The International Space Station (ISS), an incredible example of engineering and international co-operation, has been in the news more than usual this week.
For 4 days in the last week of May, the ISS has been much easier to spot than usual. It comes totally out of the Earth's shadow at this time every year, and from some places its possible to see it several times in a night if you know where to look (it orbits once every 93 minutes). Even though you can't pick out any detail with the naked eye, it's impressively bright, comparable with Venus.
Inflatable spacecraft
And on a different, more practical level, last weekend astronauts on the ISS tested a radically new type of spacecraft accommodation, by inflating the Bigelow Expandable Activity Module ('BEAM'), a blow-up living space that can be packed up to a fifth of its inflated size for travel, only being expanded to its full size when in position in space.
But apart from such headline-grabbing events, what is the ISS actually all about? We may have become used to the amazing photos of the earth taken from its viewpoint 400 km up, and to the astronaut's broadcasts and videos as they float around the spacecraft, but there is a lot more to the ISS than pretty pictures and gravity-free antics.
The astronauts on the ISS carry out many valuable scientific observations of Earth and space. Also ,and very significantly, it's actually a supremely important project for developing humankind's ability to explore and survive long-term in space. It's our first permanently occupied base outside our home planet, with changing teams of astronauts of up to 6 at a time in residence since 2000, and as such is an ideal laboratory for studying the effects of the space environment on the human body.
A lot of the experiments are concerned with issues expected to arise during a long spaceflight because of the space environment - for example:
-micro-gravity and its effects on bone density, muscle tone, and the body's overall functioning over time;
-space radiation and how to minimise exposure to it;
-changes to the human body-clock, known as the 'Circadian Rhythm', due to light/dark fluctuations that are not the same as the 24-hour pattern that we are used to on Earth, and to lack of physical activity. They rhythm of night and day is something that we take for granted, but imagine how it would feel to never see daylight for months or even years on end!
These experiments are essential in order to fully understand the effects of space on the human body, so that solutions can be developed before humans are sent on spaceflights beyond Earth orbit – NASA aims for a mission to Mars in the 2030s, only a couple of decades in the future!
Its not only the human body that needs to be considered. Long distance spacecraft need to be self-supporting and capable of being repaired or restructured in space. The ISS was actually assembled in space, from components sent up from Earth bit by bit – an amazing feat of engineering.
The 'BEAM' inflatable module is clearly a potentially important concep for extending the size of spacecraft without the need for heavy and bulky metal parts - further tests will establish the practical viability of this intrigiuing technolpgy.
As for ongoing maintenance and repairs, astronauts regularly undertake spacewalks outside the spacecraft, an essential procedure that has been carried out nearly 200 times to date, facilitating continuous improvement of safety and efficiency in these risky manoeuvres.
Oone of the most critical elements for a self-supporting mission is the ability to manufacture items on board, as and when needed, to save storage space, and to cope with unexpected situations – so 3-D printers are currently being tested! Recent experiments show that they work just fine in space – a fast and inexpensive solution that demonstrates just how innovative humankind can be.
The ISS is scheduled to stay in service until at least 2020, and hopefully its life will be much longer – its a unique laboratory, a stepping stone offering to transform the tantalising vision of future travel beyond our world into reality.
1. NASA
2. NASA
3. NASA TV