AstroNews Fall 2000

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LOOKING UP

More about the night sky under ASTROTIP!
 

THIS JUST IN FROM ORBIT

Who are they? U.S. astronaut Bill Shepherd, the station's skipper, and Russian cosmonauts Yuri Gidzenko and Sergei Krikalev. They reached ISS with a Russian Soyuz capsule. The first thing these guys did was rename their space station ALPHA.

NASA, the Russian Space Agency and the 14 other countries involved in project have high hopes for the space station. At least 15 years of scientific operation are planned, with crews eventually expanding from three to seven. The ISS, already one of the brightest objects in the night sky, will weigh 418 tons, spread out almost an acre and have as much living space as a Boeing 747 jetliner when completed, perhaps as early as 2005.

SETI@home VERSION 3.0 IS OUT!

If you are not using SETI@home, why the heck not?? This scientific experiment uses Internet-connected computers in the Search for Extraterrestrial Intelligence
(SETI). You can participate by running this free program that downloads and analyzes radio telescope data. Start hunting ET today! 

Get SETI@home version 3 NOW:
http://setiathome.berkeley.edu

USE GLOBALCOM FOR COMMUNICATION

ET Phone home!

Try the long distance services offered by GlobalCom. Cheap calls, especially for calling abroad, calling cards, and lots more telecommunication tidbits are at:
http://www.kahl.net/global

ASTROTIP

Need a SKY MAP for your location for tonight?

Try the Weather Underground site:
http://www.wunderground.com/sky/index.asp

MORE MOONS

So now Saturn’s new count of 22 moons surpasses Uranus’s 21 and Jupiter's 17.
 
 

MARS IS SLIPPERY!

Such was the case when NASA and the Jet Propulsion Laboratory announced a possible detection of water on Mars a few months ago. Scientists were pretty smug that they had Mars (mostly) figured out. We knew there was some water frozen into Mars' polar ice caps, and some scientists had begun to suggest there might be permafrost in regions near the poles, but NO ONE expected LIQUID water anywhere on Mars. Mars fooled us again!

The debate about what the surface of Mars might be like has waged for as long as we've had telescopes capable of producing even a vague, hazy view of our tantalizing neighbor. The most famous of Mars' flirtations with our collective imagination occurred during 1877, when Mars passed unusually close to Earth in its orbit around the sun. Astronomers from all over the world observed this event, including Asaph Hall, who discovered two tiny moons orbiting the planet.

The most exciting results came from Giovanni Schiaparelli, who reported seeing "CANALI" on the surface of Mars. In Italian, the word "canali" means "grooves" or "channels." Schiaparelli only meant to report the presence of dark, somewhat linear features on Mars; there was no implication these features had been deliberately constructed. But off in Boston, a man named Percival Lowell heard the word "canals" and was set ablaze. He headed for Arizona, where he constructed one of the best telescopes in the world at that time, under the clear desert skies.

Night after night, Lowell mapped hundreds of ordered linear features on Mars that revealed themselves through the eyepiece of his telescope. He named the canals, categorized them, and came to believe he was witnessing a profound and disturbing event.

The canals, he asserted, were a last-ditch effort of the Martians to save themselves from a planet-wide environmental catastrophe. Mars was drying out, turning to desert, and the Martians were using the canals to divert water from the polar caps to thirsty cities distributed around the rest of the planet.

No one else seemed to be able to see these canals in the detail that Lowell claimed to have seen. Secondly (and more convincingly), the budding technique of spectroscopy revealed that Mars' atmosphere was only about one one-hundredth the density of Earth's. At that kind of air pressure, water would immediately boil away. The thirsty Martians weren't going to get any water, canals or not.

That's about how things stood until we were finally able to send spacecraft to Mars. The Mariner and Viking orbiters were sent as our emissaries, to finally see what was going on with this contentious world. The first pictures we got back were pretty disappointing. The orbiter's first pass was made over the southern hemisphere, and it looked, basically, like a redder and dustier version of the moon. Boring. Dead. Dry.

Things got better with subsequent passes, but our first impression had been made. As more data streamed in, we discovered giant, extinct volcanoes (the biggest, Olympus Mons, is THREE TIMES the height of Mount Everest), and vast canyons (the Mariner Valley would stretch from Los Angeles to New York. A Grand Canyon that takes up the entire United States! But no Martians, no thirsty cities, and no canals.

