Messenger to the planet Hema - summary of findings

Summary of the findings of the Messenger spacecraft on its journey towards the planet Mercury.

introduction

The first spacecraft to photograph Mercury was Mariner 10 in 1974 and 1975. In a series of 3 transit flights, 3000 photographs covering 45% of its territory were broadcast to Israel. These photographs enabled an initial mapping of the planet and based on them an atlas was prepared (1). It was clear that in the future a more comprehensive study would be carried out that would give a complete picture of the entire planet. And indeed, on August 3.8.2004, 5, a research spacecraft was launched to it. The duration of the flight was 2009 years and in April XNUMX she reached her destination. It was the Messenger spacecraft (Mercury, Surface, Space, Environment, Geochemistry and Ranging).

The plan of action is to put the spacecraft into orbit around the planet, photograph and measure it for one earthly year. The goals that the researchers have set for themselves are the composition and structure of the crust, geological history, the nature of the thin atmosphere, the nature of the dynamic magnetosphere, the structure of the nucleus and the materials found at the poles. Based on the entirety of this information, the researchers hope to answer the following questions (2):

1. Why does mercury, which has the highest density in the solar system, have a core made mostly of iron?
2. Of the inner planets, excluding Earth, why does it have a global magnetic field?
3. Why does the planet closest to the sun, with a temperature of C ° 455 at the equator apparently have water ice at the poles?

To carry out its tasks, the spacecraft is equipped with a camera, a laser altimeter, a magnetometer and several spectrometers. For its protection, the side facing the sun is equipped with a heat shield made of the same ceramic materials that protect the space shuttle during its return to Earth (2). In addition, the orbit of the spacecraft was designed so that the damage from the sun's heat would be minimal. From the moment the spacecraft enters orbit around Mercury, its distance from those parts of the ground that receive most of the sun's heat is minimal, so the exposure time of the spacecraft to the solar heat reflected from these areas is as short as possible. This is an orbit where the periapsis (the point closest to the ground and also part of the orbit where the spacecraft's speed is maximum) is at high latitudes and the apoapsis (the farthest point of the orbit from the ground and the part of the orbit where the spacecraft's speed is the lowest) is far from the ground. This is a route where the infrared radiation reaching the spacecraft from the ground is at a reasonable level of safety (3).

transit flights

Unlike Mariner 10, whose flight time was 5 months, the Messenger spacecraft was designed to have a longer flight time to save fuel. On its way to Mercury, the spacecraft passed once by Earth and twice by Venus with the aim of using their gravity to reach its destination. From the time the spacecraft arrived at Mercury, it entered solar orbit and made 3 passes near Mercury and in 2011 it will enter orbit around it. On each flyby she photographed Mercury and measured it. The first transit flight was in January 2008, the second transit flight was in October 2008 and the third transit flight was in September September 2009 (4).

On the first connecting flight on the 14th. 1. 2008 1213 pictures were broadcast to Israel. In this transit flight, parts of the surface that were not observed by Mariner 10 were observed and filters were used in order to get a preliminary idea about the composition of the soil. One of the main targets on this transit flight was the Caloris Basin. The distance of the passage from the ground is 200 km (4, 5). The second transit flight was on October 6, 10, the transit distance from the ground was 2008 km and 200 km were broadcast to Israel. In total, 1200% of Mercury's surface was covered (90, 6). The third transit flight was on September 7, 28.9.2009, the transit distance was 230 km and 1559 photographs were broadcast to Israel.

