NASA's Gamma-ray Large Area Space Telescope (GLAST) has been officially renamed Fermi, in honor of Enrico Fermi.
The BBC has a short news article on Fermi's "first light" image of the Gamma-ray sky.
Thursday, August 28, 2008
Monday, August 18, 2008
Astronomy can sometimes feel like a chore.
Days (or weeks) of software troubles, problems with imperfect instrument calibrations, grant writing and/or management, dealing with PowerPoint talk preparation, rejected proposals and job applications, vanishing funding, and writers block can all combine to beat one's spirit down and make you feel like Science is not as much fun at it used be.
But it could always be worse. For example, you might have to find and collect floating whale poop in order to do your research on North Atlantic Right Whale health and reproduction [via Zooillogix].
Posted by Dave Strickland at 6:06 PM
Wednesday, August 13, 2008
Haven't had time to get back to the second Hoyle post, but on the subject I saw "The Dinosaur Feather Mystery" on the Science Channel and was blown away by the progress that has been made in both paleontology and evo-devo in the last few years on the evolution of feathers and flight. And there I was still thinking that feathers were modified scales...
Other interesting stuff to watch: a movie of the variable X-ray sky covering 1996-1999, based on RXTE, as linked to by AstroDyke.
Posted by Dave Strickland at 6:24 PM
Friday, August 01, 2008
Sciam has a short article by Larry Greenmeier ("Voyaging to the Stars on a Solar Breeze: Space Sail to Take Flight") on space sails, discussing both radiation-pressure and solar wind plasma momentum-driven designs. NanoSail-D is a mini Solar sail (from NASA) soon to be tested in space.
Unfortunately, rather contrary to the title of the Sciam article, solar sails will have problems as a means of propulsion for interstellar (as opposed to interplanetary) probes. Nevertheless they are far more plausible and practicle than Bussard ramjets or Daedalus.
For a fixed sail size the force on the solar sail due to either the Sun's radiation or the Solar wind will diminish as the inverse square of the distance of the Sail from the Sun (*). Basically you get most of your acceleration on the sail when you're closest to the Sun, and your velocity very quickly asymptotes out to a terminal velocity and then you're coasting along with little control.
I find solar sails interesting for a number of reasons, but from a professional standpoint one reason is that the physics is very similar to the standard model of clouds enveloped and accelerated in superwinds, and its really quite simple and neat too. Sadly blogger (and the web) is horrible at displaying equations so I won't bother trying .
(*) Now if you use a giant laser or maser to accelerate your sail, so that your light beam has relatively little divergence, you can accelerate your sail for much longer. This scheme is used by the Moties in Niven and Pournelle's "The Mote in God's Eye", or by humanity in Greg Bear's "Queen of Angels." Both great works of speculative fiction well worth reading.
Posted by Dave Strickland at 8:21 PM