The satellites listed are worth more than a casual glance by anyone who uses Earth imagery, because they all provide scenes with resolutions better than 39 meters—arguably the resolution that begins to image/map human-scale activities, roads, fields, urban patterns, etc. And, equally important, all are billed as “civil” satellites, implying their data might be available to the masses someday. The sheer number of satellites and the number of countries—21 at last count—using their treasure to own them makes a statement about the status of land-observing  satellites in the world economy. But does all of this activity mean the commercial takeoff of a new and vibrant industry or, because most of the satellites are government-funded, something else?

A Brief History
For the moment, let’s consider the 54 optical satellites, as radar will be discussed separately. And let’s start with a bit of history. Figure 1 provides a quick look at the number of imaging satellites and their government sponsors since the 1972 launch of Landsat 1.

There have been three distinct periods in Earth imaging’s history. The first period extends from the original Landsat, which carried the four-band 80-meter-resolution Multispectral Scanner Sensor (MSS), to the launch of Landsat 4 in 1982 with the improved seven-band 30-meter-resolution Thematic Mapper (TM) sensor. The fact that virtually all of the civil satellites flown since then have included multispectral sensors illustrates the technology’s value, but it is also a tribute to NASA’s efforts in the first period to share and extend multispectral technology to the rest of the world, particularly data-starved Third World countries.

 
The second period extends from 1978 to 1998, and is dominated by the entry of the foreign systems. Russia (4) was first, but it was followed quickly by France (4), Japan (4) and India (5). The only U.S. launch during the period, Landsat 6 in 1993, was unsuccessful. It was only the miraculous lifetimes of Landsats 4 and 5 that kept the U.S. program alive. Of the four foreign programs only France’s SPOT system had any measurable effect in the remote viewing data world. The SPOT program was planned as a commercial venture from the start, providing 10-meter panchromatic and 20-meter multispectral data, stereo images and a 7-day revisit period—characteristics that were responsible for SPOT’s $40 million in sales vs. EOSAT’s $32 million in 1991.

This period included Landsat’s ill-advised commercialization in 1984 and its return to the government in 1992, when Congress declared commercialization a failure and cited Landsat’s value to the government for science, applications and national defense. The Landsat Remote Sensing Policy Act of 1992 required Landsat data continuity to be maintained and the data to be sold for no more than the cost of fulfilling user requests—a policy still in place today.

The 1992 act also launched the current set of commercial systems by creating a licensing process for private systems that was managed by the National Oceanic and Atmospheric Administration (NOAA). Lengthy bureaucratic delays to granting a request for a 1-meter license culminated in 1994 at a dramatic meeting of the House Science and Intel committees, during which Congress introduced a 2-meter image of the National Mall purchased commercially from the Russians. It was determined that U.S. industry should be allowed to compete by developing a better product. President Clinton agreed, signing a Presidential Decision Directive to that effect two weeks later. As a result, Space Imaging was born.

And that brings us to the third and still continuing phase. As shown in Figure 1, currently there are 25 satellites in orbit—double the number in 1998—and five more are expected to launch by 2007. But besides the number of satellites, the dramatic change between the two periods is the number of countries paying for them. The five players of the first period have been joined by 12 more. The overview spread on pages 12 and 13 presents the critical discriminating factors of each satellite.

Current and Planned Satellites
To begin to understand the large numbers of satellites, it will be helpful to look carefully at the table on page 13. It provides three critical satellite image features: spatial resolution, image swath (area) and spectral bands. (Due to a lack of information, a fourth feature, radiometry quality, is missing.) Note the wide range of these values and their grouping into two main classes: high-resolution/small-swath and medium-resolution/large-swath systems. Illustrations of these features can be seen in the “Guide to Land-Imaging Satellites,” accessible online at www.asprs.org/asprs/news/satellites/satellites.html.

Now consider the actual systems composing the numbers in Figure 1. Figure 2 is an on-orbit timeline of current and planned satellites from now until 2011, listing the best resolution of each by color and identifying the commercial systems by slashed patterns. Lifelines are inherently unstable at both ends. The operational timelines are drawn to each satellite’s stated design life (traditionally five years, but the latest are designed to last seven). Planned launch dates aren’t much more reliable.

Satellite Commercialization
Ten of the 30 satellites scheduled to orbit by 2007 will be commercial—not bad for an industry that was totally government supported a decade ago. But this may be deceiving. Both the U.S. and Israel commercial systems are in the high-resolution market, which Israel believes to be viable only through government sales. Although the three U.S. companies have committed a lot of time and resources to nurture a private market, it has developed slowly. According to one high-resolution company, only 10 percent of last year’s sales were to nongovernment users. Airborne imagery providers benefit from the same technologies that bolster the satellite companies—the Global Positioning System, geographic information systems and digital data. The seriousness of this competition was underscored by ORBIMAGE’s recent petition to NOAA to let the satellite companies sell the currently restricted 0.25-meter data to the civil market to provide a more level playing field with airborne sensors.

