Category: Space

The Philae lander is scheduled to touch down on Comet 67P/Churyumov-Gerasimenko on November 12, 2014 at 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 16:02 UTC. Both NASA and ESA will provide live online coverage of this first-ever attempted landing on a comet.

The final stage of the mission — actually landing the probe on the comet — has been described as “seven hours of terror” by a scientist involved with the project, and that terror is about to begin.

Here are some times to pay attention to, if you want to watch the event live.

– Overall, NASA’s live coverage is from  1400 to 1630 UTC

– NASA’s live commentary will include excerpts of the ESA coverage from 1400 to 1500 UTC

– NASA will continue carrying ESA’s commentary from 1500 UTC to 16:30 UTC

Watch all NASA coverage here.

Translate UTC to your time zone here.

– ESA’s live coverage begins on Tuesday, November 11, a day before the landing, at 1900 UTC. Watch ESA’s coverage here.

Rosetta spacecraft will do the equivalent of transferring an object from one speeding bullet to another, when it tries to place its Philae lander on its comet. Read more about the mission’s dramatic attempt to land on a comet here.

After landing, Philae will obtain the first images ever taken from a comet’s surface. It also will drill into the surface to study the composition and witness close up how a comet changes as its exposure to the sun varies.

Philae can remain active on the surface for approximately two-and-a-half days. Its “mothership” – the Rosetta spacecraft – will remain in orbit around the comet through 2015. The orbiter will continue detailed studies of the comet as it approaches the sun for its July 2015 perihelion (closest point), and then moves away.

Comets are considered primitive building blocks of the solar system that are literally frozen in time. They may have played a part in “seeding” Earth with water and, possibly, the basic ingredients for life.

Here’s the link for NASA’s coverage: http://www.nasa.gov/nasatv

Here’s the link for ESA’s coverage: http://www.esa.int/rosetta

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]

 

Meteor explosion Milky Way Timelapse from Soulcrate Music on Vimeo.

Possibly a rare “fireball” or “bolide.” From NASA:

Fireballs and bolides are astronomical terms for exceptionally bright meteors that are spectacular enough to to be seen over a very wide area. Ground-based observers sometimes also witness these events at night, or much more rarely in daylight, as impressive atmospheric light displays.

A meteoroid is generally defined as an asteroid or comet fragment that orbits the Sun and has an approximate size between ten microns and a meter or so. Meteors, or “shooting stars,” are the visible paths of meteoroids that have entered the Earth’s atmosphere at high velocities. A fireball is an unusually bright meteor that reaches a visual magnitude of -3 or brighter when seen at the observer’s zenith. Objects causing fireball events can exceed one meter in size. Fireballs that explode in the atmosphere are technically referred to as bolides although the terms fireballs and bolides are often used interchangeably.

During the atmospheric entry phase, an impacting object is both slowed and heated by atmospheric friction. In front of it, a bow shock develops where atmospheric gases are compressed and heated. Some of this energy is radiated to the object causing it to ablate, and in most cases, to break apart. Fragmentation increases the amount of atmosphere intercepted and so enhances ablation and atmospheric braking. The object catastrophically disrupts when the force from the unequal pressures on the front and back sides exceeds its tensile strength.

Objects causing fireballs are usually not large enough to survive passage through the Earth’s atmosphere intact, although fragments, or meteorites, are sometimes recovered on the ground.

[via Reddit]

The European Space Agency’s Rosetta robotic spacecraft, currently in orbit around the comet 67P/Churyumov–Gerasimenko, recently took several amazing close-up pictures of C-G’s surface.

The appearance of dunes on the comet surprised many observers due to the lack of wind and gravitational influences that typically shape the same features on Earth. As of now researchers can only speculate as to what may be creating the formation. One commenter at the ESA site has a good analysis:

I think I’ve decided they are deposited by the gas plumes from the surrounding cliffs firing across the already Laktritz covered floor of the “crater” Logan. Just as the mounds and dunes near cliff edges are created. No need to find a different “agent”. The gas plumes don’t have to go straight up do they.

