The Game Continues to Change... and Ever More Quickly
By Ray Williamson, PhD, editor
Over the past few years, the pace of change in the satellite remote sensing marketplace, broadly speaking, has really picked up. Many more satellites, carrying electro-optical or synthetic aperture radar (SAR) sensors, are in orbit, temporal and spatial resolutions have increased dramatically, and costs of medium resolution data have dropped precipitously. Further, as people become more familiar with the imagery and how to apply it to their needs, satellite systems are increasingly being tailored for specific uses.
When I first became involved in the world of satellite remote sensing in 1982, only one land remote sensing satellite routinely delivered imagery to customersóLandsat 4, providing high quality, 30-meter multispectral data. Two years later, the still-operating Landsat 5 followed. Customers were still called users in those days, as the notion that there might be a customer out there with specific data needs that could be satisfied by a steady stream of data from a commercial marketplace was still largely a dream to a few farsighted folks.
Now, of course, 26 years later, the scene is quite different. Not only has available imagery dropped below the 1 meter mark in sharpness, but also data are sold commercially around the world, and numerous countries have launched their own parastatal systems for observing Earth's surface for a variety of public-good purposes. In fact, it is really hard to keep track of how many remote sensing satellites are in orbit at any one time. As soon as you think you have identified the lot, a new one with a unique capability is launched.
Did I say one? On August 29 this year, the German company RapidEye AG, based in Brandenberg, Germany, launched five 6.5-m resolution satellites together into the same orbital plane on one launch vehicle. Risky though it was, the launch and release into sun synchronous polar orbit was successful. As this issue went to press, RapidEye was still checking out its satellites, but if they operate successfully, the company's business model could well revolutionize the business of remote sensing.
In flying five identical satellites, RapidEye has provided the capability to revisit any site in the world once a day, vastly improving the temporal resolution of the system. That, combined with the 6.5-meter ground sample distance (GSD) of the sensors at nadir, provides a quantum jump in capability.
RapidEye has positioned itself as a service-oriented information provider. According to the company, you just need to give its experts your information needs and they will tailor information products to fit them. The resolution chosen is excellent for a wide variety of agriculture and resource management tasks, making it possible to keep up with short term changes in the environment below, a critical need for a wide variety of tasks. The company also envisions a demand for its tailored information in the utility, cartography, and government markets. If the prices are right, these products could just prove a market changer. See more in our News & Notes section on page 19.
As exciting as this development is, other recent Earth observation developments show just how fast this field is changing. For example, imagery from the moderate resolution China-Brazil CBERS-2B satellite (see Imaging Notes, Summer 2008) is now available for free to any country within reach of a CBERS-equipped ground station. Because the CBERS system has several ground stations around the globe, with more coming along, they cover millions of hectares.
Lake Merced, south of San Francisco, is shown in this 1-meter panchromatic image from OrbView-3 (re-scaled for best presentation). Launched in June 2003, OrbView-3 acquires 1-meter panchromatic and 4-meter multispectral imagery in an 8-km wide swath. OrbView-3 is owned by GeoEye, which launched their new satellite GeoEye-1 in September 2008. The first image from GeoEye-1 is published in our News & Notes section.
Following Brazil and China's lead, the U.S. Geological Survey, which operates Landsats 5 and 7, is making data from these wide-field (185 km) U.S. satellites free for download from its Sioux Falls, South Dakota station. That's a far cry from the $4000 per scene that the U.S. used to charge for Landsat data when Landsat 5 was first orbited!
The private sector has shown that, with some relatively modest funding from government, it can deliver data and information services on a routine, sustainable basis. On September 6, the U.S. firm GeoEye, Inc., launched its latest commercial remote sensing satellite, GeoEye-1. Carrying a multispectral electro-optical sensor, GeoEye-1 will be able to resolve objects as small as 0.41 meters in panchromatic mode and 1.65 meters in multispectral mode. Because of U.S. security restrictions, GeoEye must resample any imagery better than 0.5 meters to the 0.5 meters allowed.
However, even with that restriction, this new satellite will offer a powerful combination to the imagery marketplace. DigitalGlobe, which launched its 0.5-meter panchromatic Worldview-1 satellite about a year ago, will launch a multispectral competitor to the GeoEye satellite next year.
Disaster monitoring has become one of the key uses for satellite data. Witness the SSTL-led Disaster Monitoring Constellation (DMC) that was placed in orbit a few years ago; five electro-optical multispectral satellites from countries as diverse as Algeria, China, Nigeria, Turkey and the United Kingdom make up this remarkable system.
This September, China launched another two similar satellites devoted primarily to observing natural disasters, especially monitoring the aftermath of earthquakes. By 2010, these will be part of a constellation of five similar satellites focused on disaster monitoring, something this earthquake-prone country needs. China plans to follow them next year with two SAR satellites, which will be part of a second five-member constellation. Together, China's constellations will provide some of the most powerful disaster monitoring capabilities in the world.
I expect this emphasis on using Earth observation satellite systems for human security applications (mostly public-good efforts) to increase over time. Yet, as I argued in the last issue, improvements in the supply side of Earth observations will not be successful unless the daunting issues of rapid information generation and delivery to the persons who need it are solved. A number of efforts, many begun by NGOs, have pointed the way to better use of the information, but large, public-good applications such as disaster response and resource management will need significant public sector involvement to be fully successful.
Ray A. Williamson, PhD, is editor of Imaging Notes and Executive Director of the Secure World Foundation, an organization devoted to the promotion of cooperative approaches to space security (www.SecureWorldFoundation.org).