Saturn’s largest moon (the solar system’s second largest moon), Titan, was discovered in 1655 by Dutch astronomer Christiaan Huygens. In 1944, Gerard Kuiper demonstrated that Titan’s dense atmosphere has the spectral signature of methane.  Up until the arival of the Voyager 1 in 1980 and Cassini-Huygens in 2004, Titan was somewhat of a mystery with its surface features hidden beneath thick layers of clouds and haze.

Although the surface was still hidden, Voyager was able to learn much about the moon’s planet-like atmosphere. Titan’s huge atmosphere creates a surface pressure of 1.5 bars, a temperature of 94K, and a density of 5.3kg/m3.  This surface temperature is close to the triple point of methane, which could mean that Titan has a methane cycle similar to Earth’s hydrological cycle.           

In 2005, ESA’s Huygens Probe was released from Cassini and entered Titan’s atmosphere. It discovered that Titan and Earth’s atmosphere share a similar altitude/temperature relationship.  On Earth, the temperature decreases with altitude in the troposphere, increases in the stratosphere due to the absorption of UV rays in the ozone, decreases in the mesosphere due to decreasing atmospheric density, and finally increases in the thermosphere due to the release of thermal energy caused by the break up of molecules by solar radiation.  On Titan, the temperature decreases with altitude in the troposphere, and increases in the stratosphere. 

With several Cassini flybys, Titan’s mysterious surface is finally being revealed.  Titan’s surface is incredibly Earth-like with rain-cut river beds, hydrocarbon lakes, and giant equatorial sand dunes.  Much is still unknown about the surface, such as the depth of the lakes, and how the sand dunes are formed.  Cassini Radar observations also confirmed that the entire crust of Titan is floating on top of a massive water ocean.              

With a two year extention to the Cassini mission, including 26 more Titan fly-bys, there is definitely more discoveries to come.  Titan is well worth exploring with complex orbiters and landers, not only to explore Titan’s exotic surface features but also to look for signs of extremophiles.  Any such mission is far off, so in the meantime we can enjoy the only sounds ever recorded on a body other than Earth which were recorded by the Huygens Probe as it descended through Titan’s atmosphere: Sounds of Titan�

The most historically observed planet in the solar system, Mars, has been the subject of astronomy since at least 400 B.C. when the Babylonians began making sophisticated predictions of the heavens. Since 1960 there have been 38 attempted missions to Mars, with only 19 successes. This 50% success rate has become known has the Mars Curse.

Perhaps the Mars Curse has been lifted because recent missions have been more successful including 6 of 7 Martian Landers. Included in this figure is Spirit and Opportunity which were launched in June 2003 and designed to last 90 Sols. The Rovers have far surpassed this expectation, with Spirit on Sol 1647, and Opportunity on Sol 1626. The rovers have made several important discoveries, including a patch of nearly pure Silica, which could be a promising place to look for signs of past microbial life. On Earth similar patches of Silica are formed from hot-springs and fumaroles which are both full of microbial life. Also currently on the Martian surface is the Phoenix Lander which has made it share of important discoveries, including: water, clay and several different salts. Water has previously been detected on the Martian surface but this is the first time it has been detected using a direct chemical analysis of the soil.

As knowledge is built, more questions arise, and future missions are being designed to answer such questions. Future mission include the international Mars Science Laboratory which is slated to launch this fall. This Rover will be equipped to determine if organic compounds are present in the soil, and to determine what geological processes may have formed samples of rock. Other future missions may include UAV scout missions, Mars Sample Return, an Astrobiology Field Laboratory, and eventually it will be necessary to send manned missions to Mars.

Imagine a 100,000 km elevator ride with the gentle beats of muzak slowly infiltrating your mind, while simultaneously your nostrils are attacked by the pungent scent of cheap perfume and the body odor of your fellow passengers. Some people might consider this to be torture, but chances are the assaults on the other four senses will be blocked out by the visual delight of the Earth slowly shrinking into a magnificent blue sphere; a view which is currently only experienced by astronauts and the very wealthy.

The idea of an elevator into space is not new. Konstantin Tsiolkovsky was the first to publish the idea in his 1895 paper: “Day-Dreams of Heaven and Earth”. It has also appeared in several Science fiction novels by authors such as Arthur C. Clarke. In a relatively short period of time, this idea has gone from an impossible dream to something that the Lift Port Group believes could happen within 23 years.

To reduce climate issues the elevator will be located somewhere along the equator, where it will climb a 100,000 km ribbon to a space station which will act as a counterweight. This ribbon is the main technological hurdle which needs to be surpassed in order achieve this dream. Carbon nanotubes appear to be the answer and experts say that the technology to build strong enough fibers may be reached in the next couple years.

An elevator to space would have many benefits. An estimated cost of delivering cargo to orbit is only $100/lb compared to current costs of up to $60,000/lb. The savings in cost would improve exploration as more money could be spent on instruments. An elevator to space would ultimately open the doors to space tourism, mining and any number of other entrepreneurial adventures.

Besides technological requirements, will financial, and legal issues prevent the timely construction of one of mankind’s greatest dreams? Or will my generation be riding an elevator to our low-gravity retirement homes?

There is a lot of excitement lately about the wet history of Mars, but what about Venus? Did Venus once have a climate which could support liquid water, if so where is the evidence? There are mountains, volcanoes, rift valleys, impact craters, and two small areas of slightly higher elevation which resemble continents. Any physical evidence of past water on Venus would have been wiped out by geological processes which keep the majority of the Venusian surface relatively young.

The atmosphere on Venus is composed of 96% carbon dioxide, 3% nitrogen, and the remainder (less than 1%) is made up of water vapor, sulfur dioxide, argon, and carbon monoxide. The small amounts of water vapor in the atmosphere plus the high levels of CO2 and thick clouds of sulfuric acid may well have been generated by volcanic activity.

It’s difficult to hypothesize water in substantial quantities when there is less than 1% detected in the Venusian atmosphere. Recently, Venus Express observed H+, O+, and He+ ions escaping the Venusian atmosphere. This finding could suggest that the water vapor has been stripped apart by ionizing forces such as solar radiation or electro magnetic activity over billions of years. Hydroxyl was also recently discovered (for the first time on another planet) by Venus Express. Hydroxyl is closely linked to ozone, which could potentially protect a planet from solar radiation and slow the breakup of water vapor.

So what did happen to Venus? Was it at one time more Earth-like with oceans, rivers, and lakes whose evidence was all erased by volcanic activity, or by some external catastrophic event which also put the planet into a retrograde rotation? Was all of this alleged water evaporated into space and then subsequently broken into constituent ions which then escaped into space leaving massive quantities of CO2? Or rather is the premise that there was once a large amount of water inherently wrong? Perhaps there never was water on the surface of Venus and perhaps the dense atmosphere was formed primarily by volcanic activity. One thing is certain; to conclude that Venus was previously water bearing will require further exploration into the planet’s past.