to as Pioneer 12) was launched
on a Atlas-Centaur rocket on May 20, 1978 and arrived into orbit
around Venus on December 4, 1978. In July 1980, controllers stopped
using hydrazine to hold the spacecraft's perigee steady. In 1986,
Pioneer Venus made ultraviolet observations of Halley's Comet. In
August, 1990, as Magellan was making its burn for Venus orbit
insertion, Pioneer Venus attempted to observe the burn, but was
unsucessful. In January of 1991, the Approach Phase of Venus entry
began. This phase will last until May 1992 and will see the periapsis
drop from about 1000 km to 200 km. In the spring of this year, the
radar mapper, which has been off since 1981, will be turned back on to
map the southern region of Venus. In June 1992, the Entry Phase will
begin and the remaining hydrazine aboard the spacecraft will be used
for 90 days to delay the entry into Venus. Burnup of Pioneer Venus is
expected to happen in September 1992.
___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | [email protected]
| | | | __ \ /| | | | Jet Propulsion Lab |
___| | | | |__) |/ | | |___ M/S 301-355 | It's 10PM, do you know
/___| | | | ___/ | |/__ /| Pasadena, CA 91109 | where your spacecraft is?
|_____|/ |_|/ |_____|/ | We do!
|
| 699.3 | PVO Update - February 8 | ADVAX::KLAES | All the Universe, or nothing! | Fri Feb 08 1991 18:02 | 26 |
| From: [email protected] (Ron Baalke)
Newsgroups: sci.space,sci.astro
Subject: Pioneer Venus Update - 02/08/91
Date: 8 Feb 91 21:07:18 GMT
Sender: [email protected]
Organization: Jet Propulsion Laboratory, Pasadena, CA.
PIONEER VENUS STATUS REPORT
February 8, 1991
Long eclipse season #20 begins on February 12 for the Pioneer
Venus spacecraft, and will last through February 20. There will be
two penumbral eclipses, on the first and last days of the season.
On February 3, a scheduled 70 meter Goldstone support was
replaced with 34 meter Canberra support. Reloading of the spacecraft
to change the bit rate for the Canberra support resulted in a 30
minute delay in the turn on of the periapsis science instruments.
___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | [email protected]
| | | | __ \ /| | | | Jet Propulsion Lab |
___| | | | |__) |/ | | |___ M/S 301-355 | It's 10PM, do you know
/___| | | | ___/ | |/__ /| Pasadena, CA 91109 | where your spacecraft is?
|_____|/ |_|/ |_____|/ | We do!
|
| 699.4 | PVO Update - February 15 | ADVAX::KLAES | All the Universe, or nothing! | Sun Feb 17 1991 16:15 | 34 |
| From: [email protected] (Ron Baalke)
Newsgroups: sci.space,sci.astro
Subject: Pioneer Venus Update - 02/15/91
Date: 16 Feb 91 03:12:12 GMT
Sender: [email protected]
Organization: Jet Propulsion Laboratory, Pasadena, CA.
PIONEER VENUS STATUS REPORT
February 15, 1991
On February 10, a maser failure at the 70 meter Madrid station
resulted in a 48 minute loss of telemetry data, and 33 minute loss of
commanding. This loss resulted in no data being stored during the
subsequent 6 hour tracking gap. A precession maneuver will have to
be performed after the present eclipse season ends. It is tentatively
planned for February 23.
Last night, a spacecraft emergency was declared for the
spacecraft. The Goldstone 70 meter antenna lost the spacecraft
downlink yesterday at 3:40 PM (PST). The Ames Research Center reports
that they suspect the spacecraft is in an under voltage condition.
The 70 meter antenna at Canberra provided support for about 2 1/2
hours, using 300 KW to radiate the command sequence to configure the
spacecraft's prime receiver to the AFT omni antenna. The spacecraft
emergency is still in effect. The Goldstone station will be providing
support with the high power transmitter.
___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | [email protected]
| | | | __ \ /| | | | Jet Propulsion Lab | Is it mind over matter,
___| | | | |__) |/ | | |___ M/S 301-355 | or matter over mind?
/___| | | | ___/ | |/__ /| Pasadena, CA 91109 | Never mind.
|_____|/ |_|/ |_____|/ | It doesn't matter.
|
| 699.5 | PVO Update - February 18 | ADVAX::KLAES | All the Universe, or nothing! | Mon Feb 18 1991 18:50 | 63 |
| From: [email protected] (Ron Baalke)
Newsgroups: sci.space,sci.astro
Subject: Pioneer Venus Update - 02/18/91
Date: 18 Feb 91 16:34:48 GMT
Sender: [email protected]
Organization: Jet Propulsion Laboratory, Pasadena, CA.
Pioneer Venus Update
February 18, 1991
The Pioneer project has declared the Pioneer Venus spacecraft
over as of 3:45 PM (PST) on February 15, and normal support for the
spacecraft has resumed. The spacecraft is configured to the High Gain
Antenna and the prime receiver.
___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | [email protected]
| | | | __ \ /| | | | Jet Propulsion Lab | Is it mind over matter,
___| | | | |__) |/ | | |___ M/S 301-355 | or matter over mind?
/___| | | | ___/ | |/__ /| Pasadena, CA 91109 | Never mind.
|_____|/ |_|/ |_____|/ | It doesn't matter.
