The Flight Deck for April 2003, Issue 119
From the Bridge:
I just want to announce that the weekend before last, I met the
Klingon of my dreams, ran away to Las Vegas and got hitched.
Okay, so I'm not so good at April Fools' jokes.
Hello and welcome to April! Sunny, breezy, and increasingly
warm! I'm waiting for the snowstorm any day now.
I'm just back off of Spring Break, and I had a great time down in
Chattanooga at Galacticon, the Klingon "Spring Break." Amanda
and I had a smashing good time (wherein I got pretty smashed on
Aldeberan Whiskey and Saurian Brandy). A trio of the Halsey's admirals
journeyed that same weekend to Millenicon in Cincinnati. Good
times were had by all. And pictures from Galacticon are available for
$10 apiece.
March's meeting went well--once they pried me off of the bicycle
and into the meeting--and there were a pair of orders given out. Our
newest member, COMM Amy Merritt, was appointed as Chief Science
Officer. Our Chief of Communications, LT Amanda Dailey, is now
LTCDR Amanda Dailey. Congrats to both!
Several projects were discussed, including new t-shirt designs.
With any luck, I should have several possible designs ready for
discussion at the April meeting. And with the same luck, a couple of special
projects that have been under construction will also be
available for unveiling.
Speaking of meetings, the Grissom plane wash has been scheduled
and confirmed for Saturday, May 17th at 10am. This actually works out
well, since usually we have the May meeting in Georgetown.
Given as I will have a lot of family members coming in to see me graduate
from college in May, it's probably a good idea to flip-flop the
meetings.
Since the plane wash has been pushed to May, the April Halsey
meeting will be down south at the Dailey Residence on Sunday, April 13th.
Festivities will be starting at 1pm Georgetown time, which
translates into 12 noon for Indyphiles. It'll be a cookout, and the hosts
will provide the meat and some munchies/drinks. We ask that everyone
bring some form of munchies or covered dish to share and items for
the raffle.
Hope to see everyone there!
FCAPT Cathy Dailey
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Upcoming Events:
April 13th--April Halsey Meeting at the Dailey Domicile,
May 17th--Grissom Plane Washing, Grissom AFB, 10am
Sometime in June--Away Mission to Chicago
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Beamdown Coordinates:
The Dailey Domicile
1. Get on I-65 South.
Hope to see you there!
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Birthdays & Anniversaries
April 20th--Honorary CAPT George Takei
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>From the "But Are Any of Them Made of Cheese?" Desk:
What is a Moon? Definition Lags Behind Soaring Satellite Tally
By Robert Roy Britt
Senior Science Writer, SPACE.com
In the old days of astronomy, before Galileo, there was just the
Moon. Then scientists had to accept the clear and visible
evidence of four objects orbiting Jupiter, satellites the master saw through a
crude telescope in 1610.
Things have only grown more complex, especially of late.
With a spate of discoveries in the past three years, the number of
known moons in the solar system has jumped to 118 as of this
writing. That figure won't stand long. Astronomers expect the tally to
double, at least, in the next few years. Most won't be surprised if it
eventually triples. And that's not counting the small stuff --
boulders the size of football stadiums and countless smaller rocks
that are surely trapped in orbit around the big outer planets.
Meanwhile, the complexity of moon types and behavior grows with
the tally, and astronomers are struggling to sort out what it all
means.
Several interviews with moon hunters and top theorists reveal that
the definition of a moon is not clear and that there has been
almost no discussion, professional or casual, about whether there
should be any lower size limits set to separate real moons from miniature
imposters. And nobody is in a rush to do anything about it.
Last month, astronomers announced they'd found the smallest known
satellite, a moon just 0.62 miles (1 kilometer) in diameter
orbiting Jupiter. It is one of dozens of small moons that behave strangely.
Most go backwards compared to the orbits of the larger Galilean
moons. Some take long, elliptical paths and stray far above and
below the planet's plane of rotation. Few are round. Saturn, Uranus and
Neptune all have similar satellites.
