Saturn's smoggy moon Titan has hundreds of times more natural gas and other liquid hydrocarbons than all the known oil and natural gas reserves on Earth, scientists said today.
The hydrocarbons rain from the sky on the miserable moon, collecting in vast deposits that form lakes and dunes. This much was known. But now the stuff has been quantified using observations from NASA's Cassini spacecraft.
"Titan is just covered in carbon-bearing material — it's a giant factory of organic chemicals," said Ralph Lorenz, a Cassini radar team member from the Johns Hopkins University Applied Physics Laboratory. "This vast carbon inventory is an important window into the geology and climate history of Titan."
At minus 179 degrees Celsius (minus 290 degrees Fahrenheit), Titan would be an awful place to live. Instead of water, liquid hydrocarbons in the form of methane and ethane are present on the moon's surface, and tholins probably make up its dunes. The term "tholins" was coined by Carl Sagan in 1979 to describe the complex organic molecules at the heart of prebiotic chemistry.
Titan has long been viewed as a place that might be somewhat like Earth just before biology got going.
Cassini has mapped about 20 percent of Titan's surface with radar. Several hundred lakes and seas have been observed, with each of several dozen estimated to contain more hydrocarbon liquid than Earth's oil and gas reserves, according to a NASA statement. The dark dunes that run along the equator contain a volume of organics several hundred times larger than Earth's coal reserves.
Proven reserves of natural gas on Earth total 130 billion tons, enough to provide 300 times the amount of energy the entire United States uses annually for residential heating, cooling and lighting, according to the release. Dozens of Titan's lakes individually have the equivalent of at least this much energy in the form of methane and ethane.
"This global estimate is based mostly on views of the lakes in the northern polar regions," Lorenz said. "We have assumed the south might be similar, but we really don't yet know how much liquid is there."
Cassini's radar has observed the south polar region only once, and only two small lakes were visible.
The findings are detailed in the Jan. 29 issue of the journal Geophysical Research Letters.
Scientists estimated Titan's lake depth by making some general assumptions based on lakes on Earth. They took the average area and depth of lakes on Earth, taking into account the nearby surroundings, like mountains. On Earth, the lake depth is often 10 times less than the height of nearby terrain.
"We also know that some lakes are more than 10 meters or so deep because they appear literally pitch-black to the radar. If they were shallow we'd see the bottom, and we don't," Lorenz said.
The question of how much liquid is on the surface is an important one because methane is a strong greenhouse gas on Titan as well as on Earth, but there is much more of it on Titan. If all the observed liquid on Titan is methane, it would only last a few million years, because as methane escapes into Titan's atmosphere, it breaks down and escapes into space.
If the methane were to run out, Titan could become much colder. Scientists believe that methane might be supplied to the atmosphere by venting from the interior in cryovolcanic eruptions. If so, the amount of methane, and the temperature on Titan, may have fluctuated dramatically in Titan's past.
"We are carbon-based life, and understanding how far along the chain of complexity towards life that chemistry can go in an environment like Titan will be important in understanding the origins of life throughout the universe," Lorenz said.
Titan Has More Oil Than Earth
Indian Rocket Launches Four Satellites into Orbit
An Indian rocket successfully orbited a cache of four satellites Wednesday in the first space launch of the year.
Liftoff of the Polar Satellite Launch Vehicle (PSLV) was at 0353 GMT (10:53 p.m. EST Tuesday) from the Satish Dhawan Space Center on India's east coast [image]. The four-stage rocket and its payloads arrived in orbit about 16 minutes after launch, and deployment of the satellites was completed about four minutes later.
The booster was shooting for a Sun-synchronous orbit about 395 miles (635 kilometers) high, according to the Indian Space Research Organization (ISRO).
The 145-foot (44-meter) tall rocket was the first PSLV to use a dual payload adapter to launch two primary payloads on the same mission. The Cartosat 2 Earth-observation satellite rode atop the apparatus, while a recoverable capsule was housed below [image].
Cartosat 2 joins six other spacecraft currently operating in India's remote sensing satellite fleet, and is the 12th member of the program throughout its history. The 1,500-pound (680-kilogram) craft is a direct follow-on to the larger Cartosat 1 satellite, which was launched in 2005.
Data obtained by Cartosat 2 during its 5-year mission will aid officials in mapping and land management across India. The satellite carries a black-and-white camera with a resolution of better than one meter, according to ISRO officials.