A total of 98% of the face of the star was covered. This transit flight was a rehearsal for entering orbit in 2011, since the sequence of commands transmitted to the spacecraft is similar to those that will be transmitted to the spacecraft when it enters orbit around Mercury. This maneuver brings the spacecraft to the shortest distance from the equatorial region than when it orbits Mercury. Its final orbit will be closer to the polar region (8, 9). Based on these photographs, places will be chosen where the spacecraft will perform targeted measurements while it orbits the planet Balkhet (10).

atmosphere (exosphere)

Mercury's gravity is the same as that of Mars (0 that of Earth). Mars has a thin atmosphere, its density is 38% that of the Earth and the atmospheric pressure is 1 millibars. The geological evidence shows that in the past it was a star abundant in liquid water, which means that the atmospheric pressure was much higher and the density higher. This means that gravity of this large order can sustain a sufficiently massive atmosphere. Due to Mercury's close proximity to the Sun, it cannot have an atmosphere. To the researchers' surprise, Mariner 7 showed that it does have an atmosphere, but it is completely different from that of the other atmospheric planets in the solar system. Due to its thinness the particles moving in it are too far apart from each other to collide with each other and their chances are greater to collide with the ground. The source of the particles is mainly from the soil itself. They are released from it through solar radiation, solar wind bombardments and meteorite vapor. For this reason the atmosphere received the name exosphere (10).

The eccentric orbit of a comet, its slow rotation around itself, the interaction of the particles with the magnetosphere, the interplanetary medium and the solar wind, all of these together, have a great influence on the behavior of the particles, during the day, during the night and during the "seasons" of the year. The atmosphere contains atoms of hydrogen, helium, sodium, potassium and magnesium. When they are released from the ground they are accelerated by the pressure of the solar wind and form a long tail of atoms pointing away from the sun. Similar to the tail of a comet.

Their explosion depends on the time of day of the planet. During the day the explosiveness is different from the nightly explosiveness. The factors influencing this are Mercury's magnetic field, the solar wind and probably also the latitude. Despite its thinness, the atmosphere is very active (12). The seasonal changes were felt in the tail. The neutral sodium was very prominent in the first two transit flights. In the third transit flight, its strength was 10-20 times weaker. The observations showed that calcium and magnesium show seasonal differences that differ from those of sodium. Tracking all the components of the atmosphere will lead to a better understanding of the processes that generate, maintain and change it (13).

the tail of the atmosphere

As mentioned earlier, Mercury has a tail similar to the tail of comets. In terrestrial observations prior to the messenger's launch, it was estimated that the length of the tail was 40,000 km. Following the transit flights, it turned out to be much longer. A combination of different observations showed that its length reaches 3. 6 million km. It turned out that the gases emitted from the ground, when they are released from it, the gravity of Mercury is too weak to bring them back. The pressure of the sunlight pushes them at very high speeds and their flight path is from the sun and away and it is this that creates the formation of the comet's tail. It is actually a process similar to evaporation where atoms or molecules absorb enough energy to be released as vapor from a substance. In the soil of Mercury there are sodium atoms. Although they are not the main component, they are used as "tracers" for other gases that are difficult to distinguish from terrestrial observations. This is because they emit light in the visible range of the spectrum.

Compared to the tails of comets, which can be seen with the naked eye, Mercury's tail is too weak and for this purpose one must be equipped with appropriate equipment. For this purpose, several telescopes were used, two at Mount Haleakala in Hawaii and two at the McDonald Observatory in Texas. By measuring the length and width of the tail it is possible to characterize its terrestrial origins. The first observation was made in June 2006 from the observatory in Hawaii in combination with the Adaptive Optics technique. The terrestrial source turned out to be in the high latitudes of Mercury. To observe the full dimensions of the tail another observation was made in May 2007. They used 3 small telescopes one at the Haleakala observatory and two at the McDonald observatory. The intention was to occupy wider parts of the sky. A 10 cm diameter telescope was also used to get the largest field of view. While these three telescopes showed the large sodium tail, the large field of view telescope gave the surprising results of the tail being millions of kilometers long (14).

In the first transit flight made in January 2008, 10% of the sodium atoms splashed from the surface of Mercury during the daytime of the planet were seen to be accelerated into a cloud of sodium 40 km long (000). A measurement made on the second transit flight showed two broad sodium emissions at the poles, one at the North Pole and the other at the South Pole and a weak emission in the equatorial region. Unlike the sodium emission, the calcium emission is symmetrical in the equatorial regions and less bright in the polar regions. The spatial differences in the explosiveness of calcium and sodium indicate that each of them operates according to different processes (15).

