astronomy

Here are a few things that caught my eye today from the mailbag.

Red Planet News

Next week, on September 21, the MAVEN mission will slip into orbit around Mars after a 10-month journey to the Red Planet. MAVEN is a climate science mission designed and led by scientists and students at the University of Colorado and once it gets into orbit, will start studying the Martian atmosphere for clues to the history of water there. The existence of water both on the surface and in the atmosphere is important when you want to figure out if life ever existed on the planet (or still does). We can see surface characteristics that look like something flowed across the landscapes: river beds, dry lakebeds, the shores of ancient oceans — all these point to the existence of water sometime in the past.

Finding clues to water in Mars’s atmosphere is more challenging, requiring instruments that can measure the amounts of water in the upper and mid-atmosphere levels of the planet, as well as other gases in the thin envelope that surrounds the planet. For example, the amount of an isotope of hydrogen called deuterium can help tell how much water may have escaped from Mars in the past.

Artist’s concept of the passage of Comet C/2013 A1 Siding Spring past Mars at a distance of 132,000 km (82,000 miles) on October 19, 2014. Courtesy NASA/

In a lucky piece of serendipity, the MAVEN scientists will also get the chance study Comet C/2013 A1 Siding Spring as it passes very near Mars on its first trip through the solar system in . The idea is to use the spacecraft ultraviolet imaging spectrograph to study the tail components and measure their effects on the upper atmosphere of the planet.

MAVEN won’t be the only spacecraft to check out the comet during the Mars flyby.  The Indian space agency’s Mars Orbiter Mission (MOM) will arrive at the planet on September 24th, 2014, for an extended mission. The European Space Agency’s Mars Express spacecraft will also look at the comet and collect data. In addition, if conditions are safe enough to allow, the Mars Reconnaissance Orbiter’s HiRISE imaging system will acquire images, and the Mars Rovers Curiosity and Opportunity could, at the very least, watch for meteors in the sky as cometary tail pieces fall to the surface of Mars. All of the observations by orbiting and surface craft will be subject to last-minute changes if it looks like particles from the comet could pose a large threat. So far, however, mission controllers are relatively optimistic about being able to study a comet from the surface of another world. You can read more about mission preparations for the comet flyby in this Space.com article.

 

It’s “Back to the Future” for NASA’s Astronauts

The announcement yesterday that NASA had selected Boeing to build an Apollo-similar capsule for its much-vaunted return to spaceflight didn’t take a lot of people by surprise. I would have preferred something more modern-looking and exciting, like the Sierra Nevada Dream Chaser (which at least looks like a sexy, souped-up shuttle). Instead we have a capsule with updated WiFi and Dreamliner-style lighting that can seat 7 and be reused up to 10 times. It really feels like “back to the future” with designs we’ve seen before (like decades ago).  I did see that Sierra Nevada still plans to go to test flight in 2016 with the Dream Chaser, so maybe it will stay a viable alternative.

The good news about NASA’s selection is that we finally can point to a definite date (or as definite as it gets) for return to flight for the U.S. (and not having to depend on Russia for a ride to space). The announcement yesterday pointed toward a 2017 flight certification for the CTS-100.

NASA Continues Climate Change Studies

NASA’s science studies aren’t limited to distant planets and never have been. For many years, the space agency has been studying Earth as a planet, right down to changes in its surface and climate. In particular, NASA is studying how rising global temperatures affect the Arctic. The Arctic Radiation — IceBridge Sea and Ice Experiment (ARISE) is an airborne campaign to collect temperature data. this is particularly important since Arctic warming is happening 2-3 times faster than global warming.  The study was designed to look at the specific relationship between sea ice (and its retreat), and the Arctic climate. Arctic sea ice reflects sunlight away from Earth, moderating warming in the region. When sea ice is lost, more heat from the Sun gets absorbed by the ocean’s surface and that adds to Arctic warming. Loss of sea ice leads to more extensive areas of open water, which allows more moisture to get pumped into the air. That forms clouds, which can either enhance or reduce warming. Understanding the complexities of warming and its effect on the Arctic will help scientists better understand the complete climate system that operates on our planet. Learn more about NASA’s current research in the Arctic in this article released earlier this week.

CFA Asks “What is a Planet?”

Artist's impression of Pluto. Courtesy New Horizons mission.

Artist’s impression of Pluto. Courtesy New Horizons mission.

It’s been a few years since the great “Define a Planet” vote took place at the International Astronomical Union meeting. That 2006 event touched off what still remains a firestorm of controversy about what is or isn’t a planet, and in particular, whether Pluto fits the definition set out in the vote. I’ve blogged about this a few times, and my viewpoint has remained pretty constant: Pluto is a dwarf planet. That’s still a planet, but the term “dwarf” tells us something about its place in the size hierarchy of planets in our solar system. However, my opinion is just that: my opinion, based on what my understanding of the issues involved.

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