SpaceX made 4 vital changes to its Crew Dragon spaceship, and a promise for the landing, after analyzing its first astronaut mission

• SpaceX is set to launch four astronauts to the space station for NASA later this month.
• After inspecting the data from its first astronaut flight, SpaceX made four big upgrades to its Crew Dragon spaceship.
• The next capsule will have new maneuvering capabilities, a reinforced heat shield, longer-lasting solar panels, and better parachute-deployment sensors.
• SpaceX is also promising a clearer ocean landing site without a crowd of boats.

SpaceX showed the world that its Crew Dragon can safely carry NASA astronauts to and from space this summer.

Now the company is preparing the spaceship for its biggest feat yet: routine flights to and from the International Space Station.

SpaceX's first mission for NASA was a test flight called Demo-2. It rocketed astronauts Bob Behnken and Doug Hurley into orbit, after which their Crew Dragon capsule docked to the space station. They stayed there for two months before returning to Earth.

Even though that all went smoothly, SpaceX still uncovered some flaws to correct after a close analysis of the mission. This week, SpaceX and NASA described four upgrades in particular that they've made to the next Crew Dragon capsule, and also announced changes to ensure a safer landing.

The beneficiaries of those improvements are the four astronauts on the upcoming Crew-1 mission: NASA's Mike Hopkins, Victor Glover, and Shannon Walker, and the Japanese space agency's Soichi Noguchi. They're set to launch on October 31 then stay on the ISS for a full six months before riding the Crew Dragon back to Earth.

It's the first of six round-trip flights NASA has contracted from SpaceX — and perhaps the company's biggest challenge yet. Here are the improvements SpaceX has made in preparation.

The ability to switch ports on the space station

When the new Crew Dragon capsule — which the astronauts have named Resilience — reaches the ISS, it will enact a series of complex maneuvers to dock to a port there. But it might not stay attached the whole time, since it may need to accommodate the arrival of another spaceship: Boeing's CST-100 Starliner.

The Starliner, developed through the same NASA-funded effort that yielded the Crew Dragon, is set to reattempt an uncrewed test flight in 2021. During its first try in 2019, software issues prevented the spacecraft from docking to the ISS.

The schedule of its follow-up test will require the Crew Dragon to move to a different space-station port.

To do that, the Resilience capsule will use a new capability that the prior one, Endeavour, did not have. The crew will climb into the ship and run new software that should maneuver the spacecraft away from its original docking point, called the Forward Port, and re-dock to the station's Zenith Port.

The flight is programmed to be autonomous, but the crew will monitor the process and can manually maneuver the spacecraft using the touchscreen interface inside if anything goes wrong.

A reinforced heat shield

Once Behnken and Hurley were safely back on land, NASA and SpaceX set about investigating the toasted Endeavour capsule, scanning every inch for unexpected damage. They found some on a critical part of the spaceship: its heat shield.

This thermal protection system is a collection of heat-resistant tiles that line the spaceship's underbelly. It deflects and absorbs heat that can reach 3,500 degrees Fahrenheit while the space capsule plummets through the atmosphere on its return to Earth.

One of the heat shield's tiles suffered "a little bit more erosion than we wanted to see," Hans Koenigsmann, SpaceX's vice president of build and flight reliability, said Tuesday.

He emphasized, however, that "at all times the astronauts were safe and the vehicle was working perfectly."

Still, the heat shield was not supposed to wear away like that.

"I get shivers when a hear that human spacecraft heat shield showed unexpected degraded performance and requires 'minor' modification," Wayne Hale, a retired NASA Space-Shuttle flight director, said on Twitter.

Hale worked in the Space Shuttle program in 2003, overseeing much of the effort to return to space after the Columbia disaster. That shuttle's heat shield was damaged in space, allowing hot gases to squeeze through as it reentered Earth's atmosphere. The Columbia broke apart in mid-air, killing the seven people inside.

To address its problem, SpaceX set about reinforcing the heat shield with stronger materials. NASA then tested five samples of the new tile in a wind tunnel that simulates the environment of reentry.

"I'm confident that we fixed this particular problem very well," Koenigsmann said. "Everything has been tested and is ready to go for the next mission."

Parachutes should deploy earlier

As the Crew Dragon plummets to Earth at 350 miles per hour, it deploys its first two parachutes at about 18,000 feet. But on Behnken and Hurley's reentry flight, that happened closer to the ground than NASA and SpaceX expected.

"We learned a lesson with the deploy of the drogue parachutes. It was a little lower than the nominal planned altitude but within limits," Steve Stich, the manager of NASA's Commercial Crew Program, said.

As it turned out, a filter that vented air into the sensor measuring the atmospheric pressure had gotten clogged.

"That particular filter has been opened up a little bit so that it's less constrained," Koenigsmann said. "That has the effect that we measure the barometric pressure more accurately and we come down and supply the parachute right on time."

Solar panels that can weather 6 months in space

Keeping a spaceship docked to the ISS may sound easy, but as it sits there, the vehicle gets doused in solar radiation and weathers extreme temperatures. In fact, the capsule Behnken and Hurley flew probably wouldn't have survived a full-length six-month mission in space; its solar panels likely would have degraded significantly after 110 days in orbit.

So Resilience will need much more resilient solar panels.

"We plan to be docked for six months, and we have not taken that lightly. This is the first US spacecraft to be docked that long," Stich said. "We've improved the solar arrays to give us that full 210-day dock duration that we need for this mission."

No more boats of onlookers

When Endeavour splashed down in the Gulf of Mexico, a beeline of onlooker boats immediately swarmed the toasted capsule. Some passed alarmingly close to the spaceship.

That's a hazard for the astronauts and a danger for the boaters, since after plowing through Earth's atmosphere, the capsule was shrouded in low levels of a poisonous gas called nitrogen tetroxide.

To keep would-be spectators away from the Resilience capsule when it eventually returns to Earth, SpaceX and NASA plan to set up a 10-mile no-boat perimeter around the splashdown site, and to have more Coast Guard boats there to enforce it.

But altogether, this list of changes from the demo mission is relatively minor in NASA's eyes.

"It will be a great mission if Crew-1 goes exactly the same way," Kathy Lueders, who runs NASA's Human Spaceflight Office, said Tuesday, adding, "I'm counting on a beautiful mission the exact same way."