Last year was a very busy one in the final frontier.
Here's a rundown of some of the highlights, from the highly anticipated debut of SpaceX's giant Starship Mars rocket to the safe landing on Earth of NASA's first-ever pristine asteroid sample.
Related: 8 ways that SpaceX has transformed spaceflight
SpaceX's Starship launches first 2 test flights
Last year, we saw SpaceX make some significant headway in the company's development of its next-generation launch vehicle, Starship. The fully stacked rocket lifted off for the first time on April 20.
That flight lasted about 4 minutes. During the test, Starship's upper stage failed to separate from its Super Heavy booster. The vehicle began toppling end-over-end through the sky, ultimately reaching an explosive end with an autodestruct command. Super Heavy's 33 Raptor engines also blasted out a crater in the concrete beneath the launch pad at SpaceX's Starbase facility in South Texas, prompting upgrades to both the rocket and ground infrastructure.
Starship's next flight was delayed, pending the conclusion of investigations led by the United States Federal Aviation Administration (FAA) and Fish and Wildlife Service (USFWS) into the causes and consequences of Starship's April 20 mishap. SpaceX enacted 63 "corrective actions" at the direction of the FAA and was finally cleared to launch Starship again about seven months later, in November.
Starship launched for the second time Nov. 18. A water deluge system installed beneath the pad, and a new "hot-fire" staging system incorporated into Starship's launch procedures, solved two of the major issues the vehicle experienced during its first test, but Starship again failed to complete its full flight profile. A short time after stage separation, Super Heavy exploded, followed shortly by a communications loss with the Starship upper stage and its subsequent destruction.
After the November launch, SpaceX founder and CEO Elon Musk voiced optimism that the third Starship test flight could lift off shortly after, in December. And, in the middle of the month, SpaceX rolled Starship hardware to the pad for testing ahead of that anticipated launch. However, that flight still hasn't happened.
Major science missions
2023 was a great year for science missions launching into space. In April, the penultimate launch of Europe's Ariane 5 rocket sent the European Space Agency's (ESA) JUICE spacecraft on a journey to the Jovian system to study three of Jupiter's largest moons.
JUICE (short for "Jupiter Icy Moons Explorer") will spend the next eight years traveling to the gas giant, completing several gravity-assist maneuvers around Earth and Venus during the interim years. Once JUICE arrives at Jupiter in July 2031, it will begin studying the big moons Ganymede, Callisto and Europa, all of which are believed to contain liquid-water oceans beneath their icy, outer layers.
Another ESA mission launched on a SpaceX Falcon 9 rocket in July of last year, to study and map the "dark universe." The Euclid telescope is designed to study dark matter and dark energy, and will spend the next six years scoping out areas of the universe outside our Milky Way galaxy.
A third science mission, NASA's Psyche probe, launched on a Falcon Heavy in October. Psyche is on a 2.2 billion-mile (3.5 billion kilometers) journey to an asteroid of the same name, which is composed primarily of nickel and iron. Scientists believe the asteroid 16 Psyche may be the remnant of an ancient protoplanetary core, and they hope its study will yield clues into the processes of planetary formation.
OSIRIS-REx asteroid sample return landing
The return capsule from NASA's first mission to retrieve samples from an asteroid touched town in September of last year. OSIRIS-REx launched in 2016 and spent two years traveling to its target asteroid, Bennu. After an extensive survey in orbit around the space rock, OSIRIS-REx maneuvered to the asteroid's surface to collect its samples in October 2020.
After another few years in space, the OSIRIS-REx spacecraft's trajectory brought it back toward Earth, providing a window to eject the probe's sample return capsule on Sept. 24. As the capsule shot through Earth's atmosphere, the craft's heat shield protected the asteroid samples despite friction-induced temperatures as high as 5,300 degrees Fahrenheit (2,900 degrees Celsius) and speeds up to 27,000 mph (43,450 kph).
Following its fiery flight, the sample return capsule successfully deployed its main parachute and touched down for a soft landing at the Department of Defense's Utah Test and Training Range.
In a twist, NASA has yet to open OSIRIS-REx's main sample container, and is developing a new tool in order to safely remove its cover. However, even with the main samples still sealed shut, enough material was found to have collected outside the main sample container to exceed OSIRIS-REx's mission targets.
Though this is not the first material recovered from an asteroid in space, it is NASA's first such effort, and the largest amount snagged to date. Once the agency is able to open the probe's sample container, it plans to send 25% of the Bennu samples to more than 200 scientists across the globe, including those representing the space agencies of other nations.
Following the separation of its return capsule, the main OSIRIS-REx spacecraft changed its course toward a different target, an asteroid named Apophis. Now on a new mission called OSIRIS-APEX, the spacecraft will reach Apophis in 2029.
India lands on the moon
India became the fourth nation to successfully land on the moon when its Chandrayaan-3 mission achieved the feat in August of last year. Chandrayaan-3's landing duo consisted of two vehicles, the Vikram lander and the Pragyan rover. The Chandrayaan-3 propulsion module remained in lunar orbit to perform its own research.
The lander-rover duo touched in the moon's southern hemisphere, at around 70 degrees south, on Aug. 23. Once on the surface, Pragyan exited Vikram to begin its mission of analyzing the lunar soil and other surface material.
A few days after landing, the Indian Space Research Organization (ISRO) released an image of Vikram, snapped by Pragyan as it rolled along the surface of the moon. Their primary mission goals accomplished, both the rover and lander were later placed in sleep mode, as the lunar night set in on their landing site. However, after the dark, two-week lunar frost, teams at ISRO were unable to wake the vehicles.
Russia's moon crash
Russia also launched a mission to land on the moon during 2023. Unfortunately, however, its attempt was not successful.
