Dragon Re-entry Creates Rare Spectacle for Earthbound Viewers

By Bob Granath

A rocket thundering into space is a familiar sight for residents of Florida’s Space Coast. In the past two years, more than once a week windows rattle as launch vehicles send satellites to orbit and spacecraft on missions beyond Earth. However, those who were outside on a recent evening witnessed a rare spectacle. A spacecraft streaked across the night sky as four astronauts aboard a SpaceX Crew Dragon spacecraft re-entered the Earth’s atmosphere.

At just past midnight on Sept. 4, 2023, a bright object appeared in the southwest sky. As it moved northeast, the orange fireball developed a white tail that grew longer as it flew overhead heading toward a splashdown off the coast of Jacksonville. NASA astronauts Stephen Bowen and Woody Hoburg, along with Sultan Alneyadi of the United Arab Emirates and Roscosmos cosmonaut Andrey Fedyaev of Russia were returning from a six-month science expedition aboard the International Space Station.

When spacecraft re-enter the Earth’s atmosphere, it usually occurs over oceans or during daylight hours, making the fiery sight almost invisible for those on the ground. Allowing time for searching for a crewed capsule in the event of an off-target landing is no longer needed. Now landing’s are so precise, night landings are possible.

As a spacecraft capable of being navigated or following a predetermined course, it travels through the atmosphere causing friction resulting in heating to as much as 4,000 degrees Fahrenheit. A comet-like tail is created due to ionization with plasma encircling the spacecraft. Plasma is superheated matter – so hot that the electrons are ripped away from the atoms, forming ionized gas. This often makes it impossible for radio signals to be transmitted to or from the spacecraft. The result is a “communications blackout” for approximately two to five minutes.

In the late 1950s, developing a heat shield to protect returning astronauts from the heat was one of the key technologies required to bring crews safely home after trips into space. After research and testing, ablative heat shields were chosen as the best way to protect spacecraft from the dangerous heating caused by friction in the atmosphere.

As early as 1920 American rocket scientist Robert Goddard proposed ablative heat shields as the best option. In 1926, he launched the world’s first liquid propellants rocket.

“In the case of meteors, which enter the atmosphere with speeds as high as 30 miles per second (108,000 mph), the interior of the meteors remains cold, and the erosion is due, to a large extent, to chipping or cracking of the suddenly heated surface,” he said in his “Report Concerning Further Developments” of March 1920. “For this reason, if the outer surface of the apparatus were to consist of layers of a very infusible hard substance with layers of a poor heat conductor between, the surface would not be eroded to any considerable extent.”

As scientists and engineers studied the best way to protect America’s first astronauts as they returned from space, Goddard’s concept was tried on the first Project Mercury flight. Big Joe 1 launched an uncrewed boilerplate capsule from Cape Canaveral on Sept. 9, 1959. The primary goal of the flight test was to assess the re-entry dynamics of the spacecraft’s ablative heat shield. It worked just as Goddard predicted.

Similar to a meteor, Mercury, Gemini and Apollo spacecraft used ablative heat shields keep the astronauts cool by having layer after layer burn away, thus dissipating the heat of re-entry.

What is visible on the ground?

During the first flights of Project Mercury, the capsules came down so far from recovery ships that the actual splashdown under a parachute was not seen. As calculations improved, the final two flights, Mercury-8 and Mercury-9, landed close enough to aircraft carriers to be photographed as the spacecraft landed in the Pacific Ocean. Most of the Gemini and Apollo missions also landed within sight of the recovery crews.

But so far, no one saw the actual re-entry. That changed when Apollo 8 landed on Dec. 27, 1968 following that first trip in which astronauts orbited the Moon. With the splashdown occurring just before dawn, a U.S. Air Force Airborne Lightweight Optical Tracking System camera mounted on a KC-135 aircraft captured the first image of a crewed spacecraft during the fiery re-entry.

During the 30-year Space Shuttle Program, a new technology was required since the orbiters were to be used again and again. Protecting crews from the heat of re-entry were more than 25,000 thermal protection system tiles. With the Space Shuttle, the commander and pilot flew the spacecraft to precise landings at Edwards Air Force Base in California, the White Sands Missile Range in New Mexico or NASA’s Kennedy Space Center in Florida. Long-range cameras often picked up video images of the returning orbiter, but only after the fiery re-entry portion of the return was complete.

Newer, more precise technology allowed observers to see a re-entry on live television for the first time when NASA’s Orion spacecraft returned from its initial flight test on Dec. 5, 2014. Exploration Flight Test-1 launched a two-orbit test of the crew module designed for the agency’s Artemis Program designed to return astronauts to the Moon. The four-hour mission featured a high apogee at the end of the second orbit and concluded with a high-energy re-entry at 20,000 mph.

Calculations pinpointing the Orion spacecraft’s return allowed a high-altitude drone to capture video images of the capsule re-entering the atmosphere. Additionally, a television mounted in one of the Orion’s windows allowed brief live glimpses of the plasma stream from inside a spacecraft for the first time.

As spaceflight become more frequent with launches and returns at all hours, more people are likely to have an opportunity to witness the sights of not only rockets launching to space, but also spacecraft returning to Earth.

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