Titan’s long-sought sea revealed by radar

The first sea discovered on any surface other than Earth’s may have been found on Saturn’s moon Titan.

New radar images from the Cassini spacecraft, which made its eighth close approach to the moon on 7 September, have revealed what appears to be a very distinct shoreline, fed by meandering channels carved deeply in the surrounding terrain.

The dark, flat region next to the bright shoreline “is the area where liquid or a wet surface has most likely been present, now or in the recent past”, says Steve Wall, Cassini radar team deputy leader from NASA-JPL.

And several long sinuous channels can be seen cutting through the bright region and ending at the shoreline, suggesting the existence of an Earth-like cycle of evaporation, rainfall and river systems to carry the liquid back to the sea. But instead of water, the liquid in this case is believed to be methane, kept liquid at Titan’s -179°C surface temperature.

Thick atmosphere

Seas of liquid methane, perhaps mixed with other hydrocarbons, had long been expected on Titan, the second-largest moon in the solar system. It is also the only moon with a thick atmosphere – thicker than Earth’s.

Seas seemed necessary to explain the amount of methane seen in Titan’s atmosphere. The fact that no clear evidence for such seas had been found was one of the big mysteries of the Cassini mission.

“We’ve been looking for evidence of oceans or seas on Titan for some time,” Wall says. The quest was one of the main goals of the four-year Cassini mission. The discovery of the new features suggests Titan may indeed have periodic episodes of methane rainfall.

Ellen Stofan, another radar team scientist, says the network of bright channels indicate “that fluids, probably liquid hydrocarbons, have flowed across this region”.

Some of the channels extend more than 100 kilometres, says Larry Soderblom of the US Geological Survey in Flagstaff, Arizona. The channels appear to be of two different types, some long and deep with few tributaries, others forming denser networks. “Some of them may have been fed by springs, while others are more complicated networks that were likely filled by rainfall,” Soderblom said.

Earth analogue

Titan’s abundance of hydrocarbons, thick atmosphere, and now evidence for the presence of large volumes of liquid, means it is considered a close analogue of the early Earth.

It may even host some of the early complex chemistry that on Earth led to the first living organisms, but whose traces have long been obliterated here. Cassini project scientist Dennis Matson has called Titan a “time machine” for studying how the early Earth “evolved into a life-bearing planet”.

But exploring the new-found sea further will be tricky. Two coincidental glitches caused half of the data from the radar flyby to be lost. One glitch affected the spacecraft’s data recording system, the other the receiving antenna in Goldstone, California, US.

Even worse, the region will not fall within the radar’s view on any of Cassini’s 37 remaining Titan approaches. However, all the data from Cassini’s cameras and spectroscopes was saved and may reveal more details of the features.

Cassini’s next close flyby of Titan will take place on 26 October and will focus on the region where the Huygens landing probe hurtled down to Titan’s surface in December 2004.

Instant messenger could control hacked computers

A US computer programmer has created a software robot that uses instant messenger – a program that allows people to exchange messages over the internet in real time – to control a computer remotely.

So-called “chatterbotsâ€? have been created in the past, allowing programmers to use IM to automatically upload files from their computer. But “Nmapbot”, created by Virginia-based Abe Usher, is the first that allows someone to scan a remote network for machines that could be hacked into. Nmapbot also allows a hacker to use compromised machines to launch a denial of service attack.

Usher has released the bot to highlight potential security risks posed by IM. But he says that Nmapbot is also a useful tool for computer security personnel, allowing them to patrol networks from out of the office using a PDA or cellphone equipped with IM.

“This is one of those dual-use tools that can be used for good and for evil,� says Ron Gula, chief technology officer at intrusion detection firm Tenable Network Security in Columbia, Maryland.

Flaw in Google Desktop Search

A flaw in Google’s desktop search program was revealed on Monday by a team of computer researchers. They showed it could be used to capture valuable personal information from a remote user’s computer.

Google Desktop Search (GDS) lets users quickly hunt for files and documents stored on their computer using a web browser. After installation, the program runs in the background – indexing documents, emails, instant messaging conversations and web browser history – so that searches bring up results almost instantly.

Dan Wallach at Rice University in Texas, US, and two students, Seth Nielson and Seth Fogarty, discovered the flaw shortly after the application was released on 14 October 2004. They developed demonstration code to exploit the flaw and steal search results via a web page.

A query entered into Google on a computer running the desktop search program automatically adds results from the computer itself to results from the web. The researchers suspected that the way GDS integrates these results could prove a potential weak spot.

 

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Yahoo fixes Web mail security flaw!

Yahoo has fixed a security flaw in its free Web-based e-mail service that opened the door to phishing scams, account hijacks and other attacks.

The flaw, known as a cross-site scripting vulnerability, existed because Yahoo’s Web site did not detect certain script tags in combination with certain special characters, according to SEC Consult, which issued an advisory on the flaw Friday.

Cross-site scripting flaws are found regularly, including recently in Google’s Web site and earlier this year in Microsoft’s Xbox 360 site.

Flaws have also been found on Yahoo’s site. An attacker could exploit this type of flaw to hijack user accounts, launch information-stealing phishing scams or even download malicious code onto users’ computers, experts have said.

A Yahoo representative said it fixed the most recent flaws in the “last few weeks” and that its users are protected.

“Yahoo recently learned of an issue in Yahoo Mail and worked immediately to begin rollout of a server-side fix which does not require users to take any action,” said Karen Mahon, a Yahoo spokeswoman. “We are unaware of any users who were impacted by this issue.”

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