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Home , Isidis Planitia

AUTOMATED MAKING THE MAP OF ISIDIS’S

Iluhina, J. and Rodionova, J.

Sternberg State Astronomical Institute, Kashirskoe shose 57-7 kv. 514, Russia, Moscow. Tel: (7 095) 344-60-50 (home); 8 903 684-91-78 (mob.). E-mail: [email protected]

ABSTRACT

The plain of Isidis was chosen for landing of the spacecraft of European Space Agency (ESA) that will be this year. Express is the name of ESA’s Mars mission for 2003. Mars Express is the first 'flexible' mission of ESA's long- term science exploration programmer. Launch will be from Russia by a Soyuz Fregat launcher within an 11 day launch window which opens on 1 June 2003. Arrival at Mars is planned for the following December.

Mars Express comprises a number of essential components - the spacecraft and its instruments, the Lander, a network of ground and data processing stations, and the launcher itself. These are supported by an experienced team of engineers in ESA and industry and hundreds of international scientists.

The radar sounder on board Mars Express, MARSIS, will map the subsurface structure from a depth of about a hundred meters to as much as a few kilometers. This is in contrast with the Mars Odyssey, which can sense surface compositions to a depth of only one meter [1].

The cameras on Mars Express will map minerals at a high resolution, and report how they are distributed on the . This kind of data is crucial to understand the distribution of sub-surface water. The other instruments on board Mars Express will observe the atmosphere and reveal processes by which water vapor and other atmospheric gases could have escaped into space. Knowing about the water distribution on and under the surface of Mars is essential, since water is needed for the appearance of life. Understanding the water distribution will help us understand the geological history of the planet, and ultimately provide new clues about the formation of our Solar System and the evolution of Earth. Moreover, the presence of water puts mankind a step closer to the human exploration of the Red Planet. In its exciting Aurora programmer, ESA is considering systems that could be used in future extraterrestrial human colonies or stations.

Scientists hope that the instruments onboard Mars Express will detect the presence of water below the surface. This could exist in the form of underground rivers, pools, aquifers or permafrost.

Overall, the goals of the instruments to be carried by the Mars Express orbiter are: ! Sharp-eyed, 3D photography to discover more about the surface and . ! Looking at the 'invisible' beneath the surface by using radar beams to penetrate below ground. Different materials or structures will send back different radar echoes allowing scientists to produce an accurate 3D survey ! Precise determination of atmospheric circulation and composition to build up an accurate picture of Martian meteorology and climate. ! Study of the interaction of the atmosphere with outer space.

Gathering such information on the history and present day circumstances of Mars may also improve our understanding of things that influence our own environment. For example, if we can determine why Martian water disappeared in the past we may learn more about whether a similar fate is one day awaits the oceans of Earth.

Mars Express, which will also carry a small lander, will be an important element of the international flotilla of spacecraft destined to explore Mars in the first decade of the new millennium. The lander, called 2 after the ship in which Charles set sail to explore uncharted areas of the Earth in 1831, is an exciting opportunity for Europe to contribute to the search for . After coming to rest on the surface, will perform exobiology and geochemistry research [1]. The main task of scientific programmer Beagle2 is to search traces of life on the red planet.

The expected time of mission is about 350 days. Before scientists produced Beagle2 are set the following tasks: ! To search water, organic and inorganic carbonic compounds. ! To determine a structure of carbonic compounds. ! To search methane in Martian atmosphere.

Proceedings of the 21st International Cartographic Conference (ICC) Durban, Africa, 10 – 16 August 2003 ‘Cartographic Renaissance’ Hosted by The International Cartographic Association (ICA) ISBN: 0-958-46093-0 Produced by: Document Transformation Technologies In the results of experiments scientists could answer the question if there any life on Mars. If there are beneficial effects at the first point it will be said that there are conditions of life on Mars. The decisions of the second question will give the answer if there was life on Mars in the past. And at least if there is methane in the atmosphere life on Mars exists nowadays. For searching an answer at first question it will be used facilities of ground analyses around the lander. The second and the third questions will be solved by analyses of atmosphere samples.

For the purpose to learning the relief of the landing place it has been compiled the hypsometric map of Isidis by us.

