Bringing an Asteroid Home
2023 — OSIRIS-REx Delivers a Sample of Asteroid Bennu to Earth
14:52 UTC
On September 24, 2023, a small capsule descended by parachute into the Utah desert carrying something that had never before been delivered to Earth by an American spacecraft: a sample collected directly from an asteroid.
Inside were rocks and dust from 101955 Bennu, a small near-Earth asteroid whose material preserves evidence from the earliest history of the solar system.
The capsule belonged to NASA's OSIRIS-REx mission—Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer. The spacecraft had launched on September 8, 2016, beginning a seven-year journey that ultimately covered approximately 2.2 billion miles.
OSIRIS-REx reached Bennu in December 2018 and spent nearly two years mapping and studying the asteroid.
Bennu proved more surprising than expected. Instead of the relatively smooth, sandy surface mission planners had anticipated, the asteroid was covered with boulders and rubble. Scientists had to identify a sufficiently safe location from which the spacecraft could attempt its most important maneuver.
On October 20, 2020, OSIRIS-REx descended toward a site named Nightingale.
The spacecraft did not land in the conventional sense. Its robotic sampling arm briefly touched the surface and released compressed nitrogen gas, disturbing Bennu's loose material and forcing particles into the collection chamber.
The encounter lasted only seconds.
But it worked exceptionally well. NASA later determined that OSIRIS-REx had collected 121.6 grams—4.29 ounces—of material, more than twice the mission's minimum requirement.
On May 10, 2021, the spacecraft departed Bennu and began the long journey home.
More than two years later, on September 24, 2023, OSIRIS-REx approached Earth.
At 10:42 UTC, while approximately 102,000 kilometers (63,000 miles) above Earth, the spacecraft released its sample-return capsule. OSIRIS-REx itself did not land. About 20 minutes after releasing the capsule, it fired its engines and diverted away from Earth toward a new destination.
The capsule continued alone.
At approximately 14:42 UTC, traveling about 44,500 kilometers per hour (27,650 miles per hour), it entered Earth's atmosphere off the coast of California. Protected by its heat shield, the capsule survived the fiery descent while parachutes progressively slowed it.
At 14:52 UTC, it touched down at the Department of Defense's Utah Test and Training Range at only about 18 kilometers per hour (11 miles per hour).
Recovery teams quickly secured the capsule and moved it into a temporary clean room. The sample was subsequently transported to NASA's Johnson Space Center, where material from Bennu could be preserved, catalogued, distributed to researchers, and retained for scientists of future generations.
Bennu's importance reaches far beyond the asteroid itself.
Primitive asteroids contain material that has changed relatively little since the solar system formed about 4.6 billion years ago. By studying pristine samples in laboratories on Earth, scientists can investigate the chemistry and minerals present when planets were forming—and search for clues about how water and carbon-rich compounds important to life reached the early Earth.
Meanwhile, the spacecraft that delivered the sample continued onward. Renamed OSIRIS-APEX, it began an extended mission to study the near-Earth asteroid Apophis following that asteroid's exceptionally close approach to Earth in 2029.
Why It Matters: OSIRIS-REx completed the first American asteroid sample-return mission and brought to Earth a pristine collection of material from the early solar system. Instead of relying solely on telescopes or instruments aboard spacecraft, scientists can now examine pieces of Bennu repeatedly with some of the most sophisticated laboratory equipment ever built—and preserve portions for technologies that do not yet exist.
Also on This Day
1906 — Astrophysicist Pol Swings Is Born
Time unknown
On September 24, 1906, Belgian astrophysicist Pol Swings was born in Ransart, Belgium.
Swings became an important figure in twentieth-century spectroscopy, the science of separating light into its component wavelengths and using those patterns to determine the physical and chemical properties of astronomical objects.
Spectroscopy transformed astronomy.
A telescope can show astronomers where an object is and what it looks like. A spectrum can reveal what the object is made of, how hot it is, how it is moving, and what physical processes are occurring within it.
Swings applied these techniques particularly effectively to stars, comets, nebulae, novae, and interstellar matter.
His name became associated with the Swings effect, which helps explain changes in the strength of molecular emission lines observed in comets. Because molecules in a comet's atmosphere fluoresce in sunlight, their observed emission can depend upon the comet's velocity relative to the Sun and the detailed structure of the solar spectrum.
Swings's work helped demonstrate that the spectra of comets could reveal the molecules present in their gaseous atmospheres and the physical processes producing their characteristic glow.