In the first two transit flights, the emission of sodium atoms into the tail from the dark side of Mercury was also discovered, and in the third transit flight, the sodium emission was 10-20 times weaker. This small amount indicates seasonal changes in the tail caused by different levels of solar radiation as the planet's distance from the sun during its orbit changes. In this transit flight the effect of the radiation pressure was almost zero to the point that very little sodium was pushed into the tail. On the other hand, an increase in the amount of calcium and magnesium in the tail was noticed. A combination of all the data shows that each atom has seasonal changes unique to it (17).

Craters and basins

Like the moon and many of the moons of the gaseous planets, so also on the surface of Mercury many craters are found. Some are small and some are very large. The almost complete coverage of the surface in the three transit flights allowed an almost complete count of them. Most of the craters are less than 100 km in diameter. As for the rest, their distribution is: 135 craters with a diameter of 100-200 km, 17 craters with a diameter of 200-300 km, 6 craters with a diameter of 300-400 km, 2 craters with a diameter of 400-500 km, one crater with a diameter of 643 km, one crater with a diameter of 720 km and one crater with a diameter of 1550 km. This is the Cloris Basin which, according to the Mariner 10 photographs, was thought to be 1300 km in diameter and the Messenger's photographs showed its true size (18, 19). The particularly large craters, one with a diameter of 643 km, a crater with a diameter of 720 km and the Kaloris crater are basins. Topographically, the craters of Mercury are 2 times lower than the craters of the Earth's moon (12). The overall picture confirms the observation of Mariner 10 that the density of craters in the South Pole is greater than in the North Pole (20).

As with many of the moon's craters, so also with Mercury's craters, bright rays surround them. material thrown out of them during their formation. These rays can reach a distance of hundreds of kilometers. Craters with unique phenomena were found, such as a 52 km diameter crater in the center of which is an arc-shaped depression (21) and the Mattise crater with its inner crater (22), a 200 km diameter crater where land has subsided along its entire length and you can clearly see the escarpment that this subsidence created (23). Another phenomenon is craters surrounded by a black "halo". There are two explanations for this "halo". According to one explanation, dark material that was underground was exposed to the surface during the impact of an asteroid or comet and created the craters. According to a second explanation, large explosions created during the crushing melted part of the rocky surface and scattered "impact melt" along the ground. Usually such molten rock is darker than the pre-impact surface (24). Next to these craters is a crater with dark inner walls. It may be that this substance is different from its environment (25). In contrast, the Lermontov crater's floor is lighter than its outer surroundings (26). Goethe Crater with a diameter of 340 km near the North Pole whose southern side is breached. It seems that Raba's heart broke through this wall and flowed out. The surface of the basin is smooth and has few craters 1).

Cloris basin

As we have seen, the Cloris basin is actually the largest crater of Mercury and in terms of its dimensions its diameter is equivalent to a quarter of the diameter of the planet. Inside the basin you can see concentric rings rising to a height of 2-3 km (27). The extensive planes within it have a stronger light reflection than those outside it. This phenomenon is the opposite of the one observed on the moon. One explanation for this phenomenon raises the possibility that during its formation, material from many depths was dug out and contributed its part to the melt preserved in the basin floor. According to both explanations the surface of the Earth's interior was reconstructed by a trend that came from the crust or mantle as a result of the collision of an asteroid or meteorite (28). In the center of the basin is a crater with a diameter of 40 km that was named Apollodorus and around it many depressions arranged in a radial manner that are hundreds of kilometers long and were named the spider. It is possible that these depressions are a product of the stretching and fissure of the pelvic floor that was created during its formation (29). According to another estimate, these cracks were created due to volcanic activity. An upward flow of trend in the center of the basin created its own reservoir in the depths and created a radial network of dykes (Dykes - a dyke is a vertical plate-like intrusion of molten trend material into the series of rocks above it). One of the groups of researchers built a three-dimensional model of the deformations of the planet's crust in the basin and examined the effects of a meteorite impact in the center. It turned out that the pressures developing inside the crust can explain the presence of cracks on the periphery of the basin, but not the tissue of cracks in its center. When the effect of a meteorite hitting the center of the basin floor was examined, it became clear that the formation of the basin released the pressure that had built up and weakened in the central area and allowed the cracks to widen and span the full width of the sheet. Since the crater is above the cracks, it seems that this fabric was created together with the Apollodorus crater. It should be noted that this model is not accepted by other researchers and according to their assessment the reality of this crater in the center of the fabric is purely coincidental (30).