Other configurations are more complex. Saturn's rings contain
myriad chunks of ice and rocks that scientists don't consider moons. Yet
embedded in the rings are distinct moons. Size -- and the
ability to be noticed -- has so far played a role in being designated a moon.
Yet some moon-like objects are so small they are invisible.
Hydrogen atoms at the outer fringes of Earth's atmosphere orbit the
planet in an arguably moon-like manner.
"We don't call those satellites," says Alan Stern of the Southwest
Research Institute (SwRI), making a firm delineation between
moon and non-moon at least at the very lower end of the size spectrum. Dust
grains, too, are out, Stern says. From there on up, however,
nobody has thought much about where to draw the line, if at all, on what
constitutes a moon.
"There is no accepted definition," Stern said.
So what would Stern call a 6-inch rock orbiting a planet? "I would
call it a 6-inch rock." But, he acknowledges, "It's technically a
satellite."
By that strict definition, there could be thousands of moons in
our solar system, or millions if you count the debris in Saturn's
rings. Nobody is proposing such an approach. Stern thinks it might be
usefu to create a separate category called "minor moons" to
distinguish the small stuff from what is conventionally thought of as a moon.
Stern's suggestion was made to this reporter and is not an
official proposal, but someone might need to propose something official
pretty soon. NASA's Cassini spacecraft, due to arrive at Saturn next
year, may force the issue.
For now, the smallest known satellite of Saturn is Pan, at 12.4
miles (20 kilometers) wide. Pan sits within Saturn's rings and was
spotted in photos taken by the Voyager spacecraft.
The Voyager survey was incomplete, says Joe Burns, a Cornell
University mathematical theorist and astronomer who is on the
Cassini imaging team. Cassini will probably find much smaller moon-sized
rocks in Saturn's rings, Burns said, and "no jury has voted" on
whether to call these imminent discoveries moons or not. "I think
we'll have to confront that," he said.
When humans first put hunks of fabricated metal into orbit around
Earth a few decades ago, astronomers needed to differentiate them
from stuff that was already in space, so the term natural
satellite came into use. In hindsight, it might not have been an overly
inspired choice of words.
"I believe that the public is often confused when the
term 'satellite' is used," said Matthew Holman, an astronomer at
the Harvard-Smithsonian Center for Astrophysics who is a
co-discoverer of three moons around Neptune. "The public normally equates
'satellite' with artificial satellite.'"
From a lay person's perspective, Moon terminology has only become
more obscure. Astronomers have developed a loose classification
system that roughly separates moons into three types based on size
and distance from their host planet: irregular moons, regular
moons, and inner moons (sometimes called ring moons).
Irregular moons are of unknown origin. They might be captured
asteroids or comets, or perhaps they're pieces of young planetary
hopefuls that didn't survive to orbit at the big table of nine,
researchers believe. Many irregulars travel in packs that indicate
they were once parts of larger objects.
The irregulars are typically small and orbit at great distances
and often on odd trajectories. Their orbits are stretched and tilted
in just about every way you can imagine. They soar high above and
below the plane in which regular moons orbit. They come close to the
planet and then zoom far away on elliptical trajectories. More often than
not their orbits are retrograde -- opposite the direction of
regular moons and of the planet's spin.
About the only thing they don't do is orbit in a plane
perpendicular to that of the planet's orbit. Research led by Burns, the Cornell
mathematician, has shown that the Sun's gravity causes such an
orbit to be unstable, so any object captured in one would crash into the
planet or escape.
Most irregulars have probably been in orbit since their host
planet was very young, which astronomers cite as a good reason to call
them moons, despite their odd and varied behavior. Nobody knows how
they got captured, however.
Burns said it is very difficult for a planet to capture a moon.
Unless something slows an incoming asteroid or alters its
trajectory -- like a highly improbable pass at just the right angle through an
atmosphere -- it will either hit the planet or fly on past.
"If it comes from infinity, it's going to go back to infinity," he said.
