Satellites for remote sensing of the Earth have been in orbit for nearly 25 years and are now an important tool for the geosciences and innumerable practical applications. Just like astronomical instruments enabled man, at the turn of the 16th to the 17th century, to acquire a new vision of the universe, the view of the Earth from space has influenced today's perception of our Home Planet. Earth observation is now being used routinely for solving important practical problems. It is the objective of the SEA AND SPACE project to contribute to the enrichment of school curricula by putting radar observation of the Earth from Space at the reach of teachers and pupils.
The SEA AND SPACE project will in the first instance use data from ESA's European Remote Sensing Satellites, ERS-1 and ERS-2, and from the Advanced Very-High-Resolution Radiometer AVHRR onboard the NOAA satellite. For the first time in Europe, an educational project is not mainly driven by archived data but new data acquisitions will be specially programmed for the project. This data will be made available, together with appropriate image processing software, to allow the participants to compare their actual ground observations with the view satellites in Space provide. The value of archived data will at the same time be highlighted and project participants encouraged to make extensive use of them.
In line with the overall objective of the SEA AND SPACE project to focus on coastal and maritime subjects, four to six 'typical' experiments into remote sensing of a coastal environment will be proposed to the participants.
Encouraging teachers and pupils to carry out such experiments has a three-fold objective:
For this reason, the project includes, in addition to the experiments, three complementary activities:
In the following, four experiments that could be proposed to the teachers and pupils are briefly presented in order of rising complexity:
The ERS Synthetic Aperture Radar is particularly sensitive to large metallic objects like ships on Sea or in river mouths. Any SAR Image from a harbour areas contains numerous ships. Using harbour movement logbooks plus ground observations, identification of individual ships is possible. Also quantitative measurements are possible: the measurement of the ship's velocity and an estimate of the ships' sizes.
In any coastal areas with important tides, features such as tidal flats are constantly evolving. Also, near river mouths in particular, coastal erosion and sedimentation are a continuous process. The ERS Synthetic Aperture Radar is sensitive to surface roughness and microwave absorption coefficients. As these are different for water and sand/dry land, time series of ERS images at low and high tide are well suited to establish tidal maps and study coastal geography. Adding the use of archived images and of maps/ground observations enables pupils to understand the dynamics of such processes over longer times. Ground mapping could be performed using GPS positioning techniques (see part of the project below dealing with navigation). Optical satellite images, for example historical Landsat-TM or IRS 1C images, contains useful complementary information.
The heat stored in the global oceans is pushing an energy transport belt from the equator to the poles that acts as the main driver for our climate. The sea temperature is also an important parameter for weather forecasting and therefore monitored around the globe by a network of ships and buoys. In the context of teaching the basic physics of climate and weather, comparing ground observations with satellite measurements gives insight into the contribution satellites make to climate research and meteorology, and at the same time shows some of the practical problems of their use. The satellite data made available are infrared data from Meteosat, NOAA/AVHRR and ERS. These can be compared with in-situ measurements of soil, air and sea temperature.
On optical satellite images, the sea surface is a uniform area without much information. Radar images, on the other hand, can unravel a wealth of information. The most spectacular is without doubt the detection of maritime pollution: oil dampens water, and oil slicks therefore stand out as dark patches on the ocean provided there is not too much wind. But not every well-delineated dark area on a SAR image is an oil spill. Surface slicks can also originate, for example from organic matter such as algae that change the water's absorption coefficient. Sometimes, dark patches identify areas with less stronger surface winds.
SAR images allow to study many oceanographic phenomena such as currents, current interaction and internal waves. For these projects, series of archive images will be the main source of information.
It is important to note that many other projects are possible, such as studies into flooding, land recuperation from the sea, ice monitoring etc. These are mostly suited for certain geographical areas and will not be prepared in detail but rather the initiative of the pupils to develop ideas be encouraged.
For the participants, the project will start 1 March 1998. The time between its acceptation by the Commission and 1 March 1998 will be used for planning, information/publicity at schools, and set-up of the project support and the Internet server/pages. Inscription for the project should be possible earlier, possibly as from 1 January 1997.
The participants are requested to present the results of their experiments in the form of a concise report, in electronic form. These are circulated, via Internet, among the participating schools. When finalised by the participants, they will be made publicly available, also via the Internet. The deadline for finalising reports is 30 June 1998.
National juries will select the best reports and invite two pupils from every winning group plus their teacher to present the results in Lisbon in the SEA AND SPACE contest for a trip to Kourou and Cerro Paranal. For further details, see in the section on the Lisbon competition below.
The best projects will be re-worked into one-hour of two-hour units for use by teachers and loaded onto a selection of special Web pages edited for this purpose.