I spotted this some time ago at the base of a cliff in the neck area. The demarcation between exposed subsurface and dust blanket, is really sharp. Now we can see why and how. The rubble strewn area to the right of image 4, the surface blanket looks like snow melting, all patchy, where thicker drifts and mounds take longer to melt. These dust mounds must be where all the dust has been “blown” and collected into quiet zones, so these little pockets take longer to be dispersed.

The chimneys I think are the “smoking guns” for the body penetrating impacts we discussed. The molten ice stuff coming out would build a wall as it immediately freezes on reaching the surface. Frozen and semi frozen ice would slowly fall back down. By the time it reaches the surface the comet has rotated so one side of the caldera has a lot more ice deposited on it. The liquid in the caldera will soon level and freeze once the gas pressure is released and the “ice lava” tube becomes blocked. This core and crater floor will have far fewer volatile ices and gases in it making it a lot less active than the surrounding surface, hence the build up of Laktritz. As the higher side of the icy crater rim takes longer to erode we are left with lots of semicircular cliffs beside flat areas.

The overturned cups are more recent eruptions where less of the crater rim has eroded. The huge flat Star Wars Landing Zone near site C. Is perched on top of huge steep cliffs, the wall of frozen ices that built up as the cryovolcano was erupting. Then we see the partially eroded rim as the cliffs round the flat area. The little cup volcanos show that an overhang actually builds up on the taller side of the rim, so this overhang eventually collapses into the crater, hence the pile of rubble only on one side of the crater. Something that is seen in nearly all the craters.

If the refrozen ices form an amorphous solid like glass, as lava does to make basalt on Earth, we get the smooth solid material full of cracks and fissures we s most commonly on the tops of the lobes. A different composition and slower flow rate would give lumpy, rubble “ice lava, (top left Image 2).. Ices with more gases in them would give a more pumice type material when it freezes, full of holes and tunnels, (Philae landing site image). A different composite of more dense volatile ices give a material like “pillow lava”, which can also be seen in image 2 as the flat topped bulges top middle.

How far this analogy can be used in actuality, I have no idea. No one else does either, since no one has seen cryovolcanism up close before, only on flyby pictures from thousands of Kilometres away. The laws of physics don’t change and the behaviour of molten fluids on freezing is a pretty well understood phenomenon. The low gravity is the big difference, though it seems to make little difference on the Moon and Mars.

The Rosetta spacecraft has been creating a detailed map of the comet in preparation to send its Philae lander to the surface. Philae is currently scheduled to detach from Rosetta on 12 November 2014 at 08:35 UTC, with a landing seven hours later.

[via the European Space Agency]

On the afternoon of Thursday, Oct. 23, 2014, the Moon will pass in front of the Sun. A giant sunspot spitting powerful x-rays will make the eclipse that much cooler. The rare combination is pairing a powerful x-class solar flare with a partial shadow cast by the moon to create what will surely be a dramatic effect.

The sunspot providing the eclipse enhancement is already the largest seen in 25 years and its activity is expected to continue for a while. On Oct. 22, the energy released from from the solar flare was measured at a strength stronger than a million times the yield of every nuclear weapon on Earth.

Viewing is expected to be best in the United States and Canada. NASA has provided a handy chart to determine best peak viewing times by major city.

Requisite safety reminder: don’t look directly into the sun! If you’re not in the US or Canada or your view is obstructed by cloud cover, you can see a livecast of the event from the Mt. Lemmon SkyCenter in Arizona.

[via Universe Today]

This past week, the sun briefly gave NASA observers a timely and spooky show:

Active regions on the sun combined to look something like a jack-o-lantern’s face on Oct. 8, 2014. The active regions appear brighter because those are areas that emit more light and energy — markers of an intense and complex set of magnetic fields hovering in the sun’s atmosphere, the corona. This image blends together two sets of wavelengths at 171 and 193 Angstroms, typically colorized in gold and yellow, to create a particularly Halloween-like appearance.

According to NASA, the regions forming the jack-o-lantern features are “markers of an intense and complex set of magnetic fields hovering in the sun’s atmosphere, the corona.” The intense solar activity associated with the photos is not expected to threaten Earth.

See more of the pumpkin sun at NASA’s Goddard Media Studio.