From: [email protected] (Ron Baalke)
Newsgroups: sci.space,sci.astro
Subject: Pioneer Venus Update #2 - 02/18/91
Date: 18 Feb 91 17:56:12 GMT
Sender: [email protected]
Organization: Jet Propulsion Laboratory, Pasadena, CA.
PIONEER VENUS STATUS REPORT
February 18, 1991
Note: In a prior posting, I said "the Pioneer Spacecraft was over",
when I meant to say "the Pioneer Spacecraft emergency was over". Sorry
for any confusion.
On the afternoon of February 14, the Pioneer Venus spacecraft
experienced an Under Voltage Trip which turned off all non-essential
loads, including the antenna despin electronics; and the downlink went
silent. A spacecraft emergency was declared, and a large number of
receiver reverse commands at 300KW were sent in a drift through mode
to the backup (bad) receiver. On February 15, during a Goldstone 70
meter track, the spacecraft was reaquired, and is being returned to
normal configuration at this time.
Project analysis is that during the eclipse the battery sank to
an unprecedented low, setting flags to open the three power busses.
As is normal during eclipses, the low voltage protection circuitry had
been disabled prior to entering the eclipse. Upon exit from the
eclipse, telemetry showed an adequate power level, as expected. When
the low voltage protection circuitry was commanded back on, as was
routinely done on all past eclipses, the flags (latched relays) of the
low power level during the eclipse were acted upon by the control
logic. In retrospect, the relays should have been commanded to reset
prior to commanding the protection circuitry back on.
___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | [email protected]
| | | | __ \ /| | | | Jet Propulsion Lab | Is it mind over matter,
___| | | | |__) |/ | | |___ M/S 301-355 | or matter over mind?
/___| | | | ___/ | |/__ /| Pasadena, CA 91109 | Never mind.
|_____|/ |_|/ |_____|/ | It doesn't matter.
|
| 699.6 | PVO Update - March 1 | ADVAX::KLAES | All the Universe, or nothing! | Mon Mar 11 1991 16:51 | 23 |
| Date: 8 Mar 91 21:08:30 GMT
From: rex!wuarchive!sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!
[email protected] (Ron Baalke)
Subject: Pioneer Venus Update - 03/01/91
PIONEER VENUS STATUS REPORT
March 1, 1991
At the request of the Magellan project, a 70 meter Canberra track
was swapped for a 34 meter Canberra track on February 22. This required
a change in the bit rate to 512 bits/second versus the planned 1024 bits/
second on the Pioneer Venus spacecraft. An 8-degree attitude maneuver
and HGA (High Gain Antenna) adjustment was successfully executed on
February 23. On February 25, antenna problems at the 70 meter Goldstone
station caused a 1 hour and 30 minute loss of telemetry data.
___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | [email protected]
| | | | __ \ /| | | | Jet Propulsion Lab | Is it mind over matter,
___| | | | |__) |/ | | |___ M/S 301-355 | or matter over mind?
/___| | | | ___/ | |/__ /| Pasadena, CA 91109 | Never mind.
|_____|/ |_|/ |_____|/ | It doesn't matter.
|
| 699.7 | PVO Update - March 15 | ADVAX::KLAES | All the Universe, or nothing! | Mon Mar 18 1991 15:44 | 30 |
| From: [email protected] (Ron Baalke)
Newsgroups: sci.space,sci.astro
Subject: Pioneer Venus Update - 03/15/91
Date: 16 Mar 91 01:14:33 GMT
Sender: [email protected]
Organization: Jet Propulsion Laboratory, Pasadena, CA.
PIONEER VENUS STATUS REPORT
March 15, 1991
The periapsis altitude for the Pioneer Venus passed below 1000 km
on March 3. On March 9, there was a 2 hour delay at acquisition due
to antenna problems at Canberra 70 meter station. In addition, the
track was terminated 4 hours early to allow the batteries to recharge.
Long apoapsis occultations are continuing until March 20.
Tracking has been adjusted so that each occultation takes place during
a tracking gap.
An ORPA instrument check procedure that was implemented on
February 25 has detected four instances of anomalous operation. In
each case the instrument operation was corrected by real time commands.
___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | [email protected]
| | | | __ \ /| | | | Jet Propulsion Lab |
___| | | | |__) |/ | | |___ M/S 301-355 | Change is constant.
/___| | | | ___/ | |/__ /| Pasadena, CA 91109 |
|_____|/ |_|/ |_____|/ |
|
| 699.8 | Pioneer Venus Orbiter closes in on Venus | PRAGMA::GRIFFIN | Dave Griffin | Wed Sep 02 1992 14:39 | 83 |
| Paula Cleggett-Haleim
Headquarters, Washington, D.C. September 1, 1992
Pete Waller
Ames Research Center, Mountain View, Calif.
RELEASE: 92-140
Between now and year's end, the Pioneer Venus Orbiter
will skim closer to Venus than ever before, returning
significant new knowledge of the planet.
It will explore upper atmosphere regions never before
reached, helping answer questions about Venus' environment
-- whether there is lightning on the planet and whether
Venus once had oceans. The orbiter then will enter Venus'
atmosphere at hypersonic speed and burn. This is expected
to happen in October, November or December.
"Completing the picture of Venus' outer environment
will be a major achievement," said Richard Fimmel of NASA's
Ames Research Center, Mountain View, Calif. "It will
culminate 14 years of receiving information since the
spacecraft was launched in 1978."