As remote sensing of the Earth is itself a young discipline, there is no long tradition of remote sensing education in schools. But projects of different scope and size have been carried out successfully in European countries, some of them on a national, others on international level. As education is and will remain under national governmental authority, the scope of any Europe-wide project can only be to support activities in a general way so that remote sensing might eventually find its way into more and more national curriculae.
It should be highlighted that the European Commission and several governments or government agencies in Europe and abroad have promoted or are currently promoting other remote sensing education projects. One of the reasons why five months are needed to prepare the project is to establish cross links and to seek cooperation with these projects.
The fact that both archived remote sensing data plus scheduled data acquisitions will be made available, is an important new feature of the SEA AND SPACE proposal which is hoped to make it more attractive.
As the project has pilot character and its size should be kept manageable, the number of fully participating schools should not extend 60 to 70. The experiments require that the schools are located near a coast, so that this target figure also seems reasonable from this point of view. Such an number of participants finally allows to provide efficient ESA support that will be necessary in view of the complexity of radar data, and does not stress the limits of provision of specially acquired satellite data.
The organisers will establish, either at an ESA Establishment/facility and/or at ESO's Headquarters, project support through a network of experts. The ERS data acquisition plan for the project will be established before the start of the project, taking into account the geographical location and the type of project chosen by the participants as they register. This eliminates the need to 'order' acquisitions from ESA.
AVHRR data are routinely available through the SAREPTA site of the Norwegian Space Centre that has offered to contribute this data to the project.
The ERS data are, after processing into a standard ERS data product, converted into a file format and size suitable for viewing with standard Internet browsers and put onto the project Web site. As with AVHRR data on the SAREPTA site, files can be downloaded and simple operations performed with standard image processing software like PROBE. For more advanced schools or pupils, full data sets (100 MB per image) are made available on CD-R together with an software preparing this data for conversion and import into standard image processing software.
Meteosat temperature data could be made available through EUMETSAT and
An Internet hot line is established for questions and answers. A junior expert will be detached full time for a period for a period of eight months. This expert will also draft a final report on this part of the SEA AND SPACE project that will be made available in printed form.
ESA, ESO, EUMETSAT and NSC will make the following contributions to the project participants:
The financial support by the European Commission will cover the expenses for the following items:
A distinction has to be made between the weather satellites such as Meteosat in geostationary orbit, 36.000 km above the Earth, and remote sensing satellites in mostly heliosynchronous orbits, about 800 km above the Earth that feature much higher ground resolution. This project focuses on remote sensing data, acknowledging the important value weather satellites for education.
The ERS satellites carry four main instruments, two of which have been identified as providing useful data for the SEA and SPACE project: the Synthetic Aperture Radar, or SAR, generates images of the Earth's surface of 100 km by 100 km, with 12.5 metres pixel size and about 20 metres resolution, by measuring the amplitude and phase of backscattered radar waves. The backscatter amplitude depends on the surface roughness and its absorption/reflection coefficients. The second instrument is the Along-Track Scanning Radiometer, or ATSR, that generates images of the Earth's surface temperature from measurements of its thermal radiation in three spectral channels. Over sea, these measurements are accurate to 0.3 K.
It is important to note that pupils and teacher will be strongly encouraged to make observations and develop experiments other than those in the list that follows. Four 'experiments' have been chosen and will be prepared to the maximum extent with background documentation and practical support, knowing that the typical school teacher requires ready-developed practical solutions. For pupils to pursue a project running over several weeks or months, there should be room for other ideas.
Measurement of speed: on ERS-images, ship wakes can be clearly seen behind larger moving ships. As the SAR radar involves minute frequency sweeps, the Doppler effect will lead to the displacement of any object moving in east-west direction, into the north-south direction. A ship moving eats- or westward, will therefore be slightly 'above' or 'below' its wake. The displacement is proportional to the component of the ship's velocity parallel to the direction of the radar beam. Measurement of ship size: the integrated backscatter value of the image of a ship (i.e. the sum of all pixel values minus background) is a roughly correlated with the ship's size. Ground observations using harbour logbooks enable verification.
It plays a particularly important role in regional climate phenomena such as the Souther Oscillation, or El Nino climate instability.
The main problem for comparing satellite data and ground measurements is that satellites measure thermal radiation, and thus surface temperatures, whereas ground measurements determine either air, soil or water bulk temperatures. Both are, of course, correlated.
Evaluation criteria are: quality and originality of results obtained; evaluation of regional particularities; suitability of the project for inclusion into general curriculae; quality of presentation;
To our knowledge, it is also the first time that the use of so many different satellite sensors is combined in a remote sensing education project.