Rosetta mission controllers have made the first call to “Go” for an attempted landing on Comet 67P, the European Space Agency (ESA) announced in a webcast Tuesday.

Scientists say there are still a few more key decisions to take in the coming hours before a planned separation of the landing craft Philae from the mother ship Rosetta on Wednesday.

Hours before separation, Philae’s on-board batteries are prepared and a fly wheel is started to give the probe stability on its journey to the comet surface. Without the gyroscopic effect of the fly wheel there’s a danger that the lander could turn end over end.

To release Philae, wax over a latch is melted and the lander is automatically unscrewed. If it fails there’s a back-up plan. A pyrotechnic charge will fire and push the lander away at just the right speed to set Philae on the right course.

Mission controllers then face a nervous seven-hour wait for Philae to reach the surface. The comet is so far away that a confirmation signal relayed from Rosetta, which remains in orbit around the comet, will take nearly half an hour to reach Earth.

The comet’s gravity is so weak that engineers have come up with ingenious solutions to keep Philae in place. At touchdown two harpoons fire out from the legs, a thruster on top of the craft helps push it to the surface and screws on each of the three feet help attach it to the comet.

Space fans around the world are waiting excitedly for Wednesday of this week, when the ESA’s Rosetta spacecraft will attempt a first-ever soft landing of a robotic probe on a comet. The Philae (fee-LAY) lander is scheduled to touch down on Comet 67P/Churyumov-Gerasimenko on November 12, 2014 at 10:35 a.m. EST (7:35 a.m PST/15:35 UTC). We on Earth – 300 million miles (500 million km) away – won’t know the lander has set down successfully until a signal is received back at about 11:02 a.m. EST (8:02 a.m. PST/16:02 UTC). If all goes as planned, it’ll be an awesome achievement, a feat described by Dutch astrophysicist Dr Fred Jansen – Rosetta’s mission manager – as trying to:

… do the equivalent of transferring an object from one speeding bullet to another.

The comet and Rosetta are flying through space at 60,000km an hour. In many, many aspects this is an absolute first.

The landing site – formerly known simply as Site J – now has an official name. It’s been given the name Agilkia, chosen after an ESA public essay competition. The name is in keeping with Rosetta’s Egyptian theme. The mission itself was named Rosetta after a stone slab inscribed with a decree issued in 196 BC on behalf of King Ptolemy V of Egypt. The decree the key to our modern understanding of Egyptian hieroglyphs. The name Agilkia, meanwhile, refers to an island on the River Nile. Ancient buildings were relocated there after the island Philae flooded.

[via ESA]

Rosetta’s Plasma Consortium (RPC) has uncovered a mysterious ‘song’ that Comet 67P / Churyumov-Gerasimenko is singing into space. The comet seems to be emitting a ‘song’ in the form of oscillations in the magnetic field in the comet’s environment. It is being sung at 40-50 millihertz, far below human hearing. To make the music audible to the human ear, the frequencies have been increased in this recording:

When Virgin Galactic’s SpaceShipTwo began coming apart just seconds after it had been launched from its mothership and its rocket motor had fired, the pilots were wearing parachutes but had no ejection seats – just an escape hatch. Nor were they wearing oxygen masks or space suits at an altitude where the temperature was about 70 degrees below zero.

The Washington Post reports that employees of Scaled Composites (which built SpaceShipTwo) “are calling Siebold’s survival miraculous, and they describe his escape like something out of a movie script.”

“The fact that he survived a descent of 50,000 feet is pretty amazing,” said Paul Tackabury, a veteran test pilot who sat on the board of directors of Scaled Composites until it was sold to Northrop Grumman Corp. “You don’t just jump out of aircraft at Mach 1 at over 50,000 feet without a spacesuit.”

If he was still strapped into his seat (which was not designed to eject him from SpaceShipTwo, nor would it likely have allowed him to exit through the escape hatch), then he must have been thrown clear – remaining conscious and with the presence of mind to fall to a lower altitude (where the temperature was warmer and the atmosphere contained more oxygen), then unstrap from the seat, and deploy the parachute.

At a press conference this week, acting NTSB Chairman Christopher Hart said cockpit video and data showed that the co-pilot unlocked SpaceShipTwo’s unique “feathering” system earlier than planned. The system works somewhat like the wing flaps that airplanes use to slow for landing. A full investigation into the cause is expected to last a year.

[via The Washington Post]