page_title: Mars Geyser Hopper
section_title: Background
hierarchical_section_title: Mars Geyser Hopper / Background
caption_attribution_description: English: This is the south polar cap of Mars as it appeared to the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) on April 17, 2000. The polar cap from left to right is about 420 km (260 mi) across. Ελληνικά: Η νότια πολική περιοχή του πλανήτη Άρη. Εικόνα από τη διαστημοσυσκευή Mars Global Surveyor. Διακρίνεται εύκολα το κάλυμμα πάγου του Νότιου Πόλου, που εδώ έχει διάμετρο περίπου 420 km. Η φωτογραφία έχει ληφθεί κατά τη διάρκεια του καλοκαιρού στο Νότιο ημισφαίριο, κι έτσι η έκταση του πάγου είναι η ελάχιστη που σημειώνεται, καθώς κατά τη διάρκεια του καλοκαιριού το κάλυμμα πάγου στους πόλους του Άρη συρρικνώνεται. Κατά το χειμώνα, ολόκληρη η περιοχή που φαίνεται στη φωτογραφία σκεπάζεται με πάγο. Original caption This is the south polar cap of Mars as it appeared to the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) on April 17, 2000. In winter and early spring, this entire scene would be covered by frost. In summer, the cap shrinks to its minimum size, as shown here. Even though it is summer, observations made by the Viking orbiters in the 1970s showed that the south polar cap remains cold enough that the polar frost (seen here as white) consists of carbon dioxide. Carbon dioxide freezes at temperatures around -125° C (-193° F). Mid-summer afternoon sunlight illuminates this scene from the upper left from about 11.2° above the horizon. Soon the cap will experience sunsets; by June 2000, this pole will be in autumn, and the area covered by frost will begin to grow. Winter will return to the south polar region in December 2000. The polar cap from left to right is about 420 km (260 mi) across.
context_page_description: The Mars Geyser Hopper is a NASA design reference mission for a Discovery-class spacecraft concept that would investigate the springtime carbon dioxide Martian geysers found in regions around the south pole of Mars.
  The power technology that MGH proposed to use was the Advanced Stirling radioisotope generator. NASA finished the ASRG design and made one test unit of the device but the program was concluded by the mid-2010s. Neither InSight nor any of the next Discovery's semi-finalists use the ASRG or an RTG due to high demand and limited supply of the type of plutonium it relies on.
context_section_description: The Discovery program was started in the 1990s following discussions at NASA for a new program, and has achieved such missions as Genesis, Deep Impact and Kepler among others; this is the program this mission was designed for selection in, at least initially.
  One of the first unmanned robotic spacecraft to do a hop was Surveyor 6 lunar lander, which successfully soft landed on the Moon 1967 and conducted a post-landing hop. Another possibly for a hopper mission may be Saturn's moon Enceladus. Hoppers are noted for their ability to potentially visit different landing sites. Another hopper-type mission was the Comet Hopper, which won a Discovery semi-finalist award to study a hopping mission to the Comet 46P/Wirtanen.
  There was some speculation in 2012 that the Geyser Hopper mission could be flown after the InSight Mars lander.
caption: Mars south polar ice cap (note: ice in this case can also imply carbon dioxide ice as opposed to water ice)
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