|Posted by [email protected] on January 26, 2012 at 8:50 AM|
Man-made space junk has been in the news twice this week, but has anyone considered the risk to future space tourists?
Australia has backed a proposal to minimise the amount of man-made rubbish in orbit, and solar activity caused our atmosphere to expand and bring down some junk.
As Douglas Adams said, ‘Space is big, really big’, but it turns out that the bits of space we want to use aren’t so big.
We’ve been littering Earth orbit since 1958, when America put Vanguard 1 into an orbit where it remains to this day.
Over the decades, defunct satellites have been joined by spent rocket boosters, astronauts’ tools and gloves, and we’ve even been adding to it with anti-satellite tests.
Today, NASA’s Orbital Debris Program Office has catalogued more than 16,000 debris objects, but the majority of it is in low and medium orbits.
But adding in smaller particles which could still cause serious damage to spacecraft can raise estimates as high as 500,000 objects.
The Sun will reach the peak of its 11-year activity cycle in 2013, and the small increase in solar activity has caused the Earth’s thermosphere - it’s outermost layer - to expand.
This thin layer of atmosphere increases the drag on debris in low Earth orbit, causing them to enter the atmosphere and burn up sooner than expected.
So it’s no surprise that NASA actually recorded a slight decline in orbital debris at the end of 2011, and orbital mitigation programmes like the international code of conduct on space activities backed by Australia this week.
But the International Space Station has been put on alert to avoid space debris several times per year, and a single collision between defunct satellites could hugely increase the amount of junk.
If commercial manned spaceflight and space tourism into orbit become successful, they will have to both account for the risk of debris and ensure they don’t make the situation worse.
Commercial launchers like SpaceX must ensure they de-orbit all of their unused rockets and service modules, while any orbital destinations will need to be armoured against smaller particles and able to move out of the way when larger debris threatens.
In the long term, the spaceflight industry will need to develop ways to capture or de-orbit the debris, overcoming the outdated military concerns that are always brought up in the face of such proposals.
Anyone who would seriously test an anti-satellite weapon today knows that it’s likely they wouldn’t just deny their enemy some capability, they could spark an avalanche of destruction that would deny space to the whole planet. It’s a scenario of mutually assured destruction which renders such weapons a useless as nuclear arms for winning any global conflict.
So let the commercial spaceflight industry lead the way on clearing up our space trash for the sake of its own future success.