Mars is the planet most like the Earth. It has an atmosphere and the presence of water, essential for life, has been confirmed. In fact, the many winding valleys and other features over its surface suggest that there might once have been rivers, lakes and oceans on Mars. Is there life on Mars now, or did life ever exist there? Are there valuable ores and minerals on Mars that are in short supply or not present at all on Earth?

Can the cosmic history of Mars tell us anything about the ultimate fate of planet Earth? These are some of the many questions that have led to the call for manned missions to explore and develop the Red Planet. Indeed, at the time of the moon landings, many had hoped that the next step would have been a manned mission to Mars. But that did not happen. Now, 40 years later, the Augustine Commission has concluded that U.S. manned missions to the moon and Mars are not affordable.

The fundamental problem making manned missions prohibitively expensive is that the transportation, sustenance and safe return of living human bodies over the enormous distances and in the implacably hostile environment of space is extremely difficult. Mars has therefore only been explored by what are presently called unmanned robotic missions—an unfortunate terminology. It is unfortunate because the word "robot" is suggestive of an alien being such as R2D2 from Star Wars, while the term "unmanned" seems to imply the absence of a human. The false impression can thereby be created that the exploration is not really human exploration.

From that viewpoint unmanned robotic missions, no matter how sophisticated, can never be regarded as a valid substitute for the manned missions that we are unable to undertake. This confusion, which may distort space policy, can be avoided by the terminology that Mars has been explored by humans on Earth using early-stage telepresence, where telepresence is an emerging technology that can enable a human to do physical work at a distant location, without going there.

Early-stage telepresence is now being used, not only for Mars exploration with rover vehicles, but also for a number of important terrestrial applications. Soldiers are using telepresence with unmanned ground vehicles to remotely find and disable improvised explosive devices in Afghanistan. Airmen are using telepresence with unmanned aerial vehicles to remotely find and attack terrorists on the other side of the world.

Remotely operated vehicles are used to enable humans to work at great depths below the surface of the ocean. A U.S. Food and Drug Administration-approved operating room suite from Stanford Research Institute in California enables surgeons to perform minimally invasive surgery remotely by telepresence (telesurgery). Telepresence development is also being actively pursued, particularly by the military. Congress has set a goal that by 2015 one-third of the operational ground combat vehicles are unmanned.

In support of this mandate, the Defense Advanced Research Projects Agency has conducted a Grand Challenge program in which ground vehicles navigate and drive over a 132-mile route with no human driver.

The potential significance of telepresence is that it is a derivative of related technologies, originating in 1876, which transformed human life in the 20th century. The present early-stage telepresence could be developed to shape life even more dramatically in the 21st century, particularly in space.

The invention of the telephone by Alexander Graham Bell in 1876 made it possible, for the first time, to talk to another person at a distant location without going there. For all practical purposes, talking by telephone is as effective, for talking, as talking directly. Speech is not just a means of social interaction, it is an indispensable component of the world's work that must be done each day. The telephone made it possible to perfom this vital work component remotely over large distances. The world as we knew it in the 20th century, particularly the world of business, simply could not have existed without that capability.