Should humans go to Mars? President Obama says yes.

If all goes according to President Obama's plan, America will send humans to Mars by the 2030s. 

In a CNN op-ed published Tuesday, Obama announced a "clear goal": sending humans to Mars within the next couple of decades "and returning them safely to Earth, with the ultimate ambition to one day remain there for an extended time." Such a feat, he writes, can be achieved through cooperation between the government and commercial space companies. 

This lofty ambition is one that could inspire a new generation of scientists and engineers, spawning solutions and discoveries that might result in practical advances on this planet. The possibility of a Red Planet colony has set the nation abuzz. But sending humans to Mars also raises a number of ethical questions that may not be on the average American's radar, such as concerns about the cost, the physical and emotional risks to travelers, and the diversion of resources and attention from problems here on Earth.

"As a nation and a people, we are confounded by a new question: To Mars, or, not to Mars? This is a not-so-simple query worthy of an intense national debate and soul searching," wrote Thomas Taverney, a senior vice president with Leidos, for The Space Review. "And for a spacefaring nation, it’s one that generates even more questions. Will it be worth it to go to Mars?" 

Thanks to NASA and private space innovators such as SpaceX and Blue Origin, travel to Mars has become a question of when, not if. SpaceX, for its part, has vowed to send colonists to Mars by 2024 and eventually make the trip "affordable for everyone who wants to go."

Our knowledge of Mars has exploded over the past 20 years, as a fleet of orbiters and rovers have gathered millions of chemical and physical measurements, as well as countless photographs. The value of such research is virtually undisputed – but, opponents of human travel argue, flying people to Mars is much riskier, and costlier, than sending a rover. 

A round-trip flight to Mars would likely take several years (the launch window from Earth-to-Mars is once every 26 months) and involve at least six months of travel each way, during which the small crew of astronauts would live together in tight quarters. In a recent year-long experiment by NASA, six scientists lived together in a two-story dome on Hawaii's Mauna Loa volcano to simulate life on Mars. 

As the Christian Science Monitor's Lonnie Shekhtman reported at the 10-month mark, in June: 

The goal of this fourth and longest of the HI-SEAS missions, which are funded by NASA, is to learn how group dynamics play out under stressful conditions, such as the ones that explorers will one day encounter on Mars. This fourth planet from the sun is an inhospitable desert, with an average temperature of -81 degrees Fahrenheit, massive dust storms, and harsh radiation from the sun that can't be deflected by the planet's weak magnetic field, nor absorbed by its flimsy atmosphere.

Physically, exploring Mars will be a challenge. Psychologically, too. Astronauts venturing into deep space together for the first time could grapple with feelings of isolation, depression, and personality conflicts. 

The six men and women living on Mauna Loa emerged from the experiment confident that they could handle the psychological pressures of a trip to Mars, the Monitor reported. But beyond the potential for mental distress, experts say that the voyage exposes astronomers to physical harm, too. 

A study published Monday in the journal Scientific Reports found that exposure to cosmic radiation caused brain damage in test rodents. 

"This is not positive news for astronauts deployed on a two-to-three-year round trip to Mars," researcher Charles Limoli, professor of radiation oncology at the University of California, Irvine, told Forbes. "The space environment poses unique hazards to astronauts. Exposure to these particles can lead to ... performance decrements, memory deficits, anxiety, depression, and impaired decision-making."

Exploration has always posed risks, says Laurie Zoloth, a professor of medical ethics and humanities at Northwestern University. And "space is the harshest possible human environment, exceeding conditions anywhere on the planet," she writes for Cosmos Magazine, as "more is unknown about the physical and mental challenges of space travel than is known."

So, she continues, "what makes risk ethical? Historically, it has been one thing: consent. The ethical considerations change if we think of the crew as military personnel. We expect soldiers to face considerable risk. And think of the pioneers who traveled to remote and desolate places with no thought of return." 

Still, Professor Zoloth cautions, "before we set out we need a far-reaching public discussion of what space travel means to us – and what we are prepared to sacrifice for it." 

Risks aside, some critics argue that such a trip is dangerous in that it takes funding and attention away from pressing issues facing the Earth. When asked about climate change in September, Libertarian presidential candidate Gary Johnson spoke of the importance of sending humans into space, saying, "We do have to inhabit other planets. The future of the human race is space exploration." 

Michael Menaker, the Commonwealth Professor of Biology at the University of Virginia, who has conducted Mars-related basic research on circadian rhythms for NASA, agrees that it is important to study the Red Planet – but feels that the emphasis on sending people to Mars serves as an unnecessary distraction away from problems such as climate change. 

"I think it's being used as an excuse for not dealing with the problems here, and I think that’s a very bad idea," Dr. Menaker tells the Monitor in a phone interview. "People say, 'Oh well, we're going to use the Earth up and we can always go somewhere else.'" 

"I think the effort and the money and the resources really need to be put into preserving the Earth," he adds. 

Editor's note: The original version of this story misstated Thomas Taverney's title.