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# 3.22 Manned versus Robotic Missions

The debate over the relative merits of manned versus robotic exploration of space can be an emotional one. With the miniaturization of electronics, robotic probes will always be cheaper and more reliable than human spacecraft. However, many people think that the excitement of the space program depends on having human participants. Both types of exploration have their advantages and disadvantages — perhaps both have their time and place. Many people advocate a program of exploration that begins with robotic missions, until our knowledge of a planet expands to the point that sending a human is the natural next step.

An artist's concept portrays a NASA Mars Exploration Rover on the surface of Mars. Two rovers have been built for 2003 launches and January 2004 arrival at two sites on Mars. Each rover has the mobility and toolkit to function as a robotic geologist. Click here for original source URL.

Unmanned, or robotic missions, are in many ways easier and cheaper. The elaborate systems it takes to keep a human alive in space are unnecessary. Fuel doesn't have to be spent on transporting water, air, and food. Radiation shielding can be much less exhaustive. Safety systems do not have to be fail-proof. Finally, after the mission is over, you don't have to worry about returning the spacecraft to Earth. It can just be abandoned, saving enormous time, money, and effort. Because of all these lesser requirements, robotic missions are far less expensive. About 100 robotic missions could be sent to a given planet for the cost of one manned mission.

Astronaut?Bruce McCandless II, mission specialist, participates in a extra-vehicular activity (EVA), a few meters away from the cabin of the shuttle?Challenger. He is using a nitrogen-propelled hand-controlled?manned maneuvering unit?(MMU). He is performing this EVA without being tethered to the shuttle. The picture shows a cloud view of the earth in the background. Click here for original source URL.

However, many argue that human spaceflight is essential to the future of space exploration. After all, what's the point of exploring space if humans don't have the chance to experience it for themselves? Besides the emotional effect of putting a person on another planet, having a live person present could be a practical advantage. Due to the time delay between Earth and Mars, for example, it's impossible for remote scientists to react quickly to anything that happens on Mars. If some emergency crippled a robotic lander, it would take Earth-bound scientists at least 20 minutes to just hear about it, and double that for the lander to receive their response. A person could use creative thinking and flexible problem solving in real time, and could also do more science in less time.

Finally, there's no question that the publicity of putting people in space benefits the field of Solar System exploration. The excitement of space is more accessible when people can empathize with live astronauts, rather than just see pictures taken by a robot. Although we have sent numerous robotic missions to other planets and only a few manned missions to the Moon, it continues to be the manned missions that stay in people's memories and imaginations. Unfortunately, that same emotional effect can work the other way, when disasters occur like the loss of 14 lives aboard the Challenger and Columbia Space Shuttles. These losses underline the risks of human spaceflight, which must be weighed against the advantages.