From: John Conover <john@email.johncon.com>
Subject: forwarded message from root@email.johncon.com
Date: Fri, 24 Jan 1997 01:07:47 -0800
Interesting first line of "On this day" ...
John
BTW, as an interesting bit of trivia, the "Voyager 2 ..." line has an
interesting history behind it. (Actually, in case you are curious,
Neptune is now the outer most planet-Neptune and Pluto do not have
concentric orbits, and they overlap, and Neptune will be the outer
most planet well into the next century. Thanks for sharing that, huh?)
There were two Voyagers launched, several weeks apart. The primary was
launched first, and the backup, Voyager II, was launched later. They
were both intended to provide information on the gaseous planets,
Jupiter and Saturn. The primary was a disaster-about a week after the
launch, all sorts of stuff started to fail. Mission control at JPL
initiated an all out effort to fix things. And here is where it gets
interesting.
I don't know if you have ever though about it, but one of the issues
in robotic space craft design is to determine when the robot is to
switch over to backup systems. As a case in point, how does the robot
"know" to switch over to the backup communications receiver? I mean,
if the receiver is "dead," it obviously can't receive a signal to
switch over to the backup system, right? The way this was handled was
that mission control was to send a signal every few days to the craft,
and if the craft received the signal, it would "know" that the
receiver was functional.
Unfortunately, mission control was busy piddling with the first
Voyager, and some how or the other, the signal was not sent, and
Voyager II dutifully switched over to its backup communications
equipment, which had far less capability than the primary.
Voyager II, now the backup craft, running on backup communications
equipment performs its basic mission, flawlessly, (the primary craft
is now flying off through the boon docks of the solar system.) Mission
control decides that the Voyager II, (through some very clever flight
dynamics,) could possibly be rerouted to reach the outer
planets. (Uranus, Neptune and Pluto were all somewhat aligned-a
situation that happens only very few times in a millenia-and JPL
wanted to take advantage of the opportunity.) Unfortunately, the
backup communications equipment was not capable of transmitting
signals from that distance.
A bold scheme was improvised to do something that had never been done
before. The craft's computers, in a very risky operation, would be
reprogrammed to digitally compress the video signals, (it was the
first time in history that a craft had been reprogrammed after
launch,) allowing the signal bandwidth to be reduced adequately, thus
reducing the noise level, and, with some modifications to the
receiving equipment south of Albuquerque New Mexico, the signal could
be received from the outer planets. Very clever engineering.
As you will recall, the pictures were transmitted from JPL, real time,
world wide to the television media. The craft continued on, and is the
first man made object to exit the solar system. Time magazine has
called the craft "Nasa's Energizer Bunny."
Where is all this leading? Well, two folks affiliated with Sandia
National Laboratories were the architects of the compression and
computational marvel that made it all possible. Their names are Reed
and Solomon.
The same computer algorithm, that was hastily thrown together for
Voyager II, is now used in all CD players, and hard disks-that's the
way store their data.
And Voyager II? As of now, it is still working well-the plutonium
reactor that supplies electricity to the craft has run down over the
last decade to about 50% of capacity, but all systems are functional.
Plans are to permanently disable the craft in March of this year, do
to Nasa's budgetary constraints, but the craft will continue on to
somewhere in Alpha Centari, (I think it is,) where its journey will
terminate, in several tens of thousands of years ...
John
BTW, you might be careful quoting anything here-it is from my
recollections, and recollections of talking to folks at Sandia, (I was
at the University of New Mexico, studying information theory, of which
Reed and Solomon are two of the "Deans" of the science.)
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Received: (from root@localhost) by johncon.com (8.6.12/8.6.12) id AAA01402 for john; Fri, 24 Jan 1997 00:05:07 -0800
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From: root <root@email.johncon.com>
To: john@email.johncon.com
Subject: Reminders for Friday, January 24, 1997
Date: Fri, 24 Jan 1997 00:05:07 -0800
Reminders for Friday, 24th January, 1997 (today):
Sunrise 07:17, Sunset 17:22, Moon 0.97 (Decreasing)
________________________ On This Day, Jan 24 ... ________________________
1st beer in cans is sold. (1935)
51-C Discovery launched; first DoD mission (1985)
Alann (sic) Steen, communications instructor at Beirut University College, was kidnapped in Lebanon (1987)
Amazon Indians attack oil drilling crew with poison darts (1984)
BAM's award, SF, Phil Lesh "best bassist" (1978)
Christian K. Nelson of Onawa, Iowa, patented the Eskimo Pie (1922)
DG Nova introduced, 1969
Data General Nova computer introduced (1969)
Earthquake kills 890,000 people in China (1556)
Economic Liberation Day (Togo)
Economic Liberation Day in Togo
Edith Wharton, American author, is born (1862)
Ernst Heinrich Heinkel, built 1st rocket-powered aircraft. (1888)
Eskimo Pie patented by Christian Nelson, 1922
Gold discovered in California at Sutter's Mill (1848)
Gold discovered in California at Sutter's Mill, 1848
Jesse Turner, professor of mathematics and computer science at Beirut University College, was kidnapped in Lebanon (1987)
John Belushi born (Chicago, 1949)
John Belushi is born in Chicago, 1949
Lord Randolph Churchill, English statesman, dies (1895)
President Franklin D. Roosevelt and Winston Churchill conclude conference in Casablanca (1943)
San Francisco 49'ers win their 1st Super Bowl, 26-21. (1982)
Ted Bundy, confessed serial murderer of over 21 (possibly as many as 100) women during a period of 15 years, is executed (1989)
US Supreme Court rules income tax is unconstitutional (1916)
Voyager 2 encounters Uranus. Efforts will be made during the trip to Neptune to improve ground receiver sensitivity enough to allow data rates equal to the Uranus passage (4800 - 21600 bps) (1986)
Warren Zevon is born, 1947
the rubber heel is patented by Humphrey O'Sullivan. (1899)
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John Conover, john@email.johncon.com, http://www.johncon.com/