Sending a spacecraft to orbit Venus to scan for signs of life on Earth may sound a bit strange. Despite how odd a mission to scan the Earth for life from afar sounds, a mission doing exactly that has been underway with the European Space Agency (ESA) since November of 2005.

The ESA launched the Venus Express satellite with the initial intent to study Venus. After the initial 243-day mission ended, the satellite was tasked with a different mission -- to look at the earth from orbit around a distant planet and attempt to find new methods of determining life on the planet.

Space.com reports that from Venus orbit, the Earth is smaller than a single pixel in the spacecrafts cameras and no surface details are present. The idea behind the mission is to help scientists discover better methods for determining if life is flourishing on a planet. Once the methods used to determine the presence of life are optimized, scientists will use them to help find Earth-like planets in other solar systems that support alien life.

David Grinspoon, a scientist working on the Venus Express project, told Space.com, "We have initiated the first sustained program of Earth observation from a distant platform. We want to know what can we discern about the Earth's habitability based on such observations. Whatever we learn about Earth, we can then apply to the study of other worlds."

Venus Express is currently in orbit at about two million miles from Earth and is imaging Earth via its Visible and Infrared Thermal Imaging Spectrometer. According to Space.com, the project has so far determined that detecting signs of life from a long distance is not easy.

According to scientist Giuseppe Piccioni, Venus Express is able to observe the Earth two or three times per month and has taken about 40 images of the Earth in the last two years.

Piccioni said, "We see water and molecular oxygen in Earth's atmosphere, but Venus also shows these signatures. So looking at these molecules is not enough." The scientists are hoping to use a phenomenon known as the red edge as a more accurate determination of life on distant planets. Red edge is the infrared signal caused by photosynthetic life. Green plants are bright in near infrared.

Analysis of the data gleaned by Venus Express about the Earth is only in the first stages of being analyzed. Scientists hope to determine from the data if the Earth's red edge is visible from a distance.

Scientists are finding distant planets at an impressive rate; over 300 extrasolar planets have been discovered since 1995, and we get closer to finding Earth-like planets every day. Data from the Venus Express could help the scientists determine if life on Earth-like planets actually exists.

With new detection techniques Grinspoon says, "We are now on the verge of finding Earth-like planets." However, it will likely be years before any practical application of discoveries made from the Venus Express data can be applied. If scientists are having a difficult time finding signs of life from Venus orbit, a short jaunt of only 2 million miles by space travelling standards, applying any techniques discovered to extrasolar planetary observation will be incredibly difficult.