The initial values for making the map are based on Mars Orbiter Laser Altimeter (MOLA) data, an instrument (MGS) spacecraft. MGS was launched by NASA in 1997. In February 1999 interplanetary spacecraft MGS finished its braking and set on circular mars orbit that is synchronous with the Sun. The main task of MGS launching (a cartographic survey of Mars’s surface) started in March 1999. During full Martian year the instrument MOLA can photograph Mars’s surface, measure magnetic field, define mineral composition of chemical rocks. MOLA boarded on MGS is a high-accuracy laser altimeter. It gets data about elevations on Mars. MOLA gives absolutely new information about Mars’s surface. A few million measures were received. The global topography of Mars is now known to greater accuracy than Earth’s continents in a root mean square sense. Flying around MOLA determines elevations regarded to area of 160x160 meters. The data have 1-2 km spatial precision and 1 m height-precision. These data allow to obtain more information about planet’s shape, its geodetic parameters, and to use them for surface modeling. Before the MGS mission, models of Martian topography were derived from Earth based radar ranging, and Viking1 and 2 radio occultations, stereo photo clinometric observations from Mariner. Data set got by MGS with previous data of another space vehicles led to essentially new ideas in comprehension of Mars’s structure and evolution. In the results of investigations the main parameters of the planet changed [2,3].

Table 1. Mars geodetic parameters from MOLA Parameter Value Uncertainty Mean radius (m) 3,389,508 ± 3 Mean equatorial radius (m) 3,396,200 ± 160 North polar radius (m) 3,376,189 ± 50 South polar radius (m) 3,382,580 ± 50 Triaxial ellipsoid a (m) 3,398,627 b (m) 3,393,760 c (m) 3,376,200 1/flattening 169.8 ± 1.0 Directions of principal ellipsoid axes a 1.0°N, 72.4°E b 0°N, 342.4°E c 89.0°N, 252.4°E

Before making a map of Isidis’s we compiled hypsometric maps of all Mars’s surface. For mapping it was used the MOLA data about elevation of 1º trapezium (64 800 points) [3]. A digital model of the relief was constructed with software ArcGIS. It was used spline interpolation for construction the digital model. The contour lines were drawn in interval of 1 km. The following use of the map defined the map projection. For map of all surface was chosen Mollweide pseudocylindrical equal area projection, for maps of hemispheres were chosen equal area azimuth projection. It was supposed to use these maps for measuring areas within different height levels. In projection calculations values of equatorial and polar radiuses by MOLA (Table 1) were used. On maps there is only one element- the relief. Details are defined by initial data. The names of big heights- terras, plateaus, mountains and lowlands- plains and also some big craters are labeled.

An analysis of the heights of the martian relief was fulfilled. The areas between the contours were measured automatically. The results of the measurement are represented on Fig. 1.

The graphic shows the distribution of the height levels against their areas. The histogram on Fig. 1 differs from the histogram in the paper [3]. The maximum of the difference in the area of the level from 2 to 1 km and from 1 to 0 km consist of 6% or 8.7 billion sq. km. Also there are differences of about 4% in the determination of the area of the height levels from -3 to -4 km and from -4 to -5 km Figure 1. The dependence of the distribution of the heights levels versus the area occupied.

It is known that the distribution of the height levels on Mars has two maxima [3,4,5]. One can see two peaks on Fig. 1. The first, for the height levels from -2 to -5 km, corresponds to the martian plains. The total area of the plain is 50 billion km or 34.5%. The second peak is due to the levels from 1 to 3 km. 35% of the total area is occupied by these levels. The mountains above 5 km occupy 2.5% of the total surface of Mars (the highest of them above 10 km - only 1%). The transient zone from plains to the highland due to the level from -2 to 1 km and correspond 25%. The deepest depressions (less than 5 km) compose 2.5%.

Figure 2. The distribution of the areas of heights levels in the northern and southern hemispheres.

Two main peaks are represented clearly on the graphics. There are the predominant levels from -2 to -5 km in the northern hemisphere and from 1 to 3 km in the southern one. It is interesting that in the western and eastern hemispheres both maxima are represented in Fig. 3.

Figure 3. The distributions of the areas heights levels in eastern and western hemispheres of Mars.

The comparison of the heights of different regions obtained by MOLA with the previous investigations represented on the maps [5] show that there are not systematic differences there. We have compared the main large forms of Martian relief. The comparison of the heights of different regions obtained by MOLA with the previous investigations represented on the maps [5] show that there are not systematic differences there. We have compared the main large forms of Martian relief.

For example Acidalium planitia has a prevailing level from -4 to -5 km (MOLA) but from -1 to -2 km on [5] and from 0 to -3 km (MOLA) and from 1 to +3 km on [5]. Noachis terra is on the levels from 0 to 2 km (MOLA) and from 3 to 4 km on [5].