So we knew that Mars was a barren world, incapable of sustaining life. We'd accepted that. But Mars has a way of sneaking up on you! Not long after the initial return of images, scientists began to notice familiar features. Vast, if currently dry, riverbeds and flood plains. Streamlined "islands" in the middle of the river channels that could only have been shaped by flowing water.

Now the push was on to actually land on Mars and analyze the soil for water and signs of life. It was exciting -- Mars was a real contender again.In the 1970s, two Viking landers sniffed the air, scooped around in the soil, and beamed loads of data to expectant scientists on Earth. And yet again, Mars was teasing us. Chemical analysis of the soil showed the surface of Mars to be dry and barren. No organic material, no water, except in trace amounts. The experiments to search for life, interestingly, were negative but ambiguous. Scientists have debated what they might mean for almost 30 years now. But on the whole, Mars was once again dry and dead.

From the land forms, we know that Mars once had flowing water on its surface, quite a bit of it. So where did it all go? That's still a mystery, but we have some pretty good guesses. On the pessimistic side, it's likely that much of Mars' water has been lost for good. Mars is smaller than the Earth, and it's surface gravity is only about one-third of Earth's. When water evaporates on our planet, gravity is able to hold it down, even when it's in a gaseous form. Mars may not have been able to keep its water vapor.

Billions of years ago, Mars may have had a thicker atmosphere, perhaps similar to Earth's. But as water evaporated, it just drifted away into space, little by little. Eventually the air pressure got so low that liquid water couldn't exist at all. Mars was able to keep some of its water, in the form of ice, frozen in its polar ice caps. But the ice caps advance and retreat as Mars goes through its seasons (temperatures quite from 200 to 70 degrees Fahrenheit), and a little more water vapor is lost each summer.

In a way, we are watching a planet die. Mars may have been very much like Earth during the childhood of our solar system, and its possible that life could even have started there. But by inches and teaspoon-fulls, Mars lost its lifeblood.

So, rather resignedly, NASA sent the Mars Global Surveyor to chart the Red Planet in the kind of detail we've grown to expect from Earth-mapping satellites. We were still fascinated by its dramatic topography and somewhat melancholy similarity to our own home. Once again, Mars had a surprise waiting for us. The Mars Global Surveyor images are by far the most detailed view we've ever had of Mars. As scientists were sifting through the reams of new data, they saw features that startled them.

There were little RIVULETS and CHANNELS that had been carved out over active, wind-blown field of sand dunes. They can't have been there long, or the wind would have covered them up. There are crater walls that have collapsed in a way that looks, well, slushy, even kind of slippery. There are boulder fields around the craters that seemed to have been created by erosion. EROSION? On a dry world?

On some canyon and crater walls, there are rows of little gullies flowing down the side. These gullies seem to be caused by liquid seeping through soil layers, indirect evidence of aquifers under the ground. In short, there may well be liquid water on Mars right now. Any water that actually reaches the surface still boils away in the rarefied Martian atmosphere, but NASA thinks the water may exist in pockets about 100-400 feet below the surface.

The location of the possible liquid water on Mars is perplexing. Some of the clearest examples of gullies and seepage occur at about 70 degrees South in Martian latitude that's a region as close to the South pole as Antarctica is on Earth. This region spends much of the year in total darkness, and at temperatures cold enough to freeze carbon dioxide (about -150 F). How does water survive there? How does it manage to flow? It looks like Mars has sent us back to the drawing board again.

Now we're all excited and ready to think about scenarios that we would have laughed off as science fiction a few months ago. As Dr. Michael Malin, one of the leading planetary scientist working on Mars says, "If water is available in substantial volumes in areas other than the poles, it would make it easier for human crews to access and use it -- for drinking, to create breathable air, and to extract oxygen and hydrogen for rocket fuel or to be stored for use in portable energy sources." In other words, a mission to Mars may have just gotten a whole lot easier. Only this time we'll bring our sturdy boots, and be careful not to slip.

PLEASE look at these BEAUTIFUL images!

Michael Malin's site
http://www.msss.com/mars_images/moc/june2000
JPL Picture Archive
http://www.jpl.nasa.gov/pictures/mars

[Source: Michelle Thaller, Christian Science Monitor]

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BIC LIGHTER IN SPACE

After considering various thruster propellants, designers chose butane, so "in the end, we flew a Bic lighter in space, " said Jeffrey Ward, managing director of Britain’s Surrey Satellite Technology, Ltd. "It shows you can build small propulsion systems that are cheap and can work."

