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ANTARES ON MARSANTARES ON MARS

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The Mars express spacecraftThe Mars express spacecraft

•Left Earth in June 2003Left Earth in June 2003•In August 2003, the two planets were at a minimum In August 2003, the two planets were at a minimum distance, a condition that recurs every 26 month, even if not distance, a condition that recurs every 26 month, even if not always under similar conditions, because it not always always under similar conditions, because it not always happens at perihelion for both planets. In that occasion the happens at perihelion for both planets. In that occasion the two planets were distant “only” 55.758.713 kilometers, two planets were distant “only” 55.758.713 kilometers, practically the minimum distance possible;practically the minimum distance possible;•The spacecraft took 6 month to reach Mars, at an average The spacecraft took 6 month to reach Mars, at an average speed of 10800 km/h;speed of 10800 km/h;•Five days after it released the Beagle 2 lander on the Five days after it released the Beagle 2 lander on the surface;surface;•Then the orbiter spacecraft reached a highly elliptical orbit Then the orbiter spacecraft reached a highly elliptical orbit to perform observations.to perform observations.

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ReleasedReleased 13/08/2003 4:41 pm. 13/08/2003 4:41 pm. CopyrightCopyright ESA 2003. Illustration by ESA 2003. Illustration by Medialab. Medialab.

The journey from Earth to MarsThe journey from Earth to Mars

While the two planets While the two planets were at the closest were at the closest approach of the last approach of the last 60 000 years, the 60 000 years, the ESA’s spacecraft ESA’s spacecraft passed the middle passed the middle point of its journey to point of its journey to Mars.Mars.

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MarsExpress and Mars MarsExpress and Mars

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Antares and Mars in 2003Antares and Mars in 2003The Antares Association The Antares Association organized a special evening organized a special evening for the opposition of Mars in for the opposition of Mars in 2003 at the Municipal 2003 at the Municipal Observatory, which was a Observatory, which was a huge public success.huge public success.Here is the picture done by the Here is the picture done by the member Stefano Ceccucci member Stefano Ceccucci with the use of a 90mm with the use of a 90mm refractor, a 1300mm focal refractor, a 1300mm focal length and a webcam. We can length and a webcam. We can easily see the south polar cap.easily see the south polar cap.

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The VMC camera The VMC camera The visual monitoring camera is The visual monitoring camera is placed on the Mars Express, the ESA placed on the Mars Express, the ESA spacecraft, which is currently in orbit spacecraft, which is currently in orbit around Mars. around Mars.

At the beginning it needed only to At the beginning it needed only to control the lander Beagle’s control the lander Beagle’s separation with simple photographs.separation with simple photographs.

Nowadays, however, it is used as a Nowadays, however, it is used as a “Mars Webcam”. It is not a scientific “Mars Webcam”. It is not a scientific tool but provides us beautiful Mars tool but provides us beautiful Mars photos, that cannot be obtainable photos, that cannot be obtainable from Earth.from Earth.

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'Mars Webcam''Mars Webcam'Since 2007 the VMC has been used by the ESA team in Since 2007 the VMC has been used by the ESA team in order to get pictures of Mars, simple photos but taken at a order to get pictures of Mars, simple photos but taken at a few thousands kilometers to the surface of the planet.few thousands kilometers to the surface of the planet.

It was so possible to observe the climate variation during It was so possible to observe the climate variation during Martian Seasons or the main geological conformations.Martian Seasons or the main geological conformations.

The photos are available to everyone in flickr canal: The photos are available to everyone in flickr canal: https://www.flickr.com/photos/esa_marswebcam

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Polo nord visionPolo nord vision

• Mars seen Mars seen at 01:53:24 at 01:53:24 UTC on 16 UTC on 16 May 2014. May 2014. Credit: Credit: ESA ESA

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Technical specificationsTechnical specifications•Sensor CMOS (IMEC IRIS-1)Sensor CMOS (IMEC IRIS-1)•Filters B/N and RGBFilters B/N and RGB•Image size: 640x480 pixelsImage size: 640x480 pixels•Dynamics: 8 bitsDynamics: 8 bits•Field of view: 40 x 31 degreesField of view: 40 x 31 degrees•Distance from the surface of Mars: : 300-10000 kmDistance from the surface of Mars: : 300-10000 km•Resolution calcolated to 10000 km: 11.5 km/pixelResolution calcolated to 10000 km: 11.5 km/pixel•Resolution calcolated to 300 km: 0.347 km/pixelResolution calcolated to 300 km: 0.347 km/pixel•Mass: 430gMass: 430g•Dimensions: 65 x 60 x 108 mmDimensions: 65 x 60 x 108 mm•The VMC isn’t controlled by scientists as the other The VMC isn’t controlled by scientists as the other board instruments, but by the team flight control of the board instruments, but by the team flight control of the Mars express (Mars Express Flight control team) Mars express (Mars Express Flight control team) located in Darmstadt, Germany.located in Darmstadt, Germany.•The MEFCT loads VMC images in a flickr account with The MEFCT loads VMC images in a flickr account with an automatic process that makes images freely an automatic process that makes images freely available to the general public shortly after being available to the general public shortly after being discharged by the spacecraft.discharged by the spacecraft.

