January 2007 Newsletter

At the December 14 meeting, the following were elected by unanimous vote to serve as officers for 2007:

President:	Lloyd Altamirano
VP/Program Director:	Jerry Hyatt
Secretary:	Christie Abbott
Treasurer:	Glen Mortensen
Newsletter Editor:	Trevor Atkinson
Member-at-Large:	Becky Greider
Member-at-Large:	Roger Stark

Members of the 2007 Executive Committee will be installed at the January 11 annual dinner.

Please use the coupon on page 11 [of the January newsletter] to make your reservations for the dinner. This is our annual break from the monthly meetings in the planetarium, always an enjoyable evening with an opportunity to get to know other members. The China Palace lays on a delicious dinner. No one leaves hungry, that's for sure. We hope to see you there.

Members and Guests of the Stockton Astronomical Society
are cordially invited to the
Fourteenth Annual SAS
Installation/Recognition Dinner
Thursday, January 11, 2007
at the China Palace Restaurant,
5052 West Lane, Stockton

(SE corner West Lane & March Lane, near Longs Drugs)
No-host bar 6:30 p.m., dinner at 7:00 p.m.
$18 per person, including tax and gratuity.

After dinner program:
Tribute to Carl Sagan

Pre-paid dinner reservations must be received by January 9th.
Use dinner reservation coupon on page 11 of the newsletter.
Mail with check for $18 per person to: SAS, P.O. Box 243, Stockton, CA 95201

(Important: Due to short notice, please also call Frank Wheeler at
the phone number listed in the newsletter with verbal reservation.)

Here is what scientists have found out.

Comets are part of the solar system. They orbit the Sun, just as planets do, except a comet usually has a very elongated orbit. Part of its orbit is very, very far from the Sun and part is quite close to the Sun.

A comet's nucleus is like a dirty snowball made of ice. As the comet gets closer to the Sun, some of the ice starts to melt and boil off, along with particles of dust. These particles and gases make a cloud around the nucleus, called a coma. The coma is lit by the Sun. The sunlight also pushes this material into the beautiful brightly lit tail of the comet.

Scientists have now had a look inside a comet's nucleus.

On July 4, 2005, NASA's Deep Impact spacecraft's "smart impactor" scooped out . . . well, more like blasted out a crater in the nucleus of Comet Tempel 1. What did they find? Was it dark and crusty like the surface, or soft and squishy like a marshmallow, or full of holes like Swiss cheese, or full of big rocks like nutty nougat?

Here's some of what they have found out so far from looking at Deep Impact's encounter with Tempel 1:

The comet's nucleus is spongy, with lots of holes inside. No one knows yet whether there are a few large holes or many smaller ones.

So what?

If there are a few large holes, it might mean that the comet was formed from large, dirty ice boulders. If there are many smaller holes, it might mean the comet was formed from many more dirty ice snowballs.

Parts of the surface are very fragile and weak.

So what?

It may be that the comet's ice was the "glue" that held the comet dust and rocks together. Then, as the comet came closer to the Sun, the surface ice evaporated, leaving little or no "glue." The rocky and dusty structures would then be fragile and crumbly.

The surface of the nucleus is covered with fine dust, like baby powder.

What is this dust and where did it come from?

Originally, the comet's surface ice probably contained a lot of fine dust. When the orbit of the comet brings it close to the Sun, the ice evaporates into space, leaving some of the fine dust sitting on the surface. The dust is fine like talcum powder because comets are too small to have enough gravity to squeeze the dust together into larger particles.

The surface is very black.

What is this black stuff?

The very black material on the surface is carbon-based material similar to the greasy black goo that burns onto your barbecue grill. The comet originally formed from ices (mostly water ice), silicate dust (like powdered beach sand), and this type of black space gunk.

Some parts of the nucleus are smooth and young, while other areas are cratered and old.

What happened?

The old-looking part of the surface has been battered for thousands of years by small, rocky asteroids or other comets. So why are some areas smooth? It is possible that as the comet has approached the Sun over the years, the ices on the surface have vaporized, and taken some of the embedded dust particles with it. Then, some of the dust particles could have settled back down on the surface, filling in some of the craters. Or, maybe the smooth surface areas that are covered with dust and dirty ice are disappearing as the comet repeatedly gets close to the Sun. After a long time, the smooth icy regions may have retreated, revealing the older cratered surface below.

The nucleus seems to have formed from overlapping layers of different materials.

Why?

The layers must have formed as the comet grew. As it got bigger, gravitational forces drew in ices, dust, and the black "space gunk" we talked about earlier from the comet's neighborhood.