Luna-25, the first Soviet/Russian lunar mission in 47 years, launched from the Vostochny Cosmodrome, in Russia's eastern Amur Region, on Aug. 10. Its mission was to land in the moon's south polar region, near Boguslawsky Crater, but a malfunction during one of the spacecraft's engine burns caused the probe to crash into the lunar surface.
"At about 14:57 Moscow time [on Aug. 19], communication with the Luna-25 spacecraft was interrupted," the Russian space agency, Roscosmos, wrote in a Telegram update (in Russian; translation by Google). "The measures taken on August 19 and 20 to search for the device and get into contact with it did not produce any results."
Several days later, NASA's Lunar Reconnaissance Orbiter (LRO) photographed the location of Luna-25's crash, and the crater its impact created.
Frank Rubio sets record for longest US spaceflight
International Space Station (ISS) Expedition 68/69 Flight Engineer Frank Rubio broke the U.S. single-spaceflight duration record last year. Rubio and his Russian cosmonaut crewmates, Sergey Prokopyev and Dmitri Petelin, launched to the ISS on Sept. 21, 2022, and were originally scheduled for a six-month stint aboard the orbital laboratory.
However, their MS-22 Soyuz spacecraft, which was supposed to carry them back to Earth, sprang a coolant leak in December 2022.
A replacement Soyuz (MS-23) was sent up as their ride home, but Rubio and his crewmates were unable to leave the space station without getting a replacement crew in place — which wasn't possible until September of last year.
Finally, Rubio and crew were able to return to Earth aboard the MS-23 Soyuz, landing in Dzhezkazgan, Kazakhstan on Sept. 27, 2023. In total, Rubio spent 371 continuous days in space, breaking the previous U.S. spaceflight record of 355 days, held by NASA astronaut Mark Vande Hei.
Russian spacecraft leak
About that Soyuz leak.
The MS-22 Soyuz launched with Rubio, Prokopyev and Petelin on Sept. 21, 2022, and docked with the ISS later that day. All was nominal for the trio's first few months, but just a couple of weeks before the end of 2022, the Soyuz spacecraft sprang a significant leak, draining all its coolant out into space.
The leak ostensibly stranded Prokopyev, Petelin and Rubio aboard the space station with no way home, though contingencies were put into place should the ISS crew need to evacuate in an emergency situation. An empty replacement Soyuz arrived at the station in February, finally offering the three a dedicated ride back to Earth.
However, the Soyuz they received (MS-23) was originally slated to fly Expedition 69's replacement crew. Its use in place of MS-22 meant the next ISS crew couldn't launch to the space station until Soyuz MS-24 was ready to fly, which wasn't until September, when Rubio, Prokopyev and Petelin finally came home.
The leaky Soyuz MS-22 returned to Earth without crew, and was recovered by Roscosmos for evaluation in March of last year. Russian officials have yet to announce a definitive cause for the coolant leak, but initial hypotheses at the time of the event suggested it may have been the result of a micrometeor impact.
'Silent Barker,' the mysterious US military launch
The United States National Reconnaissance Office (NRO) launched a sizable classified satellite last year on a mission called "Silent Barker."
The September launch took place aboard a United Launch Alliance Atlas V rocket, accompanied by the vehicle's largest payload fairing option. The launch took the satellite, designated NROL-107, to a geosynchronous orbit (GEO) above Earth, essentially parking the spacecraft in place in the sky.
Prior to launch, U.S. Space Force Lt. General Michael Guetlein, commander of Space Systems Command, said in a teleconference, "A huge element of deterrence is the ability for the adversary to know what we can and cannot see."
"So we actually want our competitors to know that we have eyes in GEO and that we can see what's happening in GEO," Guetlein added. "Not only are we going to maintain custody and the ability to detect what's going on in GEO, but we'll have the indications and warnings to know there's something out of the normal occurring, and that goes a long way towards deterrence."
Virgin Galactic begins commercial spaceflights
After years of delays, Virgin Galactic began flying regular private missions to suborbital space in 2023.
The company's first mission, Galactic 01, took off June 29 and carried members of the Italian Air Force and Italy's National Research Council on a research flight that provided the trio a few minutes of weightlessness at their trajectory's apex.
Before launching under its own power, Virgin Galactic's VSS Unity space plane is flown to altitude by the double-fuselaged carrier aircraft VMS Eve. At around 50,000 feet (15,000 meters) up, VSS Unity is released from Eve to burn its rocket motor and complete its climb to space.
Both carrier aircraft and space plane then return for landing on the same runway where the duo take off, at Spaceport America in New Mexico.
After Virgin Galactic's first commercial launch in June, the company kept pace with another mission every month for nearly the rest of 2023, flying a total of 15 private customers. Topping off the year with Galactic 05 in November, the company announced it would ground Unity in December, and resume flights again in January 2024.
On Dec. 19, Virgin Galactic announced Galactic 06 would fly Jan. 26 of this year using VSS Unity, which is expected to be grounded sometime in 2024 and replaced with the company's next-generation "Delta class" vehicle.
SpaceX tops its own launch record, again
SpaceX has, once again, had its busiest year yet. In 2022, the company set a new record with 61 orbital launches. SpaceX blew through that total in 2023, with more than 90 orbital liftoffs — though the company likely won't hit the century mark, a milestone Elon Musk had floated earlier in the year.
The majority of SpaceX launches last year have used the company's mainstay Falcon 9 rocket, and have supported the growth of SpaceX's Starlink broadband megaconstellation. Thanks to its increased launch cadence, SpaceX was able to increase the number of its internet spacecraft on orbit by nearly 2,000 last year.
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