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VMCVMC

We can easily see on all images taken, two artifacts (which We can easily see on all images taken, two artifacts (which may have been caused by space debris that have settled or may have been caused by space debris that have settled or have scratched the lens); other artifacts appear randomly.have scratched the lens); other artifacts appear randomly.The MEFCT is always at work to define the best exposure The MEFCT is always at work to define the best exposure conditions, because the light and pointing conditions change at conditions, because the light and pointing conditions change at each new orbit.each new orbit.

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During the conjuction with the Sun, when Mars is on the During the conjuction with the Sun, when Mars is on the opposite side of the Sun from the Earth, there’s a period of opposite side of the Sun from the Earth, there’s a period of five weeks in which comunications must be interrupted.five weeks in which comunications must be interrupted.

In 2005, during this period, the Mars Epress Team has In 2005, during this period, the Mars Epress Team has interrupted scientific works four days before, to realize a interrupted scientific works four days before, to realize a special project.special project.

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The VMC Schools CampaignThe VMC Schools Campaign

Make available to groups of astronomers or students Make available to groups of astronomers or students the VMC, for amateur projects.the VMC, for amateur projects.

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Campaign of observations Campaign of observations From the 25th to the 27th of may 2015 groups of students, From the 25th to the 27th of may 2015 groups of students, astronomers or scientific centers involving young people astronomers or scientific centers involving young people worldwide have been able to propose goals for the filming of worldwide have been able to propose goals for the filming of the VMC.the VMC.This goals had to be compatible with the orbits of the Mars This goals had to be compatible with the orbits of the Mars Express.Express.They had to have a scientific or artistic value.They had to have a scientific or artistic value.

They have been selected 25 including ours! They have been selected 25 including ours!

The results will be published on the blog of ESA The results will be published on the blog of ESA (blogs.esa.int/VMC)(blogs.esa.int/VMC)

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Our purposeOur purposeThe chosen region of Mars The chosen region of Mars (Cavi Angusti, a latin name (Cavi Angusti, a latin name as almost all the geological as almost all the geological Mars structures) is located Mars structures) is located in the south polar region of in the south polar region of the Red planet, and is the Red planet, and is characterized by vast and characterized by vast and deep valleys where the thin deep valleys where the thin atmosphere of Mars can atmosphere of Mars can produce fogs or mists with produce fogs or mists with daily development.daily development.

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Our projectOur projectIn this month of May 2015 summer is ending in the In this month of May 2015 summer is ending in the southern hemisphere of Mars ,and on Cavi Angusti southern hemisphere of Mars ,and on Cavi Angusti day and night are alternate as on Earth, waiting to day and night are alternate as on Earth, waiting to dive for several months in the continuous polar dive for several months in the continuous polar night.night.The low Sun will casts long shadows and the The low Sun will casts long shadows and the change in temperature between night and day may change in temperature between night and day may give rise to condensation and dissolution of low give rise to condensation and dissolution of low clouds of water vapor or carbon dioxide.clouds of water vapor or carbon dioxide.

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The expectationThe expectation

During the days spent on the project, the Mars During the days spent on the project, the Mars Express spacecraft will pass several times on Cavi Express spacecraft will pass several times on Cavi Angusti at a distance of about 3000 km, at different Angusti at a distance of about 3000 km, at different times of martian days, thus allowing to study the times of martian days, thus allowing to study the area with a detail of a few kilometers, enough to area with a detail of a few kilometers, enough to reveal any cloud formations.reveal any cloud formations.

Mars atmosphere 1Mars atmosphere 1The atmospheric pressure on Mars is an average of 600 The atmospheric pressure on Mars is an average of 600 Pascal (0087 psi), about 0.6% of the Earth's 101.3 Pascal (0087 psi), about 0.6% of the Earth's 101.3 kilopascals (14.69 psi).kilopascals (14.69 psi).