Pioneer Venus provided data for the first topographic
maps of 90 percent of the planet's previously unknown
surface. It identified mountain ranges, plateaus, plains
and deep depressions.
The expected findings about Venus' outer environment,
Fimmel said, relate to atmosphere/plasma interactions.
Plasmas (electrically charged gases) are the most
common form of matter in the universe. The million-mile-an-
hour solar wind is an ionized gas which continuously batters
Venus' atmosphere . The solar wind and Venus' atmosphere
interact in many ways.
Studying these complex interactions on Venus may
increase knowledge of similar interactions in the
atmospheres of comets, planets, moons and star systems as
well as processes in the early solar system and interstellar
gas clouds.
Researchers also hope to find out more about Venus'
water-loss mechanisms by measuring for the first time the
top of Venus' "mixed" atmosphere and the densest part of the
planet's ionosphere.
In the final phase, gravity will bring Pioneer's orbit
down into Venus' upper atmosphere. With Pioneer about 84
miles above the planet, NASA Ames officials will raise the
low point of its orbit by firing thrusters early on Sept. 7
and then every 5 days thereafter until the estimated four
pounds of remaining hydrazine propellant is gone. Then, the
spacecraft will plunge into the Venusian atmosphere and
burn.
The Pioneer Venus mission has had three phases. NASA
researchers held the orbit's lowest point, known as
"periapsis," at 93 miles above Venus' surface to map and
study the ionosphere and atmosphere during the first 19
months at Venus. In phase two, with only 10 percent of
propellant left, they allowed solar gravity to gradually
raise periapsis to 1,500 miles and then return it to low
altitude.
By June of this year, with periapsis at 125 miles, the
orbiter's instruments began to measure Venus' ionosphere
again. By Sept. 7, the sun will pull periapsis down to 82
miles. If enough hydrazine remains, thrusters will be fired
to raise periapsis eight more times.
By Nov. 22, solar gravity will briefly raise periapsis
to about 98 miles, but will pull it down to about 87 miles
by Dec. 10. Officials then plan to fire any remaining fuel
to obtain more data from farther into Venus' "day side"
before the orbiter's final entry into the atmosphere.
|
| 699.9 | Out of Fuel...End of Mission Near | PONIL::J_BUTLER | E poi, si muove... | Mon Oct 05 1992 11:05 | 30 |
| Article 2113 of sci.space.news:
Newsgroups: sci.space.news
Path: nntpd2.cxo.dec.com!nntpd.lkg.dec.com!news.crl.dec.com!deccrl!decwrl!sun-barr!ames!dont-send-mail-to-path-lines
From: [email protected] (Ron Baalke)
Subject: Pioneer Venus Out of Fuel, Orbit Deteroriating
Message-ID: <[email protected]>
Followup-To: sci.space
News-Software: VAX/VMS VNEWS 1.3-4
Sender: [email protected] (Usenet)
Nntp-Posting-Host: kelvin.jpl.nasa.gov
Reply-To: [email protected]
Organization: Jet Propulsion Laboratory
Date: Sun, 4 Oct 1992 12:13:33 GMT
Approved: [email protected]
Lines: 12
Pioneer Venus ran out of fuel yesterday (October 2) when it tried to fire its
thrusters to raise its orbit around Venus. This was much sooner than
expected - it was thought that there was enough fuel for another two months.
The spacecraft's orbit is deteroriating, and it is expected to plunge into the
atmosphere of Venus within a week.
___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | [email protected]
| | | | __ \ /| | | | Jet Propulsion Lab |
___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Einstein's brain is stored
/___| | | | ___/ | |/__ /| Pasadena, CA 91109 | in a mason jar in a lab
|_____|/ |_|/ |_____|/ | in Wichita, Kansas.
|
| 699.10 | Ending of an era | VERGA::KLAES | All the Universe, or nothing! | Mon Oct 05 1992 12:55 | 33 |
| Article: 2747
From: [email protected] (UPI)
Newsgroups: clari.tw.telecom,clari.news.gov.agency,clari.news.disaster
Subject: Pioneer spacecraft out of fuel; orbit deteroriating
Date: Sat, 3 Oct 92 16:42:00 PDT
MOUNTAIN VIEW, Calif. (UPI) -- After 14 years in orbit around
Venus, the Pioneer spacecraft ran out of fuel Saturday, and NASA
officials expect to lose contact with it some time next week.
Scientists at the National Aeronautics and Space
Administration's Ames Research Center said an attempt to fire the
spacecraft's thrusters Saturday failed to produce any impulse.
Ames spokesman Peter Waller said the failure means scientists
cannot raise the low point of the spacecraft's orbit.
``Pioneer will enter Venus' atmosphere and lose communications
due to the frictional heat of atmosphere entry on some day next week,''
Waller said, adding that the veteran spacecraft will eventually
disentegrate as it spirals toward's the planet's surface in a
decaying orbit.
Pioneer has been orbiting Venus since 1978, beaming back
thousands of pictures that have helped scientists map the planet.
The craft is still transmitting data back to Earth about
Venus's upper atmosphere.
