1. THE SIRENS OF TITAN
Don’t miss this one: I’d suggest clicking right now on http://saturn.jpl.nasa.gov/home/index.cfm to see the countdown to our first landing on the surface of a world in the outer solar system. That’s right — the Huygens probe arrives at Titan on Friday morning. If all goes well, it will collect data during its descent and send back pictures of the surface for up to about a half-hour before its batteries run out. Watch the data come in on the web on Friday morning starting at about 7am PST, 8am MST, 9am CST, 10am EST; many universities and science centers will have special live programs as well. For those who may have forgotten why Titan is so exciting, here’s a few facts repeated from one of my prior e-mails:
- Although it is a "moon" because it orbits the planet Saturn, Titan is bigger than the planets Mercury and Pluto. In fact, it’s the 10th largest object in our solar system (after the Sun, the other 7 planets, and Jupiter’s moon Ganymede).
- Titan is the only moon in the solar system with a substantial atmosphere, and this atmosphere shares two interesting characteristics with Earth’s atmosphere: A similar atmospheric pressure (Titan’s surface pressure is only about 50% more than Earth’s) and a composition of mostly nitrogen (Earth’s atmosphere is 77% nitrogen and Titan’s is 90% nitrogen). Of course, there are also two important differences: (1) the rest of Earth’s atmosphere is mostly oxygen, while the rest of Titan’s atmosphere is argon, methane, ethane, and other hydrogen compounds; (2) Titan is extremely cold, with a surface temperature of nearly 300 degrees below zero (Fahrenheit).
- While the temperature is far too low for liquid water, there’s good reason to think that Titan may have lakes or oceans of liquid methane and ethane, and perhaps even methane/ethane rain or snow.
- And the possibility of these cold liquids raises at least some small potential for life: Although all life on Earth requires liquid water, it’s at least marginally possible that other liquids could support life. (Some sort of liquid is generally deemed necessary for life in order to transport chemicals from one place to another.) Don’t get overly hopeful: water has several chemical advantages over other liquids that make it seem far more suitable than other liquids as a molecule for life. Still, I won’t be completely blown away if we discover little cold-liquid critters on Titan.
- Finally, Titan has literary and art connections: (1) The title of this e-mail (The Sirens of Titan) is the title of an entertaining 1959 novel by Kurt Vonnegut. (2) It is also the title of a very cool song by Al Stewart, which he based on the Vonnegut novel. (3) And Titan is the destination of choice in the 1997 movie Gattaca, which I enjoyed a lot.
Questions you might want to ask your students in class:
- Make a prediction: What do you think Huygens will find on Titan? Explain why you think your prediction is reasonable. (Answer: obviously a subjective question, but here’s my admittedly unlikely prediction: The surface photos will show something that does not move, but looks enough like certain Earth-based organisms that we’ll be left wondering if there is actually life on Titan.)
2. BOUND FOR A COMET
This just in… Today, NASA successfully launched the Deep Impact mission, which will fire a projectile into the heart of a comet in July. For the latest, see the Deep Impact web site at http://deepimpact.umd.edu/.
Questions you might want to ask your students in class:
- What is a comet? (Answer: a chunk of ice and rock, though not necessarily packed solid, that orbits the Sun. Comets are thought to be leftovers from the formation of our solar system.)
- Could the projectile from Deep Impact destroy the comet? (Answer: Highly unlikely. Use the Deep Impact web site to contrast the size of the comet with the size of the spacecraft, and you’ll see why.
3. BOUND FOR AN ASTEROID
There’s another mission that I myself just learned about — it’s garnered very little publicity but is potentially VERY exciting. The Japanese spacecraft Hayabusa is en route to an asteroid, where it will fire a projection to blast asteroid chunks from the surface, and then collect these to return to Earth. Even more fun: It will deploy a small robot to land on the surface and hop around! This is so cool that I wish I could tell you more. If anyone has any additional info about this mission, please let me know. I found some info at http://www.jaxa.jp/missions/projects/sat/exploration/muses_c/index_e.html.
4. SEE A COMET FOR YOURSELF
There’s a comet visible in the sky right now. Comet Machholz is not particularly bright, but beautiful through a telescope. See the photo at http://antwrp.gsfc.nasa.gov/apod/ap050105.html and the NASA science news article http://science.nasa.gov/headlines/y2005/05jan_machholz.htm.