It varies from a minimum of 30 pascal (0.0044 psi) on It varies from a minimum of 30 pascal (0.0044 psi) on Olympus Mounth to over 1,155 pascal (0.1675 psi) in the Olympus Mounth to over 1,155 pascal (0.1675 psi) in the depression of Hellas Planitia.depression of Hellas Planitia.

This pressure is well below the limit of Armstrong for the This pressure is well below the limit of Armstrong for the protection of human body from solar radiation. The overall protection of human body from solar radiation. The overall mass of the atmosphere of Mars of 25 teratonnes compared mass of the atmosphere of Mars of 25 teratonnes compared with that of the Earth of 5148 teratonnes with a height of with that of the Earth of 5148 teratonnes with a height of about 11 kilometers (6.8 mi) against 7 kilometers (4.3 mi) of about 11 kilometers (6.8 mi) against 7 kilometers (4.3 mi) of the Earth.the Earth.

Mars atmosphere 2Mars atmosphere 2It is composed of the following layers:It is composed of the following layers:LOWER ATMOSPHERE: a warm zone affected by the heat LOWER ATMOSPHERE: a warm zone affected by the heat of ground and sand storms.of ground and sand storms.MIDDLE ATMOSPHERE: the area where fast jet streams MIDDLE ATMOSPHERE: the area where fast jet streams blowblowUPPER ATMOSPHERE OR THERMOSPHERE: area with UPPER ATMOSPHERE OR THERMOSPHERE: area with very high temperatures, caused by solar heat. Atmospheric very high temperatures, caused by solar heat. Atmospheric gases start to separate each other at this altitude.gases start to separate each other at this altitude.ESOSPHERE: It begins at 200 km and over, in this area the ESOSPHERE: It begins at 200 km and over, in this area the last atmosphere’s tracks disappears into the void.last atmosphere’s tracks disappears into the void.There is also an area of IONOSPHERE and a layer of There is also an area of IONOSPHERE and a layer of seasonal ozone over the South Pole.seasonal ozone over the South Pole.

Mars atmosphere 3Mars atmosphere 3This graph shows the abundance of gas in This graph shows the abundance of gas in the Martian atmosphere, as measured by the Martian atmosphere, as measured by the NASA rovers in 2012.the NASA rovers in 2012.

The graph uses a logarithmic scale to The graph uses a logarithmic scale to display the values of very different display the values of very different concentrations.concentrations.

Carbon dioxide (carbon dioxide CO2) is Carbon dioxide (carbon dioxide CO2) is definetly the more abundant gas, in fact definetly the more abundant gas, in fact reaches the 95.9% of the volume.reaches the 95.9% of the volume.

The other four most abundant gases, are in The other four most abundant gases, are in order argon (Ar), nitrogen (N), Oxigen(O) order argon (Ar), nitrogen (N), Oxigen(O) and carbon monoxide (CO). These data are and carbon monoxide (CO). These data are obtained from the rover CURIOSITY in the obtained from the rover CURIOSITY in the Gale crater, and have never shown Gale crater, and have never shown environmental conditions prosperous to life.environmental conditions prosperous to life.

Climate 1Climate 1Of all the planets of solar system, Mars is the one Of all the planets of solar system, Mars is the one with the climate more similar to the Earth one, with the climate more similar to the Earth one, because of the inclination of its axis of rotation. because of the inclination of its axis of rotation. However seasons last about twice, since the However seasons last about twice, since the distance from the Sun leads it to have a revolution distance from the Sun leads it to have a revolution in just under 2 years. Temperatures range from -in just under 2 years. Temperatures range from -140 ° C of polar winters to +20 ° C summer. The 140 ° C of polar winters to +20 ° C summer. The strong temperature difference is due to the fact that strong temperature difference is due to the fact that Mars has a thin atmosphere (and therefore a low Mars has a thin atmosphere (and therefore a low atmospheric pressure) and a low capacity to keep atmospheric pressure) and a low capacity to keep the ground heat.the ground heat.

Climate 2Climate 2Both polar caps are mainly composed of ice Both polar caps are mainly composed of ice covered with a layer of about one meter of solid covered with a layer of about one meter of solid carbon dioxide (dry ice) to the North Pole, while the carbon dioxide (dry ice) to the North Pole, while the same layer reaches eight meters in the south one; same layer reaches eight meters in the south one; the overlap of dry ice above that of water is due to the overlap of dry ice above that of water is due to the fact that the first condensate at much lower the fact that the first condensate at much lower temperatures, and then after water during the temperatures, and then after water during the cooling season. Both poles have spiral designs cooling season. Both poles have spiral designs caused by the interaction between the unevenly caused by the interaction between the unevenly solar heat and sublimation and condensation of solar heat and sublimation and condensation of ice. Their sizes change also depending on the ice. Their sizes change also depending on the season.season.