Building the 1-pound (450-gram) thruster system for $15,000 with off-the-shelf parts "brings us one step closer to swarms of nanosatellites performing cooperative missions" while flying in formation.

Butane is not ignited by the newfangled thruster, but instead vaporizes "like gas coming out of a spray can," Ward said. The propulsion system is aboard the14-pound (6.5-kilogram) SNAP 1 satellite, which was launched June 28 on a COSMOS rocket that blasted off from Russia’s Pletsesk Cosmodrome. The rocket also carried the 110-pound (50-kilogram) Tsinghua 1 microsatellite and a much larger search-and-rescue satellite that is part of a joint U.S.-Russian system to detect beacons from downed aircraft and ships in trouble.

The entire propulsion system carries a mere 1.15 ounces (32.6 grams) of butane.

SNAP 1 is "the smallest propulsive satellite that’s ever been flown" and the thruster "the smaller propulsion system ever flown."

One of the propulsion system’s unusual features is that its fuel "tank" is not tank-shaped, but instead is made of $25 worth of triangular-shaped coils of titanium alloy tubing.

SNAP 1 – the Surrey Nanosatellite Applications Platform satellite – "is about the size of a soccer ball" and was designed, built and launched in only seven months, said Ward, whose company is a commercial-satellite-building arm of the University of Surrey.

SNAP 1 Website:
http://www.sstl.co.uk/missions/mn_snap_1.html

[Source: Lee Siegel]
 

SPEEDY EARTH

The problem with questions like that is they fail to take into account the scope of the universe – how dynamic it is. Nothing in the universe is standing still. When you ask how fast something is moving, you have to specify - COMPARED TO WHAT? Say you're driving at 80 miles an hour. You overtake a car driving 60 miles an hour. They see you move away at only 20 miles an hour.

Let's begin with the motion of the earth. Earth's circumference = 25,000 miles. It makes one rotation every 24 hours; so a point on the earth's equator moves at approximately 1,000 miles per hour. That's just the daily rotation of our planet! We never feel this speed because GRAVITY rivets us to the Earth's surface, and our atmosphere is moving right along with us – or we'd have constant 1,000 mph winds to contend with!

The Earth orbits the sun yearly. We're 93 million miles from the sun, so to make one complete orbit in the allotted time, the Earth moves at 67,000 miles per hour around the sun. We're up to several tens of thousands of miles per hour, and we haven't considered any motions OUTSIDE of our own solar system yet.

At larger scales things get much scarier – HOLD ON TO YOUR CHAIR! Our sun is moving through the Milky Way galaxy, a trillion stars clustered into a giant disk about 100,000 light years across. A light year is a HUGE. It's the DISTANCE light travels in a year, and given that light travels at 186,000 miles per second, a light year is roughly SIX TRILLION MILES.

So, our Milky Way galaxy – one of billions of galaxies in the universe – is 600,000,000,000,000,000 miles across. OOH! The sun (and all its planets along for the ride) orbits around the center of our galaxy at about 490,000 miles per hour. We're not done yet!

The Milky Way galaxy (you guessed it) is not standing still either! Galaxies feel each other's gravity and fall toward areas where lots of galaxies cluster together. We commonly observe galaxies orbiting around each other, or colliding and merging into a chaotic super-sized glob of stars and dust. The galaxies in our neighborhood are all moving toward a titanic supercluster of galaxies, called the GREAT ATTRACTOR.

We're not really sure what all entails this structure (exotic stuff called "dark matter,"), but it's about 150 million light years away. Judging from how fast our massive galaxy is falling toward it, its mass is about 100 quadrillion (don't even try to write that one out) times the mass of our sun. The Milky Way is falling toward this Great Attractor at 2 million miles per hour. Makes your head spin.

Every motion we've talked about so far is in reference to something else. We're always moving around the Sun, or toward the Great Attractor, or some such thing. But is there any universal frame of reference to which we can compare the motion of everything in the universe?

The answer may be yes. In 1989, the Cosmic Background Explorer (COBE) satellite measured something called the MICROWAVE BACKGROUND RADIATION. The entire universe is bathed in a mild bath of microwaves, leftover heat from the Big Bang. This slowly fading glow from the formation of the universe creates a background (hence the name) that's the same wherever we look.

Now we have some standard – something against which we can measure the motion of everything else. The result? The earth is moving at 877,500 miles per hour toward the constellation Leo.

So how fast is the earth moving? 
877,500 miles per hour!
 
 
 

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