Nasa astronaut Scott Kelly on a spacewalk
Scott Kelly during a spacewalk. Nasa

The International Day of Human Space Flight has been held for the past six years on 12 April – the day that the first human flew into space, more than five decades ago. Since then, men and women have kept pushing back the boundaries of space exploration, breaking new records and furthering our knowledge of space and astronomy.

Nasa scientists are now planning to take human space journey even further, as they prepare to send humans to the Red Planet in the 2030s. IBTimes UK takes a look at some of humans' key achievements in space.

1) First person in space

12 April 1961 will always be remembered as the first milestone of human space flight. Soviet cosmonaut Yuri Gagarin, then aged 27, completed a 108-minute orbit of the Earth. This was a major victory for the USSR in the context of the cold war and the space race.

April 12 was officially made International Day of Human Space Flight in 2011 to mark the 50th anniversary of Gagarin's pioneer journey, which paved the way for all subsequent human missions in space.

The first woman in space was Soviet cosmonaut Valentina Tereshkova, who launched on the Vostok 6 mission on 16 June 1963.

2) First person to walk on the Moon

On 16 July 1969, Nasa launched the Apollo 11 mission, sending three of its cosmonauts to the Moon – Neil Armstrong, Buzz Aldrin and Michael Collins.

Armstrong was the first to set foot on the Moon on 20 July 1969, quickly followed by Aldrin. They both walked for three hours, conducting experiments and leaving the US flag on Earth's natural satellite. They safely returned on 24 July 1969 – less than 10 years after the US first decided to send men to the Moon.

No astronauts have been back on the Moon in nearly 50 years (the last one was Eugene Cernan in 1972) and so far, no women have made the journey or walked on its surface.

Moon walk
21 July 1969: American astronauts Neil Armstrong and Buzz Aldrin become the first men to walk on the Moon, effectively bringing an end to the space race Nasa

3) Most time spent in space

In 2015, Gennady Padalka broke the record for the most time spent in Space. Over the course of his career, the Russian cosmonaut spent a cumulative total of 878 days in space – almost two and a half years.

However, he does not hold the record for the greatest number of days spent continuously in space without coming back to Earth. This one belongs to his fellow countryman Cosmonaut Valeri Polyakov who returned to Earth in 1995 after having spent 437 aboard the Mir space station.

American astronaut Peggy Whitson had for her part spent a total of 377 days in space throughout her career. But on 17 November 2016, she launched once more for the International Space Station – also becoming the oldest woman in space at the age of 56.

She has now just assumed command of the station for the second time and will stay there until September – breaking Jeff Williams' standing United States record of 534 cumulative days in space in the process.

ISS Peggy Whitson
The International Space Station (ISS) crew member Peggy Whitson of the US waves before a space suit check at the Baikonur cosmodrome, Kazakhstan, November 17, 2016. REUTERS/Shamil Zhumatov

4) Longest time spent on the Moon

This record was broken during Apollo 17, the final mission of Nasa's program to land humans on the Moon. Astronauts Eugene Cernan and Harrison Schmitt spent 74 hours 59 minutes 40 seconds on the surface of the Moon after landing on 11 December 1972.

5) Farthest humans from Earth

The Apollo 13 crew flew at the greatest distance from Earth on 15 April 1970, reaching 254 km (158 miles) from the lunar surface, on the far side of the Moon, and 400,171 km (248,655 miles) above the Earth's surface.

6) Youngest person to fly in Space

The youngest person ever to journey in space was the Russian Gherman Titov, who was 25 years old when he flew Vostok 2. He was also the first person to suffer from space sickness.

7) Oldest person to fly in Space

In 1998, the American John Glenn became the oldest man to fly in space aboard the space shuttle Discovery, at the age of 77.

John Glenn
John Herschel Glenn Jr on 14 April, 1998 NASA

The mission lasted nine days and was intended to test how his body responded to the microgravity environment, to study how spending time in space can age the human body.

8) Greatest number of spacewalks

The first person to go on a spacewalk was the Russian Alexei Leonov on 18 March 1965. The walk lasted for 10 minutes.

However, the world record for the most spacewalks is by another Russian astronaut called Anatoly Solovyev. He participated in 16 spacewalks, spending more than 82 hours walking in space.

9) First music video on the Moon

In May 2013, Canadian commander Chris Hadfield posted a video to YouTube of him singing a version of David Bowie's Space Oddity. The video was unique as it was the first ever entirely recorded in space, during his last mission on board the International Space Station (ISS).

As for the music, the vocals and guitar were recorded on the station, while piano and other musical accompaniment were added by performers on Earth.

10) First married couple in space

Nasa didn't originally want couples to go together in space. The first married couple to fly in space together were astronauts Jan Davis and Mark Lee. They were part of a crew aboard the space shuttle Endeavor, and took part in a mission that started on 12 September 1992 and lasted eight days.