As they walked onto Wayback Farm’s soybean and corn fields for practice, Jasmyn Logan and Nia’mani Robinson examined their handiwork: A two-foot-tall black rocket with pink fins, an encapsulated large Grade A egg and a red 15-inch parachute.

They wondered what would happen after liftoff.

Would the polyurethane foam keep the egg intact? Would the rocket soar the required 750 feet? Would it stay in the air for 48 to 50 seconds?

The Central High School freshmen — known in competition as Rocket Power — will be one of 100 teams in the finals of the Team America Rocketry Challenge this week, a contest sponsored by the Aerospace Industries Association and the National Association of Rocketry for seventh to 12th-grade students across the country. Students from six other schools in the Washington region also are competing in the finals.

The girls, both 14 and Largo residents, are one of just eight female teams that qualified for the finals. They are the only squad of African American students to participate in the closing round.

“I’m definitely proud of them,” said Kamili Jackson, the team’s adviser. “They have put a lot of work into it and it has paid off for them.”

Modeled around the aerospace industry’s process, the teams must build a rocket that can reach a certain altitude, land within a specific flight-time window and safely return a raw egg (the astronaut) without cracking.

The May 11 competition will end an eight-month experience for the girls that began in September at NASA’s Goddard Space Flight Center in Greenbelt. There, they learned each weekend about rockets and how to build and design them.

The girls have taken the nearly hour-long ride to Howard County trying to perfect their launches over the past two months.

Jasmyn said she can’t wait to compete.

“I’ve never been in a competition like this before,” she said. “I’ve been in a science fair, but never like this.”

“Me either,” said Nia’mani.

The National Society of Black Engineers has been trying to expose black students to STEM (science, technology, engineering and mathematics) disciplines and encourage them to pursue a career in the field, where they are underrepresented. The Greenbelt space chapter of the engineers society mentored the girls through the development process.

Similar initiatives are being promoted by educators and policymakers who are concerned that U.S. students trail their peers from around the world in STEM areas.

African American women earned just 5 percent of the STEM-related bachelor’s degrees awarded to women in 2009, and African American men earned 3 percent of the degrees, according to the National Academy of Engineering.

Jackson said it is generally in middle school when most girls and minority students tend to steer away from STEM subjects.

“Those numbers are quite a shame,” Jackson said. “With these girls participating, maybe we will get more girls and teens involved. It seems like the numbers are improving, but we still have a lot of work to do.”

She said that is why it is important for girls like Jasmyn and Nia’mani to see people who look like them working in the engineering field.

In a field on a recent practice day, Jasmyn, who wants to be a physician’s assistant, and Nia’mani, who is interested in architecture and journalism, anxiously set the rocket on a metal pad.

Jasmyn placed a key into a small box and turned it.

“Five, four, three, two, one . . . launch,” she said.

Nothing happened. The girls stared at each other. Without making adjustments, they tried again.

“Three, two, one . . . launch,” Jasmyn said, a second time.

Still nothing.

They wondered whether they’d placed the key correctly. They cleaned the heads on the transmitters. They tried a third time.

With a blast, the rocket soared and spun about 150 feet into the air before plummeting to the ground, breaking two of its fins. From takeoff to landing: 18 seconds. But the egg was intact.

“We kind of had a bad flight,” Jasmyn said as they walked back to a folding table to make repairs and adjustments.

On the next launch, the rocket soared 706 feet.

Jackson said that each week the girls have progressed, learning how to make the rocket go higher, stay afloat longer.

“They are honing on getting as close to the goal as they can,” Jackson said. “They have one more practice . . . one more try, so it’s do or die.”