To make matters worse for the U.S. players, several countries are developing high-resolution systems of their own—France, India, Russia and Korea plan to launch systems with 1-meter resolution or better. In addition, Europe announced a “dual use” policy by which various governments will develop and operate satellites because their data are required for defense applications. However, they’ll also sell the data commercially. The case can be made that the Europeans are simply being a little more realistic and honest about their satellite support than the United States. The two recent National Geospatial-Intelligence Agency (NGA) awards of $500 million each to ORBIMAGE and DigitalGlobe for their next-generation satellites were made to ensure a viable industry would be available for vital intelligence needs. Thus, it is reasonable to expect the high-resolution business will continue to be government-sponsored and/or subsidized in one way or another for the foreseeable future.

Another commercial system, Germany’s RapidEye, is planning a mostly civil market. RapidEye’s total budget to build and launch five satellites is about 150 million euros (30 million from the German government). Compare this with Resource 21’s rumored $500 million proposal to NASA for the Landsat Data Continuity Mission and to the two similarly priced NGA awards, all of which were for one satellite each. To keep its investment at its low level, RapidEye is defying conventional wisdom and using six visible and near-infrared bands for its vegetation evaluation function. If RapidEye is a commercial success, its modest startup costs will have played a major part.
 

The DMC satellites weigh about 100 kilograms—RapidEye’s just 150 kilograms. Compare these numbers with the weight of DigitalGlobe’s QuickBird and Space Imaging’s IKONOS satellites (951 and 728 kilograms, respectively), and it is easy to explain the better than an order of magnitude cost difference between the two satellite types. For comparison purposes, Landsat 7 weighs 2,200 kilograms and cost about $750 million.

The DMC microsatellites cost as little as 10 million euros. Such a price makes satellite constellations affordable, and constellations are the only way to have reasonable resolution and frequent—up to daily—overpass capability. This combination has been sorely needed, but never was possible in the Landsat Cadillac world. (Plus the redundancy inherent in constellations is virtually a requirement for commercial and operational systems.) The DMC constellation data will be sold commercially, and only time will tell if the three VNIR bands are up to all of the tasks they attract because of their daily visit capability. However, their success in the disaster management field is assured, and the results of early quality tests are promising.

The Latest on Landsat
It is fitting to include some remarks on the fate of the program that started it all. After 28 years of cliff-hanging, the current plan is to launch Landsat’s replacement sensor, the Operational Land Imager (OLI), late in 2009 as part of NOAA’s National Polar-orbiting Operational Environmental Satellites (NPOES) program. As shown in Figures 1 and 2, this means there will be no Landsat in orbit in 2008. It is probable there won’t be any in 2007 and 2009 either, given Landsat 7’s failing health and the likelihood of a slip in the planned NPOES OLI launch. Now that the operational decision has been made, it is vital for the United States to maintain the lead in broad-area technology so science and applications will get the best data products possible. This will require going beyond the current continuity-only-based specifications to take advantage of the technology gains that already have enabled one company to provide global coverage with daily revisits and six bands at 6-meter resolution two years before the planned NPOES launch. As the coming hiatus in Landsat data proves, scientists can’t count on always having a custom-built Cadillac at their disposal and might have to learn to get where they want to go by flagging a taxi or, even better, gangs of rickshaws.

It appears from their planning allocations that the European Union countries believe the all-weather 1-meter radar systems will serve their defense needs better than their optical counterparts. The COSMO and TerraSAR systems are being developed under the aforementioned “dual use” philosophy, raising the question of whether the U.S. Air Force’s troubled radar satellite program would benefit from the dual-use approach.

Final Observations
Satellites are global by nature. Digital multispectral technology has made it technically and economically possible to monitor the rapidly changing global land surface of our common home with sufficient detail to understand and someday control undesirable changes in forests, farms, villages, cities, countries and continents wherever they’re located. Nations have, in their sputtering and chaotic way, recognized this and responded with a sky full of cameras. It is time for the international remote sensing community to get together and plan to share the planet’s photo album.
Such a plan is under way. NOAA, with NASA and USGS support, convened an Earth Summit in 2003 that has sponsored international meetings during the last year to help define a system of systems for global satellite observations.  Its goal is to include all Earth observations from space of the air and the land. A final report should be presented in the coming months.

A modest goal for the land part of this effort would be an international agreement that would require all acquired scenes from all satellites to be entered into a virtual meta database that can be queried by everyone, and that all nations agree to make such data available to the scientific community after a period of exclusivity for commercial use and at the cost of reproduction.

In summary, satellite land remote rensing has become a significant “space dividend,” along with communications and weather satellites, as well as the Global Positioning System. The technology’s availability to all nations, large and small, as well  as all citizens, has opened the door to a global information transparency that will change the relationships among nations and even among citizens and their governments.

 

  See  Featured Images
 
  Subscribe to Earth Imaging Journal

  Go to Home Page