Imagine a space exploration vehicle that needs little fuel, and can continually accelerate as long as it is in contact with solar radiation. This is the idea behind solar sails, which were first dreamt up by the great German astronomer, Johannes Kepler. Since then they have been in the minds of many astronomers, engineers, and science fiction authors. To date there has not been a successful deployment of a solar sail.

A spacecraft would deploy a large membrane of reflective material, this “sail” would reflect protons delivered by solar radiation. This exchange of momentum by reflecting photons would cause a resulting thrust of the space craft. Even though such a sail would generate a continuous acceleration, this technology is thought to be impractical for long distance travel because of the enormous sail that would be needed, the relatively slow start acceleration, and the small amounts of radiation available at distances far from the sun. By aiming the sail against the Sun, a reverse thrust, or deceleration would be achieved, making solar sails a fuel saving technology useful in repositioning satellites in Earth’s orbit or slowing satellites as they approach other planets.

NASA and Ames Research Center recently built NanoSail-D. The Sail was made from a composite of Aluminum and space age plastic. When opened the sail was suppose to span 100 square feet, and the entire space craft weighed less than 10 pounds. The purpose of this mission was to see if sails could be used to direct a satellite back into the Earth’s Atmosphere where it can be burned up, thus leaving less clutter in Earth’s orbit due to unused satellites.

However, not all missions end in glory. On August 2, the NanoSail-D space craft was launched from the Kwajalein Atoll aboard the SpaceX Falcon 1 rocket. There was a system failure in stage 1 of the launch, and the craft never reached orbit. This resulted in the loss of NanoSail-D. NASA has a spare NanaSail-D and is currently working on plans for a future launch. A similar mission also failed in 2005, when the Planetary Society and Cosmos Studios launched Cosmos 1.

If the technology for making and deploying large sails becomes available the practicality for deep space missions would change. It took Voyager more than three decades to escape the solar system using conventional rockets, but a spacecraft using large and efficient sails would be able to catch up to the Voyager spacecrafts in less than ten years.

One-fifth of the entire world population watched the live broadcast of the first Moon-walk, so it is no surprise that we all remember or have heard those famous words spoken by Neil Armstrong in 1969. The Apollo program and lunar landings aided the advancement of many fields of engineering, and is considered by many to be the greatest achievement of mankind. Nearly forty years after the end of the Apollo missions, NASA finally plans on returning to the Moon.

Before NASA returns man to the Moon, they plan on doing extensive studies. The first mission to the Moon will be the Lunar Reconnaissance Orbiter (“LRO”), which is scheduled to launch by the end of this year or early next year. The LRO will be equipped with the most sophisticated technology ever sent to the Moon–including instruments to make detailed 3-D maps of the entire lunar surface, locate subsurface water-ice, and record radiation levels to help develop technologies which will ensure the safety of future crews.

Launching with the LRO is the Lunar Crater Observation and Sensing Satellite (“LCROSS”). In 1999, NASA’s Lunar Prospector detected the spectral signature of hydrogen in the Moon’s permanently shadowed polar craters. LCROSS will impact the Moon in one of these craters. The impact will send a plume of material into space, which will be observed by a near-infrared camera, which will analyze the plume for traces of water. Presence of water on the Moon would be an important natural resource for a future lunar colony.

NASA plans on having mankind back on the Moon by 2020. Utilizing the new equipment which is currently being developed as part of the Constellation program, four astronauts will land on the Moon aboard the new Altair Lunar Lander, which will provide life support for the initial week long mission to the Moon. The Lunar Lander will be launched into low-Earth orbit aboard an Ares V Rocket, where it will rendezvous with the Orion crew vehicle.

Returning man to the Moon is the important first step in NASA’s new Moon Mars and beyond initiative proposed by George Bush. The Lunar surface will be explored and studied in an attempt to learn how to build a successful space colony. Risks such as radiation and psychological trauma will have to be fully understood and overcome before any long-term manned missions to Mars, or elsewhere, can be pursued. Having a colony on the Moon will also help us study how the Earth and Moon were formed, and giant telescopes on the Moon will not have the atmospheric interference which is a problem on Earth. Along with the many scientific advances which will follow future lunar landings, returning to the Moon will renew the general population’s interest in space exploration.

