Tag Archive for planetary
by Olivia Drake •
Seth Redfield, assistant professor of astronomy, spoke on “Properties of the Interstellar Medium Surrounding the Sun and Nearby Stars” during a conference held March 11-15 in the Physikzentrum in Bad Honnef, Germany.
The conference, which was 527th in a series, was sponsored by the Wilhelm und Else Heraeus Stiftung, a German foundation that supports scientific research and education. The topic of the conference was “Plasma and Radiation Environment in Astrospheres and Implications for the Habitability of Extrasolar Planets.”
by Olivia Drake •
By looking at high-resolution images captured by the Mars Reconnaissance Orbiter, scientists are able to see gullies, which are argued to be geologically recent. Because they are most likely formed by water, it is believed that they can answer the question of whether or not there is still “active” water on Mars.
As a summer Wesleyan McNair scholar, astronomy major Lavontria Aaron ’14 used a hyperspectral instrument to determine if the gullies contained minerals (salts) which would be left behind by water brines.
“By examining the spectrum of the brines, we’ll be able to learn more about Mars’ history and possibly man’s future in pursuit of exploring the red planet,” says Aaron, who worked on the project with her faculty advisor Marty Gilmore, chair and associate professor of earth and environmental sciences.
Aaron and her 13 McNair peers are supported by the Ronald E. McNair Post Baccalaureate Achievement Program, which serves students in their second, third, and fourth college semesters. It provides career-oriented activities,
by David Pesci •
In a nearby solar system, a planet the size of Jupiter orbiting a star similar to our own sun is doing something that has astrophysicists very intrigued: It’s dissolving–albeit very, very slowly.
The findings are detailed in a study by primary investigators Adam Jensen, visiting assistant professor of astronomy, and Seth Redfield, assistant professor of astronomy. They made the majority of their observations using the 9.2 meter telescope at The University of Texas’s McDonald Observatory. The paper, “A Detection of Ha In An Exoplanetary Exosphere,” will appear in the June 1 issue of The Astrophysical Journal.
The planet in question, a gas giant similar in size to Jupiter called HD 189733b, orbits a class K star, which is about 63 light years from Earth–a virtual next-door neighbor in astronomical terms.
What Jensen and Redfield observed was HD 189733b discharging significant amount of atomic hydrogen into space.
“This type of evaporation of atomic hydrogen, or what is called ‘hot hydrogen,’ is something that has never been observed before,” says Redfield. “When we first saw the evidence we thought, ‘Wow, can that be right?’ But more careful analysis and cross-checks confirmed it. At that point we got really excited because we knew we’d found an important phenomenon.”
The orbital path of HD 189733b is 12 times closer to its star (HD 189733) than Mercury is to our own sun (a class G star, and 32 times closer than the Earth is to the sun. While somewhat smaller than the sun, the star HD 189733 is more volatile–often discharging massive solar flares hundreds of miles into space–and dangerously close to HD 189733b.
The astronomers’ observations indicate an interaction between the stellar activity and the planet’s atmosphere. This can have implications for understanding other planetary systems, especially those which may have potentially habitable planets.
That is not the case with HD 189733b, a gas giant orbiting very close to a somewhat volatile star. But is it that very degree of proximity that is causing the planet to slowly evaporate?
“This mass loss is almost certainly due to the proximity of the planet HD 189733b relative to its central star, HD 189733, along with the star’s radiation,” says Jensen. “This isn’t to imply it’s not going to last much longer. It is a very slow evaporation, and ultimately the planet will lose only 1 percent of its mass. Still, that is significant.”
What Jensen, Redfield and other observers contributing to the paper saw to indicate this was a significant spike in spectrographic readings suggesting the planet was shedding significant amounts of hydrogen. They were also able to detect it using visible light–another first. Past detections of hydrogen dissipation, which have been rare, used ultraviolet light.
“We’ve only been able to observe exoplanets for about 20 years, and we’ve detected atmospheres in just a few dozen of those, so this is an exciting finding,” Redfield says. “We’re hoping to do more observations of this planet and others that are similar in their composition and positioning to their stars. This will help us determine how rare of a phenomenon this is.”
The astronomers hope to do further studies at the McDonald Observatory, and perhaps try to book time on the Hubble Telescope, which would afford them the clearest view of HD 189733b.