Within the rim of the Kaloris Basin is the largest volcano found on the planet Balkhet. An irregularly shaped depression was found that is probably used as a volcanic vent and the edges of a domed configuration indicating the limits of the flow of lava from this opening (31). The extensive plains and the lower part of the basin appear to be covered in lava similar to the basaltic flow found on Earth's moon, but unlike the lunar plains, the amount of iron in them is small and therefore represent a different type of rock. The meaning of these planes is the existence of many sources of trend within the upper part of the mantle. Red spots were also found in the basin, the origin of which is probably also volcanic, and their retreat boundaries are not sharp, and sometimes they are in the center of rimless depressions. According to an estimate, their origin is in pyroclastic eruptions (fragments of volcanic origin) (32).

Outside the basin we observed what appears to be a shield volcano surrounded by smooth plains relatively free of craters, which indicates that this is a young area. Considering the scope of the volcanic activity, it may be that these plains were created recently, in geological time terms (30).

Inside the basin are many craters of different sizes, such as the Nawahi crater, which is 34 km in diameter and whose outer walls are darker than their surroundings, which suggests a different chemical and mineralogical composition (33). , the 34 km diameter Kertèsz crater whose floor is particularly bright and a small crater located near it and around it is material in the shape of horns (34). Another observed phenomenon is a series of fractures hundreds of kilometers long that did not affect the craters around them at all, which indicates that this cracking developed before the formation of these craters. These fractures were created as a result of tensile forces in the crust that deformed it and resulted in land subsidence (35).

other basins

The basin discovered by the messenger is a crater with a diameter of 720 km and which received the name Rembrandt. The floor of the basin has a series of radial cracks similar to those found in Pantheon Fossae (36). The floor of the basin is preserved in good condition and is not covered by a thick layer of volcanic dust and is estimated to have been formed 3.9 billion years ago, near the end of the period when the inner planets were crushed (37).

Volcanic activity

As we saw in the Kaloris basin and its surroundings, lava flows were noticed, including what looked like a volcano. This flow phenomenon, in which stratigraphic cuts can be made, is also found in other places on the surface of Mercury and in this respect it has parallel phenomena on the Earth's moon. Examples of this are in the western part of Mercury where there are many flood plains including crater floors (38, 39, 40). In the third transit flight, another area of ​​the planet was photographed that looks like a volcanic vent that has exploded (9).

tectonic activity

As in the photographs that were broadcast to Israel by Mariner 10, so also in the photographs that came from the messenger, long grooves can be noticed. It is believed that they were formed when Mercury's interior cooled and the entire planet contracted due to this (41). The result is cliffs that can reach a length of hundreds of kilometers. There are cliffs that are all inside craters and those that start at some point outside the craters and penetrate into them. Their height is 1 km (23, 42). There are those who break the wall of one of the craters. Such a situation facilitates the determination of their relative age (which geological event preceded another geological event close to it) (43).

Characterization of the soil

Of all the terrestrial planets, Mercury is the one that has undergone the strongest space weathering. The reason for this is its close proximity to the Sun, the interaction of the solar wind and the flow of micrometeorites that hit and are hitting its surface can spray neutral and charged particles into the exosphere and into space. The explosiveness of silicon, sodium and sulfur relative to oxygen in the solar wind is very low and their ionization states are too high in relation to the measured explosiveness, so there is no doubt that their origin is on the surface of Mercury (12). The solar wind changes the chemistry of the soil during space packing. These changes can help in determining the age of the soil in different places and these particles of it have recently been exposed (45). 40% of Mercury's surface is flat and originates from volcanic material. Much volcanic material erupted out to the surface and flattened them. The impression given is that there were several such outbreaks on a global scale (44).

