What’s next for America’s aspiring astronauts?

(This report is the third and final in a Yahoo! News series on the shutdown of the space shuttle program.)

When Atlantis lands at Cape Canaveral on Thursday, back from the very last mission to the International Space Station, 20-year-old Amanda Premer will be getting ready to move to Houston. The fourth-year aerospace engineering major is headed to Johnson Space Center's Cooperative Education program, where she will be alternating her last semesters at Wichita State University with three "work tours" at the NASA site. She hopes to secure a full-time job with NASA.

"I want to be an astronaut," said Premer, who has spent the last four summers working at the Cosmosphere space camp in Hutchinson, Kan. "Even though NASA doesn't have anything lined up to follow the shuttle program, the world's always going to need astronauts. And I'd like to be one of them."

As NASA's 30-year space shuttle program draws to a close, the next generation of aspiring astronauts and talented aerospace engineers must rely on international vehicles to fly up to the ISS, and depend on private industry to create the next best rocket. They are entering a new, nebulous era of American spaceflight, but are fervent in their desire to carry the torch lit by their predecessors during the Apollo era.

"The shuttle is old. Amazing, but old," said Sara Gurnett, who is three semesters away from earning a degree in professional aeronautics from Embry Riddle Aeronautical University in Prescott, Ariz., and also works summers as a counselor for the Cosmosphere. "So it's not disappointing to me that it's retiring."

She hopes to join the U.S. Navy's Officer Candidate School after graduation, and eventually become an astronaut pilot. "I want to one day be able to fly the most exotic thing out there," said Gurnett, who keeps her pilot license, along with her scuba certification, literally in her back pocket. "That used to be the space shuttle, but now, who knows what it'll be. … It'll probably be built by private industry."

President Obama thinks so too. Atlantis' crew deposited on the ISS an American flag that flew on the first shuttle mission, and when Obama spoke to the crew last week before it returned to Earth, he challenged the commercial space industry to "capture the flag."

Shortly afterward, California-based company SpaceX posted via Twitter: "SpaceX commencing flag capturing sequence…"

Founded by engineer-entrepreneur Elon Musk (of PayPal and Tesla fame), SpaceX made history in November when it became the first private company to launch a spacecraft into orbit and guide it safely back to Earth. It plans to send that same spacecraft to the ISS by the end of this year. Fueling this effort will be the company's cadre of bright young engineers—the average age at SpaceX is early 30s.

"There's all this incredible energy happening in the private sector," said Garrett Reisman, a former astronaut who rode on Atlantis' penultimate trip to the ISS last year, but recently hung up his spacesuit to join SpaceX as a senior engineer. "We have a great mix of these senior guys and these young guys who are the best and the brightest."

One of those young guys is 26-year-old Matt McKeown , who sat in mission control during SpaceX's historic launch last year. A lead propulsion engineer, he gave the iconic "go/no-go" cues from the propulsion standpoint.

"It's definitely a challenge for us young engineers because we've never done this before," said McKeown, who joined SpaceX after earning a master's degree—and a 3.9 GPA—in aerospace engineering from the University of Michigan in 2008. "But we know we have to make progress or we're not going to have jobs! That's a great motivator."

McKeown started building model rockets in elementary school, and he continued to build them throughout junior high and high school. In college, he set his sights a little higher and co-founded the Michigan Aeronautical Science Association, an organization specifically designed to construct space vehicles. He received a $10,000 scholarship from the Astronaut Scholarship Foundation, which was founded by the six surviving astronauts of Project Mercury, NASA's first major undertaking. The foundation rewards college students who excel in the sciences.

"Ever since I was 5, I knew I wanted to be an engineer," said McKeown, who was inspired by shuttle technology. "Now I'm working on vehicles that will take manned spaceflight to the next level. … I hope that will inspire people."

Sara Gurnett believes that renewing public interest in space exploration is the key to continued funding and support.

"We have to get parents interested in space, and then they'll inspire their kids," she said. "Some kids see these things as faraway dreams and they don't feel like they're good enough. … But they could really do this one day!"

Aerospace engineer Doug Hofmann, 30, was inspired to pursue a career in space by his father, a retired Army lieutenant colonel with a strong interest in the space program. (In 1985, the elder Hofmann, then a seventh-grade teacher, was a finalist for the ill-fated Challenger mission.)

"I grew up wanting to be an astronaut," said Hofmann, who knew his best chances were to become an engineer or a military fighter pilot. "My dad told me I was more apt for research than the military."

From then on, Hofmann relentlessly pursued the space field and took every opportunity to get advice from former astronauts. Sally Ride, the first American woman to enter space, and one of Hofmann's professors at the University of California, San Diego, convinced him to go to Caltech for graduate school rather than MIT. He went on to earn both a master's and PhD in materials science.

Hofmann is now working in what he calls his dream job, designing new materials for spacecraft at NASA's Jet Propulsion Laboratory. He hopes the job will bring him one step closer to becoming an astronaut (he currently has funding for research projects on the ISS).

In the meantime, he's trying to pass on the wonder and excitement for all things space to his 5-month-old son: "When I was in Washington, D.C., I got the autographs of three astronauts for my son. When he's older he'll appreciate them."

Though many view the end of the shuttle program as an end to American spaceflight, this new generation of aspiring astronauts, engineers and space enthusiasts are excited as ever for the future, and hope that they can leave their mark, much as their predecessors from Apollo and the shuttle missions did. Whether it's by hitching a ride on another country's vehicle or inaugurating a shiny new ride built by commercial industry, they will continue to explore the great unknown, and stake their flag to inspire the next generation.

More specifically, according to Gurnett: "Space travel to the moon, Mars and beyond: That's the legacy I want my generation to leave."