LAKE ELSINORE, Calif. — The mission to turn space into the next frontier for express deliveries took off from a modest propeller plane above a remote airstrip in the shadow of the Santa Ana mountains.

Shortly after sunrise on a recent Saturday, an engineer for Inversion Space, a start-up that’s barely a year old, tossed a capsule resembling a flying saucer out the open door of an aircraft flying at 3,000 feet. The capsule, 20 inches in diameter, somersaulted in the air for a few seconds before a parachute deployed and snapped the container upright for a slow descent.

“It was slow to open,” said Justin Fiaschetti, Inversion’s 23-year-old chief executive, who anxiously watched the parachute through the viewfinder of a camera with a long lens.

The exercise looked like the work of amateur rocketry enthusiasts. But, in fact, it was a test run for something more fantastical. Inversion is building earth-orbiting capsules to deliver goods anywhere in the world from outer space. To make that a reality, Inversion’s capsule will come through the earth’s atmosphere at about 25 times as fast as the speed of sound, making the parachute essential for a soft landing and undisturbed cargo.

Inversion is betting that as it becomes cheaper to fly to space, government agencies and companies will want to not only send things to orbit but also bring items back to earth.

Inversion aims to develop a four-foot-diameter capsule carrying a payload equivalent to the size of a few carry-on suitcases by 2025. Once in orbit, the capsule could, the company hopes, navigate itself to a private commercial space station or stay in orbit with solar panels until summoned back to earth. When it was time to return, the capsule could drop out of orbit and re-enter the atmosphere.

The capsule would deploy a parachute to slow its descent and land within a radius of tens of miles from its target location. The company has planned a smaller demonstration capsule with a 20-inch diameter to be ready by 2023.

If Inversion is successful, it’s possible to imagine hundreds or thousands of containers floating around space for up to five years — like some (really) distant storage lockers.

The company’s founders imagine the capsules could store artificial organs that are delivered to the operating room within a few hours or serve as mobile field hospitals floating in orbit that would be dispatched to remote areas of the planet. And one day, a shortcut through space could allow for unimaginably fast deliveries — like delivering a New York pizza to San Francisco in 45 minutes.

Inversion’s founders think what seems like a pipe dream may become more realistic as launch costs drop from current prices, which start at $1 million (and increase depending on weight) to share space on a SpaceX rocket. Inversion declined to offer an estimate of how much its capsules will cost.

“The big obstacle that everyone in the sector is trying to overcome is that at current costs, there just isn’t that much demand to do much in space,” said Matthew C. Weinzierl, a professor at Harvard Business School who has published research about the economic potential of space.

For decades, people have imagined living and working in space as an extension of life on Earth. That vision seemed like a Hollywood fantasy until an influx of private rocket companies greatly reduced the costs of getting to space, making commercial activity beyond Earth more feasible.

The cost of launching one kilogram, about 2.2 pounds, of payload to outer space has fallen roughly 90 percent in the last 30 years. SpaceX is expected to push costs even lower with Starship, its next-generation rocket still in development. Elon Musk, SpaceX’s chief executive, has said he expects launch costs for the massive rocket to be less than $10 million within three years — compared with the $62 million advertised price for launching the Falcon 9, the company’s widely used rocket.

For space to be more accessible than it is today, inexpensively launching rockets is only one part of the equation.

Another important factor is facilities in space. Last year, NASA selected three companies to receive funding for commercial space stations as part of a plan to eventually replace the International Space Station. A fourth company, Axiom Space, was awarded a $140 million contract in 2020 to build a habitable module attached to the ISS.

Mr. Fiaschetti, who interned for SpaceX before dropping out of college last year to pursue his own start-up dreams, thinks physical goods — not just satellite data — could be sent back from space.

Today, the main cargo for rockets is satellites that stay in space. The vehicles carrying humans or experiments from space are large, cost more than $100 million and usually work in tandem with a specific rocket. Inversion said it designed its smaller capsules to fit into any commercial rocket so they can catch a ride to space frequently and inexpensively.

What Inversion is trying to do is not easy. Designing a vehicle for re-entry is a different engineering challenge than sending things up to space. When a capsule enters the atmosphere from space, it is traveling at such high speeds that there is the danger of burning up — a huge risk for human travelers and precious nonhuman cargo alike.