But NASA said such contact will end when Pioneer enters the
planet's lower atmosphere, heating up to temperatures that will
disable the probe's radio.
|
| 699.11 | PVO may burn up over Venus on October 8 | VERGA::KLAES | All the Universe, or nothing! | Tue Oct 06 1992 13:20 | 21 |
| Article: 2752
From: [email protected] (UPI)
Newsgroups: clari.tw.space,clari.local.california,clari.local.sfbay
Subject: Pioneer spacecraft to burn up in Venus atmosphere Thursday
Date: 6 Oct 92 00:03:22 GMT
MOUNTAIN VIEW, Calif. (UPI) -- Scientists at NASA Ames
Research Center predicted Monday that the Pioneer spacecraft would
burn up on Thursday as it hurtles through the atmosphere of Venus.
Peter Waller, a NASA Ames spokesman in Mountain View, Calif.,
said the historic spacecraft's main thrusters have run out of fuel and
it is descending into the Venusian atmosphere. He said scientists at
Ames predict the craft would enter the atomsphere on Wednesday and
burn up Thursday.
Pioneer, which has been orbiting Venus since 1978, ran out of
fuel Oct. 3. However, the spacecraft continues to return close-in
science data about the top of Venus's atmosphere. It is currently
operating in a region never before reached by an orbiting spacecraft.
|
| 699.12 | Update - October 8 | VERGA::KLAES | All the Universe, or nothing! | Fri Oct 09 1992 11:36 | 28 |
| Article: 27159
Newsgroups: sci.space,sci.astro
From: [email protected] (Ron Baalke)
Subject: Pioneer Venus Update - 10/08/92
Sender: [email protected] (Usenet)
Organization: Jet Propulsion Laboratory
Date: Thu, 8 Oct 1992 23:34:50 GMT
PIONEER VENUS STATUS REPORT
October 8, 1992
Pioneer Venus is still alive and hanging in there. The spacecraft's
spin rate was doubled on October 5 to provide better stabilization as
the spacecraft passed through the atmosphere of Venus, and this
extends the use of the High Gain Antenna. Also, it was estimated that
about 4 oz of fuel still remained in the fuel tanks, and the increased
spin rate would move any remaining fuel towards the thrusters. A
thruster maneuver was attempted today and was successful in raising
the periapsis an additional kilometer. Pioneer Venus continues to
experience increasing drag on each orbit around Venus.
___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | [email protected]
| | | | __ \ /| | | | Jet Propulsion Lab |
___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Einstein's brain is stored
/___| | | | ___/ | |/__ /| Pasadena, CA 91109 | in a mason jar in a lab
|_____|/ |_|/ |_____|/ | in Wichita, Kansas.
|
| 699.13 | The end of an era | VERGA::KLAES | All the Universe, or nothing! | Fri Oct 09 1992 12:08 | 27 |
| Article: 2757
From: [email protected] (UPI)
Newsgroups: clari.tw.space,clari.local.sfbay,clari.local.california
Subject: Pioneer spacecraft burns up in Venus atmosphere
Date: 8 Oct 92 23:56:59 GMT
MOUNTAIN VIEW, Calif. (UPI) -- Researchers at NASA's Ames
Research Center said Thursday the Pioneer spacecraft, which had been
orbiting Venus since 1978, had burned up while entering the planet's
atmosphere.
NASA spokesman Peter Waller said Pioneer was 79.5 miles above
the surface of Venus when researchers lost contact at 12:22 p.m. PDT.
``There is a one in a million chance it may not have burned
up,'' said Waller. ``But I think we've all come to the conclusion that
it is gone.''
Trouble began with the spacecraft on Oct. 3 when the hydrazine
propellant ran out in its main thrusters. Using secondary thrusters,
the researchers were able to keep some contact with the craft until
early Thursday.
The orbiter played a vital role in the understanding of Venus,
making the first maps of the planet and returning thousands of
pictures of Venus's cloud cover over the years.
|
| 699.14 | Press briefing for PVO | VERGA::KLAES | All the Universe, or nothing! | Fri Oct 09 1992 14:28 | 61 |
| Article: 27198
Newsgroups: sci.space,sci.astro,alt.sci.planetary
From: [email protected] (Ron Baalke)
Subject: Pioneer Venus Briefing Set for Today
Sender: [email protected] (Usenet)
Organization: Jet Propulsion Laboratory
Date: Fri, 9 Oct 1992 23:37:48 GMT
Donald L. Savage
Headquarters, Washington, D.C. October 9, 1992
(Phone: 202/453-8400)
Peter W. Waller
Ames Research Center, Mountain View, Calif.
(Phone: 415/604-3938)
NOTE TO EDITORS: N92-89
PIONEER VENUS BRIEFING SET FOR TODAY
The Pioneer Venus spacecraft, which has been orbiting Venus since
1978, did not survive its passage through Venus' upper atmosphere at
3:22 p.m. EDT yesterday.
A briefing will be held at NASA's Ames Research Center, Mountain
View, Calif., today at 1 p.m. EDT to summarize the mission. Also
presented will be quick-look science information from the past month,
when Pioneer Venus has been passing through the planet's high
atmosphere, a region never before reached by an orbiting spacecraft on
any planet. Participating in the briefing will be Jack Dyer, Project
"Navigator," and Richard Fimmel, Project Manager.
The briefing will be carried live on NASA Select TV, Satcom F2R,
72 degrees west longitude. There will be two-way question-and-answer
capability from NASA Headquarters and centers.
The spacecraft passed through the lowest part of its orbit, which
repeats every 24 hours, at 3:22 p.m. EDT. During this period, the
radio signal could not be tracked from Earth because Pioneer was
hidden behind Venus. No radio signal could be detected from the
spacecraft when it should have emerged from behind the planet.
