By Patricia Daukantas

Thanks to a NASA environmental-studies satellite that uses lidar technology, scientists have produced a first-of-its-kind map of tree-canopy heights around the world. The study will help climate researchers gain new insights into the rate of carbon recycling through global forests.

According to a paper coming out in Geophysical Research Letters, Michael Lefsky of Colorado State University (U.S.A.) used lidar data taken by ICESat, part of NASA’s Earth Observing System mission, to measure the height of forest trees. The ICESat instrument known as the Geoscience Laser Altimeter System, or GLAS, measured the time-of-arrival distance between laser pulses reflected off the ground and those reflected off treetops.

Unfortunately, due to problems with its lasers, GLAS was able to perform direct sensing of only 2.4 percent of Earth’s total forest cover. Lefsky thus combined the lidar data with additional data from the imaging spectrometers aboard two other NASA satellites, Terra and Aqua.

I wrote about ICESat in my “Lidar in Space” article in the June 2009 issue of OPN. In February 2010, NASA ended ICESat’s science mission after the third and final GLAS laser failed. Last week, the U.S. space agency fired ICESat’s thrusters one more time to lower its orbit, and sometime in the next couple of months, the satellite will re-enter the atmosphere, where most of it is expected to burn up before it could reach the ground.

A second-generation laser altimeter mission, ICESat 2, is still in the early phases of development, with a launch tentatively scheduled for late 2015.

2010-07 July, Astrophysics, Miscellaneous Optics lidar, laser, satellites, environment

By Patricia Daukantas

A smorgasbord of recent developments in U.S. energy policy, astrophysics and the deep sea:

• The barren desert that once hosted hundreds of nuclear fission explosions will become a testing ground for collecting energy from that ultimate source of fusion power, the Sun. The U.S. Department of Energy has announced it is creating a solar energy demonstration zone at the Nevada Test Site. U.S. Energy Secretary (and OSA Honorary Member) Steven Chu recently signed an agreement with his counterpart at the Interior Department, which owns the land. The 25 square miles of desert, which is away from the regions of the test site that actually saw nuclear explosions, will host demonstrations of concentrated solar power (CSP) technologies.
• The Hubble Space Telescope’s master repairman has gotten himself a second ground-based gig. John Grunsfeld, who has made three space trips to fix and upgrade the 20-year-old orbiting instrument, will be a research professor of physics and astronomy at Johns Hopkins University in Baltimore, Md., U.S.A. Grunsfeld, an astrophysicist by training, now serves as deputy director of the nearby Space Telescope Science Institute.
• Finally, I stumbled upon this nifty Q&A with Emory Kristof, the National Geographic contributing photographer-in-residence whose photographs appeared in the cover story of OPN’s October 2005 issue. You can also check out his photo gallery, “Discovering the Titanic,” and some of his images are included in “Milestones in Underwater Photography” as well.

2010-07 July, Astrophysics, Energy, Photography steven chu, energy, energy policy, solar power, hubble, hubble space telescope, photography

By Patricia Daukantas

Since we’re just past the summer solstice in the Northern Hemisphere, it seems appropriate that solar-powered vehicles are sailing through the news.

First of all, the University of Michigan’s solar car team, based in Ann Arbor (U.S.A.), won last week’s American Solar Challenge road race through heartland America, from Tulsa, Okla., to Naperville, Ill.

Michigan was one of 17 competing teams, mostly from the United States, but also representing Canada, Germany and Taiwan. The University of Minnesota (U.S.A.) finished in second place and the Hochschule Bochum – Bochum University of Applied Sciences (Germany) came in a strong third, less than 10 minutes behind Minnesota.

Although the winner’s elapsed racing time was just under 28 hours and 15 minutes, the race took a full week to complete, because of the mandatory checkpoints and overnight stops along the winding route.

Check out the photos of the Michigan car and its rivals in the links above – from the front, the Michigan vehicle looks to me like one of the UFOs from sci-fi movies of the 1950s, and from the side, it looks a bit like a small boat on wheels. Plus, the tiny compartment for the driver ensures that the car will never become the family sedan of the future. Still, one can’t argue with success.

Another solar-vehicle race – this one for high school students – will take place July 18-25 on steeper American terrain (Fort Worth, Texas, to Boulder, Colo.). Twenty-two teams have applied to take part in the Hunt-Winston School Solar Car Challenge. Yes, the drivers of the cars actually do have to have their driver’s licenses. But it’s still amazing what these teenagers can do.

Finally, the Japan Aerospace Exploration Agency, or JAXA, has deployed a solar sail in outer space. Its unpiloted satellite, IKAROS, was launched six weeks ago and had to “stretch its wings” once it got several million kilometers away from Earth. JAXA will monitor the output of the thin-film solar cells and learn how to maneuver with the combined force of radiation pressure on the sails and the energy generated from the photovoltaic sail. The agency explains how the sail was deployed and has a website with other details of the mission.

2010-07 July, Energy, Miscellaneous Optics solar power, students, energy, energy policy