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CelestiaCelestiaCelestia’s software (free) Celestia’s software (free) allows you to see the allows you to see the planets of our solar planets of our solar system as if we were in a system as if we were in a spaceship in orbit around spaceship in orbit around the planet.the planet.

We used it to identify the exact times of transits of Mars We used it to identify the exact times of transits of Mars Express on Cavi Angusti.Express on Cavi Angusti.ESA has provided a script for Celestia that allows to display ESA has provided a script for Celestia that allows to display exactly the spacecraft orbit in the period of interest.exactly the spacecraft orbit in the period of interest.

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Mars seen by the Hubble Space Telescope in the opposition of 2003. We Mars seen by the Hubble Space Telescope in the opposition of 2003. We can easily see the South polar cap, during late spring.can easily see the South polar cap, during late spring.In the right picture is clearly visible the Mount Olympus in the center of the In the right picture is clearly visible the Mount Olympus in the center of the northern lowland.northern lowland.

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Detail of the HST photo of South polar cap.Detail of the HST photo of South polar cap.Cavi Angusti is under the hood of the ice.Cavi Angusti is under the hood of the ice.The scale is about 7 km / pixel, but the polar area is The scale is about 7 km / pixel, but the polar area is seen very inclined, so the resolution is much worse.seen very inclined, so the resolution is much worse.

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The studyThe studyThe south cap of Mars, seen on two maps made with the data The south cap of Mars, seen on two maps made with the data of the Viking orbiter’s mission. Along with the software of the Viking orbiter’s mission. Along with the software Celestia they have been used to identify craters on the Celestia they have been used to identify craters on the surface of Mars.surface of Mars.

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Guys of AntaresGuys of AntaresStudents visiting the Observatory to observe Venus and Students visiting the Observatory to observe Venus and Jupiter at twilight.Jupiter at twilight.

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The images obtainedThe images obtainedPhotos of VMC were taken at intervals of one minute at Photos of VMC were taken at intervals of one minute at shutter speeds of 1s, 0.5s, 0.25s. All of this was in order to shutter speeds of 1s, 0.5s, 0.25s. All of this was in order to show well areas that were saturated with longer exposures.show well areas that were saturated with longer exposures.In our case, given the grazing light, also the poses of 1s were In our case, given the grazing light, also the poses of 1s were slightly underexposed.slightly underexposed.Of the three orbits dedicated to the project by the ESA team, Of the three orbits dedicated to the project by the ESA team, only one was suitable for us, because in the other two only one was suitable for us, because in the other two passages of Cavi Angusti was night.passages of Cavi Angusti was night.A total of 46 photos were taken, 16 of which are well exposed A total of 46 photos were taken, 16 of which are well exposed (80/255 counts).(80/255 counts).It wasn’t so possible to search the formation effects of haze at It wasn’t so possible to search the formation effects of haze at different hours of the day, as the original project.different hours of the day, as the original project.The minimum distance of the spacecraft from Cavi Angusti The minimum distance of the spacecraft from Cavi Angusti was 1980 km.was 1980 km.

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Plan BPlan BSo we developed our project in three parts:So we developed our project in three parts:1.1.Making a movie of overflying the south polar area, using Making a movie of overflying the south polar area, using the best frames available.the best frames available.2.2.Measure the diameter of the polar cap, the main crater of Measure the diameter of the polar cap, the main crater of Cavi Angusti and the near crater Schmidt.Cavi Angusti and the near crater Schmidt.3.3.Search of possible soil color variations because of the Search of possible soil color variations because of the different amounts of Martian atmosphere interposed between different amounts of Martian atmosphere interposed between the spacecraft and the ground during transit.the spacecraft and the ground during transit.

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Whatch the video (separately)

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DiametersDiametersMeasurement of diameters of some craters:Measurement of diameters of some craters:

The measurement was made only on images of 1s to have a The measurement was made only on images of 1s to have a better S / N ratio. The measurements were made with GIMP, better S / N ratio. The measurements were made with GIMP, using the ruler tool, and zooming images x4 in order to minimize using the ruler tool, and zooming images x4 in order to minimize the error in the mouse position.the error in the mouse position.

The distance from Cavi Angusti’s spacecraft was obtained with The distance from Cavi Angusti’s spacecraft was obtained with Celestia, using the script ESA to identify its location at the time Celestia, using the script ESA to identify its location at the time of each photo.of each photo.