Project officials believe the spacecraft was disabled by the heat
of friction with Venus' atmosphere, with spacecraft insulation and
other fragile components melting or breaking off. Although the
spacecraft's remains will continue to orbit Venus for a short while,
no further data can be collected without the radio signal.
Pioneer Venus made the first maps of Venus and has returned
thousands of pictures of the planet over the past 14 years.
Video animation, a press kit and photos are available to news
media by calling the Ames Public Information Office on 415/604-9000.
___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | [email protected]
| | | | __ \ /| | | | Jet Propulsion Lab |
___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Einstein's brain is stored
/___| | | | ___/ | |/__ /| Pasadena, CA 91109 | in a mason jar in a lab
|_____|/ |_|/ |_____|/ | in Wichita, Kansas.
|
| 699.15 | Silent but not yet gone | VERGA::KLAES | All the Universe, or nothing! | Fri Oct 09 1992 20:42 | 72 |
| Article: 3492
From: [email protected] (ROB STEIN, UPI Science Editor)
Newsgroups: clari.tw.science,clari.tw.space,clari.news.aviation
Subject: Pioneer Venus probe perishes after 14 years
Date: Fri, 9 Oct 92 14:31:49 EDT
WASHINGTON (UPI) -- An unexpectedly resilient space probe that
has been orbiting Venus since 1978 apparently finally perished
Thursday while passing through the hot upper atmosphere of Earth's
sister planet, NASA announced Friday.
NASA's Pioneer Venus passed behind Venus and out of radio
contact at 3:22 p.m. EDT Thursday as the craft entered the lowest part
of its 24-hour orbit around Venus and pierced the planet's unexplored
upper atmosphere.
When the craft should have emerged from behind Venus, ground
controllers were unable to detect Pioneer's radio signals, presumably
because the probe was disabled when the heat of friction with the upper
atmosphere melted or broke off insulation and other fragile components.
While Pioneer's remains will continue to orbit Venus for a
short time, no furthur data can be collected without radio signals and
the craft presumably will be further damaged and eventually destroyed
by the planet's atmosphere.
Launched May 20, 1978, the craft began orbiting Venus Dec. 6,
1978. Pioneer was supposed to orbit Venus for less than one Earth year
but ended up lasting more than 14 years, sending back 400 billion bits
of data. The total cost was a relatively paltry $170 million.
``This has been an enormously successful and productive
mission,'' said project manager Richard Fimmel during a televised
briefing from NASA's Ames Research Center in Mountain View, Calif.
``In spite of the fact that we're sad at the loss of an old
friend...the high science productivity gives us really great cause
for satisfaction and a job well done,'' he said.
Pioneer Venus made the first maps of the tortured surface of
Venus, returned thousands of pictures of the second planet from the
Sun and produced a wealth of new information about the planet's hellish
atmosphere, providing possible insights into what may await Earth.
In many ways, Venus is Earth's twin in the solar system. Both
planets are roughly similar in size and mass, both are relatively close
to the Sun and both probably were almost identical early in solar system
history.
But the environments of Venus and Earth eventually diverged,
leaving Venus the victim of a runaway greenhouse effect in which the
solar radiation trapped by the planet's thick cloud cover produces
surface temperatures of 900 degrees -- hot enough to melt lead -- and
pressures comparable to those found at an ocean depth of 2,500 to
3,000 feet.
Ground controllers knew the craft was virtually out of fuel
when they decided to plunge the craft into the planet's upper
atmosphere, ``approaching the ultimate calculated temperatures that we
thought the outer surfaces of the spacecraft could stand without
destruction,'' said Jack Dyer, project navigator.
But ``when it went behind the planet and through its lowest
passage it apparently died because we were unable to communicate with
it after that,'' he said. ``But we had gotten data very very much
deeper then we ever expected.''
Despite the death of Pioneer, NASA will continue to explore
Venus with the Magellan spacecraft, which has been orbiting Venus
since August 1990. Magellan uses radar beams to penetrate the planet's
thick clouds and create photograph-like images of the surface.
|
| 699.16 | Update - October 9 | VERGA::KLAES | All the Universe, or nothing! | Mon Oct 12 1992 12:51 | 101 |
| Article: 27249
Newsgroups: sci.space,sci.astro,alt.sci.planetary
From: [email protected] (Ron Baalke)
Subject: Pioneer Venus Update - 10/09/92 (End of Mission)
Sender: [email protected] (Usenet)
Organization: Jet Propulsion Laboratory
Date: Sun, 11 Oct 1992 13:39:24 GMT
PIONEER VENUS STATUS REPORT
October 9, 1992
End of Mission
On October 8, 1992 at 12:30 PM PDT, the 70 meter antenna in
Goldstone, California (DSS-14), failed to detect a signal from the
Pioneer Venus spacecraft after periapsis on orbit 5056. It was
assumed that the either the drag of the atmosphere had knocked the
spacecraft's High Gain Antenna (HGA) off Earth point, or the
spacecraft did not survive its last trip through the upper atmosphere
of Venus. DSS-14 and DSS-43 (70 meter antenna in Canberra, Australia)
continued to search for a signal from the spacecraft for several more
hours, including attempts to acquire a signal from the forward Omni
antenna, but still no signal was detected. Pioneer Venus end of
mission was declared on October 8, 1992 at 17:55 PM PDT by the Pioneer
Project Controller. The spaceraft's remains will continue to orbit
Venus for a short while, but no data can be collected without a radio
signal.
