Back in 1978, excitement about the future of NASA, with the space shuttle soon to debut, was palpable. So when the space agency called for astronaut applications, a record 8,000 people responded. That number has stood as a record for applications until today, when the space agency announced that a whopping 18,300 people applied to join its 2017 astronaut class.

The agency's administrator, Charles Bolden, said the total number of applications reflects public approbation for NASA's Journey to Mars. “It’s not at all surprising to me that so many Americans from diverse backgrounds want to personally contribute to blazing the trail on our Journey to Mars,” the four-time astronaut said. “A few exceptionally talented men and women will become the astronauts chosen in this group who will once again launch to space from US soil on American-made spacecraft.”

NASA’s astronaut applications have surged even as its flight opportunities have fallen by about 90 percent. Back in the early 2000s during the peak of the space shuttle program, NASA had more than 150 active astronauts. That’s because the shuttle, with six to seven launches a year, afforded 40 to 50 annual flights into space. The number of active astronauts is now about one-third of that peak due to the shuttle's retirement in 2011.

For now, the sole destination for US astronauts is the International Space Station, which NASA is committed to flying through 2024 and possibly 2028. This affords only about four to six flight opportunities a year, however. At least the new astronauts are unlikely to have to travel to Kazakhstan to launch aboard a Russian Soyuz spacecraft to reach the station. American spacecraft, made by Boeing and SpaceX and expected to come online by late 2017 or 2018, will launch NASA astronauts from Florida.

NASA has set a goal of sending humans to the surface of Mars by the 2030s, but with its current funding and approach to exploration, it's not clear that can happen. The first human mission in the new Orion spacecraft is unlikely before 2023, the agency has said, and this is likely to be a lunar flyby. After that, NASA had planned to send astronauts to a small boulder stashed in a distant orbit around the moon in 2025.

During the president's budget rollout earlier this month, NASA Chief Financial Officer David Radzanowski said a robotic mission to grab that boulder and return it to orbit near the Moon may not be ready to launch before 2023. If that's the case, it's not clear what human missions NASA would have beyond low-Earth orbit before about 2030.

Interest in NASA's Journey to Mars may nevertheless have contributed to a rise in astronaut applications. Additionally, with its 15 million Twitter followers and active social media accounts, the agency did a masterful job of calling attention to this opportunity when it opened in December. NASA may also have had fortuitous timing, with the recent blockbuster movie The Martian and its heroic rendering of astronauts spurring interest.

"I think public interest in the space program is on the upswing," Andy Weir, author of The Martian book, told Ars Friday. "The Martian is one small part of that, but not the only part. There's a virtuous cycle in progress. People are fascinated by space again, causing the entertainment industry to make more space fiction, which causes more people to be fascinated by space."

During the next 18 months, NASA will review the applications and then conduct a multi-part interview process with the most highly qualified candidates. The agency said it will announce eight to 14 astronaut candidates in mid-2017.