Taking the point of view of the VMC technical specifications, we Taking the point of view of the VMC technical specifications, we calculated the approximate flat angular scale per pixel, and from calculated the approximate flat angular scale per pixel, and from this, the linear scale on surface.this, the linear scale on surface.

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Cavi Angusti area at the center of the VMC image and the Cavi Angusti area at the center of the VMC image and the correspondent card of Marscorrespondent card of Mars

In the vertical of Cavi In the vertical of Cavi Angusti. Angusti. Distance 2280 Distance 2280 km, scale 2.48 km/pixelkm, scale 2.48 km/pixel

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Cavi AngustiCavi AngustiScale 2.5 km / pix, much better than the picture of the HST, Scale 2.5 km / pix, much better than the picture of the HST, and we see it from above !!and we see it from above !!

South Pole at South Pole at the top.the top.

Cavi Angusti in Cavi Angusti in the middle.the middle.

Schmidt crater Schmidt crater at the bottom.at the bottom.

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The theoryThe theory

From the technical specifications the angular scale of VMC is 225 "/ pixel.From the technical specifications the angular scale of VMC is 225 "/ pixel.The apparent diameter d (in radians) of a crater of diameter D (km) at a The apparent diameter d (in radians) of a crater of diameter D (km) at a distance r (km) is d = tan (D / r);distance r (km) is d = tan (D / r);

If the angle is small (less than 2 degrees) tan (alpha) = alpha, and then d If the angle is small (less than 2 degrees) tan (alpha) = alpha, and then d = D / r.= D / r.Turning to arc seconds (arcsec) instead of radians from = D / r * 206265 Turning to arc seconds (arcsec) instead of radians from = D / r * 206265 (number of seconds of arc in a radiant).(number of seconds of arc in a radiant).To switch from the measure in arcseconds to that in pixel simply divide by To switch from the measure in arcseconds to that in pixel simply divide by the nominale scale factor mentioned (225 "/ pix).the nominale scale factor mentioned (225 "/ pix).For a crater of 100 km we have that the diameter in pixels (dp)For a crater of 100 km we have that the diameter in pixels (dp)dp = D / r * 917.dp = D / r * 917.So the diameter in kilometers and 'D = dp * r / 917So the diameter in kilometers and 'D = dp * r / 917

We measured the diameters in pixels of three formations:We measured the diameters in pixels of three formations:Cramped cables, Schmidt, Polar Cap snow.Cramped cables, Schmidt, Polar Cap snow.

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Trend expectedTrend expectedMeasurements of diameters in the Measurements of diameters in the various pictures at different various pictures at different distances: the curves show the distances: the curves show the values expected in pixels values expected in pixels according to the angular scale.according to the angular scale.

Our values are in good agreement Our values are in good agreement with those obtained by the Viking with those obtained by the Viking map map

Crater Our VikingCrater Our VikingSchmidt 200 178Schmidt 200 178Cavi Ang. 80 74Cavi Ang. 80 74Calotta P. 460Calotta P. 460

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Atmospheric Atmospheric absorption absorption

We’ve tried to verify if the We’ve tried to verify if the presence of the Martian presence of the Martian atmosphere produces visible atmosphere produces visible effects in the VMC.effects in the VMC.During the overflight, the height During the overflight, the height of Mars Express above Cavi of Mars Express above Cavi Angusti’s horizon changed from Angusti’s horizon changed from 40 to 90 degrees, and 40 to 90 degrees, and consequently the thickness of consequently the thickness of atmosphere changed from 1:55 atmosphere changed from 1:55 to 1.00.to 1.00.The measured Blue/Red flux The measured Blue/Red flux changed from 1.13 to 1.64changed from 1.13 to 1.64The color difference of the The color difference of the ground is visible in the two ground is visible in the two images.images.

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ConclusionsConclusions

This project has allowed to perform several operations with an This project has allowed to perform several operations with an important educational content:important educational content:1.1.realize a team with the division of works.realize a team with the division of works.2.2.use an astronomical software for the measurement of the use an astronomical software for the measurement of the distance of the Mars Express spacecraft from the surface of distance of the Mars Express spacecraft from the surface of the planet .the planet .3.3.Familiarize ourselves with the Martian geography and the Familiarize ourselves with the Martian geography and the coordinate systemscoordinate systems4.4.Measure the dimentions of some structures with success.Measure the dimentions of some structures with success.5.5.Understand the informatic structure of color imagesUnderstand the informatic structure of color images

When we’re going to watch Mars through a telescope once When we’re going to watch Mars through a telescope once again we will see him with eyes much more aware.again we will see him with eyes much more aware.