Here's a recap of the spacecraft events from the past week:
October 2 - The sixth altitude raising maneuver was successfully
performed and raised the periapsis from 132.9 km to
141.7 km.
October 3 - In an attempt to reorient the spacecraft during apoapsis
between orbits 5050 and 5051, Pioneer Venus apparently
ran out of fuel. After firing 90 pulses, only a 1 degree of
precession was achieved. The propellant tank pressure
dropped by two data numbers to 54.1 psi, indicating that
pressurant gas instead of fuel was expelled.
October 5 - Pioneer Venus was spun up with full thruster response for
150 seconds on orbit 5053. The resultant near-doubling of
spin rate will reduce reorientation suffered from drag at
periapsis and will facilitate use of the HGA through the
next several orbits if the spacecraft survives the deeper
penetrations of the atmosphere. It was also suspected that
4 oz of propellant still remained and the spin up would aid
in moving the propellant towards the thrusters.
October 6 - Pioneer Venus survived periapsis on orbit 5054, at an
altitude of 130.8 km and a drag of 0.91 m/s.
October 7 - Pioneer Venus survived periapsis on orbit 5055,
at an altitude of 128.9 km and a drag of 1.9 m/s. Attempts
to reorient the spacecraft with thrusters after periapsis
was 25% effective. At 22:25 PM PDT, a pulsed apoapsis
manuever of 200 pulses resulted in a gain of 1 kilometer
in periapsis altitude. The tank pressure held at 52.6 psi,
indicating that propellant probably still existed.
October 8 - DSS-14 failed to detect any signal from the spacecraft
after periapsis on orbit 5056. When the signal acquistion
continued to be unsuccessful for several more hours, the end
of the mission for the Pioneer Venus spacecraft was
declared. The estimated periapsis altitude of the final
orbit was 128.0 km, and the final estimated drag was at
2.5 m/s.
___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | [email protected]
| | | | __ \ /| | | | Jet Propulsion Lab |
___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Einstein's brain is stored
/___| | | | ___/ | |/__ /| Pasadena, CA 91109 | in a mason jar in a lab
|_____|/ |_|/ |_____|/ | in Wichita, Kansas.
Article: 27260
Newsgroups: sci.space,sci.astro,alt.sci.planetary
From: [email protected] (David Knapp)
Subject: Re: Pioneer Venus Update - 10/09/92 (End of Mission)
Sender: [email protected] (USENET News System)
Organization: University of Colorado, Boulder
Date: Sun, 11 Oct 1992 21:48:40 GMT
In article <[email protected]>
[email protected] writes:
>An earlier post suggested that data on Venus's atmosphere would be gathered
>upon reentry. I take it that since the probe re-entered on the far side and
>was lost, no data was gathered?
>
>-Mike
Data were gathered but at a low s/n. This was the fluorescnec of
collisionally excited gases. We did see some lyman alpha and hints of
perhaps CO 4+ but this is up for further analysis. There were only
two or three orbits which dipped deep enough to see this fluorescence.
More later as the data are deconvolved.
--
David Knapp University of Colorado, Boulder
Perpetual Student [email protected]
|
| 699.17 | Pioneer Venus Last Findings | PONIL::J_BUTLER | E pur, si muove... | Thu Mar 25 1993 10:48 | 133 |
| Article 3338 of sci.space.news:
Newsgroups: sci.space.news
Path: nntpd2.cxo.dec.com!pa.dec.com!decwrl!ames!dont-send-mail-to-path-lines
From: [email protected] (Ron Baalke)
Subject: Pioneer Venus Last Findings
Message-ID: <[email protected]>
To: [email protected]
Followup-To: sci.space
News-Software: VAX/VMS VNEWS 1.41
Keywords: Pioneer Venus, Ames Research Center
Sender: [email protected]
Nntp-Posting-Host: kelvin.jpl.nasa.gov
Organization: Jet Propulsion Laboratory
Date: Wed, 24 Mar 1993 19:48:00 GMT
Approved: [email protected]
Lines: 114
Paula Cleggett-Haleim
Headquarters, Washington, D.C. March 24, 1993
(Phone: 202/358-0883)
Peter Waller
Ames Research Center, Mountain View, Calif.
(Phone: 415/604-3938)
RELEASE: 93-51
EVIDENCE POINTS TO OCEANS, LIGHTNING ON EARLY VENUS
The last findings by the Pioneer Venus Orbiter spacecraft have provided
strong new evidence that planet Venus once had three and a half times more
water as thought earlier -- enough water to cover the entire surface between 25
and 75 feet deep (762 and 2286 centimeters).
These findings also give new support for the presence of lightning on
Venus and discoveries about the ionosphere and top of the atmosphere of
Venus. Considered Earth's twin planet, Venus today is very dry and searing hot.
Pioneer entered Venus' atmosphere on Oct. 8, 1992, and burned up soon
after, ending 14 years of exploration.
"Many of us have long thought that early in its history Venus had
temperate conditions and oceans like Earth's," said Dr. Thomas Donahue,
University of Michigan, head of the Pioneer Venus science steering group.