The astronomers were supported in this study by a grant from the National Science Foundation.
by David Pesci •
In the summer of 2010 Craig Malamut traveled to the Easter Islands to study and photograph a rare solar eclipse. Soon after his eclipse observations were completed, NASA used one of his photographs in their official materials on the event. He also spent a week collaborating with astronomers from the University of Chile in Santiago to study Pluto’s atmosphere as it obscured the light from a faint star. This year, Malamut has coauthored two papers for astronomical journals and is analyzing data from the Hubble Space Telescope on gas and dust clouds lying near the sun and other nearby stars.
It’s the kind two-year research run that many scientists would be proud and excited to have accomplished. But Craig Malamut is not a paid researcher or a member of any faculty. He’s a college student who is still working through his senior year at Wesleyan.
Malamut, an astronomy major, has been working at an advanced level for someone who has yet to earn a bachelor’s degree. While the experience has been intense, he hasn’t been intimidated by the complexity of the work or felt limited by his undergraduate standing. “I’ve felt very prepared for this level of research from the courses, discussions, and advising I received from the astronomy department,” he says. “Professors Herbst, Moran, Redfield, and Kilgard do a great job getting their students involved early in astronomy research, whether at Wesleyan or abroad.”
He also took part in the Keck Northeast Astronomy Consortium Research Experience for Undergraduates (KNAC REU) Williams College. Several members of astronomy faculty also recommended him for the Keck-sponsored program in the Easter Islands.
by Olivia Drake •
James Greenwood, research associate professor of earth and environmental sciences, received a grant worth $494,517 from NASA. The grant will support his research titled “Water in Lunar Rocks: Petrologic and Isotopic Analyses of Phosphate Minerals in Apollo’s Samples” through June 30, 2014.
by Olivia Drake •
James Greenwood, visiting assistant professor of earth and environmental sciences, was mentioned in a June 14 BBC News science article on “Much More Water Found in Lunar Rocks.”
Greenwood and Professor Lawrence Taylor from the University of Tennessee in Knoxville, have come up with evidence on the origins of lunar water: comets. According to the article, they believe there were a lot of comets flying around at the time of the Moon’s formation, “hitting the little, nascent, early Moon some 4.5 billion years ago.”
by David Pesci •
Soon after the Apollo spaceflights to the moon, experts examined the rocks brought back by the astronauts and declared with certainty that the moon was a dry, waterless place.
Forty years later, James Greenwood begs to differ. Not only does he have proof, his findings strongly suggest that some of the lunar water he found is not indigenous to the moon or earth but appears to have originated from somewhere else in space.
Greenwood, research associate professor, visiting assistant professor, Earth and Environmental Sciences, pioneered a new method of analyzing the rocks using a combination of light, electron and ion-beam microscopes. He and his international team of planetary geologists and geochemists, announced their findings at the 41st Annual Lunar and Planetary Science Conference in Houston, Texas, in March.
It was a discovery almost didn’t happen, however. In fact, the only reason Greenwood found proof of water on the moon was because he was looking at a rock from Mars.
“I was in a lab at Hokkaido University in Sapporo, Japan, using an ion microscope to measure water in Martian meteorites,” Greenwood, who is a planetary geochemist, says. “We had pioneered this new technique to use two-dimensional ion imaging and were looking at this mineral in the meteorites called ‘apatite,’ which is a common phosphate mineral and holds water. Our analyses had been very good, probably better than ever before. So I thought, ‘What if we used this technique on moon rocks?’”
Greenwood thought of moon rocks because a 2008 study from Brown University had found possible evidence of water in volcanic moon rocks. However, the study had been problematic and its results disputed. Still, Greenwood was intrigued that the possibility of water in the lunar rock samples had not been thoroughly vetted.
“The rocks were all declared devoid of water when they were first analyzed 40 years ago,” he said. “But I thought our new technique held some promise.”
Greenwood’s technique and the advanced instruments he gained access to, made it possible for him and the other scientists on his team to analyze the sample’s chemical composition over areas as small as 5 x 5 microns.
“In the past, they had actually ground up the analyzed samples. This created conditions that put the chemical analysis out of context,” he says. “Our method let us look at the samples as they are, in situ.”
The hardest part was getting permission to examine a sample. Less than 900 rocks were brought back from all the Apollo missions combined. Access is strictly limited.
It took several months, but Greenwood was able to get a few samples to analyze. The first were from the lunar highlands, which he thought might hold promise. But no water-holding apatite was found. Then he gained access to a sliver of rock brought back from the southwestern edge of the Mare Tranquillitatis – the “Sea of Tranquility” – where Apollo 11 had set down in 1969.