Perhaps, Burns speculates, the irregulars ran into an extended
envelope of gas that might have surrounded a giant planet shortly
after its birth 4.5 billion years ago. That would explain why
irregulars tend to be small, because a smaller object has more
surface area in relation to its mass, and is more likely to be
captured than a large object.
Scientists aren't sure how the giant planets formed, let alone
what conditions were like around them back then. So figuring out moons
will help astronomers understand planets, researchers agree.
While irregular moons define the outer orbital reaches of a
planet's domain in space, the next region in is dominated by regular moons.
Examples include Saturn's moon Titan and Jupiter's Galilean
satellites: Io, Europa, Ganymede and Callisto.
These classic, large and round moons tend toward entirely stable,
simple, nearly circular orbits. All move through a plane in space
that is roughly equal to the planet's equatorial plane. This
conformity leads theorists to believe the moons formed out of the
same nebula of gas and dust that built the planet.
Other so-called regular moons were probably carved by collision.
Our own Moon likely developed after a Mars-sized object slammed into
Earth. Some Uranian satellites might have been formed by an impact
that flopped the planet over on its side.
Pluto's moon Charon is thought to have been created by collision,
too, says the SwRI's Stern, who leads NASA's New Horizons
mission to study the planet and set for launch in 2006. Interestingly, the
gravitational midpoint around which those two objects revolve is
not inside Pluto, but instead out in empty space. Some researchers
prefer to call this a binary planet system (others don't consider Pluto a
planet at all).
The Pluto-Charon system is not unlike pairs of other rocks
orbiting each other out there on the fringes of the solar system, a region
known at the Kuiper Belt. The dancing Kuiper Belt Objects,
so-called KBO binaries, often involve a primary object with a smaller
satellite and further stretch usage of the word moon.
"The KBO binaries aren't rocks, they are worlds," Stern says. "In
fact, most are large enough to be rounded by gravity and therefore
mini-planets in their own right."
More than 30 asteroids are known to have moons, too.
Inside the orbits of the regular moons, things get crazy.
Inner moons, sometimes called ring moons because they often travel
amidst other debris, are almost surely the youngest. They're
also the most likely to disappear. Here's why:
Planets, especially the large ones, act like gravitational brooms,
gradually clearing the solar system of comets. That's bad news for
any moon close to the broom.
"It's more dangerous down there," says Kevin Zahnle of NASA's Ames
Research Center.
If you are a moon, the odds of being hit by a comet grow the
closer you are to your host planet. Zahnle imagines flies buzzing
around a hunk of raw meat. Pretend your hand is a moon, and pass it a few
feet from the meat: you might not be hit by a single fly. Pass your
hand a couple inches from the meat, and many flies might hit it.
Making matters worse, orbital mechanics dictates that inner moons
travel more swiftly than outer moons, so collisions are more
fierce, making it less likely that a moon will survive a hit. "And if
you're smaller to begin with, it's more precarious to begin with," Zahnle
adds, because you don't have the self-gravity to survive an encounter.
All this means that the life of an inner moon is very unstable.
"These are the most ephemeral and are presumably young," Zahnle
said. He suspects inner moons might be well less than a billion years
old, but cautions that there are no data to support that view. More
needs to be learned about the population of comets, he said, and how
frequently they impact the giant planets.
So are these precarious little objects moons? Definitely, Zahnle
said. He adds, however, that in a ring system, the smaller rocks
are constantly running into each other, their movement governed more
by collision than by traditional orbital mechanics. Zahnle would tend
toward calling these things debris, not moons.
Outside the traditional categories of satellites are two sorts of
objects that really stretch definitions.
Ahead of and behind Jupiter are two packs of asteroids -- tens of
thousands of them -- that orbit the Sun but are also
gravitationally bound to Jupiter. Astronomers call them Trojan asteroids. They are
technically satellites of Jupiter, some astronomers say, but
others, including Burns, consider them mere companions to Jupiter.
"The one property that I think a satellite must possess to be a
satellite is an orbit that encircles its planet," Burns said.
Earth, Mars and Neptune are each known to control one or more
Trojan objects in similar fashion.
