The eye of the storm

5 min read

In the wake of Hurricane Katrina’s devastation of New Orleans detailed satellite imaging, operated by a Surrey company, has been pivotal in co-ordinating the relief effort.

Aid from around the world has poured into the American southern states since the devastating arrival of Hurricane Katrina. But amid the food, clothing and medicine can be found one commodity the US, of all nations, might be expected to need no help in providing: advanced satellite imaging technology.

In fact, a small disaster-response satellite network operated from the UK has been a welcome component of the relief effort since its earliest stages.

Collating detailed data about the damage wrought on New Orleans by Katrina is of paramount importance for the emergency services and aid agencies in co-ordinating their work. As part of this information gathering, a UK satellite operator has joined NASA and the international effort by employing its constellation of hi-tech satellites.

After the hurricane struck the Disaster Monitoring Constellation (DMC) was asked to acquire images of New Orleans to send to the US Geological Survey. The DMC is an international consortium led by the UK’s Surrey Satellites, a spin-out from Surrey University. It consists of a network of five small satellites and ground stations specifically designed to act as a disaster-response system. Each 80kg satellite can give high-resolution images over a 384,000km2 swathe of land, and zoom down to a 32m2 area. It is the DMC’s wide-area coverage that makes it so important in large-scale disaster relief.

So far DMC has been used to gather information about a range of natural disasters including volcanoes, floods, earthquakes and forest fires. Man-made catastrophes such as oil spills and train crashes have also been imaged.

According to Paul Stephens, marketing director at DMC International Imaging (DMCII), which manages the system in disasters, the idea originated at a 1999 UN conference, called Peaceful Uses for Outer Space. ‘It was decided to set up a system where a constellation of satellites would cover the globe and could give up-to-date, accurate data about any given disaster zone within a short time frame,’ he said.

Delegates from the space nations agreed that there should be a specific satellite-based disaster-response system available free of charge to any country. Surrey Satellites, recognised as one of the world’s leading specialists in micro-satellites, won the contract to manage the network. The satellite previously used for ground imaging was the NASA-run Landsat, which has been providing images of Earth for more than 30 years.

But in the case of a disaster, the ageing Landsat was seriously lacking, according to Stephens. ‘Landsat can only image a certain point on the globe every 17 days, which is just no good in a disaster, when you need information immediately,’ he said.

Surrey Satellites had to design a system that not only covered a wider area, but also had more satellites. Imaging accuracy was also greatly increased. Whereas Landsat achieved 6,800 pixels, each DMC satellite boasts 20,000. The key to DMC is its ability to pick up detailed images over a large area.

‘Our images are 640km wide by 600km long, meaning we can squeeze nearly the whole of England and Wales in a single shot,’ said Stephens. ‘That in itself isn’t unusual for modern satellites but it is unusual to be able to zoom right down to a 32m2 area and be able to pick out roads and structures.’

Although Surrey Satellites built all five satellites, a different country manages each one. The DMC satellites were offered to fledgling space nations as a package that includes engineers, training and a base station. The first to be set up was by Algeria, swiftly followed by Turkey, Nigeria and the UK’s own satellite. The final one, owned by China, is due to be launched later this year.

In the event of a major disaster such as Katrina, DMCII in Surrey informs each DMC operator of its targets. The operators then program their satellites accordingly and send the data back to DMCII. The information is disseminated from DMCII to whichever agencies have requested assistance.

Although designed specifically for disaster-relief, the satellites’ high-quality images are also used for commercial and scientific purposes, providing extra income that allows the operators to keep disaster monitoring as a free service. The system is currently monitoring illegal logging activity in the Amazon basin.

The DMC’s most recent application, before Katrina, was in the wake of the Asian tsunami. ‘We activated as soon as we heard the news,’ said Stephens.

‘Our project leader got co-ordinating all the satellites immediately. For the next two weeks we collected data and images and sent it to the UN for use in the relief effort.’ DMC completed a survey of the entire Indian Ocean coastline, images that are now being used for reconstruction work by aid agencies.

Officially classified as high-resolution satellites — each image is a hefty one gigabyte of information — DMC is accurate enough that infrastructure is easily visible. If further detail is needed, other even higher-resolution satellites can be called upon that can focus down to 1m2, zooming in on individual cars and buildings.

The Disaster Monitoring Constellation has provided real-time high-resolution images of New Orleans.

The Surrey-controlled network is by no means the only advanced satellite imaging technology to have been pressed into service following Katrina.

One of the specialised earth-orbiting satellites operating alongside the DMC is NASA’s Experimental Advanced Airborne Research Light Detection and Ranging System (EAARL lidar). This was first used to monitor the damage caused by Katrina’s less destructive cousin, Isabel, which hit the Carolina coast in 2003. The system, carried on a Cessna 310, has been surveying the coastline and was used to assess the damage done to the crucial levee surrounding New Orleans. It can see through vegetation such as trees and bushes so it can detect the solid land beneath. It can also map the beach surface under water.

EAARL uses lidar technology, which works like radar but uses light waves rather than radio waves to measure the distance to objects. Plants, water and solid ground all absorb and reflect the different wavelengths of light in different ways. Because of this, most conventional lidar mapping systems are set up to map only one or two types of terrain because different lasers and receivers are needed for each type of surface to be mapped. The EAARL system differs in this regard because it can make around four billion measurements per second using multiple detectors, so mapping a variety of terrain with a single unit.

DMC is now joining the International Charter, a worldwide agreement that also came out of the Peaceful Uses of Outer Space conference. This allows member states to call upon images from a wider selection of satellite constellations in the aftermath of a disaster. ‘It sets out to pool the resources of individual space agencies,’ said Stephens.

‘Although most of these satellites are not there specifically for disaster-relief purposes, each brings different types of imaging techniques and resolution types to the table.’

Every week the International Charter nominates a duty operator who can activate all these spacecraft. They contact the project manager at the relevant space agency who retrieves the data and turns it into usable maps.

This is then shared with aid agencies and relief workers. Argentina, Canada, Europe, Japan and India are all members.

But later this month the International Charter is set to increase hugely in size as its newest member comes on-board. ‘The US is joining, which is great for everybody as it has a lot of satellites,’ said Stephens.