"Findings that Venus was once fairly wet does not prove that major
oceans existed, but make their existence far more likely," he said. "The new
Pioneer data provides evidence that large amounts of water were definitely
there," said Donahue.
"Most scientists think Venus' early oceans vaporized and 'blew off' 3
billion years ago in a runaway greenhouse effect when the cool early sun
increased its luminosity and heated the planet very hot," he said. "The oceans
evaporated. Solar ultraviolet radiation split the water molecules into
hydrogen and oxygen, and the hydrogen was lost to space.
"Pioneer Venus Probe and Orbiter data showed early in the mission,"
Donahue said, "that on Venus heavy habundant relative to ordinary hydrogen
than on Earth and everywhere else we've looked in the solar system -- Mars,
Comet Halley, meteorites, Jupiter and Saturn." Venus' remarkable
hydrogen/deuterium ratio has since been confirmed by independent measurements.
Abundant deuterium is taken as clear evidence that Venus once had 150
times as much water in its atmosphere as today, he said. This is because the
water's ordinary hydrogen has escaped. But most of the water's heavy hydrogen
(deuterium - twice as heavy as hydrogen) stayed behind because of its weight.
When the Orbiter made its final descent to unexplored regions only 80
miles (129 kilometers) above Venus' surface, it found evidence for 3.5 times as
much water as previously suggested by the deuterium ratio.
"We found a new and important easy-escape mechanism, which
accelerates hydrogen and deuterium away from the planet," he said. "This
means that much more hydrogen had to escape to build up the present high
deuterium concentration. A lot more hydrogen lost means a lot more water
early on," he said. "This also rules out theories of a dry-from-the-beginning
Venus, whose present meager supply of water comes from an occasional comet
impact."
The data also show that at Pioneer's lowest altitude 80 miles (129
kilometers) "whistler" radio signals, believed generated by Venus' lightning,
were the strongest ever detected. Pioneer has long measured such "lightning"
signals. They are the same as the radio signals used in most lightning studies
on Earth.
In its final orbits, Pioneer penetrated 7 miles (11 kilometers) below
the peak of Venus' ionosphere, which tends to block these radio signals.
Here also, the magnetic fields which channel the signals were the strongest
ever seen on Venus' night side.
"These results are best explained by a strong and persistent source of
lightning in the Venus atmosphere," said Robert Strangeway of UCLA, Pioneer
electric field investigator.
Some scientists continue to doubt Venus lightning. They say only
optical sightings can prove lightning. A Russian spacecraft has reported
visible-light sightings of lightning. Four Russian spacecraft and the U.S.
Galileo craft also have observed radio signals believed from lightning.
Pioneer found the peak density of Venus' ionosphere for the first
time - at 87 miles (139 kilometers). The ionosphere was much different
between solar maximum and minimum, which are high and low periods of storm
activity on the sun and in the solar wind. At minimum, it was far smaller.
It was gone altogether above 85 miles (136 kilometers), and its lower layer
was half as dense. It was more variable, much cooler, and full of small
structures (1-60 miles in size (1.6-96 kilometers).
For the ionosphere on the night side, at solar minimum, hydrogen ions
were reduced 20 times. Its lower layer was half as dense as at maximum.
Over 3 months, Pioneer provided data from 80 to 210 miles (129 to 336
kilometers) altitude. It found the beginning of Venus' real, mixed atmosphere
(transition from oxygen to carbon dioxide) at 80 miles (129 kilometers). Below
85 miles (136 kilometers), it identified various waves and a 4-day oscillation
of Venus' atmosphere top. The neutral atmosphere above 185 miles (296
kilometers) was more than 10 times denser and 2120 F (1,000 degrees Celsius)
hotter than thought.
Working with Donahue were Drs. Richard Hartle and Joseph Grebowsky of
NASA's Goddard Space Flight Center, Greenbelt, Md. Ames Research Center
manages the Pioneer project for the Office of Space Science, NASA
Headquarters, Washington, D.C.
- end -
___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | [email protected]
| | | | __ \ /| | | | Jet Propulsion Lab |
___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Don't ever take a fence
/___| | | | ___/ | |/__ /| Pasadena, CA 91109 | down until you know the
|_____|/ |_|/ |_____|/ | reason it was put up.
|
| 699.18 | Media view on Venus' possible ancient oceans | VERGA::KLAES | Life, the Universe, and Everything | Mon Mar 29 1993 17:50 | 110 |
| Article: 3010
From: [email protected] (LIDIA WASOWICZ, UPI Science Writer)
Newsgroups: clari.tw.space,clari.local.texas,clari.local.sfbay
Subject: Final message from spacecraft: arid Venus once had oceans
Date: 25 Mar 93 01:43:18 GMT
MOUNTAIN VIEW, Calif. (UPI) -- In its last hurrah, the Pioneer
space probe spewed out evidence of oceans on early Venus, raising the
possibility Earth's twin planet once may have harbored life,
scientists reported Wednesday.
``The data we have suggest conditions were such as to allow
the formation of primitive lifeforms,'' Thomas Donahue, of the
University of Michigan, said at the National Aeronautics and Space
Administration Ames Research Center.
Researchers cautioned they have insufficient information on such
essential factors as whether water existed in liquid form on the
brilliant planet to offer conclusive proof. They probably never will,
they told reporters.
The Pioneer spacecraft, which had been orbiting Venus for 14
years, burned up shortly after bursting through the cloud-enshrouded
planet's sizzling atmosphere on Oct. 8, 1992 -- when it ran out of fuel.