The high resolution camera marks an improvement over Cartosat 1, which could only resolve objects as small as about eight feet (2.5 meters) in black-and-white images. Cartosat 2's camera will take pictures in swaths approximately six miles (9.6 kilometers) wide, while Cartosat 1's camera produces imagery covering much larger areas almost 20 miles wide.
Cartosat 2 can also be pointed up to 45 degrees along and across its ground track as it flies above Earth, allowing it to gather different views of imagery targets.
Also released from the rocket's upper stage was the Space Capsule Recovery Experiment, a 1,200-pound (544-kilogram) cone-like craft that is India's first recoverable satellite [image].
The capsule, also known as SRE, will spend between 13 and 30 days in orbit conducting materials science and biotechnology experiments within a small laboratory inside the spacecraft.
After the experiments are complete, the craft will fire on-board thrusters to slow its velocity and drop into the atmosphere to a parachuted landing in the Bay of Bengal about 100 miles (160 kilometers) offshore from the Indian east coast.
The capsule includes an inflatable flotation system to keep the craft afloat until recovery forces arrive. Teams from ISRO and the Indian Coast Guard will take part in recovery operations, said an ISRO spokesperson.
Indian space officials hope a successful mission for the capsule will lead to the development of a recoverable platform for scientific experiments in microgravity.
Two secondary payloads were also launched Wednesday for international organizations [image].
LAPAN Tubsat is a microsatellite jointly managed by the Indonesian space agency and the Technical University of Berlin. The 123-pound spacecraft features a pair of medium and low resolution video cameras to be used for surveillance and remote sensing.
A small 13-pound (5.8-kilogram) craft called Pehuensat 1 was built by students in Argentina. The satellite also includes an amateur radio payload to broadcast telemetry data and voice messages in English, Spanish and Hindi.
The next launch of the PSLV will loft Italy's AGILE astrophysics observatory later this year. India also plans a launch of the larger Geosynchronous Satellite Launch Vehicle (GSLV) in July with INSAT 4CR, a communications satellite to replace the spacecraft lost in the GSLV's failure on its most recent mission in July 2006, according to an ISRO spokesperson.
First Asteroid Trio Discovered
An asteroid known to astronomers for more than a century has now been found to harbor two small satellites.
It is the first asteroid trio ever discovered.
And there may be more than three.
The main asteroid, named 87 Sylvia, is one of the largest known to orbit the Sun in the main asteroid belt, between Mars and Jupiter. It is potato-shaped, about 175 miles (280 kilometers) in diameter and 235 miles (380 kilometers) long. It was discovered in 1866.
The first moon was found four years ago and the second one was announced today.
Asteroid moons common
There are about 60 asteroids known to each have one companion. The first pair was noted in 1993, when the Galileo spacecraft spotted the moonlet Dactyl orbiting asteroid Ida. Some pairs involve a smaller satellite, while in others the two objects are roughly equal in size.
Asteroid 87 Sylvia was named for Rhea Sylvia, the mythical mother of the founders of Rome. Now its moons will be called Romulus and Remus, for the ancient city's founders.
Romulus is some 11.3 miles (18 kilometers) across and orbits the main asteroid every 87.6 hours. Remus, the newfound object, is about 4.4 miles (7 kilometers) wide and orbits Sylvia every 33 hours.
Sylvia completes one rotation about its axis -- a day -- every 5 hours and 11 minutes.
The three-rock setup was likely created in a collision, astronomers said.
"People have been looking for multiple asteroid systems for a long time, because binary asteroid systems in the main belt seem to be common and formation scenarios, such as a collision between two asteroids followed by disruption and re-accretion, suggest that fragments should be orbiting bigger asteroids," said Franck Marchis, a researcher at the University of California, Berkeley who led the discovery.
The details are reported in the Aug. 11 issue of the journal Nature.
More to find?
There may be smaller moons around Sylvia that still evade detection, Marchis told SPACE.com. Satellites up to 3 miles (5 kilometers) wide could lurk between the two known moons, he said, and an even larger object could exist inside the orbit of Remus and escape detection.
Observations of Sylvia itself support the idea of a collision. The asteroid's low density and known size allowed astronomers to calculate that it must be a rubble pile, rather than a solid rock.
"It could be up to 60 percent empty space," said French researcher Daniel Hestroffer, a co-author of the study from the Observatoire de Paris.
The small satellites are thought to be collision debris that went into orbit rather than getting re-stuck to Sylvia.
Based on what they've seen so far, astronomers estimate that about 6 percent of asteroids have companions, Marchis said, adding that it is too early to guess how many systems might contain multiple rocks.
