 | Issue: | Latin America I 1998 |
| Article no.: | 11 | |
| Topic: | The Antarctic Mapping Mission | |
| Author: | Paul Ondrus | |
| Title: | Ground System Integration Manager | |
| Organisation: | NASA | |
| PDF size: | 20KB |
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Article abstract
The Antarctic Mapping Mission demonstrated the scientific application of Synthetic Aperture Radar imaging to enhance our understanding of the Antarctic and the physical processes that are taking place on it. More importantly, it has demonstrated the ability to work scientific and applications issues simultaneously. It is seen as a prototype of future science activities where different countries work together for a common goal. It also exemplifies the roles that governments and commercial enterprises play.
Full Article
The Antarctic Mapping Mission (AMM) is a joint science project between the Canadian Space Agency (CSA) and the US National Aeronautics and Space Administration (NASA). This mission accomplished a complete mapping of the Antarctic continent from September 26th to October 28th, 1997. CSA’s RADARSAT spacecraft, which is equipped with a C-band Synthetic Aperture Radar (SAR), conducted this mapping after performing a complicated and risky yaw manoeuvre (180 degree turn). Initial data analysis has demonstrated that this data set will significantly enhance our understanding of the Antarctic and the physical processes that are taking place on this continent. During the mission, CSA was responsible for the management of the AMM, calibration of the payload, executing the data acquisition plan, and for ensuring the successful reception of the data to various receiving stations. NASA, through the Alaska SAR Facility, will process the data and use a Pathfinder Project at the Byrd Polar Research Centre of Ohio State University to create a digital mosaic of the entire continent. The Principle Investigator for the Pathfinder Project is Dr Ken Jezek, Director of the Byrd Polar Research Centre. RADARSAT was launched in November 1995 and is operated by CSA from Saint-Hubert, Quebec. RADARSAT uses a sophisticated microwave radar system to produce images of extraordinary clarity through heavy cloud cover and even in darkness. The satellite can be programmed to capture images of an area as big as 500 km wide, and can detect objects as small as 8 m across. Marketing and distribution of RADARSAT data has been licensed to the Canadian firm, RADARSAT International (RSI), of Richmond, British Columbia. Science Objectives The science opportunities envisioned for the project include studying the dynamics and variability of the Antarctic Ice Sheet, and large scale mapping of faults, volcanic features and mountain building processes. The AMM data set will enable a significant advancement in our understanding of all these aspects of the Antarctic. One of the keys to meeting these science objectives was to have a robust acquisition plan. The complexity of the plan can be seen in Figure 1, which shows the Antarctic Continent overlaid by the different spacecraft passes. This plan was developed by Dr John Crawford of the Jet Propulsion Laboratory in Pasadena, California. This plan had to take into account the necessary completeness of the mapping and key areas where descending and ascending spacecraft passes were required over the same terrain so that three dimensional images could be constructed. SAR has several unique attributes that, when used in combination with other sensor and in situ data, enables new and exciting research opportunities. The imagery itself provides a high resolution, continental scale view of the geology and glaciology of Antarctica. In fact, the first image over the South Pole clearly showed the infrastructure of the Amundsen-Scott Station operated by the US National Science Foundation. The image not only showed the surface man-made infrastructure, but it also showed the old runway and station buried under about 15 m of snow. The ability of the SAR to penetrate the snow cover and show ice structures and flow is significant. One of the key science objectives of the AMM was to explore the Antarctic’s ice sheets and their relationship to sea level changes. Presently, sea level is rising at a rate of about 2 mm annually. About one quarter of the current rate is attributable to wastage of small glaciers and ice caps. A- portion of the remainder may be due to the volume of the great polar ice sheets. The Transantarctic Mountains reach heights of over 4000m and span more than 3500km of the Antarctic continent, making the range one of the longest and highest intracontinental mountain chains in the world. Geo-dynamic processes associated with the exceptionally large-magnitude uplift of the mountain belt may involve interaction between rift-related mechanical and thermal processes and erosional processes tied to the evolution and behaviour of the Antarctic ice sheet. The 3500 images taken during the AMM will be used to determine whether previously unrecognised large-scale structures and regional geologic boundaries mapped by the satellite images can be traced beneath adjacent ice-covered regions. Also, RADARSAT made possible stereo imaging of much of the Transantarctic Mountains. Programmatic Objectives Besides the significant science returns, the AMM has been a success from a programmatic perspective. The CSA and NASA worked very closely together to create a scientific success through a partnering arrangement. This program is a prototype for future science activities where different countries will work together for a common goal. It also exemplifies the roles that governments and commercial enterprises play. NASA provided a delta launch vehicle and communication support from its tracking networks to support the critical yaw manoeuvre and spacecraft reorientation for the AMM. CSA’s agreement was to provide two mapping missions and a certain amount of access to RADARSAT for scientific activities on a monthly basis. RSI, a commercial enterprise, is the main marketer and distributor of RADARSAT data. While the AMM was taking place, RSI was able to collect and distribute data from other parts of the world. RSI also licenses the various tracking stations around the world who acquire and distribute RADARSAT data. This data can be procured by any country to deal with disasters (i.e. floods or oil spills) or governmental planning. The ability to address scientific and applications issues simultaneously is one of the key success stories of this mission. Summary The AMM has provided what I believe will be a historic data set of the Antarctic. It has already surpassed the expectations of the science community and has presently raised more scientific questions than it has answered. The completion of the mosaic this year will mark a significant step in raising our understanding of the Antarctic and the processes which govern its ice sheets. This mission has also demonstrated the scientific application of SAR imaging. The images are spectacular and will be able to be used by a diverse set of scientific investigators. Conclusion This mission has also demonstrated the benefits of international partnering and how commercial enterprises can help to make these events happen. AMM demonstrated that science and commercial applications can work together simultaneously.