Next step was the making of Isidis’s map. MOLA data with more accuracy were used for compiling this map. The MOLA data represent the matrix of measured elevations on each 1/64 degrees. The data were done for all surface of Mars. So the values were extracted for mapping area of plain Isidis. The mapping area was specified by 57 and 122, and by 32 n.l. and 17 s.l. The obtained digital elevation model (DEM) had 1325000 measured points. This DEM was processed by ArcGIS programs to make vector data. With the application Spatial Analyst contours lines were constructed. The interval between contours is 500 meters. With the ArcMap the map of Isidis was designed.

The areas between contours were measured by this map. The area of measurement is marked on the map by the red line oval. For measuring areas without distortions cylindrical equal area projection of map was defined. The result of measurement represent in the Fig. 4.

Figure 4. The dependence of the distribution of the heights levels versus the area occupied.

Fig. 4 shows the distribution of height levels against their areas. There is one maximum. It is from -4 km to (-3) km. These heights correspond to the plain. These heights occupy the most part of the Isidis’s basin, about 60% of all surface. The other part corresponds to slopes surrounded the plain. In Fig. 5 the part of the map is represented, the area of measures.

Figure 5. The fragment of Isidis’s map. The western boundary and southern part of the basin are on the height level about 0 km. The northwestern part of the boundary is 1 km lower. Isidis plain is surrounded by hills at its western, southern and east southern sides. On the west there is The which has the heights more then 3 km. On the south Libia Montes reach the heights from 1 till 2 km. The eastern part of the Isidis planitia boundary is very smooth and represents the broad and very low rampart which is destroyed in the place of contact with Elisium planitia. The medium height of Isidis basin and its volume can calculate using a hypsographic curve. A hypsographic curve allows to analyze a distribution of big shapes of relief. It gives different numerical parameters.

Figure 6. The hypsographic curve of Isidis basin.

The medium height of the plain is (-2.6) km. The volume is about 4 billion km3. There are two big craters of 80 km in diameter in the plain. One of them is on the north. It’s called Teridier. The second, Du Martheray is located on the south where Libia Montes begin. There are a lot of small craters on the bottom of Isidis Planitia which represented in contours. But the craters have no names.

For more detailed analyses the place of the Beagle2 landing we compiled using these MOLA data the map in 100 meter interval. The lander Beagle2 will land at 11.6N and 90.75E. As we can see the landing site is not too rocky and it is important for a safe landing. The most part of landing site has height -3.7-(-3.8) km. Around the point of landing within the box of 4x4 degrees there are a lot of craters. Two of them are big. One on the west of landing site has 30 km diameter and about (-5) km height. The other is on the east. It has 50 km diameter and the height more then (-5) km. There are about 10 craters with 10 km diameter and (-4.5) m. height. The other crates are less then 4 m. in diameter. They are counted about 15 on this map.

In future we’re planning to continue learning the relief of red planet. We hope new data will give us the opportunity to make more detailed maps. We’re planning to make a geodatabase of Mars, where will be not only maps of the relief but maps which represent the other aspects of Mars. These made maps are the base for further work.

REFERENCES

[1] http://sci.esa.int/home/marsexpress/ [2] http://wufs.wustl.edu/missions/mgs/mola [3] D.E. et all: 1999. «The Global Topography of Mars and implications for Surface Evolution» – Science, vol. 284 – 1495-1503 pp. [4] Lipskiy Yu.N., Kazimirov D.A., Rodionova J.F. et all: 1975. « O volnoobraznom haraktere gipsograficheskoy krivoy i nekotorih gipsometricheskih osobennostyah poverhnosty Marsa» – : «Dokladi akademii nayk», Vol. 224, № 1, 58 - 61 pp. [5] Atlas of Mars : 1991. « 1:15 000 000 series». USGS, USA AUTOMATED MAKING THE MAP OF ISIDIS’S

Iluhina, J. and Rodionova, J.

Sternberg State Astronomical Institute, Kashirskoe shose 57-7 kv. 514, Russia, Moscow. Tel: (7 095) 344-60-50 (home); 8 903 684-91-78 (mob.). E-mail: [email protected]

Biography

Julia Iluhina Date of birth: 1979, 16, March

Work Experience ! 1999 «DATA+», Authority International Distributor ESRI and Leica Geosystems in Russia. Project department. Electronic map editor.

Education History ! 2003 The researching laboratory of earthly planets of Sternberg State Astronomical Institute, post-graduate student ! 2002 (April) ArcGIS8, Course ! 2000 (March) Erdas Imagine, Course ! 1996 - 2001 Geographical Faculty of Moscow State University, Speciality: Geoinformatics and Cartography, GIS Specialist, Master of Science (M.Sc.).