Dear Friends,
My apologies for the long time since my last space news update — I got a little busy! Lots going on; here’s the contents for this e-mail:
1. Boulder/Denver-area folks: This Saturday (4/29) is CU Astronomy Day – FREE!
2. Life on Enceladus?
3. New Horizons en route to Pluto
4. MRO in Mars Orbit.
5. Venus Express in Venus Orbit.
6. Global warming data extended.
7. A new round of donations of Max Goes to Mars for schools — preliminary info
1. Boulder/Denver-area folks
This Saturday (4/29) is CU Astronomy Day, with lots of free activities for kids and families, including demonstrations, talks, solar observing (weather permitting), and much more. Starts at noon at Fiske Planetarium; more information at http://cosmos.colorado.edu/sbo/public/special.html. As part of the event, I’ll be doing a reading of Max Goes to Mars in the planetarium theater at 2pm.
2. Life on Enceladus?
The Cassini mission at Saturn (http://saturn.jpl.nasa.gov) has been spectacular since its start, but perhaps nothing has been quite so surprising as its recent findings at the moon Enceladus. This relatively small moon is spraying out fountains of ice crystals, and may contain liquid water or a colder liquid water/ammonia mixture inside it. Liquid water makes scientists think about the possibility of life… Personally, I think life on Enceladus is unlikely, but the mere raising of the possibility suggests that there might be many more homes for life than we had imagined even quite recently. For example, if Enceladus could have life, why not Triton, or some of the moons of Uranus, or…? Clearly, it’s an issue worthy of further study.
Questions for class:
*How big is Enceladus? (Answer: At about 500 km in diameter, it is barely 1/7 the diameter of our Moon.)
*How can such a small moon be warm enough for liquids in its interior? (Answer: Scientists are still investigating this question, but we know that Enceladus is subject to tidal heating, and presumably that is the answer.)
*When is NASA planning a follow-up mission to investigate Titan and Enceladus further? (Answer: Sadly, there are no such plans at this time.)
3. New Horizons en route to Pluto.
I had the good fortune to attend the spectacular launch of New Horizons on January 19. Now, barely 3 months later, it has already crossed the orbit of Mars. It will pass Jupiter next year, and reach Pluto in 2015. More info and great launch photos at http://pluto.jhuapl.edu.
Questions for class:
*What is the Kuiper belt, and what makes us think that Pluto is a member? (Answer: The Kuiper belt is a “reservoir” of icy objects out beyond the orbit of Neptune; Pluto shares many traits with other Kuiper belt objects.)
*Is Pluto the largest member of the Kuiper belt? (Answer: No; a slightly larger one was discovered last July; others may yet be found.)
*How many moons does Pluto have? (Answer: Two small ones were discovered just last summer, making a total of 3; the largest of the 3, Charon, was discovered in 1978.)
4. Mars Reconnaissance Orbiter (MRO) in Mars Orbit.
MRO reached Mars orbit about a month ago. It is now in the period during which it skims the martian atmosphere at the low point of each orbit, thereby shedding orbital energy (“aerobraking”) that helps circularize its orbit. It has already returned some spectacular pictures, and will begin full operations toward the end of this year. More info at http://marsprogram.jpl.nasa.gov/mro.
Questions to ask in class:
*How many spacecraft are now operating at Mars? (Answer: 6: Two rovers on the surface, Spirit and Opportunity; Mars Global Surveyor, Mars Odyssey, Mars Express, and MRO.)
*What is the point of the aerobraking to alter MRO’s orbit? (Answer: The trajectory from Earth to Mars would send a spacecraft on a single flyby. To obtain any orbit of Mars, a spacecraft must slow down — and the lower the orbit (which is desirable for closer-up observations), the more it must slow. It can slow either by firing its engines (in reverse) or by shedding energy to friction with the atmosphere. The former requires carrying more fuel, which raises the spacecraft weight and hence its launch costs. The latter is “free,” since it just relies on the martian atmosphere.)
5. Meanwhile, at Venus…
The European Venus Express mission is now in orbit of Venus, and promises our best-ever views of our nearest planetary neighbor. More info at http://sci.esa.int/venusexpress.
Questions for class:
*Venus is on average closer to Earth than Mars. Why, then, do we think about sending people to Mars before sending people to Venus? (Answer: Venus is way, way, way too hot.)
*Why is Venus so hot? (Answer: An extreme greenhouse effect, caused by having almost 200,000 times as much carbon dioxide in its atmosphere as is present in Earth’s atmosphere.)
*Why should Venus give us a scare? (Answer: Earth is in little danger of becoming like Venus for the next few billion years, but Venus certainly stands as proof that global warming can get out of hand.)
6. Speaking of global warming…
The ice core data showing past carbon dioxide concentrations has recently been extended to go back 650,000 years; lots of articles reporting on this, but here’s a good one from New Scientist: http://www.newscientist.com/article.ns?id=dn8369. The big news is that the data show that the current carbon dioxide concentration is significantly higher than Earth has experienced during the past 650,000 years. Now that’s a reason to be concerned…
Questions for class:
*Is this proof that global warming is a serious problem? (Answer: No, but it sure makes you think.)
*Is global warming responsible for the recent upsurge in hurricanes? (Answer: No one really knows, and making a direct connection to short-term events is nearly impossible. Nevertheless, global warming basically means increased energy in Earth’s atmosphere, which would be expected to mean more and more severe storms. So no proof — but the upsurge is consistent with what we might expect.)
7. Max Goes to Mars School Donation Program
Preliminary Info on Round 2. I am tentatively planning to donate another 5,000 copies of Max Goes to Mars to schools around the nation; first round info is at https://www.jeffreybennett.com/donation.html. I’m still working out the logistics, but it will probably involve my shipping books only to large districts or groups of districts, because it is too difficult for me to send the books out in small batches. If you know a school system that might be interested, please let me know and start the process of the initial contacts.
All for now!
Jeff