Mosaic of the Valles Marineris hemisphere of Mars projected into point perspective, a view similar to that one would see from a spacecraft. The distance is 2500 kilometers from the surface of the planet. Credit: NASA/JPL-Caltech

I read with great interest both Rick Tumlinson’s and Robert Zubrin’s op-eds about the cost and reasons for exploring Mars. One calls for another John F. Kennedy moment in which the United States would mount a very large exploration program [“We Must Be Our Own Kennedy”]. The other argues that we must go to Mars and set up a permanent base there so as not to disappoint future generations [“Misdirection on Mars”]. Each says we have to send humans to Mars because — well, because … because this sort of thing is in our nature.

Unlike many people, we at the Planetary Society accept that there will almost certainly never be another Kennedy moment. The world has changed. There is no Cold War. NASA’s budget is a line item in the federal budget, competing with every other program our government supports.

We want to explore Mars to look for signs of life. Everyone, Mr. Tumlinson and Dr. Zubrin included, would agree that if we were to discover evidence of ancient life on Mars, let alone if we were to discover something still alive there, it would change the course of human history. It would change the way each and every one of us feels about being a living thing in the cosmos. It would be a discovery as profound as Copernicus proving that our world orbits the sun, or Galileo observing that the Moon and Saturn are other worlds with a primordial connection to our own. The profound philosophical perspective aside, just imagine what understanding extraterrestrial life might mean to biology or even medicine.

With this in mind, the Planetary Society convened a workshop to assess whether or not NASA could afford to get humans in orbit around Mars in 2033, a particularly efficient orbital opportunity. NASA could — within its current budget, adjusted only for inflation, and presuming the agency divests itself of the International Space Station in 2024 or 2028 as planned. The agency would make use of the existing programs including the Orion capsule, the Space Launch System rocket, and a very large solar electric propulsion system similar to the one proposed for the Asteroid Redirect Mission. A human landing mission could be mounted a few years later. If the U.S. program is able to engage international partners, the cost becomes even more reasonable.

Human explorers on Mars will be more capable than our very best rovers and landers, designed and operated by our best engineers and scientists. Humans will recognize geographic and geologic patterns immediately; their explorations will be directed and efficient. And, of course, they will have adventures that will engage every citizen back here on Earth. To get people there will require new technologies to address problems that have never been solved before. It will bring out the best in us just as Apollo did. Who knows what new ideas will emerge when people go where they have never gone before?

The search for life will help us seek answers to the deep questions: Where did we come from, and are we alone in the universe? These are reasons to follow the National Research Council’s decadal survey and complete the task of robotically returning samples from Mars, which will enable earthbound scientists to use our large laboratories to understand and characterize the Martian environment. At the same time, we can mount an affordable, executable humans at Mars exploration program that will make real progress in the intervening decades. Here’s hoping we all consider the U.S. budget constraints, the real ones.

Let’s get humans farther and deeper into space. Let’s go to Mars and look for living things. The exploration of our neighboring world will profoundly change this one. Let’s support a humans at Mars program and get to work.

Bill Nye, New York

The writer is chief executive of the Planetary Society.

Bill Nye is executive director of the Planetary Society.