His broader research contributed to the rapidly developing understanding that the seemingly empty spaces between stars contain detectable atoms and molecules and that spectroscopy could be used to investigate environments far beyond the reach of any spacecraft.
Why It Matters: Pol Swings helped extend spectroscopy into the study of comets and interstellar space. His career represents one of astronomy's most powerful developments: learning to use light not merely to see distant objects, but to determine their composition and physical behavior.
1930 — Astronaut John Young Is Born
Time unknown
On September 24, 1930, John Watts Young was born in San Francisco, California.
Few astronauts would participate in as many distinct eras of American human spaceflight.
Young joined NASA's second astronaut group in 1962 and made his first spaceflight aboard Gemini 3 in March 1965. With Gus Grissom, he participated in the first crewed Gemini mission—and became famous for smuggling a corned-beef sandwich aboard the spacecraft.
He returned to space aboard Gemini 10 in 1966, commanding a demanding mission involving rendezvous and docking.
Then came Apollo.
Young served as command module pilot aboard Apollo 10 in 1969, the full-scale dress rehearsal for the first lunar landing. While Thomas Stafford and Eugene Cernan descended toward the Moon in the lunar module, Young remained in lunar orbit aboard the command module Charlie Brown.
In April 1972, Young returned as commander of Apollo 16.
This time, he landed.
Young and Charles Duke spent more than 20 hours outside the lunar module exploring the Descartes Highlands, while Ken Mattingly remained in lunar orbit. Young thereby became the ninth person to walk on the Moon.
But his career was far from finished.
On April 12, 1981, Young sat beside Robert Crippen aboard Columbia for STS-1, the first flight of the Space Shuttle. No uncrewed orbital test had preceded them. The first complete Shuttle system to reach orbit carried astronauts.
Young flew once more, commanding STS-9 in 1983, the first Shuttle mission to carry the European-built Spacelab laboratory.
Across six spaceflights, Young flew aboard Gemini spacecraft, Apollo command and lunar modules, and the Space Shuttle. NASA records his total time in space as more than 34 days.
Why It Matters: John Young's career forms a remarkable bridge across the history of American human spaceflight. He flew during Gemini, orbited and walked on the Moon during Apollo, and commanded the maiden flight of the Space Shuttle. Few individuals personally participated in so many transitions in spacecraft and exploration.
1970 — Luna 16 Returns a Piece of the Moon to Earth
Approximately 06:26 UTC
On September 24, 1970, a small Soviet capsule descended by parachute onto the steppes of Kazakhstan.
Inside were approximately 101 grams (3.5 ounces) of lunar soil.
The capsule belonged to Luna 16, which had accomplished something no robotic spacecraft had ever done before.
It had gone to another world, landed there, collected material, launched that material from the surface, and returned it to Earth.
Luna 16 had launched on September 12 and landed in Mare Fecunditatis—the Sea of Fertility—on September 20. Its automated drill penetrated approximately 35 centimeters into the lunar regolith and transferred the collected material into a sealed return container.
On September 21, the ascent stage lifted off from the Moon.
Three days later, it reached Earth.
A NASA historical chronology records that the return vehicle entered Earth's atmosphere at approximately 06:00 UTC on September 24 and descended by parachute about 26 minutes later, giving a landing time of approximately 06:26 UTC.
The capsule was recovered and transported for scientific examination.
Apollo 11 and Apollo 12 astronauts had already returned much larger quantities of lunar material. But Luna 16 demonstrated an entirely different approach: sample return without a human crew.
That capability would eventually be applied far beyond the Moon.
Robotic spacecraft have since returned particles from a comet, material from asteroids, and samples of the solar wind. Future missions may attempt sample returns from still more distant destinations.
Why It Matters: Luna 16 completed the first successful robotic sample return from another celestial body. It demonstrated that machines could perform the complicated sequence of landing, sampling, launching, navigating home, and delivering extraterrestrial material safely to scientists on Earth.
2014 — India's Mars Orbiter Mission Reaches Mars
Mars orbit insertion burn began 01:47:32 UTC
On September 24, 2014, India's Mars Orbiter Mission, popularly known as Mangalyaan, fired its main engine and successfully entered orbit around Mars.
The achievement made India the first nation to reach Mars successfully on its first attempt.
The Indian Space Research Organisation—ISRO—had launched Mangalyaan on November 5, 2013, aboard a Polar Satellite Launch Vehicle from the Satish Dhawan Space Centre.
Because the launcher could not send the spacecraft directly toward Mars, Mangalyaan initially entered Earth orbit and gradually raised its orbit through a series of engine burns before departing for interplanetary space.