Saturn’s sixth largest moon, Enceladus, was discovered in 1789 by British Astronomer William Herschel. With a low albedo and close proximity to Saturn, Enceladus is difficult to observe. Because of this difficulty little was known about this moon until the Voyager flybys in the 1980’s. Voyager 1 discovered that Enceladus is located in the densest part of Saturn’s E Ring, and Voyager 2 discovered that Enceladus has diverse and relatively complicated surface features.

The Voyager missions generated a number of questions about the small moon: “Is there a connection between Enceladus and Saturn’s E-ring?” “What is causing the tectonic activity which is deforming Enceladus’s surface?” The recent Cassini mission was able to answer these questions, along with generation new discoveries and new questions.

To answer the first question, Cassini discovered that Enceladus is the fourth known body in the solar system with active volcanism. The other three are Earth, Jupiter’s moon Io, and Neptune’s moon Triton. This volcanism causes icy jets, plumes of water vapor, and other materials to be shot into the atmosphere. It is this cryovolcanism which was determined to be the cause of Saturn’s E Ring. Just recently Cassini photographed the volcanic southern pole. These pictures revealed a geological feature scientists are calling “tiger stripes”. These tiger stripes are 300 meter deep fractures and are surrounded by chunks of ice, and are the source of Enceladus’s volcanism.

Cassini also discovered the cause of the tectonic activity. Enceladus, like many other moons is traped in orbital resonances, this causes tidal heating on the moons interior. Like thought to exist on Jupiter’s moon Europa, this could also cause Enceladus to have a subsurface liquid ocean. Because of the volcanic activity a subsurface ocean on Enceladus is though to be only tens of meters beneath the surface, where the oceans on Europa are thought to be 100 kilometers beneath the surface.

Does Enceladus have a subsurface ocean? If it does, is this another place to look for signs of life? With many more Enceladus flybys to come, we may yet find out if there is a subsurface ocean, but we will certainly have to wait for the right mission if we want to determine if life exists.

Can life exist in the harsh conditions of our solar system? Could life evolve and survive under the extreme heat and pressure of Venus, under the icy crust of Mars, or in the oceans of Europa? To find out just how resilient life is, scientists have been looking for answers in some of the most hostile environments on Earth. And in recent years, life has been discovered in the most extreme conditions, previously thought to be uninhabitable. These microorganisms are sometimes called extremophiles.

There are many different classes of extremophiles, which are named according to the environmental conditions in which they thrive. For example, a thermophile is an organism which lives in conditions between 60˚ and 80˚ Celsius. Recently, a thermophile was discovered nearly two miles beneath the Earth’s surface in the Mponeng Gold mine of South Africa. This particular discovery is interesting because these thermophiles are completely devoid of sunlight, surviving on the byproducts of radioactive decay.

Where might we look for extremophiles outside of Earth? Mars is a good place to start. With the recent confirmation of ice in the crust, it is possible that water has trickled deep into the Martian interior, where thermophiles can survive off of radioactive materials like previously discussed. On Earth, we have discovered halophiles, which require high amounts of salt to survive; recently, the Phoenix Lander discovered several different types of salts in the Martian soil, which could be another location to search for life. Other types of extremophiles discovered on Earth may also apply to Mars, such as: xerophiles, hypoliths, and radioresistant extremophiles.

Europa is another great place to look for extremophiles. It is theorized that there is a global ocean beneath Europa’s thick layer of surface ice. Sattelite images of Europa’s surface show a complex system of tectonic activity–places where the ice has broken and liquid water has upwelled to the surface and refrozen. This tectonic activity is likely the result of tidal flexing, due to the gravitational pull of Jupiter. This tidal flexing may also produce hydrothermal vents. Earth’s hydrothermal vents are host to a large amount of biological activity, meaning Europa is a very promising place to look for extremophiles.

There are future plans in the works to search for extremophiles in the Martian crust. Astrobiological missions to Europa, Titan, or elsewhere are probably deep into the future. Given the amount of life discovered in the harshest places on Earth, I will be surprised if we find that our solar system is devoid of life.