For generations, people have dreamed of traveling to Mars to explore Earth's closest planetary neighbor. NASA and other space agencies have announced plans to send people to the Red Planet. But such a manned mission is years away.
In the United States, some volunteers are learning how people will react to months of separation from other humans on a Mars base.
What would it be like to live on the planet Mars? Volunteers are spending eight months in an area that looks much like the surface of Mars. But actually, they are living in Hawaii.
Six people are isolated high on top of Mauna Loa, a volcanic mountain on the Big Island of Hawaii. They are living on a simulated, or make-believe, Mars Base. The American Space Agency, NASA, has provided financial support for the work. The project is called HI-SEAS, or Hawaii Space Exploration Analog and Simulation.
Kim Binsted of the University of Hawaii is supervising the project.
She walks across red lava rock from the volcano, 2,500 meters above sea level. Because it is so high, the land is not warm or rich with plants, like the rest of Hawaii. Ms. Binsted says this stark environment is as close to Mars as you can find here on Earth.
"Visually, it is very similar to what you see on Mars. You will see that there is really no visible plant life, there is no visible animal life. And you have got this wonderful volcanic material. We are on a cinder cone here on Mauna Loa. Mauna Loa is geologically very similar to Olympus Mons on Mars."
Mauna Loa is almost as tall as that Martian mountain. When measured from its base, deep in the ocean, Mauna Loa is the second largest mountain in our solar system, after the one on Mars.
The six member HI-SEAS crew is mostly self-sufficient. They take care of themselves. Food and supplies are brought to them. But the individuals bringing those supplies cannot communicate with volunteers inside the habitat, or base.
Kim Binsted says this experiment looks at how the astronauts interact, or get along with each other.
"We study how well they work together, how we can keep them happy and supported, and not wanting to kill each other over these long durations."
The current crew has been living in the habitat since October, and will stay until June. Two earlier crews lived there before them. Crew members communicate with the outside world through e-mail and blogs. They also produce videos on the YouTube website, like this one from mission commander Martha Lenio:
"Hi Mission Support. This is Commander Martha from the HI-SEAS Crew Three...."
Crew members also are using a smartphone app, or program, that creates a 20-minute delay for communications. That would be the same as if you were communicating from Mars.
"I am really enjoying this opportunity to live in this dome and pretend that I'm on Mars and get to learn all sorts of new skills.”
This is not the only group of volunteers with sights set on Mars. A group called Mars One has appealed for would-be Mars astronauts from around the world. Mars One is a private, non-government project based in The Netherlands.
Others believe the American or European space agencies are the most likely to put people on Mars, maybe in the 2030s, or later.
Whoever gets there first, the trip will not be easy, says Kim Binsted.
"It is going to be challenging."
For now, on a mountaintop in Hawaii, volunteers are getting a taste of life on a future Mars base.