For several years it was estimated that the surface underwent contraction on a global scale from the moment the iron-rich core began to cool. This estimate was confirmed when the surface was almost completely photographed. One sees in them slopes that have been deformed into various geological forms, including craters that have been cut in half. It seems that this contraction was a third larger than they thought (45). In terms of the rays adjacent to many craters, a unique phenomenon was found on Mercury. Rays extending almost to its full length. They extend from pole to pole and look like lines of longitude and are all bright (46).

The nucleus

The density of Mercury in relation to its size is very high - 5.44 g/cm60. From its measurement it became clear that the mass of the nucleus is 3% of its mass. 47 theories have been put forward to explain the size of the nucleus. According to one theory, high-density particles were attracted to the Sun before the planet formed. According to the second explanation, the sun probably eroded part of the rocky outer side of Mercury early in its life and according to the third explanation, huge collisions removed its outer layers from it (12). It turned out that the magnetic field created in the outer part of the core and which is driven by the cooling of the core creates a strong and complex interaction between the interior of the planet, the surface, the exosphere and the magnetosphere (48). The core is made mainly of iron and it probably also contains sulfur which lowers the melting point of the iron and probably has a role in creating Mercury's magnetic field. Radar observations from Earth of the planet's rotation around itself indicate its slight fluctuation, which suggests that the core is partially molten (49). Observations from Earth and MESSENGER in visible and near-infrared light have shown that the iron content of soil silicates is low. This figure raises a fundamental question regarding the evolution of Mercury. What caused the high concentration of iron in the core and its sparseness on the surface? (XNUMX).

magnetic field

MESSENGER found that Mercury's magnetic field is almost identical in characteristics to that observed by Mariner 10 30 years ago. The average dipole has almost the same strength, with a slight deviation in the range of a few percent and its small angular inclination is the same. Magnetic fields of planets like Earth's are generated by an electrical dynamo acting on the outer, liquid part of the core. Among the terrestrial planets, Mercury has a core structure similar to that of Earth. The magnetic field, in its nature, protects the earth from the solar wind. It forms a bubble around the Earth - the magnetosphere and together with the thick atmosphere protects the ground from high-energy particles coming from the sun and also from cosmic rays. The Earth's magnetic field is dynamic in nature. It moves around the planet and the poles move cyclically over geologic timescales and change the soil's exposure to the hazardous particles (28). In this, Mercury is similar to the Earth and what surprised the researchers is that the core of Mercury should have cooled a very long time ago and should have stopped the creation of magnetism. Among the researchers there were those who thought that its magnetic field was a relic of the past and frozen in the outer crust. MESSENGER's measurements showed that the magnetic field is bipolar, indicating the existence of north and south magnetic poles. The meaning is a modern and active dynamo (12). The comparisons made between the findings of the first transit flight and the second transit flight of the Messenger with the findings of Mariner 10 showed that the magnetic field has a symmetrical structure. This is of great significance since it indicates that the dipole is closer to the axis of rotation of the planet around itself (50).

Magnetosphere

On the first flyby the magnetosphere was different from that observed by Mariner 10. MESSENGER found a quiescent magnetosphere with some evidence of significant plasma pressure within it. Although no energetic particles were found (evidence of the influence of the solar wind), low energy ions were found in the magnetosphere and correspond to plasma pressure within the magnetic field (28). Although Mercury's magnetosphere is weaker than Earth's, it can block much of the solar wind from reaching the ground in at least a few places. The evidence for this is a layer of the magnetosphere moving around the planet more slowly. It could be that the magnetosphere has holes. Ions were found in it that were probably scattered by the solar wind at the poles. It is also possible that the origin of the ions is in Mercury's thin atmosphere. It turns out that Mercury does not have its own Van Allen belts—belts of wing-like particles created by Earth's magnetic field (51).

