WASHINGTON — A new poll finds that the American public broadly supports NASA but thinks the space agency should be focused more on Earth science and planetary defense than human missions to the moon or Mars.

The study by the Pew Research Center, released June 6, also showed support for private space ventures among the general public, but with concerns that such companies won’t be able to minimize the creation of space debris.

The poll of more than 2,500 people, carried out from March 27 through April 9, found that 72 percent believed that it was essential for the United States to continue to be a world leader in space exploration, compared to 58 percent in a June 2011 poll. The survey found that 80 percent believed that the International Space Station has been a good investment, versus 64 percent in an August 2014 poll.

While the survey found broad support in general for NASA, results were mixed for the agency’s various programs. In the poll, 63 percent of respondents said they considered monitoring key parts of the Earth’s climate a top priority for the agency, and 62 percent said that monitoring potentially hazardous asteroids, known as “planetary defense” within NASA and a relatively small part of its overall budget, was a top priority.

At the opposite end of the scale, only 18 percent of respondents said that sending humans to Mars should be a top priority for NASA, and only 13 percent said sending humans to the moon should be a top priority. A larger share of those polled — 45 percent for Mars and 42 percent for the moon — said that such exploration was important, but a lower priority.

The poll results showed some pronounced splits based on political affiliation, education and gender. Among those who identified as Democrats, or leaning Democratic, 78 percent said climate science was a top priority and 53 percent said basic research was a top priority. Among those who said they were Republicans or leaning Republican, the results were 44 and 38 percent, respectively.

The poll showed increasing support for climate science with education, with 58 percent of those with no more than a high school diploma saying it was a top priority versus 74 percent of those with postgraduate education. Support for human exploration of the moon declines, though, from 15 percent to 10 percent from high school to postgraduate education.

Men showed more support for human space exploration than women, with 25 percent of men saying human missions to Mars were a top priority versus 11 percent for women, and a split of 16 versus 10 percent for human missions to the moon.

The poll also revealed varying levels of confidence in the capabilities of private space ventures. In the survey, 80 percent said they had a “great deal” or “fair amount” of confidence that such companies could be profitable, and 77 percent expressed confidence they could make safe and reliable launch vehicles and spacecraft. However, 53 percent said they had confidence that such companies could minimize the creation of space debris, with only 13 percent saying they had a great deal of confidence.

Much of the public, though, admits to knowing little about commercial space efforts. Asked how knowledgeable they are of companies like Blue Origin, SpaceX and Virgin Galactic, 45 percent said they knew only a little, and 37 percent said they knew nothing at all about them.

Asked if they would be interested in orbiting Earth in a spacecraft, 58 percent said they were probably or definitely not interested, compared to 42 percent who said they were probably or definitely interested. The question didn’t say if such a flight would be on a government or commercial spacecraft, and did not state how much, if anything, the person would be expected to pay for such a flight.

For those who said they were interested, 45 percent said “to experience something unique” was the main reason to go. Seeing the Earth from space was the main reason for 29 percent, and 20 percent said they wanted to learn more about the world. Experiencing microgravity was not one of the specific poll options.

Those who said they did not want to orbit the Earth were split evenly among three options, with 28 percent each saying it would be too expensive, too scary or that their age of health wouldn’t permit them to go.

The survey, part of the Pew Research Center’s American Trends Panel, featured 2,541 respondents. The overall margin of error in the poll is 2.7 percentage points.