Image: public domain, available at http://en.wikipedia.org/wiki/Titan_(moon)
Huygens Probe replica, by David Monniaux, available at http://commons.wikimedia.org/wiki/File:Huygens_probe_dsc03686.jpg
The above image, taken from the surface of Titan, moon of Saturn, is the only image from a moon other than the moon (of Earth). It was taken by the Huygens probe, which landed on Titan in 2005.
While the portion of the surface of Titan shown in the surface image appears bare, Titan is in fact strongly evidenced as elsewhere having surface bodies of liquid hydrocarbons (as well as an atmosphere with which such liquids may chemically interact). These surface liquids represent the first stable bodies of liquid found beyond Earth. In addition, Titan is evidenced to have a subsurface liquid water/ammonia ocean.
It has been (very speculatively) theorized (including by astrobiologist Chris McKay) that methanogenic (methane-producing) microbes may live in the surface lakes of Titan, using, as a solvent, not water as all Earth-based life does, but liquid hydrocarbons, such as methane, in the lakes of Titan (for some more overview information on this, see the Fosdick’s Astrobiology Series article on this subject).
Image: public domain, http://photojournal.jpl.nasa.gov/catalog/PIA06230
The above image shows roughly what Titan would actually look
Methane polar clouds of Titan (left) compared with water/ice polar clouds on Earth (right), http://www.nasa.gov/sites/default/files/thumbnails/image/titan-earth-polar-clouds-lg.jpg
like.
Titan is the only moon known to have a substantial atmosphere – and, like Earth’s, it is rich in nitrogen.
The orange color of Titan is attributable to hydrocarbons in its atmospheric haze. Organic compounds in Titan’s atmosphere, as well as, it is thought, in its surface and subsurface liquids, give rise to intriguing speculations regarding hypothetically possible life there.
Image: public domain, http://photojournal.jpl.nasa.gov/catalog/PIA00502
In the above image, the dark orange lines crisscrossing Europa’s
Mosaic of images of the surface of Europa taken by the Galileo spacecraft, including the Conamara region, and showing surface features including lineae. Public domain image, http://photojournal.jpl.nasa.gov/catalog/PIA01092
surface are called lineae, and may result from fracturing of the surface crust of Europa from tidal flexing, a force related to the gravity exerted on Europa by Jupiter.
Europa is strongly evidenced as having subsurface oceans of liquid water, with tidal flexing believed to provide the heat that keeps its oceans from freezing.
Possible hydrothermal vents in the subsurface oceans of Europa (which could be caused by tidal flexing) could hypothetically provide a habitat for life, just as life clusters around hydrothermal vents in the oceans of Earth.
The on the above image, actress Jodie Foster’s character shows
From the 1997 movie, “Contact”
the flash of excitement and amazement at the recognition of what seems to be non-“naturally”, non-randomly occurring radio signals from a distant star system – not merely signals, but, in fact a communication – a repeating pattern, a structure, bespeaking an intelligent formulation, and thus an intelligent source.
One area of astrobiology includes
The Very Large Array (VLA) Radio Astronomy Observatory in New Mexico, USA. Source: http://en.wikipedia.org/wiki/Radio_astronomy#mediaviewer/File:USA.NM.VeryLargeArray.02.jpg
the search for intelligent life beyond earth (and generally beyond the solar system), often including the use of radio astronomy in attempting to receive, identify and interpret hypothetical radio frequency communications from such intelligent life (a large part of the activities collectively known as SETI – the Search for ExtraTerrestrial Intelligence).
The ultimate homerun of astrobiology, success in this effort would not only affirmatively answer the massive question of whetherlifeexists beyond Earth (and indeed beyond the Solar System), but also the exponentially more massive question of whether intelligent life exists beyond Earth and in another star system.
Radio communications (that is, radio frequency electromagnetic communications) would seem the most promising form of communication for potential interstellar communications.
Just as visible electomagnetic signals (i.e., light) can be received from sources very close by (look up and see light with the source being a ceiling light fixture a few feet away) or incredibly far away (look into the night sky and see light from a star a hundred light years away, or even a thousand), so can radio electromagnetic signals.
Like light, radio signals can be received from sources very close by (such as by a receiver in radio controlled car, the source being the radio controller held by a child across the room), or from not as close by (such as by a person’s car stereo receiver from an FM broadcasting tower), or, in fact, from incredibly far away, such as by a radio telescope, from a distant star or another galaxy.
Radio astronomy generally, and radio SETI, can use telescopes with large “dish”-like receivers, or arrays of many such telescopes essentially working together (called radio interferometry), to receive, in the strongest and clearest fashion practical, radio signals from distant star systems and celestial bodies.
Image: public domain, http://mars.nasa.gov/mer/gallery/press/spirit/20050420a.html
The above strikingly detailed image shows a region of Mars called
Artist’s concept of a Mars Rover, public domain image, http://photojournal.jpl.nasa.gov/catalog/PIA04413
Gusev Crater. It was taken by the Mars Spirit rover in 2005.
Mars, today, can be described as appearing similar to a harsh desert on Earth. It is indeed mostly void of liquid water – essential to all life as known on Earth.
Yet, abundant evidence, including present-day Martian landforms, strongly suggests that, during some times in its extremely ancient history, Mars flowed with water over large portions of its surface – a wet world truly different than the Mars of today.
Did life perhaps thrive in the waters of ancient Mars? Conditions may have been too salty or acidic, at least for life as known on Earth, but perhaps not.
Mars echos, but moons in the Solar System – Europa, Titan, Enceladus – ring out, now, with the real possibility of harboring life.