In the second transit flight, differences were found in the magnetosphere compared to the first transit flight. It turned out that on the first flyby the spacecraft entered the dim part of the tail of the magnetosphere and it measured relatively quiet regions of magnetic fields closer to the planet and then stimulated the magnetic field near dawn. On the second flyby, a strong leakage of magnetic flux was measured on the dayside of the magnetosphere, 10 times stronger than what was observed from Earth during its stronger activity. A large energetic amount of the solar wind in the large amplitude of the plasma waves and in the large magnetic structures measured by the spacecraft at the same time as changes in the behavior of the magnetosphere, supports the hypothesis that the large daily changes in Mercury's atmosphere are a product of changes in the shielding provided by the atmosphere (44).

Sources

1. Davis M. et al- Atlas of Mercury NASA SP-423

2. "NASA gives official nod to first Mercury Orbiter Mission" 7.6.2001
http://www.spacedaily.com/news/mercury-01a.html

3. "Messenger to feel the heat during hot periapsis" 4.9.2007
http://www.spacedaily.com/reports/ Messenger_ To_ Feel_ The_ Heat _During _Hot _Periapsis_999.html

4. Paulette B. - "NASA spacecraft to make historic flyby of Mercury" 11.1.2008
http://www.spacedaily.com/reports/ NASA_ Spacecraft__ To_ Make _Historic_ Fflyby_ Of _ Mercury_999.html

5. "Message from Mercury safely down to Earth" 19.1.2008
http://www.spacedaily.com/reports/ Message_ From_ Mercury_ Safely _Down_ To _Earth_999.html

6."NASA'S Messenger spacecraft returns to Mercury" 2.10.2008
http://www.spacedaily.com/reports/ NASA’S_ Messenger_ Spacecraft_ Returns _To_ Mercury_999.html

7. "A global view of Mercury's surface" 14.1.2008
http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_ID=2&imageID=307

8.Clark S.-"NASA probe set for close encounter with Mercury" 28.9.2009
http://www.spaceflightnow.com/news/n0909/28messenger/

9. Philips T. – “Hidden territory on Mercury revealed” 4.11.2009
http://www.spacedaily.com/reports/ Hidden_ Territory _On_ Mercury_Revealed_On _Revealed_999.html

10. PIA12274: A bright spot in the lasting image
http://photojournal.jpl.nasa.gov/ PIA12274

11. Phillips T.-"An active Mercury" 1.5. 2009
http://www.spacedaily.com/reports/ An _Active _Mercury_999.html

12. Campbell P. - "Messenger settles old debates and makes discoveries at Mercury" 3.7.2008
http://messenger.jhuapl.edu/newscenter/pressreleases/2008/080703.asp

13. "Mercury rising" 5.11.2009
http://www.spacedaily.com/reports/ Mercury_ Rising_999.html

14"Boston university astronomers map full extent of Mercury's comet-like tail" 7.2.2008
http://www.spacedaily.com/reports/ Boston _University _Astronomers_ Map_ Full_ Extent_ Of _Mercury’s _Comet_ Like_ Tail_999.html

15. "Magnesium detected during second flyby of Mercury" 5.5.2009
http://www.spacedaily.com/reports/ Magnesium _Detected _During _Second_ Flyby_Of_ Mercury_999.html

16. "First simultaneous Measurements of Sodium and Calcium in Mercury's exosphere" 6.10.2008
http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_ID=2&imageID=258

17.Stephen C.-"More secrets of Mercury unveiled in September flyby" 3.11.2009
http://www.spaceflightnow.com/news/n0911/03messenger/

18. Gazetteer of Planetary nomenclature - mercury
…ane&show=Fname&show=Late&show=long&show=Diam&show=Stat&show=Orig

19. "The great Caloris Basin on Mercury"
http://messenger.jhuapl.edu/news_room/multi03.html

20. "Messenger looks to the north" 14.1.2008
http://www.nasa.gov/mission_pages/messenger/multimedia/mercury_color114624.html

21.PIA10186: Mercury views an intriguing crater
http://photojournal.jpl.nasa.gov/ PIA10186

22. "Messenger dances by Matisse" 24.1.2008
http://www.space-travel.com/reports/ Messenger _dances_ by _Matisse_999.html

23."Using reprojections to examine Mercury's surface" 2.6.2009
http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_ID=2&imageID=310

