Stranded in Space?

Spacecraft are extremely complex machines. They have thousands of parts—all of which need to be tested and retested to ensure they’ll work correctly during a mission. When designing a craft, engineers make mathematical models of and conduct experiments on every valve, wire, and screw. But the real test of how everything will work can’t happen until the spacecraft is fully assembled, says Barrett Caldwell. He’s an engineer at Purdue University in Indiana who works with NASA to research space travel technology. That’s why test flights are so important. They allow engineers to monitor the entire system, pinpoint problems, and find ways to fix them before an actual mission.

During Starliner’s recent test, its thrusters fired when they weren’t supposed to. “That is very dangerous,” says Caldwell. If the thrusters aren’t doing their job properly, a spaceship might not be able to reach its destination, he explains. It could also mean the craft won’t reenter Earth’s atmosphere at a safe angle or speed on its return flight. Because of these safety concerns, NASA decided to send Starliner back to Earth without passengers. “As the commander of your spacecraft, you don’t want to see it go off without you,” said Wilmore during the August ISS broadcast. “But that’s where we wound up.” This past September, Williams and Wilmore watched as Starliner left the ISS without them. Six hours later, the empty capsule landed safely on Earth.

Spacecraft are complex machines. They have thousands of parts. All parts must be tested and retested to make sure they work correctly during a mission. When engineers design a craft, they make mathematical models of every valve, wire, and screw. They also conduct experiments on each of these parts. But this isn’t the real test of how everything will work. That can’t happen until the spacecraft is fully assembled, says Barrett Caldwell. He’s an engineer at Purdue University in Indiana, and he works with NASA to research space travel technology. That’s why test flights are so important. They allow engineers to monitor the entire system and find problems. Then they can fix the problems before an actual mission.

During Starliner’s last test, its thrusters fired at the wrong time. “That is very dangerous,” says Caldwell. If the thrusters don’t work properly, a spaceship might not reach its destination, he explains. This could also cause problems on the return flight. The craft might not reenter Earth’s atmosphere at a safe angle or speed. Because of these safety concerns, NASA sent Starliner back to Earth without passengers. “As the commander of your spacecraft, you don’t want to see it go off without you,” said Wilmore during the August ISS broadcast. “But that’s where we wound up.” This past September, Starliner left the ISS without Williams and Wilmore. The empty capsule landed safely on Earth six hours later.

Williams and Wilmore aren’t the first astronauts to get stuck on the ISS. And thankfully, the ordeal isn’t as scary as it might seem. Since the first human spaceflight in 1961, many others have spent more time in orbit than expected (see Extended Stays in Space).

In fact, remaining on the space station is often the safest option for astronauts when something goes wrong. “It isn’t as worrying as flying on something dangerous,” says Caldwell. “And we always keep extra food and supplies on the space station so that the astronauts never run out.” Not only did Williams and Wilmore have everything they needed aboard the ISS, they also had plenty to keep them busy and entertained. They used their time on the station to help other astronauts already living there with ongoing experiments and maintenance tasks. They also had to adjust to living in the weightlessness of space. That meant exercising every day to prevent bone loss and to keep their muscles from atrophying, or wasting away, while floating in a low-gravity environment.

So Williams and Wilmore were stuck on the ISS. But they aren’t the first. And their situation isn’t as scary as it might seem. The first human spaceflight was in 1961. Since then, many other astronauts have stayed in orbit longer than expected (see Extended Stays in Space).

When something goes wrong, astronauts might remain on the space station. Often, that’s the safest choice. “It isn’t as worrying as flying on something dangerous,” says Caldwell. “And we always keep extra food and supplies on the space station so that the astronauts never run out.” Williams and Wilmore had everything they needed aboard the ISS. They also had plenty to keep them busy and entertained. Other astronauts were already living on the station. Williams and Wilmore helped them with ongoing experiments and maintenance tasks. They also had to adjust to the weightlessness of space. Every day, they exercised. This prevented bone loss and kept their muscles from atrophying, or wasting away. These problems can occur in a low-gravity environment.

Of course, the unexpected stay had its downsides. “We miss our families, I miss my two dogs, I miss my friends,” said Williams during the August interview. “But everybody understands, and everybody’s cheering for us to get back.” With a return trip scheduled for the end of next month, the astronauts should soon be safely back on Earth.

Space travel is hard, says Caldwell. And sometimes things don’t go according to plan. But there are many people behind the scenes working to make the best possible decisions to keep everyone safe. It’s important to be brave, test things, and take risks, adds Caldwell. “It takes a lot of care and work and attention to detail to build a spaceship. And it takes a lot of bravery to ride in one.”

Of course, the unexpected stay had its downsides. “We miss our families, I miss my two dogs, I miss my friends,” said Williams during the August interview. “But everybody understands, and everybody’s cheering for us to get back.” Since their return is scheduled for next month, the astronauts should be safely back on Earth soon.

Space travel is hard, says Caldwell. And sometimes things don’t go as planned. But many people are working behind the scenes. They try to make the best possible decisions to keep everyone safe. It’s important to be brave, test things, and take risks, adds Caldwell. “It takes a lot of care and work and attention to detail to build a spaceship. And it takes a lot of bravery to ride in one.”