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For two decades, the International Space Station has been humanity’s home in space.
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The track laboratory was launched in 1998 and has exceeded its expected lifespan of 15 years.
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ISS science led to ground-breaking research and international scientific collaborations.
The International Space Station has been humanity’s only inhabited outpost in space for decades.
NASA aims to keep the space station running until 2030 and beyond, even opening it up to commercial spaceflight.
Russia’s space chief announced on Tuesday that it would pull out of the aging station after 2024. But officials have since told NASA they want to continue the cooperation at least until it builds its own space station, according to Reuters. This could mean the ISS will remain a beacon of international cooperation for at least another six years, Reuters reported.
Here are eight unforgettable moments from the ISS’s 24 years in space:
The landmark ‘Twins Study’, which showed that living in space can change human DNA
Much of the research at the ISS is preparatory to understanding the effects of space exploration on humans, before setting foot on the moon and Mars. NASA’s groundbreaking “Twin Study” compared the health and biology of astronaut Mark Kelly with his Earth-bound identical twin, Scott Kelly.
The study, published in 2019, found that Kelly’s DNA changed in space. When Scott returned to Earth after 340 days aboard the ISS, scientists found that his telomeres – the protective caps at the end of DNA strands – were unexpectedly longer than Mark’s telomeres.
Scientists are also conducting experiments aboard the ISS to combat bone and muscle loss. According to NASA, astronauts lose between 1 and 2% of their bone density for every month they spend in space.
The first observation of an unusual ‘cool flame’
During an unrelated experiment, conducted in 2012, scientists aboard the ISS were able to observe large fuel droplets of heptane being extinguished twice. While the first burn was at the traditional higher temperature, the second time it went out, the researchers observed low-temperature, soot-free flames in steadily burning fuel for the first time.
This so-called “cool flame” flickers at about 600 degrees Celsius (about 1,120 degrees Fahrenheit), according to NASA. That’s about half the temperature of a candle flame, which burns at about 1,400 degrees Celsius (2,500 degrees Fahrenheit).
The flame burns much longer in a low-gravity environment, such as aboard the ISS, which allowed scientists to see the flame in heptane fuel burning for the first time, according to NASA.
The discovery could help scientists use fuel more efficiently in the future and improve fire safety on the ISS.
Astronauts send the first tweets from the ISS
In 2010, astronaut Timothy “TJ” Creamer sent the first live tweet from the International Space Station, after the space station upgraded to a better Internet connection, giving astronauts access to social media.
However, this was not the first tweet sent from an astronaut aboard the ISS.
Internet access on the space station was limited until 2010, so astronaut Mike Massimino had a tweet sent by NASA on his behalf in 2009. Massimino sent messages to NASA’s Mission Control Center on Earth and NASA tweeted them out:
“From orbit: The launch was amazing! I’m feeling great, working hard and enjoying the amazing view, the adventure of a lifetime has begun,” tweeted Massimo, with help from NASA.
The ISS became one of the first destinations for space travel
The first space tourist was Dennis Tito, an American millionaire who boarded the ISS on April 30, 2001, and stayed on board for eight days.
A total of 14 people have gone to the space station as commercial astronauts, the official term for space tourists, including Cirque du Soleil founder Guy Laliberté, Russian film director Klim Shipenko, actor Yulia Peresild, billionaire Yusaku Maezawa, and production assistant Yozo Hirano.
NASA has also opened up the ISS commercial space capabilities in recent years. In April 2022, Axiom Space, a commercial space company, launched the first private mission to the ISS. “We are opening a new era in human spaceflight,” Michael López-Alegría, a former NASA astronaut who is also an Axiom executive and mission manager, said on Twitter in April. “We are taking the first step in a next-generation platform initiative that will bring working, living and researching in space to a much wider and more international audience.”
Astronauts grew plants on the ISS and made space tacos
Astronauts have successfully grown fresh food aboard the space station to help NASA study plant growth in low gravity, providing them with fresh grub and gaining insight into how to provide future astronauts with a sustainable, long-lasting food source. The agency says the ISS astronauts have successfully harvested three types of lettuce, radishes and peas. In 2021, scientists aboard the ISS grew chili peppers grown in space and used them, along with fajita beef and vegetables, to make the first space tacos.
Astronauts don’t just grow edible plants. In 2016, astronaut Scott Kelly shared photos of his space-grown zinnia flower, making it the first flower to bloom in space.
A Russian film crew filmed the first fiction film to be shot entirely in space
A Russian film crew went to the ISS in October 2021 to film a full-length film aboard the space station. The film follows a Russian doctor sent to the station to treat a critically ill cosmonaut.
“I feel a little sad today,” actress Yulia Peresild said on Russian state television, after landing on Earth after 12 days of filming, according to CBS News. “It seemed like 12 days would be a lot, but I didn’t want to leave when it was all over.”
Nevertheless, there is disagreement as to whether this is the first fiction production to be filmed in space. An eight-minute film shot by space tourist Richard Garriot called “Apogee of Fear” took place aboard the ISS in 2008 and starred astronauts on the ISS.
An ongoing example of international cooperation in a divided world
The ISS has been a shining example of international cooperation since it was launched in 1998. The station involves space agencies from the US, Europe, Canada and Japan, with a rotating crew of astronauts.
As of May 2022, hundreds of individuals from 20 countries have visited the ISS, according to NASA.
In July 2022, amid high tensions between Russia and the United States over the war in Ukraine, Russia’s space agency announced its plans to withdraw from the ISS after 2024, ending a decade-long partnership with NASA at the orbiting outpost. In a statement on July 26, NASA Administrator Bill Nelson said the agency has not been notified by Roscosmos of any plans to end the ISS collaboration.
“NASA is committed to the safe operation of the International Space Station through 2030, and is coordinating with our partners,” Nelson said in the statement, according to The New York Times. “NASA has not been made aware of decisions by either partner.”
Dazzling views of Earth from space – including northern lights and volcanic eruptions
Astronauts aboard the ISS — like the station itself — travel at 17,500 mph, 250 miles above the planet, orbiting it every 90 minutes. With this vantage point, they regularly share beautiful images looking down on the earth, taking pictures of phenomena such as the northern lights, severe storms, volcanic eruptions and light pollution. In a 1987 book, author Frank White coined the term “overview effect,” referring to the high report astronauts experienced after viewing Earth from space.
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