Its final data show the arid, searingly hot planet once was
drenched with 3.5 times as much water as thought earlier -- enough to
cover the entire surface with between 25 feet to 75 feet of either
liquid or vapor.
``Many of us have long thought that early in its history Venus
had temperate conditions and oceans like Earth's,'' Donahue said.
``Findings that Venus was once fairly wet don't prove major oceans but
make them far more likely.''
Researchers -- who have been pouring over the new information
relayed by Pioneer before its demise -- said the data provide ``strong
evidence large amounts of water were definitely there.''
``It's entirely conceivable that liquid water existed on the
surface of Venus for a period as long as a billion years. We know in
the case of Earth this was long enough for life to develop,'' Donahue
said.
``If the water was in the form of liquid -- and we can't prove
that from our data -- and if it lasted for as long as a billion years,
then .. .. primitive lifeforms could have evolved.''
Any fossils that could offer proof would have long ago been
obliterated by the massive lava flows that cover all traces of the
planet's most distant past, researchers said.
``Most scientists think Venus' early oceans vaporized and
'blew off' 3 billion years ago in a runaway greenhouse effect when the
cool early sun increasd its luminosity and heated the planet very
hot,'' said Gerald Keating of the NASA Langley Research Center.
``The oceans evaporated. Solar ultraviolet radiation split the
water molecules into hydrogen and oxygen, and the hydrogen was lost to
space.''
Earlier data showed that on Venus heavy hydrogen, or
deuterium, is 150 times more abundant relative to ordinary hydrogen
than anywhere else humans have peeked in the solar system -- Earth,
Mars, Comet Halley, meteorites, Jupiter and Saturn.
Scientists take this as ``clear evidence'' Venus once had at
least 150 times as much water in its atmosphere as it does today.
``This is because the water's ordinary hydrogen has escaped, but
most of the water's twice-as-heavy deuterium remained,'' Donahue said.
When Pioneer made its fatal descent to unexplored regions only
80 miles above Venus' surface, it found evidence for 3.5 times as much
water as previously suggested by the deuterium ratio, the researchers
told the news briefing.
The Pioneer data also corroborate earlier evidence of
lightning on Venus, believed to generate ``whistler'' radio signals,
as it does on Earth. Venus' thick ionosphere tends to block these
signals, but Pioneer penetrated seven miles below the peak to detect
the strongest signs to date.
``These results are best explained by a strong and persistent
source of lightning in the Venus atmosphere,'' said Robert Strangeway
of the University of California, Los Angeles.
Pioneer's three-month survey of Venus' ionosphere from an
altitude ranging between 80 and 210 miles identified the peak density
for the first time at 87 miles and found it to be more variable and
cooler than anticipated and full of structures ranging in size from 1
mile to 60 miles, said Strangeway.
``It's appropriate the last orbit produced such exciting
results,'' said Lawrence Colin of the University of Michigan, noting
the entire enterprise -- once expected to last no more than 14 months
-- cost a total of $200 million.
Scientists now have more data on the planet whose thick veil
kept its secrets shrouded for centuries than on any other extraterrestrial
body in the solar system.
The most brilliant of planets -- called Earth's twin because
of their similarities in size, composition and distance from the sun
-- has been visited by 15 Soviet and seven U.S. spacecraft since 1961.
Donahue said because of its uncanny resemblance to Earth,
Venus ``in many ways is the one which by exploring can help us best to
understand the secrets of our own planet. ''
|
| 699.19 | PVO did gravity studies, but MAGELLAN is more sensitive | VERGA::KLAES | Quo vadimus? | Sat Jul 17 1993 12:34 | 35 |
| Article: 39236
From: [email protected] (Peter G. Ford)
Newsgroups: sci.space,sci.astro,alt.sci.planetary
Subject: Re: Magellan Update - 07/12/93
Date: 14 Jul 1993 06:20:30 GMT
Organization: MIT Center for Space Research
In article <[email protected]>
[email protected] (andrew john wohrley) writes:
>If time and money are running out for Magellan to do its gravity studies of
>Venus, why didn't anyone use the Pioneer Venus orbiter to study the
>gravitational fields of Venus...
But it did. The results were less accurate than has been achieved to
date by Magellan because the Pioneer Venus experiment was performed at
S-band (ca. 2.2 GHz), whereas Magellan carries both S-band and X-band
(ca 8.4 GHz) transponders. Doppler shift is proportional to carrier
frequency, so Magellan has 4 times the sensitivity. Also, as you point
out, its higher orbital inclination (85.5 vs. 75 deg) and lower
eccentricity (0.39 vs. initial Pioneer 12 value of 0.84), have kept
Magellan closer to Venus than Pioneer 12 at almost all latitudes, and
therefore more sensitive to high-frequency components of the Venus
gravity field. Finally, although Pioneer 12 spent 14 years in Venus
orbit, it spent 11 of those at periapsis altitudes above 500 km.
The original Pioneer 12 gravity papers are:
Ananda et al., J. Geophys. Res. 85, A13, 8303-8318 (1980)
Reasenberg et al., J. Geophys. Res. 86, B8, 7173-7179 (1981)
Sjogren et al., J. Geophys. Res. 85, A13, 8295-8302 (1980)
Peter Ford
MIT and Magellan Project
|