March 28, 2018

When astronaut Scott Kelly returned to Earth from a year-long mission aboard the International Space Station (ISS) on March 1, 2016, he was a changed man. Literally. Compared to his identical twin brother, fellow astronaut Mark Kelly, there were several noticeable differences. Scott Kelly had grown about 2 inches (5 centimeters) taller in space, and his overall body mass had decreased a bit. However, National Aeronautics and Space Administration (NASA) scientists were most interested in the changes that could not be seen, changes in Kelly’s genetic makeup. And unlike his physical metamorphosis (his body soon resumed its Earthbound proportions), some changes in Kelly’s DNA seem to be permanent.

U.S. astronaut Scott Kelly poses inside the International Space Station in 2015. Kelly’s body and genetic makeup changed during his weightless year in space.

In 2015, Scott Kelly and Russian cosmonaut Mikhail Kornienko began a unique experiment to learn about the effects of long-term space travel on the human body. The pair spent 340 consecutive days on the ISS as part of a study that will help NASA scientists understand the challenges they must conquer if humans are ever to journey to Mars and beyond. Kelly and Kornienko orbited Earth more than 10,000 times speeding at 17,500 miles per hour (28,165 kilometers per hour) while floating in the weightlessness of microgravity (a condition of very low gravity). During this time, they experienced the stresses and solitude of long-term space flight and were exposed to cosmic radiation above the protective filter of Earth’s atmosphere.

NASA astronaut Scott Kelly (left) and Russian cosmonaut Mikhail Kornienko pose during training at NASA’s Johnson Space Center prior to their year in space. Credit: Bill Stafford, NASA

For experimental control, Scott’s brother Mark remained on Earth. As Scott’s identical twin brother, Mark’s genetic makeup is exactly the same as Scott’s. After Scott returned, NASA scientists studied the twin brothers. Any differences between Scott and Mark could be seen as the effects of the long-term space travel.

The growth spurt that Scott Kelly experienced in orbit turned out to be short-lived and he soon shrank back to his normal height as he returned to Earth’s gravity. But NASA scientists were surprised to find that Scott’s DNA, the genetic material that makes up his genes, was now significantly different from his twin. They found that about 7 percent of Scott’s genes, including those involved in bone formation, DNA repair, oxygen use, the immune system, and eyesight, had altered function when compared to Mark’s genes. Many of these genetic changes appear to be permanent.

NASA scientists think that Scott’s long-term mission in space altered his DNA through processes called epigenetics. Scientists have long known that environmental factors can alter how genes are expressed (how they function) in organisms through epigenetic processes. These processes are not mutations, nor are they physical changes in the DNA. Rather, the processes change how a particular gene functions. Various factors may switch a particular gene on or off or otherwise change how it is expressed. Such environmental factors include nutrition, exposure to certain chemicals, and stress. Scott and Mark remain genetically identical twins, but some of Scott’s genes are now expressed differently compared to Mark’s because of his time in space.

December 9, 2016

One of the heroes of the early Space Age is gone. United States astronaut and Senator John Glenn died yesterday afternoon in Columbus, Ohio, at the age of 95. He was the first American to orbit Earth, on Feb. 20, 1962.

Astronaut John H. Glenn Jr. in his Mercury spacesuit, February 1962.
Credit: NASA

John Herschel Glenn, Jr., was born on July 18, 1921, in Cambridge, Ohio. He grew up in New Concord, Ohio. He became a pilot for the U.S. Marine Corps, serving in both World War II (1939-1945) and the Korean War (1950-1953). After the wars, he served as a test pilot for new supersonic aircraft, which travel faster than the speed of sound. In 1959, he was chosen to be one of the first seven National Aeronautics and Space Administration (NASA) astronauts. Being the oldest of the group, he actively lobbied to be the first American sent into space, but the honor instead went to Alan Shepard.

At the start of the 1960’s, it was clear that the United States was losing the space race. The space race was a period of intense competition between the United States and the Soviet Union (a powerful state made up of what is now Russia and several other surrounding countries) to achieve supremacy in space exploration. The Soviet Union launched the first artificial satellite, Sputnik, in 1957, several months before the United States launched its first satellite, Explorer 1. On April 12, 1961, Soviet cosmonaut Yuri Gagarin became the first human space traveler by orbiting Earth in his spaceship Vostok (later called Vostok 1). Two U.S. flights followed that year, but neither Alan Shepard nor the next American astronaut, Virgil (Gus) Grissom, orbited Earth. The flights were short, lasting only about 15 minutes.