There is ice beneath the surface, both water ice just below the surface and carbon dioxide ice (also known as "dry ice") farther down.

Why different kinds of ice at different depths?

Most of the ice in our solar system, including the ice in comets, is water ice. In Comet Tempel 1, almost all the ice is water ice, but some is carbon dioxide ice-or "dry ice." Carbon dioxide ice vaporizes faster than water ice. (That is why you might use "dry ice" to make "smoke" for a model volcano or "fog" for a stage play.) As the comet gets close to the Sun, the carbon dioxide ice will vaporize before the water ice. So, after thousands of years, even though the two kinds of ice were initially mixed together near the surface, only the water ice remains. The carbon dioxide ice a meter or so beneath the surface is more protected from the Sun's heat, so may survive, with water ice above it.

Tempel 1 contains materials from the outer, middle, and inner parts of the solar system.

Why?

We are not sure. Comets probably formed in the outer solar system. The inner solar system type of dust particles found in them could have traveled to the outer solar system where the comets formed. Or, not as likely, these dust particles could have arrived from other solar systems. Water and carbon dioxide ices are both found in the outer solar system, so comets could pick up both ices while forming.

Of course, not every comet may be just like Tempel 1.

Deep Impact blasted lots of material from beneath the surface into the comet's coma. Remember, the coma is the cloud of dust and gas that boils off the nucleus as the comet's orbit takes it closer and closer to the Sun.

The coma contains material from near the surface of the nucleus. This material is what the Sun heats up most and what boils off first. Scientists saw what was in the coma right after the impact, and compared that with what was there before the impact. This way, they could get an idea what was added from the material blasted out of the hole in the nucleus.

But, whether before or after the blast, how do the scientists know what the coma is made of? After all, the comet and its coma are millions of miles away!

Here's how: They observe the coma through a telescope equipped with a spectrometer.

Comet Tempel 1's coma before impact. Colored dots stand for different materials that have boiled off the surface of comet's nucleus.

Comet Tempel 1's coma after impact. Added dots, some of different colors, stand for materials from below the surface of the nucleus that were "splashed" into the coma from the impact crater.

A spectrometer creates something like a rainbow. Like droplets of water may do after a rain, a spectrometer breaks light apart into its different wavelengths, or "colors." Depending on what gases (such as those in air) the light has passed through, the "rainbow" will look different. That is because each gas absorbs one or more particular colors of the light that passes through it.

We have lots more on spectrometers, by the way!

Did you see the "Cosmic Car Crash" page on The Space Place Web site? (http://spaceplace.jpl.nasa.gov/en/kids/deepimpact/deepimpact.shtml) If so, you know that the Deep Impact Flyby Spacecraft observed and recorded the impact with its telescope and spectrometer.

But it wasn't the only telescope with its eyes on this first-of-its-kind cosmic event. The Hubble Space Telescope, the Spitzer Space Telescope, the huge Keck telescopes on top of a tall mountain in Hawaii, as well as many other space and ground telescopes recorded the impact and what followed. Even backyard astronomers-people like you who have their own telescopes-were able to see and photograph the impact.

It will take scientists a long time to understand all the comet information from all the telescopes and spectrometers. But already, they have a better idea of what this particular comet is like and what lies beneath its surface.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

In March 2004, voters passed Measure L, the $250 million bond to fund expansion and critical improvements of San Joaquin Delta College facilities. Scope of plans is extensive and includes, in addition to new satellite campuses, some demolition and major new construction on the Stockton campus.

According to the Delta College Bond Program Website, "Measure L represents a large portion of the College's $307 million Facilities Master Plan and only includes the most critical needs of the College." Measure L funds are expected to run out by 2010. Additional state and/or bond funding will be required to complete the Master Plan over the next 10-15 years. (www.bond.deltacollege.edu/index.asp)

Of particular interest to SAS members of course is the future of the Clever Planetarium, which has been our 'home' for over thirty years. I spoke recently with Lee Belarmino, Associate Vice President of Information Services at Delta, to get the latest scoop on plans for the planetarium. I also checked the minutes of the August 2006 meeting of the Citizens' Oversight Committee. Construction of a new Cunningham Math & Science Center is planned in Cycle Phase 3, [Lee estimates in 3-5 years]. The existing Cunningham Building will then be demolished, including the Clever Planetarium [5 years +/-].

