T he difficult decision made recently by NASA Administrator Michael Griffin to launch the Space Shuttle Discovery, despite objections from NASA’s safety chief and top engineer, demonstrated solid leadership and the very qualities America has always embodied — boldness and daring in the face of calculated risk.

Leaders make decisions. Great leaders surround themselves with discipline specialists and rely upon their expertise to guide those decisions. Those leaders have to factor in competing recommendations of many experts, weigh the various risks and opportunities against the goals and objectives and make a choice.

In the case of the latest Discovery mission, now back from a successful 13-day mission to the international space station (ISS), Griffin indeed relied upon a panel of leading experts. In a face-to-face flight readiness review two of his most senior experts voted against launch, doing so based on their discipline’s view of the risks for this specific mission. It was not their job to weigh the risks to the entire program. That was up to Griffin, who is arguably the most technically competent administrator in NASA’s history.

Griffin had to weigh many factors pertaining to the shuttle program, ISS and manned civil spaceflight. Another redesign of the shuttle’s fuel tank could cause the next launch to slip another year. Delaying Discovery’s launch would have brought additional risk to ISS assembly and the shuttle program.

Why? A delayed launch would have forced six flights within one year before the shuttle fleet’s 2010 scheduled retirement. The shuttle program is not designed to accommodate such a packed flight rate without incurring considerable risk. Another risk factor that was key to Griffin’s decision was the possibility of the United States failing to meet its international commitments to complete the ISS.

Exploration and settlement have always entailed risk, requiring the courage of brave souls to venture forth. Nations and leaders who understand this principle prosper. Only a few hundred years ago the mortality rate of explorers and settlers was quite high. Dutch sailors figured that they only had an even bet of making it back home alive. In America, the first English colony, Roanoke, disappeared completely. Half the settlers in Plymouth died during their very first winter. The risks were great all across the continent. Death Valley wasn’t named after the scenic view.

Space exploration is the greatest adventure embarked on by humanity with perhaps the greatest rewards, and its ultimate potential justifies significant risk.

Space is worth the risk because exploration excites the human soul. Because it is so exciting and hard, it challenges the best of our minds. Space exploration encourages young people to study the hard subjects, like engineering, math, and the sciences, which are critical to future economies. In America only 5 percent of our college graduates are engineers, and that number is dropping. The Chinese graduated 45 percent of their students as engineers. — and i n China the number is increasing.

The Apollo moon program spurred tens of thousands of students to pursue engineering and these engineers had an enormous impact on the American economy. To keep up with evolving world economies America needs to do this again.

The Moon and asteroids may hold part of the key to addressing global warming and developing sustainable energy resources. Platinum group metals (abundant in asteroids) may be found on the Moon at impact sites of metallic asteroids. Development of these resources may enable the world to establish a hydrogen economy, since there may not be enough platinum group metals on Earth to produce the fuel cells for all the world’s cars.

Lunar Helium-3 might enable a safe form of fusion power that could be used around the world without the risk of contributing to weapons enrichment. Helium-3 fusion does not produce the radioactive byproducts to enable weapons development. You could give Helium-3 reactors to North Korea and Iran and sleep like a baby after the deal.

The members of the National Space Society believe the United States has become too risk averse. John Augustus Shedd wrote, “A ship in harbor is safe, but that is not what ships are built for.”

There are two roads before America: one, full of excessive caution and introspection, leads to diminishment and decline; the other, guided by visionary consideration of risk and reward, leads to a renewed sense of purpose and continued world leadership.

Space exploration and development activities are worth the risk. It is time for the nations of Earth to embrace calculated risk, risk for a purpose, risk that makes our souls sing. This mission of Discovery was a stepping stone toward our future in space. Now that she is back home and NASA is back on track, let us be thankful for the brave who dare to be great. Dr. Griffin made the right call.

George T. Whitesides is the executive director of the National Space Society.