Glenn orbited Earth three times during his historic flight. He was probably the first human being to “fly” a spacecraft manually for any length of time. During the flight, the autopilot malfunctioned, causing the spacecraft to tilt to the right. Glenn held the spacecraft in its proper position for the rest of the flight using the vehicle’s manual controls.

Glenn’s flight brought confidence back to the U.S. space program and made him a national hero. Spurred on by its own success and the continued advances of the Soviet Union, NASA surged ahead in the space race, putting U.S. astronauts on the moon less than 10 years after Glenn’s orbital flight. Glenn’s fame likely cost him his career as an astronaut, however. He was eager to fly in more missions, but U.S. President John F. Kennedy deemed his value as a national hero too great to risk another dangerous spaceflight. Frustrated, Glenn resigned from NASA in 1964.

After he left NASA, Glenn decided to go into politics. He won election to the Senate from Ohio in 1974. In the Senate, Glenn worked to stop the spread of nuclear weapons and was a supporter of providing federal aid to industries suffering from financial problems, such as the steel and automobile industries. Glenn campaigned for the 1984 Democratic presidential nomination but dropped out early in the race. He continued to serve as a senator until 1998.

Glenn’s wish to return to space was finally granted in 1998, when he traveled aboard the space shuttle Discovery. During the flight, he took part in experiments dealing with physical problems experienced by astronauts in space and elderly people on Earth. Glenn was 77 years old at the time of the mission, making him the oldest person ever to take part in space travel.

As a fighter pilot in two wars, an astronaut in two missions 36 years apart, and a senator for 24 years, Glenn leaves behind a towering legacy of service to his country matched by few people in U.S. history. His humility and patriotism impressed everyone he met. Glenn was an American hero, the likes of which may never be seen again.

Back in Time article

• Space exploration (1998)

Feb. 20, 2012

Fifty years ago today, astronaut John H. Glenn, Jr., became the first American to orbit Earth. As millions of people watched on television, he circled the planet three times in slightly less than five hours in his Friendship 7 spacecraft. Glenn’s mission helped reassure Americans that the United States could successfully compete in the “space race” with the Soviet Union (now Russia). The Soviets had launched the first human being, Yuri A. Gagarin, into space on April 12, 1961. In May 1961, Alan B. Shepard, Jr., became the first American in space. Later that year, two Soviet cosmonauts (astronauts) made the first orbital flights around Earth.

Glenn’s historic flight lasted 4 hours 55 minutes from launch to landing. Friendship 7 lifted off from Cape Canaveral, Florida, at 9:47 a.m. (EST) on Feb. 20, 1962. Each of Glenn’s three orbits lasted about 1¹/2 hours. He traveled 80,966 statute miles (130,302 kilometers) at altitudes ranging from 98.9 to 162.5 miles (159.2 to 261.5 kilometers). Glenn was probably the first human being to “pilot” a spacecraft manually for any length of time.

Astronaut John H. Glenn, Jr., became the first American to orbit Earth. On Feb. 20, 1962, Glenn circled the planet three times in less than five hours. He made his historic flight in a spacecraft named Friendship 7. Glenn resigned from the astronaut program in 1964. NASA

After crossing the Atlantic Ocean, Glenn flew over Africa, the Indian Ocean, and Australia. Then the spacecraft sped over the Pacific Ocean, the West Coast of the United States, and back again over Florida. Eighteen radar stations around the world kept track of the spacecraft.

Upon his return to Earth, Glenn found himself a national hero, with huge parades staged in his honor. In New York City, Glenn was honored with one of that city’s famous ticker tape parades. Glenn eventually retired from the U.S. Marines, and in 1974, he was elected to the U.S. Senate from Ohio.

In 1998, when Glenn was 77, he returned to space aboard the space shuttle Discovery. On this mission, he became the oldest person ever to take part in space travel.

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• Space exploration
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