Seetha Raghavan, a professor in the University of Central Florida’s mechanical and aerospace engineering department, said it would be even more difficult to handle the heat, vibration and deceleration of the capsule when the vehicle size shrank.

“It all becomes harder when you have a smaller item to control,” Ms. Raghavan said.

Inversion’s plan for capsules in orbit raises questions about whether it will contribute to congestion in space, already a problem with the megaconstellations of satellites. And the abundance of satellites interfering with observations of planets, stars and other celestial bodies has been a common complaint among astronomers.

But Inversion said it was using materials to make its capsules significantly less reflective to decrease visual pollution. In addition, the company said its capsule would come with systems to avoid debris and collisions in orbit.

Mr. Briggs, 23, and Mr. Fiaschetti met when they sat next to each other at a matriculation ceremony for freshmen at Boston University. They became active in the school’s Rocket Propulsion Group working on rocket designs. They moved to Los Angeles during the pandemic. One night, they were discussing the future of the space industry — “We’re nerds. This is what we do,” Mr. Fiaschetti said — and they homed in on creating less expensive re-entry vehicles to carry cargo from space.

They moved into a guesthouse in the San Pedro neighborhood of Los Angeles, paying $1,250 a month each, including for the use of a garage that became the company’s workshop. Using Mr. Fiaschetti’s woodworking equipment, they designed and made a working rocket engine out of aluminum in an effort to prove to potential investors that they had the necessary technical chops.

In June, Inversion Space joined Y Combinator, a Silicon Valley start-up incubator known for early investments in Airbnb and Stripe. Five months later, it said it had raised $10 million based in part on letters of intent worth $225 million from potential customers interested in reserving space on Inversion’s capsules. Mr. Fiaschetti declined to identify the customers.

Venture capital has started to see the potential of space. Globally, venture capital firms invested $7.7 billion in space-related technology last year, up nearly 50 percent from a year earlier, according to data compiled by PitchBook.

Inversion moved into a 5,000-square-foot warehouse in an office park in Torrance. It is a tinkerer’s dream workshop, with machining tools for making parts, welding equipment and a 20-ton hydraulic shop press to pack parachutes as densely as oak.

Tucked away at the far end of the warehouse — next to a floor-to-ceiling American flag and a basketball hoop — is a black, 10-foot shipping container for testing rocket engines and parachute deployment mechanisms. The structure features steel-reinforced concrete walls, ceiling sprinklers and a system to replace oxygen with nitrogen in the case of a fire.

On a recent visit, Inversion was preparing to test a new parachute design. Parachutes are tricky. They have to unfurl perfectly to make sure a capsule will slow down and not rock too much. Many factors, like including fabric choice and seam design, can affect a parachute’s effectiveness.

While most rocket companies outsource parachute design and production, Inversion sees building their own as an advantage.

In an earlier test, Inversion had noticed that the capsule oscillated a lot. On that day, Mr. Fiaschetti, Mr. Briggs, and two engineers had arrived before sunrise on a recent Saturday at an airstrip largely used by sky divers to test a new design.

Connor Kelsay, an engineer who oversees Inversion’s parachute design, climbed into the plane with the test capsule, which was affixed with a GoPro camera and an inertial measurement unit to gauge its movements. After he tossed the capsule out of the plane, he waited a few seconds and jumped out after it. An experienced sky diver, Mr. Kelsay circled the capsule, shooting video of its movements from another camera on his helmet.

When he landed, he shared the same observation as everyone else: The parachute had been slow to deploy. The team quickly scanned the video and ran down a list of possible factors. Did Mr. Kelsay toss the capsule too roughly? Was there a lot of turbulence when the drop occurred? Was it because they used a differently shaped capsule last time?

In the second test, the parachute opened as expected. However, the GoPro camera taped to the capsule fell off in the descent — prompting a frantic search. (They eventually found it.) After the second test, the team thought it had pinpointed the problem: An adhesive fabric tape used to patch a hole had caused the parachute to stick.

Afterward, Mr. Fiaschetti said he wasn’t disappointed by the slow parachute opening because it was part of the process.

“Early in development, you expect things to not go as perfectly as you wanted,” he said. “I guess that’s why they call hardware ‘hard tech.’”