Imaging the ground under the Greenland ice sheet

In a paper published today in Geophysical Research Letters of the American Geophysical Union, scientists describe how they have been able to produce remarkably detailed images of the ground buried almost a mile under the ice sheet of Greenland. These radar techniques are the same used in the past by spacecraft to image the hidden surface of Venus, only far more sophisticated.

The grooves on the surface of Greenland

This image from the paper compares the radar image of the Greenland surface (on the left) to an photograph of a known surface feature in the Northwest Territories of Canada, produced thousands of years ago by the giant icesheets of the last Ice Age. Both are at the same scale, about a third of a mile across, and are looking at the surface at an oblique angle of about 45 degrees. With the radar-produced image on the left, sunlight is simulated as coming from the right, with the elevation increasing as the colors go from green (lowest) to yellow to brown to purple (highest).

The long grooves, generally 30 to 100 feet deep and extending sometimes several miles, are produced as the icesheet slides across the ground. In the radar image, however, these grooves are slowly being ground out now.

It is the resolution of this technique that is so exciting. That they can look through ice almost a mile thick and resolve objects that are only tens of feet across tells me that someday it will be possible for spacecraft to map the smallest features on the surface of Venus or Titan. More exciting, this suggests that the technology will one day exist to even map the unknown surface of gas giants like Jupiter or Saturn, and do it in breathtaking detail.

Yowza!

0 comments

Speech codes for the year of 2010 and for January 2011

Freedom of speech alert! Fire’s speech codes for the year of 2010 and for January 2011. For the yearly “award,” get these rules::

UMass Amherst’s policy on “Rallies” has special regulations applicable to what it calls “controversial rallies”โ€”and it leaves “controversial” wholly undefined, giving the administration unfettered discretion to invoke the policy when it sees fit. If a rally is deemed controversial, it may only take place between noon and 1 p.m. on the Student Union steps, and must be registered at least five days in advance. That’s just one hour a day on one tiny area of a campus of more than 27,000 students! Worse yet, the policy also requires that when holding a controversial rally, “The sponsoring RSO [Registered Student Organization] must designate at least 6 members to act as a security team.” In other words, student groups wishing to publicly express a controversial opinion on campus must give at least five days notice, may only do it on one small area of campus for one hour a day, and must be willing to put themselves in harm’s way by acting as their own security in order to do so.

0 comments
1 255 256 257 258 259 263