After a journey lasting more than ten months, the spacecraft approached Mars.
At 07:17:32 Indian Standard Time—01:47:32 UTC—on September 24, Mangalyaan's 440-newton liquid apogee motor and eight smaller thrusters began firing. The burn lasted approximately 1,388.67 seconds, reducing the spacecraft's velocity by about 1,099 meters per second.
Mars captured it.
Mangalyaan entered a highly elliptical orbit with an initial periapsis of approximately 422 kilometers and an apoapsis of roughly 77,000 kilometers.
The achievement was remarkable for several reasons.
India became the first Asian nation to place a spacecraft into Martian orbit, and ISRO achieved Mars orbit on its first attempt. The mission had also been developed on a comparatively modest budget and schedule, demonstrating India's rapidly advancing capability in deep-space navigation, spacecraft autonomy, propulsion, and communications.
Mangalyaan carried five scientific instruments designed to investigate the Martian surface and atmosphere. Its Mars Colour Camera returned striking global images of the planet and its moons, while other instruments investigated atmospheric composition, surface properties, and the Martian exosphere.
Originally designed for a mission life of only about six months, Mangalyaan continued operating for years.
Why It Matters: Mangalyaan established India as an interplanetary spacefaring nation and demonstrated that sophisticated Mars exploration could be achieved with a relatively small spacecraft and carefully constrained resources. Its success significantly broadened the international community capable of conducting deep-space planetary exploration.
The Bigger Picture
September 24 provides an extraordinary opportunity to watch robotic planetary exploration mature across more than half a century.
In 1970, Luna 16 brought approximately 101 grams of the Moon to Earth.
The achievement was revolutionary. A machine had traveled to another world, collected part of it, and brought that material home.
In 2014, Mangalyaan demonstrated another transformation. Deep-space exploration was no longer an enterprise confined primarily to the United States, Russia, Europe, and Japan. India had successfully navigated a spacecraft to Mars on its first attempt.
Then, in 2023, OSIRIS-REx brought the sample-return idea to an entirely different kind of world.
Bennu has almost no gravity compared with the Moon. OSIRIS-REx could not simply land, drill, launch, and return in the manner of Luna 16. Engineers devised a different solution: approach the surface, touch it briefly, stir up material with nitrogen gas, capture the particles, retreat, and eventually carry them back across interplanetary space.
Between these missions stands the career of John Young, representing the parallel human story. He helped humans learn to maneuver in Earth orbit, traveled twice to the Moon, walked upon it, and then commanded the first flight of a reusable orbital spacecraft.
And Pol Swings reminds us that exploration does not always require going anywhere at all. By analyzing light, astronomers can determine the chemistry and physics of objects that remain impossibly distant.
The progression is remarkable:
analyze distant matter through its light → send humans to another world → bring another world's material home robotically → expand planetary exploration to new nations → retrieve material from a tiny asteroid millions of kilometers away.
But September 24 reveals something deeper as well.
When Luna 16 returned lunar soil in 1970, scientists gained material that could be studied with instruments available at the time—and then preserved for future researchers.
OSIRIS-REx follows the same philosophy. Not all of Bennu's sample will be consumed by today's experiments. A substantial portion is being preserved so that scientists decades from now can examine it using techniques that have not yet been invented.
Sample-return missions therefore do something unusual.
They bring the past of the solar system into laboratories on Earth—and preserve some of it for the future of science.
At a Glance
1906 — Time unknown — Belgian astrophysicist Pol Swings is born; his later spectroscopic work advances understanding of stars, comets, and interstellar matter.
1930 — Time unknown — John Young is born in San Francisco; he will fly six missions spanning Gemini, Apollo, and the Space Shuttle and become the ninth person to walk on the Moon.
1970 — Approximately 06:26 UTC — Luna 16's return capsule lands in Kazakhstan carrying approximately 101 grams of lunar material, completing the first successful robotic sample return from another celestial body.
2014 — 01:47:32 UTC — India's Mars Orbiter Mission begins its orbit-insertion burn and successfully enters orbit around Mars.
2023 — 10:42 UTC — OSIRIS-REx releases its Bennu sample-return capsule toward Earth from approximately 102,000 kilometers away.
2023 — 14:42 UTC — The capsule enters Earth's atmosphere off the California coast at approximately 44,500 kilometers per hour.
2023 — 14:52 UTC — The OSIRIS-REx capsule touches down in Utah carrying 121.6 grams of material from asteroid Bennu, completing the first U.S. asteroid sample-return mission.
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