Today, every one of us lives well and truly in the space age. We may not yet be taking holidays on the Moon, but our day-to-day lives are becoming more and more reliant on satellite technology.
Military surveillance and communications, of course, depend on orbiting hardware, as does television and the navigation systems we use in our cars. But most people don't realise that mobile phones, the internet, cashpoint machines and stock markets, not to mention many farms, the emergency services and the National Grid also rely on satellites.
What would happen if we were ever to lose this space-based functionality? It's not just a hypothetical question.
As anyone who has seen last year's film Gravity knows, the low Earth orbits where many satellites reside are full of debris - tens of thousands of bits of "junk'', from nuts and bolts to an astronaut's glove - which are flying around at speeds of up to 17,000 mph and could cause enormous damage if they collided with any other object. Even a fleck of paint could have a serious impact.
And if one satellite fragments, those fragments can hit other satellites, in a chain reaction that could potentially wipe out a great deal of the world's orbital assets.
Alternatively, if a large solar flare - a huge burp of energetic charged particles - were to be directed towards the Earth, it could inactivate not only satellites in low Earth orbit, but those in the much higher geostationary orbit, such as those used by BSkyB and the BBC.
A recent report even speculated that space debris could spark a nuclear war. Dismayed by America's dominance of space - the US owns 43 per cent of all satellites, many of which are used for military spying - countries such as China have started investing heavily in anti-satellite weapons and testing them by blowing up old satellites.
The resulting debris could quite easily destroy a US military satellite, said the report by the Council on Foreign Relations, with disastrous consequences.
Read the report here.
The above scenario may seem far-fetched, but here are just a few reasons why the world would be a very different place without satellites.
The world would grind to a halt
Most of us know that the Global Positioning System (GPS) is the constellation of satellites that provides the data for satnavs. Turn on the machine in your car and, within seconds, it can pinpoint where you are in the world to within a matter of metres.
Apart from a few humorous examples of over-reliance on the technology - we've all heard about the four-wheel drive that drove obediently into a lake - satnavs have saved huge amounts of time by directing motorists on to optimal routes.
A recent study commissioned by Google estimated that driving times have been reduced worldwide by more than one billion hours a year, and this increase in efficiency, coupled with a billion-gallon reduction in fuel usage, is calculated to save the world, annually, about $22 billion.
What's more, the same study calculated that the faster response times achieved by the emergency services using precise satellite navigation saves more than 150 lives a year in the UK. And, of course, the military, for which GPS was originally invented, uses the system for navigation and precision bombing.
But GPS isn't just useful for navigation and warfare. The positioning system works by the precise timing of transmissions received from several satellites at once, and, to make this possible, each craft is fitted with an atomic clock. Each clock has a margin of error of one second in every 300,000 years.
For this reason, GPS is used by many organisations that need extremely accurate timing signals, from mobile-phone networks and power distribution grids to stock markets and cashpoint machines, which time-stamp withdrawals. Many businesses's IT systems also use it. If GPS went down, stock markets would close, mobile phones and cash machines would stop working, and our power supply would seize up.
Planes would fall from the sky
The aircraft we take to go on business trips and holidays also rely on GPS technology more than ever, allowing pilots to fly the most direct point-to-point routes between airports rather than following ground-based radio navigation beacons.
Photo / Getty Images
The Federal Aviation Administration in the US reports that the incorporation of precise satellite-based location information into cockpit warning systems has also reduced some categories of accidents by up to 40 per cent. And when a crash does occur, satellite technology can support the search for the aircraft's debris and black box to help accident investigators work out what went wrong.
Most recently, several nations provided their satellite imagery in the hunt for wreckage of the missing Malaysian Airline flight MH370, and even a camera aboard the manned International Space Station joined the search.
Congestion would reach critical levels
In 2005, Germany became the first country to start using satellites to combat congestion. Trucks were fitted with receivers that tracked their movements and charged them according to the distance they travelled on certain popular roads.
Photo / Getty Images / Fuse
Such a system is considered by its proponents to be fairer than a simple flat fee applied to vehicles as soon as they cross into a restricted area, such as the charge you pay if you only nip a street or two into the London congestion zone.
The courier firm, UPS, is also helping to ease congestion by using software which minimises the number of left-turns its drivers take on busy roads.
