Postcard From the Middle of Nowhere

Rosetta is a spacecraft built and launched by the European Space Agency. Its travel partner is a robotic lander named Philae. Their job is to study a comet named 67P/Churyumav-Gearsimenko, or 67P/C-G for short.

The Rosetta mission launched in March, 2004. A little over a month ago, Rosetta and Philae quietly dropped into orbit around the massive comet.

On November 12, in little under a month, Philae will attempt to land on the comet.

Go, go human species! Philae, do the job; we’re all behind you.

Meanwhile, a holiday snap?

What you’re looking at in the picture above is none other than 67P/C-G; Philae took the snapshot, which includes part of the Rosetta structure, from a range of under ten miles

Elizabeth Howell, writing for Universe Today explains:

So this spacecraft — taking this picture — is going to land on the surface of THAT comet. Doesn’t this give you a pit in your stomach? This is a selfie taken from the Philae spacecraft that, riding piggyback, captured the side of the Rosetta spacecraft orbiting Comet 67P/Churyumov-Gerasimenko.

The image is so close-up — just 9.9 miles (16 kilometers) from 67P’s surface — that mission planners can even spot Landing Site J on the comet’s smaller lobe.

Additionally, Howell notes, we will hear tomorrow whether or not Site J is cleared for landing; the next data set will be gathered at a range of six miles away from 67p/C-G.

The article comes with a fun, attention grabbing headline, “Creepy Comet Looms In The Background Of Newest Philae Spacecraft Selfie”, but might well overstate the case. After all, when you two hundred ninety eight million miles from home, and all of ten miles away from the only thing in the Universe you can reach, yes, that thing might seem creepy. It’s four and a half miles long. Four miles wide. And it is two hundred ninety eight million miles out in the middle of nowhere and running away from you, yeah, that can be a heart-fluttering moment.

And yet our intrepid explorers push on. Good luck, Philae. And thank you, Rosetta. We know you’re not coming home, but we are so amazed.

And good show, ESA. As we creep toward the climax, we can only wait in thankful awe at the spectacle you’ve given us.

____________________

European Space Agency. “Rosetta”. (n.d.)

Howell, Elizabeth. “Creepy Comet Looms In The Background Of Newest Philae Spacecraft Selfie”. Universe Today. 14 October 2014.

“Comet 67P (Churyumov-Gerasimenko) and The Rosetta Spacecraft”. Live Comet Data. 14 October 2014.

(Hat tip and many thanks to S.L.)

Nothing to See Here: Titanian Clathrate Edition

NASA would like your attention long enough to explain a thing or two about how—

Icy aquifers on Saturn's moon Titan transform methane rainfall: http://t.co/C7i4g01xGU   @CassiniSaturn pic.twitter.com/wmXCP9LG75

— NASA (@NASA) September 4, 2014

—absolutely cool the Cassini-Huygens mission really is.

The NASA and European Space Agency Cassini mission has revealed hundreds of lakes and seas spread across the north polar region of Saturn’s moon Titan. These lakes are filled not with water but with hydrocarbons, a form of organic compound that is also found naturally on Earth and includes methane. The vast majority of liquid in Titan’s lakes is thought to be replenished by rainfall from clouds in the moon’s atmosphere. But how liquids move and cycle through Titan’s crust and atmosphere is still relatively unknown.

A recent study led by Olivier Mousis, a Cassini research associate at the University of Franche-Comté, France, examined how Titan’s methane rainfall would interact with icy materials within underground reservoirs. They found that the formation of materials called clathrates changes the chemical composition of the rainfall runoff that charges these hydrocarbon “aquifers.” This process leads to the formation of reservoirs of propane and ethane that may feed into some rivers and lakes.

And it doesn’t stop there.

YORP: Rock and Roll

“This is a rock. Seeing it fall apart before our eyes is pretty amazing.”

—David Jewitt

For months, the Hubble Space Telescope has been checking in on asteroid P/2013 R3. First observed by Catalina and Pan-STARRS, observations at Keck two weeks later revealed what might be a once in a lifetime spectacle.

“Keck showed us that this thing was worth looking at with Hubble,” [David] Jewitt [of UCLA] said. With its superior resolution, the space-based Hubble observations soon showed that there were really ten distinct objects, each with comet-like dust tails. The four largest rocky fragments are up to 200 metres in radius, about twice the length of a football pitch.