"Cycle 4 Phase: Conceptual I (broad scope, loose program only) [Lee estimates 5-10 years]:

Holt Center - the reconstruction of Holt will create a Fine Arts and Applied Science and Technology neighborhood in a modernized facility. The project will create the following: new Planetarium [probably as a separate, stand-alone building, per Lee]; increased number of laboratory space; reconfiguration of academic space; reconfiguration of current registration, logistics, and student services space." http://www.bond.deltacollege.edu/documents/coc_docs/coc_minutes_081006.pdf

While there is recognition on campus of the need for a new planetarium as an important community educational resource, and while a new one is included in "conceptual" plans, it is clear that there is considerable uncertainty. Much will depend on the scope and availability of future state funding. At best, it appears that there will very likely be an interim period of years during which there will be no planetarium on campus.

A lot can happen in five years, for better or worse. In the meantime, let's appreciate what we have. The SAS is indeed fortunate to have had the use of the Clever Planetarium for these many years. Our public outreach through monthly Sky Tours on campus and hundreds of school star parties over the years has been a small price to pay for the privilege we enjoy.

Hold a good thought for the future. In the meantime, let's make the most of what we have.

The Science Directorate at NASA's Marshall Space Flight Center sponsors the Science@NASA web sites. The mission of Science@NASA is to help the public understand how exciting NASA research is and to help NASA scientists fulfill their outreach responsibilities.

Dec. 11, 2006: Readers of Science@NASA may remember six fun months in 2002-03 when astronaut Don Pettit circled Earth onboard the International Space Station (ISS). Don was the expedition's science officer-and more than that, he was infected with a mischievous sense of experimentation.

In the shower, he assembled giant blobs of floating water. He spun them, inflated them with air, and made them vibrate in ways impossible in the water-squashing gravity of Earth. Physicists are still puzzling over some of the things he observed.

In the lab, he built a "barn-door tracker" for cameras using odds and ends he found around the station. This device allowed him, essentially, to nullify the 17,000 mph motion of the station in order to take steady photos of cities, aurora borealis, stars and planets. The ISS became Don's personal Hubble.

In the kitchen, he demonstrated that High Tea can be taken with chopsticks. Literally, using sticks of wood, he plucked droplets of Russian tea from mid-air and popped them into his mouth.

He called these activities (and many others like them) "Saturday Morning Science" because he did most of them in his spare time on Saturday mornings. All were shared with the general public.

Now, four years after the ISS, Don is about to serve up a new batch of experiments-this time from Antarctica. He calls them Saturday Morning Science on Ice.

"We're on a bit of an adventure," explains Don. "I've joined a scientific expedition to Antarctica to hunt for meteorites. The name of the expedition is ANSMET, short for Antarctic Search for Meteorites, and it is funded by the National Science Foundation and operated by principal investigators from Case Western University. ANSMET has been making annual trips to Antarctica since the mid-70s. The scientific value is immense. More than 10,000 meteorites have been found including such jewels as the famous Allan Hills meteorite from Mars." "I was fortunate enough to be asked to tag along as the token astronaut," he laughs. "Why me? It was mainly dumb luck. One of the ANSMET scientists dropped out at the last minute for medical reasons. Because the principal investigator had dealt with astronauts before, he knew they would not have trouble passing the medical exam and could be called up on short notice. When my boss asked me if I wanted to go, I thought about it for perhaps a nanosecond and said yes!"

"So here I am in Antarctica with the ANSMET team looking for little chunks of extra-terrestrial debris that just happened to rain down on the Antarctic continent where the glaciers have this amazing habit of concentrating them well beyond their natural abundance."

"There will be some spare time during our search. We'll have tent days, days where the weather is so bad we have to stay in our Scott tents. From past history, this will probably happen one day a week. So what do you do when bad weather confines you to an 8 foot square tent whose basic design has not changed since 1920?"

"I plan to continue my Saturday Morning Science that I started on the space station four years ago. I have a microscope, a centrifuge, cameras and other gear for all kinds of scientific investigations."

A selected list: Don plans to make a census of microbes in the upper layers of Antarctic ice. He's going to capture and photograph south-polar snowflakes and study their structure. He'll use his centrifuge to separate space dust from melted ice-and so on.

The ANSMET team reached the ice fields of Antarctica's Grosvenor Mountains on Dec. 8th and they are busily setting up camp. They'll spend the next six weeks there-plenty of time for discovery.

Science@NASA is going to cover the expedition, highlighting Don's new Saturday Morning Science experiments. "So stay tuned," he says, "and see what tantalizing adventures appear on these pages."

Author: Dr. Tony Phillips | Production Editor: Dr. Tony Phillips | Credit: Science@NASA


Comet Tempel 1's coma before impact. Colored dots stand for different materials that have boiled off the surface of comet's nucleus.	Comet Tempel 1's coma after impact. Added dots, some of different colors, stand for materials from below the surface of the nucleus that were "splashed" into the coma from the impact crater.