Radio Signals from Jupiter Aids Search for Life and Liquid Water

This artist's impression shows Jupiter and its moon Europa using captured Jupiter and Europa images in visible light. 

The Hubble ultraviolet images showing the faint emission from the water vapour plumes have been superimposed, respecting the size but not the brightness of the plumes. 

Image courtesy NASA, ESA, and M. Kornmesser, University of California, Santa Cruz.

Powerful radio signals that Jupiter generates could be used to help researchers scan its giant moons for oceans that could be home to extraterrestrial life, according to a recent study submitted to the journal Icarus (In PDF format).

Jupiter, the largest planet in the Solar System, possesses 67 known moons, including three giant icy moons that might possess liquid oceans underneath their frozen surfaces.

Astrobiologists want to investigate Europa, Ganymede and Callisto for extraterrestrial life, as there is life virtually wherever there is liquid water on Earth.

Of Jupiter's three largest icy moons, Europa, which is roughly the size of Earth's moon, is favored as having the greatest potential to sustain life.

Magnetic readings captured by NASA's Galileo spacecraft provided compelling hints that it has an ocean, and radio scans by the probe suggest a water-rich layer beneath the surface between 50 to 105 miles (80 to 170 kilometers) thick.

Recent findings even suggest its ocean could be loaded with enough oxygen to support millions of tons worth of marine life.

Scientists would like to analyze Europa's ocean directly, perhaps with missions to bore into Europa's icy shell using heat to melt through the ice, whirling blades to clear away rocks, and robot subs to explore the ocean.

However, it remains uncertain how thick this shell is, complicating any plans to penetrate it.

Models of its thickness, based on the amount of heat the shell receives from the Sun and Europa itself, predict it to be roughly 18 miles (30 kilometers) thick.

In contrast, analyses of the Galileo spacecraft's data suggest the shell is no more than 9 miles (15 kilometers) thick, and maybe as little as 2.5 miles (4 kilometers) thick.

True colour and feature-highlighted photos of Europa. 

The bright feature towards the lower right of the disk is the 45 km diameter crater Pwyll. 

Credit: NASA.

Ice-penetrating radar is currently the most promising technique to directly confirm the existence of any ocean hidden within Jupiter's icy moons.

Radar works by transmitting radio signals, detecting any radio signals that reflect back, and analyzing these signals to deduce details about what they reflected off of, much like how a person might use a flashlight to illuminate objects hidden in the dark.

Ice and ground-penetrating radar systems look for signals that indicate buried objects and boundaries between layers.

In Europa's case, this means looking for the boundaries between the icy crust and any hidden ocean, and between such an ocean and Europa's rocky core.

To detect these oceans with ice-penetrating radar, low-frequency signals of less than 30 megahertz are needed to overcome radio wave absorption by the ice, as well as the unpredictable scattering of radio waves by the crinkled surfaces of these moons.

The low-frequency radio waves that researchers would like to use are decametric, meaning they have wavelengths tens of meters long.



Jupiter's Decametric waves
One problem with attempting ice-penetrating decametric radar on Jupiter's moons has to do with the powerful decametric radio bursts coming from Jupiter itself.

Altogether, these signals are more than 3,000 times stronger than any leaking into the Solar System from the rest of the galaxy.

Jupiter's decametric waves come from clouds of electrically charged particles trapped in Jupiter's magnetic field.

To overcome Jupiter's loud radio signals, a mission probing Jupiter's moons would need a relatively strong transmitter, a massive device that might be difficult to power and fit aboard the limited confines of a spacecraft.

Read the full article about how the research team plan to overcome the difficulties of Jupiter's natural emanation and generation of decametric waves.

More Information: A Passive Probe for Subsurface Oceans and Liquid Water in Jupiter's Icy Moons - Authors: Andrew Romero-Wolf, Steve Vance, Frank Maiwald, Essam Heggy, Paul Ries, Kurt Liewer

NASA JPL mission to send quadcopter drone to search for life on Titan

Although Titan's landscape presents one of the more intriguing potential habitats for life in our solar system, there are plenty of reasons to be skeptical.

The moon's seas are comprised of liquid ethane or methane, while the atmosphere is much colder than Earth's and made up of hydrogen cyanide.

While NASA Cassini probe whizzes by Saturn's moon Titan on Thursday to analyze its atmosphere, the American space agency is also considering a plan to send a quadcopter drone capable of searching for life.

The ambitious idea was outlined by Larry Matthies, a research scientist and supervisor at NASA's Jet Propulsion Lab in California, and involves a drone that would be capable of flying out of a lander or balloon.

The drone would explore the moon's landscape and seas, collect samples, and return to the "mothership" to recharge its batteries and submit whatever it collects for analysis.

If successful, the new plan could drastically change the way humans explore space.

Current rovers on Mars are akin to moving laboratories, but their grounded nature means they can be rather limited when it comes to exploring terrain.

The 22-pound drone conceived by Matthies would eliminate that barrier with flight capability, allegedly at much lower costs than other options.

As quoted by Gizmodo, he described the plan as follows: "We propose a mission study of a small (10 kg) rotorcraft that can deploy from a balloon or lander to acquire close-up, high resolution imagery and mapping data of the surface, land at multiple locations to acquire microscopic imagery and samples of solid and liquid material, return the samples to the mothership for analysis, and recharge from an RTG on the mothership to enable multiple sorties."

Matthies also noted that while this kind of plan would not have been feasible even just a few years ago, advancements in drone technology and other robotics have "revolutionized" older mission concepts, meaning sending a drone capable of exploring Titan is now a real possibility.

Options are also available regarding exactly what form the mission takes. NASA could either have the drone operate out of an airborne balloon-like mothership or out of a land-based vehicle.

"For a lander mission, it enables detailed studies of a large area around the lander, providing context for the micro-images and samples; with precision landing near a lake, it potentially enables sampling solid and liquid material from one lander," he said.

"For a balloon mission, it enables surface investigation and sampling with global reach without requiring a separate lander or that the balloon be brought to the surface, which has potential for major cost savings and risk reduction."

According to the Huffington Post, NASA has awarded Matthies' team $100,000 to continue working on designs for the unmanned concept, which includes a mothership outfitted with a nuclear reactor.

Still, any lift-off dates are still a long ways into the future. Although technology has gotten to the point where such a plan can be planned, it still needs to be developed further. The agency is hoping a launch sometime in the 2040s would be possible.


Meanwhile, NASA's Cassini probe is scheduled to fly by Titan on Thursday and bounce radio signals off its surface for the second time in two months.

The mission is intended to reveal more information about the moon's atmosphere and lakes, which could come in handy for future missions and determining whether life could exist in its hydrocarbon seas.

"We held our breath as Cassini turned to beam its radio signals at the lakes," Cassini radio science team member Essam Marouf said, referring to the May mission.

"We knew we were getting good quality data when we saw clear echoes from Titan's surface. It was thrilling."

Although Titan's landscape presents one of the more intriguing potential habitats for life in our solar system, there are plenty of reasons to be skeptical.

The moon's seas are comprised of liquid ethane or methane, while the atmosphere is much colder than Earth's and made up of hydrogen cyanide.

Cassini has, however, revealed the possibility that liquid water may exist under the moon's icy shell, and there's speculation other forms of life could be present.