24. "Craters with dark halos on Mercury" 21.2.2008
http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_ID=2&imageID=166

25. "An intriguing dark halo" 9.10.2008
http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_ID=2&imageID=227

26. "Lermontov's turbulent history" 6.10.2008
http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_ID=2&imageID=315

27. Paulette B.- "NASA spacecraft to make historic flyby of Mercury" 11.1.2008
http://www.spacedaily.com/reports/ NASA_ Spacecraft _To _Make_ Historic_ Fflyby_ Of_ Mercury_999.html

28. "Surprises stream from Mercury's Messenger" 31.1.2008
http://www.spacedaily.com/reports/ Surprises_ Stream_ From_ Mercury’s_ Messenger_999.html

29. “The Spider” – Radial troughs within Caloris”
http://messenger.jhuapl.edu/news_room/multi03.htm

30."Mercury's Spider Pantheon Fossae formation lined to asteroid impact" 24.9.2008
http://www.spacedaily.com/reports/ Mercury’s _Spider_ Pantheon _Fossae _ Formation_ Lined_ To_ Asteroid _Impact_999.html

31.PIA11013: Mapping a volcano
http://photojournal.jpl.nasa.gov/ PIA11013

32. "Mercury's surface dominance by volcanism and iron-deficiency" 3.7.2008
http://www.spacedaily.com/reports/ Mercury’s _By_ Volcanism _And_ Iiron_ Deficiency_999.html

33. "Say aloha to Nawahi" 14.1.2008
http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_ID=2&image-ID=278

34. "Messenger captures a shot of Kertėsz" 14.12008
http://messenger.jhuapl.edu/gallery/sciencePhotos/pics/EN018826812M_label.jpg

35. "Exploring the evolution of Caloris Basin" 19.3.2008
http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_ID=2&image_ID=174

36. "MESSENGER discovers an unusually large basin on Mercury" 6.10.2008
http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_ID=2&image_ID=279

37. "Evidence of past volcanic activity on Mercury" 2.5.2009
http://www.cosmosmagazine.com/news/2726/evidence-past-volcanic-activity-mercury

38. "Volcanism on Mercury" 20.1.2009
http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_ID=2&image_ID=288

39.PIA12313: Mercury's geology: A story with many chapters
http://photojournal.jpl.nasa.gov/ PIA12313

40.PIA12330: Flooding Mercury surface
http://photojournal.jpl.nasa.gov/ PIA12330

41. "Mercury's long cliffs" 14.1.2008
http://www.nasa.gov/mission_pages?messenger/multimedia/longcliffs.html

42. "Beagle Rupe gives Sveindottir an uplifting experience" 14.1.2008
http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_ID=2&image_ID=191

43. "Craters deformed and shortened" 14.1.2008
http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_ID=2&image_ID=194

44. "Messenger reveals Mercury as a dynamic planet" 30.4.2009/XNUMX/XNUMX
http://messenger.jhuapl.edu/news_release0433009.html

45. Thompson A.-"Volcanoes on Mercury solve 30 year mystery" 3.7.2008
http://www.msnbc.msn.com/id/25518217/print/1/displaymode/1098

46.PIA11245: Mercury as never seen before
http://photojournal.jpl.nasa.gov/ PIA11245

47. "Spacecraft set to probe Mercury's mysteries" 16.7.2004
http://www.newscientists.com/news.jsp?id-ns99996171

48. "Iron 'snow' maintains Mercury's magnetic field" 7.5.2008
http://www.spaceflightnow.com/news/n0805/07mercury/

49.PIA12362: Mercury's surface has more Iron+Titanium than previously thought
http://photojournal.jpl.nasa.gov/ PIA12362

50. "Messenger unveils more 'hidden' territory of Mercury" 29.10.2008
http://spaceflightnow.com/news/n0810/29messenger

51. "Mercury magnetosphere fends off the solar wind" 1.2.2008
http://www.spacedaily.com/reports/mercury_ Magnetosphere_ Fends _Off_ The _Solar_ Wind_999.html