Illegal poachers would thrive
Earth observation satellites don't just watch developing weather systems to let us know if it will be rainy tomorrow. They also track potentially disastrous hurricanes or wildfires, providing early warnings of where and when these will strike.
Photo / AP
Endangered wildlife, such as southern right whales, have also been tracked using satellite. A new system being tested in Kenya uses a network of satellite-linked cameras to triangulate the sound of gunfire. It takes photographs of poachers and relays the images in near real-time to park rangers so they have a better chance of catching perpetrators red-handed.
Thousands would be lost
Satellite tags are used to locate and track far more than just endangered animals; devices can be fitted to monitor the whereabouts of offenders on probation or dementia patients, to save police or family members time searching for those who regularly go missing.
GPS tags are also used by skiers, in case they need to be rescued in the event of an avalanche.
But perhaps the most interesting application is one currently being tested by police in Iowa and Florida. Rather than risking danger to the public with a high-speed car chase, specially adapted police cars can fire a tracking device from a compressed air launcher onto a getaway vehicle.
The device attaches with high-strength adhesive and doesn't require a warrant because it remains in plain sight. The hope is that when the fugitives see the police pulling back they will slow to safer speeds. The police, meanwhile, can track them back to their home.
Food production would plummet
GPS has revolutionised agriculture. Satnav allows farmers to continue operating their tractors despite adverse conditions, such as rain, fog or darkness. If the precise location of field boundaries, roads and irrigation equipment is entered, the system can steer the tractor automatically, ploughing or planting seeds to an accuracy of just a few inches.
A recent US study found that such GPS-based practices accounted for a gain of almost $20 billion in crop production per year.
Photo / Hawkes Bay Today
Beyond this, satellite imagery is also used to monitor crops in the field. Orbital photography of farmers' fields can identify problems such as waterlogging and poor drainage, and spectral analysis of high-resolution images can even determine deficiencies of growing plants, such as whether they are dehydrated or lacking in nitrogen.
This enables significant improvements in crop yields, while minimising the application of artificial fertilisers and pesticides - with obvious benefits for the environment.
Archaeological treasures would lie undiscovered
Satellite imagery allows the identification of potentially important archaeological sites in remote regions of the world, and much of this from freely available data.
In 2012, for instance, a team from Bristol University found the secret desert camp that TH Lawrence used to launch his guerrilla operations against the Ottomans during the First World War.
Photo / Thinkstock
Lawrence of Arabia's base had been lost for almost a century and was rediscovered after a roughly-sketched 1918 map of the camp turned up in the National Archives and was compared against Google Earth images of the Jordanian desert. Navigating to the site using GPS coordinates, the team found a host of historical artefacts, including spent gun cartridges and broken gin bottles.
Similarly, the archaeological history of Saudi Arabia's large desert region has been difficult to piece together due to a lack of aerial photography. But an archaeologist based at the University of Western Australia has identified almost 2,000 potential archaeological sites, some of which may be up to 9,000 years old, by scouring the freely available satellite imagery on Google Earth from the comfort of his office chair.
Investors would lose billions
Perhaps most surprising is how Cold War-era satellite surveillance techniques are now being adopted by hedge fund managers and commodity traders looking for a competitive advantage.
Photo / NZ Herald
Satellite imagery enables you to survey a potential investment, particularly one located in a remote area that makes a direct site visit difficult and so reliable information scarce, to better determine the level of risk you would be exposed to before you commit.
You can check up on the progress of construction projects, or identify which potential investment is the better bet - by assessing coal production from two neighbouring mines, for example.
The same orbital techniques used in satellite farming to assess the likely yield come harvest, can also be exploited for advance information when speculating on the commodity markets or considering investment in an agricultural company.
In 2010, UBS investors used analysis of satellite imagery of branches of the American supermarket Walmart to count, month on month, the number of vehicles in their car parks. From this raw data, they were able to estimate the store revenue and so predict the quarterly earnings of the chain.
Orbitally derived insights such as this offer investors who pay for these data products and forecasts a distinct advantage over competitors relying solely on traditional market analysis or waiting for the official quarterly reports.
Dr Lewis Dartnell is a research fellow at the University of Leicester and author of 'The Knowledge: How to Rebuild our World from Scratch'