Rethinking Gliese 581g

A huge stir zipped through the scientific community and beyond recently with the announcement by astronomers of the discovery of a world with only three or four times the mass of Earth that orbited in the habitable zone of the red dwarf star Gliese 581, only 20 light years away. The mass told us the planet was a rocky world like Earth, and the location of the orbit told us that liquid water could exist on its surface.

Well, maybe not.

Other astronomers are now questioning whether the world, dubbed Gliese 581g, even exists. The discovery of this exoplanet-- as well as of most of the hundreds of other such planets so far discovered-- was done by monitoring tiny movements by the parent star that could be caused by the gravity of planets tugging on it. Obviously, more massive planets close to the star are easier to detect than less massive ones. A few astronomers who have looked at the Gliese 581g discovery data say they see no obvious pattern in it. The Gliese 581 system already has four confirmed exoplanets, and the announcement of "g" was coupled with the announcement of another, even smaller world. Any pattern, therefore, would be extremely complex and subtle, possibly difficult to distinguish from the random "noise" always present in such endeavors.

So, does a slightly larger version of Earth orbit Gliese 581, or not? Answering that question is within our capability, and will be even more within it as technology develops. So, we will know what actually exists in the system of this particular red dwarf, but it could take a while.

More Moon Interplay

Scientists are increasingly finding that, perhaps contrary to common assumptions, bodies in space can and do interact with each other on a regular basis. For a few years now, the case has been made that some meteorites found on Earth originated on Mars. Recent studies expand on that theme. Using data from the extraordinarily successful Cassini mission to Saturn, scientists now think the geysers of Enceladus may seed the upper atmosphere of the giant moon Titan with organic molecules that originate in Enceladus' subsurface ocean, thus making life on Titan more likely.

Nor is that all Enceladus does. A new study suggests electrons from that moon, propelled by the geyser eruptions, reach five more Saturnian moons in a plasma, interacting with the surfaces of those moons.

With Saturn's system as a model, some are saying much the same interplay could take place among the moons of Jupiter. In that case, the extreme vulcanism of Io would drive the process.

All this indicates a level of complexity in planetary systems not imagined in any depth before the Space Age.

Dragon To Fly

SpaceX is ready for the first test flight of its cargo-carrying capsule, Dragon, atop the company's Falcon 9 rocket. The launch is planned for early November from Florida. The flight is scheduled to last perhaps four hours, during which all Dragon's systems will be tested, and the capsule is to splash down in the Pacific off southern California.

Dragon is supposed to take supplies to ISS after the space shuttle is retired, so demonstrating the company can in fact fly it in space is important to SpaceX, to NASA, and to President Obama's plan to use private spacecraft to serve low Earth orbit while NASA concentrates on deep space exploration. Dragon, indeed, is designed to eventually ferry humans to and from orbit.

The Falcon 9, so far, has only one successful launch to its credit, so a successful flight in November would allow SpaceX to build momentum and confidence. A failure, however, could increase the doubt some analysts have that private companies are ready for their expanded role in NASA's new marching orders.

Orbital Expeditions

Interorbital Systems, an American NewSpace firm which is probably better known in Europe than it is in the U. S., is moving ahead with a program to offer tourists, and others, orbital spaceflights. Launched from the waters of the South Pacific kingdom of Tonga, the IOS spacecraft will carry up to six passengers plus a pilot. IOS is planning a two-man orbital flight sometime in 2011-12, with commercial flights to begin in the 2012-13 period.

Orbital Expedition flights will last about a week and cost $5 million per ticket. However, the company is offering a bargain deal-- the first ten tickets sold will go for $250,000 apiece. Two of the ten have already been snapped up, and, according to IOS CEO Randa Milliron, the company will begin a marketing effort to tell the public about the program soon. In an interesting comparison, Virgin Galactic is offering suborbital flights that will feature a few minutes of weightlessness in a fairly small cabin for $200,000 whereas a few people, for $50,ooo more, would get to experience true spaceflight-- days of weightlessness in a module with a large enough volume to allow real exploration of the possibilities of microgravity, dozens of sunrises and sunsets, and extended opportunities to observe the Earth and other celestial bodies from space-- on an early Orbital Expeditions flight.

Whether IOS, or, indeed, VG, can actually turn their plans into profitable reality is still open to question, but IOS is moving across a broad front, pursuing both manned and unmanned projects. It is even looking at the Moon-- in the context of the Google Lunar X-Prize competition, but also in flying a lunar sample return mission, and in establishing a substantial, private, manned lunar base in just a few years. If IOS succeeds across the board, it will have secured a place as one of the most important corporations in human history.

VG Moving Closer

Virgin Galactic took another step towards providing commercial suborbital spaceflights today when its SpaceShipTwo was released from its giant WhiteKnightTwo mothership during a test flight for the first time. The spaceship glided on its own for about 15 minutes before making a perfect landing in Mojave, California.

VG plans to offer its tourist flights from Spaceport America in New Mexico, and in a related matter, the main runway of Spaceport America will be dedicated later this month.

VG already has at least 340 people ready to pay the $200,000 the company is charging per ticket, with SpaceShipTwo capable of carrying six passengers per flight. VG plans to begin commercial flights next year.

Simulating Chemistry On Titan

A new study looks at what could be going on in the upper atmosphere of Saturn's extraordinary moon, Titan, by roughly replicating in a laboratory the chemical and energy environment there. The results are amazing. Many complex organics formed, including all the base acids of Earth's DNA molecules. The raw materials for the chemistry seems to come, at least partly, from another of Saturn's moons, Enceladus. Scientists are seeing meaningful interactions among the moons of both Jupiter and Saturn, a phenomenon not necessarily anticipated before the missions of Galileo and Cassini, respectively.

Not only does the study's findings make the case for life on Titan stronger, they also throw another possibility into the debate on how and where life started on Earth. The prevailing view is that water was critical to that event, but water plays no role in the study, as water is frozen on Titan. So, if Titan's atmosphere-- except for the temperature, which might be a major factor-- is similar to early Earth's, and if the basics of life are created in Titan's upper atmosphere without water, then it's possible life on Earth did not, in fact, require water to get started. That, as they say, would be a game changer.

Water In Asteroids

A second asteroid, 65 Cybele, has been found to contain both water and organic molecules. A view is emerging in the scientific community that water may be common on asteroids. If true, it would significantly change how we see the Solar System. First, it would further blur the line between comets and asteroids. If both are small bodies containing volatiles-- water-- the only differences between the two may be location in the Solar System and orbital characteristics.

Second, the discovery that water may be common in asteroids strengthens the theory that water, and possibly life, came to Earth from outside.

Third, if substantial amounts of water are easily accessible throughout the Solar System, exploring and settling space would be much easier. Water could be used as water, or split into its hydrogen and oxygen components and used as rocket fuel, or the oxygen could be used for breathing while hydrogen is used in another way. Water and rock are also good protection against radiation. Eventually, too, asteroids laden with water ice could be moved to where the water was needed. Space could be open to humanity.