By Soulskill from Slashdot's take-that-wesley department
An anonymous reader writes: Physicists at Australian National University have developed a tiny tractor beam that improves in several ways upon previous attempts. First, it operates on scales which, while still tiny, are higher than in earlier experiments. The beam can move particles up to 200 microns in diameter, and it can do so over a distance of 20 cm. "Unlike previous techniques, which used photon momentum to impart motion, the ANU tractor beam relies on the energy of the laser heating up the particles and the air around them (abstract). The ANU team demonstrated the effect on gold-coated hollow glass particles. The particles are trapped in the dark center of the beam. Energy from the laser hits the particle and travels across its surface, where it is absorbed creating hotspots on the surface. Air particles colliding with the hotspots heat up and shoot away from the surface, which causes the particle to recoil, in the opposite direction. To manipulate the particle, the team move the position of the hotspot by carefully controlling the polarization of the laser beam."Read Replies (0)
By Soulskill from Slashdot's for-really-bad-days department
An anonymous reader writes: With the construction of Orion, NASA's new manned spacecraft, comes the creation of a new Launch Abort System — the part of the vehicle that will get future astronauts back to Earth safely if there's a problem at launch. The Planetary Society's Jason Davis describes it: "When Orion reaches the apex of its abort flight, it is allowed to make its 180-degree flip. The capsule of astronauts, who have already realized they will not go to space today, experience a brief moment of weightlessness before the capsule starts falling back to Earth, heat shield down. The jettison motor fires, pulling the LAS away from Orion. ... Orion, meanwhile, sheds its Forward Bay Cover, a ring at the top of the capsule protecting the parachutes. Two drogue chutes deploy, stabilizing the wobbling capsule. The drogues pull out Orion's three main chutes, no doubt eliciting a sigh of relief from the spacecraft's occupants."Read Replies (0)
By timothy from Slashdot's couple-of-jockeys-too department
writes "Alan Drysdale, a systems analyst in advanced life support and a contractor with NASA concluded, "Small women haven't been demonstrated to be appreciably dumber than big women or big men, so there's no reason to choose larger people for a flight crew when it's brain power you want," says Drysdale. "The logical thing to do is to fly small women."
Kate Greene, who wrote the linked article, took part in the first HI-SEAS experiment in Martian-style living, and has some compelling reasons for an all-women crew, energy efficiency chief among them: Week in and week out, the three female crew members expended less than half the calories of the three male crew members. Less than half! We were all exercising roughly the same amount—at least 45 minutes a day for five consecutive days a week—but our metabolic furnaces were calibrated in radically different ways. During one week, the most metabolically active male burned an average of 3,450 calories per day, while the least metabolically active female expended 1,475 calories per day. It was rare for a woman on crew to burn 2,000 calories in a day and common for male crew members to exceed 3,000. ...
The calorie requirements of an astronaut matter significantly when planning a mission. The more food a person needs to maintain her weight on a long space journey, the more food should launch with her. The more food launched, the heavier the payload. The heavier the payload, the more fuel required to blast it into orbit and beyond. The more fuel required, the heavier the rocket becomes, which it in turn requires more fuel to launch.Read Replies (0)
By timothy from Slashdot's tine-to-weigh-priorities department
New submitter Tsolias
writes It appears that systemd is still a hot topic in the Debian community. As seen earlier today, there is a new movement shaping up against the adoption of systemd for the upcoming stable release [of Debian], Jessie. They claim that "systemd betrays the UNIX philosophy"; it makes things more complex, thus breaking the "do one thing and do it well" principle.
Note that the linked Debian Fork page specificaly says that the anonymous developers behind it support a proposal to preserve options in init systems
, rather than demanding the removal of systemd, and are not opposed to change per se. They just don't want other parts of the system to be wholly dependent on systemd. "We contemplate adopting more recent alternatives to sysvinit, but not those undermining the basic design principles of "do one thing and do it well" with a complex collection of dozens of tightly coupled binaries and opaque logs."Read Replies (0)