The Hubble data showed that the fragments are drifting away from each other at a leisurely 1.5 kilometres per hour—slower than the speed of a strolling human. The asteroid began coming apart early last year, but the latest images show that pieces continue to emerge ….

…. The ongoing discovery of more fragments makes it unlikely that the asteroid is disintegrating due to a collision with another asteroid, which would be instantaneous and violent in comparison to what has been observed. Some of the debris from such a high-velocity smash-up would also be expected to travel much faster than has been observed.

It is also unlikely that the asteroid is breaking apart due to the pressure of interior ices warming and vaporising. The object is too cold for ices to significantly sublimate, and it has presumably maintained its nearly 480-million-kilometre distance from the Sun for much of the age of the Solar System.

This leaves a scenario in which the asteroid is disintegrating due to a subtle effect of sunlight that causes the rotation rate to slowly increase over time. Eventually, its component pieces gently pull apart due to centrifugal force. The possibility of disruption by this phenomenon—known as the YORP effect—has been discussed by scientists for several years but, so far, never reliably observed.

For break-up to occur, P/2013 R3 must have a weak, fractured interior, probably the result of numerous ancient and non-destructive collisions with other asteroids. Most small asteroids are thought to have been severely damaged in this way, giving them a “rubble pile” internal structure. P/2013 R3 itself is probably the product of collisional shattering of a bigger body some time in the last billion years.

Herschel: Water at Ceres

What’s that? You never met Herschel?

Via ESA:

ESA’s Herschel space observatory has discovered water vapour around Ceres, the first unambiguous detection of water vapour around an object in the asteroid belt.

With a diameter of 950 km, Ceres is the largest object in the asteroid belt, which lies between the orbits of Mars and Jupiter. But unlike most asteroids, Ceres is almost spherical and belongs to the category of ‘dwarf planets’, which also includes Pluto ….

…. [U]sing the HIFI instrument on Herschel to study Ceres, scientists have collected data that point to water vapour being emitted from the icy world’s surface.

“This is the first time that water has been detected in the asteroid belt, and provides proof that Ceres has an icy surface and an atmosphere,” says Michael Küppers of ESA’s European Space Astronomy Centre in Spain, lead author of the paper published in Nature.

Although Herschel was not able to make a resolved image of Ceres, the astronomers were able to derive the distribution of water sources on the surface by observing variations in the water signal during the dwarf planet’s 9-hour rotation period. Almost all of the water vapour was seen to be coming from just two spots on the surface.

“We estimate that approximately 6 kg of water vapour is being produced per second, requiring only a tiny fraction of Ceres to be covered by water ice, which links nicely to the two localised surface features we have observed,” says Laurence O’Rourke, Principal Investigator for the Herschel asteroid and comet observation programme called MACH-11, and second author on the Nature paper.

And, really, what can you say? Good show, Herschel. Congratulations, ESA. And thank you. That is really, really cool.

Herschel is named for the guy who discovered Uranus; William Herschel also identified infrared radiation over two hundred years ago. This latest announcement is one of the satellite’s last dramatic gifts; Herschel ran its course, with final commands sent in June, 2013.

It was certainly a good run. And there are probably myriad little gifts remaining to be discovered in the data.

Talk about a show. Water at Ceres. Makes as much sense as anything else, to be certain, but it is also good to know.

Mars Express Seeks Evidence of Watery History on Mars

NASA is, obviously, not the only space agency in the world. Nor are they the only agency doing really cool work at Mars. The European Space Agency is currently operating the Mars Express, in orbit around the Red Planet, and the produce of that mission is absolutely astounding.

The latest update from the Mars Express team focuses on Amenthes Planum:

ESA’s Mars Express took a high-resolution stereo image on 13 January of the southeast corner of the Amenthes Planum region on Mars, near to Palos crater and the mouth of a well-known sinuous valley, Tinto Vallis.

At the bottom-centre of the full-colour image … is a nearby shorter and wider valley, which is fed by a number of tributaries before it joins the mouth of Tinto Vallis as both empty into Palos crater, just off the bottom of the image.

The 190 km-long Tinto Vallis is seen in the context image and is named after the famous Rio Tinto river in the Andalucía region of Spain. It is believed to have formed around 3.7 billion years ago, during the early history of Mars.

The network of shorter valleys shown in the first perspective image is thought to have formed through volcanic activity melting subsurface ice and liberating water to the martian surface via seeps and springs.