Until yesterday, when two other cosmonauts and an astronaut came down, the Space Station was getting a bit crowded with 10 people on board.

However, even just for a day, it will get even more crowded when four astronauts - two American, one Japanese, and one French - head up to space on SpaceX Crew-2, bringing the total of people to 11.

It is planned this will only be for a few hours before the SpaceX Crew-1 comes down with four, leaving seven people in space.

Seven on the International Space Station can be a bit cozy.

The pressurized volume (i.e. the parts that can support humans) is just over 915 cubic metres.

This is about the size of a large, five-bedroom house.

While that may sound not bad, keep in mind, you can't exactly step outside for some fresh air.

Your sleeping and private area is the size of a hallway closet, so it is hard to get some alone time.

In the past, the Space Station has generally been designed to support about six people.

However, there have only been three to four on board for the past few years.

The limitation was mainly only having the Russian Soyuz to take people up and down.

Now, with SpaceX Crew Dragon, and later this year, Boeing's CST Starliner, more rides into space means more people can go up.

Eleven isn't quite the record though for the most people in space.

Three times, in 1995 and twice in 2009, there have been 13 people in space.

However, in all of those cases, they were not in the same spot.

In 1995, three people were on board the Russian Mir, seven were in the Space Shuttle, and another three were travelling in a Soyuz capsule.

And during both times in 2009, the Space Shuttle was up there with seven people on board.

Upon reflection, we've come a long way in a quite a short time with human space flight.

On Monday, we celebrated the 60th anniversary of the first person in space, Yuri Gagarin.

On April 12,1961, Yuri boarded Vostok 1 and did an orbit of the Earth, spending just a bit over 100 minutes in space.

Vostok, however, was a far cry from the spacious room the Space Station offers modern-day astronauts.

At 2.3 metres, it had a volume of only 1.6 cubic metres.

A two-hour flight in economy doesn't sound all that bad now does it?

In fact, one of the reasons Yuri was selected was that he was only 157cm tall and was short enough that he could fit inside.

So, while 11 is not the record, it is awfully crowded for the Space Station. And it is going to get even busier.

With plans for private stations built by Axiom Space, space tourism flights from Virgin Galactic, Blue Origin, SpaceX and others, missions to the Moon and more, it doesn't look like it will be long at all until there are more people in space than, say, on Macquarie Island or even towns in Australia.