Earth has acquired a sort of enhanced Trojan, too. A rock called
2002 AA29 orbits the Sun while also carving a horseshoe-shaped path
around Earth. Every few centuries it gets close enough to Earth to be
considered more than a Trojan, becoming what astronomers now
call a quasi-satellite.
To astronomers, all this is quite clear, but there might be room
for further definition.
"I do not think a new classification [system] is needed," said
Earth's quasi-moon co-discoverer Martin Connors of Athabasca
University in Canada. "For technical purposes we may wish to
define sub-categories."
Nobody has found more moons than David Jewitt of the University of
Hawaii. Along with colleague Scott Sheppard, Jewitt's team has
found three dozen satellites orbiting Jupiter and has more in the
observational pipeline. Jewitt is not keen to redefine moon
terms or set any lower size limit.
"To me, they're all natural satellites," he said. "Is a small
dog not a dog because it is small?"
If there is some confusion now, Jewitt says, then that reflects
the healthy progress of discovery, and greater clarity will be the
ultimate result. Jewitt realizes, however, that from a public
perspective there can be some "pain" associated with no longer
being able to look satellites up in a textbook. "Many people are not
comfortable with a world that changes quickly."
One thing that hasn't changed, not since well before Galileo's
time: There is still only one natural satellite you can step outside and
see with your naked eye, the one we call, simply, the Moon.
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From the "And Spielberg is Heartbroken" Desk:
Eastwood to direct film about Armstrong's moon landing
LOS ANGELES (AFP) - Clint Eastwood is lifting off with a new
feature film in space, this time chronicling the life of the first man to
walk on the moon, Neil Armstrong, Warner Brothers studio said.
The 72-year-old actor, director and producer will sit in the
director's chair rather than star in the film, based on the as-yet
unpublished biography of Armstrong.
The authorized biography, by US historian James Hansen, recounts
Armstrong's life from his time as a fighter pilot in the Korean
War through his role in the space program and his historic steps on
the moon.
"Millions of people watched Neil Armstrong step out onto the
moon's surface, and millions more have seen those images since the event
happened. However, Armstrong himself is a very enigmatic person,"
Eastwood said in a statement.
Eastwood produced, directed and starred in the 2000 film "Space
Cowboys" about a fictional space mission. He won an Oscar for
directing the 1992 western "Unforgiven."
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>From the "Ever Get the Feeling We're All Speaking Different
Languages?" Desk:
On some air bases the Air Force is on one side of the field and
civilian aircraft use the other side of the field, with the
control tower in the middle. One day the tower received a call from an
aircraft asking, "What time is it?"
The tower responded, "Who is calling?"
The aircraft replied, "What difference does it make?"
The tower replied "It makes a lot of difference. If it is an
American Airlines flight, it is 3 o'clock. If it is an Air Force
plane, it is 1500 hours. If it is a Navy aircraft, it is 6
bells. If it is an Army aircraft, the big hand is on the 12 and the
little hand is on the 3. If it is a Marine Corps aircraft, it's Thursday
afternoon and 120 minutes to "Happy Hour".
********************
end transmission
Go to this page to view older issues of the Halsey Newsletter.
Georgetown, IN 1pm local time, 12pm Indianapolis time
8003 Maple Grove Drive
Georgetown, IN
2. Stay on I-65 South.
3. Continue going south on I-65.
4. Go south on I-65 some more. (hint: if you wind up in Nashville,
you've gone too far!)
5. Take exit 6B, I-265 to I-64 New Albany
6. Follow I-265 all the way around to the I-64 split.
7. Go to the right; I-64 West to St. Louis.
(be careful, both 265 and 64 are notorious for speed traps)
8. Take exit 118 Georgetown.
9. Turn right at bottom of ramp.
10. Go straight at the light.
11. Continue until you pass the drive-in on the right.
12. Immediately look for Canal Lane on the right.
13. Turn right onto Canal.
14. Go up and over several hills; look for Maple Grove on the left.
15. Turn left onto Maple Grove.
16. First house on the left facing the street.
