Day 2: Planetary Defense conference in Bucharest, Romania
Posted by Bruce Betts
10-05-2011 17:59 CDT
One nice thing about the Planetary Defense conference is that I not only get to talk with the NEO community of experts all in one place and hear their new science, but I also get updates on projects the Planetary Society has funded. One case is Alison Gibbings from the University of Strathclyde in Scotland. She is a grad student working with Massimiliano Vasile on the Planetary Society?funded Mirror Bees project. They are looking into what appears to be a very promising technique for moving a dangerous asteroid. The concept is to use lasers on spacecraft hovering near the asteroid to gradually vaporize the rock of the asteroid, creating jets that push the asteroid to a different orbit. These researchers are setting up and doing fun looking lab tests using a high powered laser to vaporize part of a rock, then measure things like the ejecta plume. So far, they have succeeded in carrying out the initial tests. Soon, we'll post an update with some of the super cool pictures. When Alison gets back from this conference, she'll be setting up a vacuum chamber so the experiments can be done in a more space-like environment.
On to a small sampling of the science talks from the conference. Various speakers have reiterated what started to come out at the last conference: a space based telescope dedicated to NEO studies and preferably put considerably inwards of Earth's orbit would greatly increase the efficiency of NEO detection. Paul Abell from Johnson Space Center spoke on this topic yesterday, and, in his case, he also focused on finding NEOs that could be targets for human missions next decade since very, very few meet the criteria now.
Today, Amy Mainzer from JPL described a mission that was designed to do various IR astronomy and was used in part to find NEOs -- and it sure was successful. From a non-optimized orbit, NEO-WISE, as they called the NEO part of the Wide-field Infrared Survey Explorer, discovered 132 near Earth asteroids. Lance Benner from JPL talked about the all-important radar tracking of NEOs. When asteroids are close enough for radar observations, one gets a wealth of properties about them not otherwise obtainable.
Mark Boslough from Sandia National Laboratory talked about airbursts: objects that explode and break up in the atmosphere. Mark did the modeling that led to a downgrading of the size of the Tunguska impactor by incorporating its momentum traveling through the atmosphere into the models. Today he noted that in a statistical sense, because there are lots more small objects, it is likely the next deadly NEO "attack" will be from an airburst, not a cratering impact. He was also quick to point out the likelihood is very low at any particular time. A Tunguska happens once in roughly 1000 years or so ? statistically. He also said we should consider a prediction capability for a zone of impact for future airburst sized object, similar to hurricane track predictions made by the National Weather Service. Then, local authorities could coordinate evacuation.
Also discussed today were "tsunamis" that could be caused by NEO impacts into oceans or seas. Galen Gisler from the University of Oslo reiterated his interesting conclusion about deep ocean impacts: that because of the different physics involved including shorter wavelengths, lots of energy from the hypervelocity impact going into vaporizing water, there actually would not be ocean basin scale tsunami like waves from a large impact. Today he looked in more detail at continental shelf impacts, which can create a rather ugly situation for the nearby coastline with everything from huge surge to sandblasting from high velocity winds carrying bits of sand/glass from the impact itself.
You can find more info on the conference including abstracts at least for all the oral talks at http://www.pdc2011.org/