Mars has a climate highly inhospitable to human life, but the Defense Advanced Research Projects Agency (DARPA) has new plans to terraform the planet with human-engineered organisms. If successful, this idea could sculpt Mars into a world capable of supporting human life.

Science fiction writers, along with real-world scientists, have pondered for years how to create a climate on the Red Planet into one more like those seen on Earth.

In many ways, Mars is the most Earth-like of all planets in the Solar System. The gravity of the Red Planet is 62 percent that on our home world. Although this is significantly less, a space traveler weighing 200 pounds on the Earth would still weigh 124 pounds on Mars. Mars is smaller than our home world, but because it does not have any oceans, the two worlds each have about the same amount of land area. The two worlds also have 24-hour days, permanent ice caps and a similar tilt to their axis in relation to the sun. All of these similarities, along with the proximity of Mars to the Earth, make the Red Planet the logical next planet to be colonized by human beings.

Mars, however, poses significant challenges to organizations, including NASA, looking at sending colonists to the world. Among these are the frigid temperatures in the world, averaging 122 degrees below zero Fahrenheit. The entire planet is a desert, so without terraforming, all the water needed by astronauts and crops would need to be transported or created on the surface of the world. The atmosphere is mainly carbon dioxide, and Mars is also subject to vast, powerful sand storms that can last for weeks.

Currently, DARPA is exploring ways to use genetically engineered algae, bacteria and plants to radically transform the climate of that world.

"For the first time, we have the technological toolkit to transform not just hostile places here on Earth, but to go into space not just to visit, but to stay," said Alicia Jackson, deputy director of the Biological Technologies Office at DARPA. As she delivered the remarks to the audience at a biotech conference, the spokesperson pointed to an artist rendering of a transformed Mars.

Other ideas to alter the climate on Mars include melting the polar ice caps, which are composed largely of frozen carbon dioxide, known as dry ice. The idea here is to create an extreme greenhouse effect, thickening the atmosphere enough to hold in solar energy, warming the planet. Some researchers believe this process could result in water rain falling from the sky. Giant mirrors in space could reflect enough light to the surface to melt water ice found as permafrost beneath the surface of the Red Planet. Planetary seas could be formed in this way in the Hellas Basin and the northern lowlands.

Although the process is uncertain, the best chance for human beings to permanently colonize Mars will likely be terraforming.