“So there we were in the lab at about 3 a.m. and the first sample we looked at, boom, there it was. Water. At first we couldn’t believe it. But we double-checked and we were just blown away. It was clearly there.”
The apatite, which is the same mineral that teeth are made of, was rife with water molecules. However, as Greenwood and his colleagues continued to analyze the samples they found that the water contained in the rocks was not from the earth or the moon.
“It was consistent in the water that comes from comets,” Greenwood says.
How could he tell? Water molecules found on earth – and those indigenous to the moon, since it was once part of the earth – contain a specific ratio of hydrogen to deuterium, which scientists use as a standard. The water Greenwood has found in some of the lunar samples has nearly twice the deuterium.
“The only things that falls into this range with any consistency are comets,” Greenwood says.
He adds that comets have long been known to hold frozen water and that perhaps as much as 10% of the earth’s water had come from comets, as well.
Microscopic water in minerals inside moon rocks is a tremendous find, but in a practical sense it does not open the door to, say, astronauts extracting this water to use on a lunar base or colony. Greenwood says that process would be too expensive and energy-exclusive with current methods. However, his discovery does open up another possibility.
“The level of water we found in the samples are consistent with the amount of water one would find from the mantle in the earth,” he says. “So there may be a reservoir of water within the mantle of the moon. Somewhat like groundwater here on earth.”
How far within the mantle, how deep below the surface is another challenge for another completely different type of study.
But Greenwood and his team have confirmed what many people have wondered for centuries, perhaps millennia. There is water on the moon.
by Olivia Drake •
Astronomers interested in black holes generally study small, low-mass types within our own galaxy, or super-massive black holes found in the center of other large galaxies. But during the 18th Annual Undergraduate Research Symposium Nov. 7-8 at Wesleyan. astronomy major Hannah Sugarman ’09 explained the importance of finding intermediate mass black holes in the local universe.
“Small black holes are about 30 times the mass of the sun, and the big, super-massive black holes have a mass of about a million times the mass of the sun. Intermediate mass black holes are in between these mass limits,” Sugarman says. “They are important because if super-massive black holes are made by slightly smaller ones combining, we want to be able to observe the smaller ones to see how this works.”
by Olivia Drake •
|Members of the Committee on Planetary and Lunar Exploration (COMPLEX) met at Woodhead Lounge July 20-22. Martha Gilmore, assistant professor of earth and environmental sciences, (pictured second from left in the first row) coordinated the meeting.|
|Martian oceans, solar system exploration and telescopic studies of Neptune were all topics of discussion during a planetary committee meeting at Wesleyan.The Committee on Planetary and Lunar Exploration (COMPLEX) met at Wesleyans Woodhead Lounge July 20-22. COMPLEX advises the National Academies Space Studies Board on the entire range of planetary system studies that can be conducted from space as well as on ground-based activities in support of space-based efforts.
The 10-member committee assists the board in carrying out studies, monitoring the implementation of strategies, and providing evaluations of programs and strategic priorities for NASA and other government agencies.
Martha Gilmore, assistant professor of earth and environmental sciences and COMPLEX member, coordinated the Wesleyan meeting. The committee meets about three times a year in various locations.
Some of the work we performed in this meeting is to consider some of the consequences of the change to a new NASA administrator and the president’s Vision for Space Exploration on solar system exploration priorities as they were defined by the community prior to these changes, Gilmore says. It is anticipated that the group will formulate and participate in studies to address this issue.
Andrew Dantzler and Douglas McCuistion of NASA Headquarters provided a Mars Exploration Program status report and the status of NASA solar system exploration activities.
In addition, Gilmore spoke about the geology and rocks from the opening of the Atlantic Ocean; James Greenwood, research assistant professor and visiting assistant professor of earth and environmental sciences, spoke about geochemistry of a martian ocean; and William Herbst, the John Monroe Van Vleck Professor of Astronomy, chair of the Astronomy Department and director of the Van Vleck Observatory, discussed the circumstellar disk of KH15D.
Members of the board included representatives from NASAs Jet Propulsion Laboratory, University of Michigan, University of Texas, University of Arizona, University of Hawaii, University of California, Los Angeles and Johns Hopkins University.
For more information on the committee or their projects, visit: http://www7.nationalacademies.org/ssb/complex1.html or http://www.nasa.gov/missions/solarsystem/explore_main.html.
|By Olivia Drake, The Wesleyan Connection editor|