Instructions: In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.
Input: A study published in Geophysical Research Letters confirms the existence of a large open lava tube in the Marius Hills region of the moon, which could be used to protect astronauts from hazardous conditions on the surface. 
  
 No one has ever been on the moon longer than three days, largely because space suits alone can't shield astronauts from its elements: extreme temperature variation, radiation, and meteorite impacts. Unlike Earth, the moon has no atmosphere or magnetic field to protects its inhabitants. 
  
 The safest place to seek shelter is the inside of an intact lava tube, according to the study. 
  
 Lava tubes are naturally occurring channels formed when a lava flow develops a hard crust, which thickens and forms a roof above the still-flowing lava stream. Once the lava stops flowing, the tunnel sometimes drains, forming a hollow void. 
  
 "It's important to know where and how big lunar lava tubes are if we're ever going to construct a lunar base," said Junichi Haruyama, a senior researcher at JAXA, Japan's space agency. "But knowing these things is also important for basic science. We might get new types of rock samples, heat flow data and lunar quake observation data." 
  
 JAXA analyzed radar data from the SELENE spacecraft to detect underlying lava tubes. Near the Marius Hills Skylight, an entrance to the tube, they found a distinctive echo pattern: a decrease in echo power followed by a large second echo peak, which they believe is evidence of a tube. The two echoes correspond to radar reflections from the moon's surface and the floor and ceiling of the open tube. The team found similar echo patterns at several locations around the hole, indicating there may be more than one. 
  
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 SELENE's radar system wasn't designed to detect lava tubes -- it was built to study the origins of the moon and its geologic evolution. For these reasons, it didn't fly close enough to the moon's surface to get extremely accurate information on what is (or isn't) underneath. 
  
 When the JAXA team decided to use their data to try and find lava tubes, they consulted scientists from the GRAIL mission, a NASA effort to collect high-quality data on the moon's gravitational field. By surveying the areas where GRAIL had identified mass deficits, or less mass under the surface, they narrowed down the data they needed to analyze. 
  
 "They knew about the skylight in the Marius Hills, but they didn't have any idea how far that underground cavity might have gone," said Jay Melosh, a GRAIL co-investigator and Distinguished Professor of Earth, Atmospheric and Planetary Sciences at Purdue University. "Our group at Purdue used the gravity data over that area to infer that the opening was part of a larger system. By using this complimentary technique of radar, they were able to figure out how deep and high the cavities are." 
  
 Lava tubes exist on Earth, but their lunar counterparts are much larger. For a lava tube to be detectable by gravity data, it would need to extend several kilometers in length and at least one kilometer in height and width -- which means the lava tube near the Marius Hills is spacious enough to house one of the United States' largest cities, if the gravity results are correct. 
  
 The existence of lava tubes on the moon has been speculated in the past, but this combination of radar and gravity data provides the clearest picture of what they look like and how big they are yet. This information might be more useful than previously expected. 
  
 At the first meeting of the National Space Council in decades, Vice President Mike Pence announced that the Trump administration will redirect America's focus in space to the moon. This marks a fundamental change for NASA, which abandoned plans to send people to the moon in favor of Mars under President Obama. 
  
 "We will return NASA astronauts to the moon -- not only to leave behind footprints and flags, but to build the foundation we need to send Americans to Mars and beyond," Pence said. ||||| Researchers say they may have found the perfect spot for a space base on the moon 
  
 Researchers may have found the perfect spot for NASA to build a base on the moon. 
  
 According to a release from Purdue University, a large, open lava tube discovered on the moon could shield astronauts from hazardous conditions. 
  
 "Lava tubes are naturally occurring channels formed when a lava flow develops a hard crust, which thickens and forms a roof above the still-flowing lava stream. Once the lava stops flowing, the tunnel sometimes drains, forming a hollow void," the release reads. 
  
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 Astronauts have only been able to stay on the moon for three days maximum, due to the lack of atmosphere. Space suits can't protect people from extreme temperature variations, radiation and meteorite impacts note researchers. 
  
 The lava tubes are in the Marius Hills, the largest volcanic dome field on the moon, according to NASA. The lava tube opening pictured has been dubbed the Marius Hills Skylight. Even if a base isn't built in the lava tube, scientists believe studying it would be beneficial. 
  
 "It's important to know where and how big lunar tubes are if we're ever going to construct a lunar base," Junichi Haruyama, a senior researcher at Japan's JAXA, told Purdue University. "Not knowing these things is also important for basic science. We might get new types of rock samples, heat-flow data and lunar-quake observation data." 
  
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 JAXA discovered the lava tubes by analyzing radar data from the SELENE spacecraft. However, the spacecraft wasn't designed to detect lava tubes so it wasn't able to get more accurate readings of the area in which it was discovered. 
  
 Researchers at Purdue used gravity data with the JAXA radar data, theorizing the lava tube is several kilometers in length and at least one kilometer in height. One model shows the lava tube being big enough to house the entire city of Philadelphia. 
  
 The area could become a major site of focus in the near future, as U.S. Vice President Mike Pence said the Trump administration said it'll push for more moon exploration at an Oct. 5 meeting of the National Space Council. 
  
 Scroll through the slideshow above to see strange things that have been captured in NASA photos. ||||| ESA Astronauts training in terrestrial lava tubes in Lanzarote during the PANGEA 2016 course. Credit: ESA/S. Sechi Lava tubes, underground caves created by volcanic activity, could provide protected habitats large enough to house streets on Mars or even towns on the moon, according to research presented at the European Planetary Science Congress (EPSC) 2017 in Riga. A further study shows how the next generation of lunar orbiters will be able to use radar to locate these structures under the moon's surface. 
  
 Lava tubes can form in two ways: over-crusted tubes form when low-viscosity lava flows fairly close to the surface, developing a hard crust that thickens to create a roof above the moving lava stream. When the eruptions end, the conduit is drained leaving a tunnel a few metres beneath the surface. "Inflated' tubes are complex and deep structures that form when lava is injected into existing fissures between layers of rock or cavities from previous flows. The lava expands and leaves a huge network of connected galleries as it forces its way to the surface. Lava tubes are found in many volcanic areas on Earth, including Lanzarote, Hawaii, Iceland, North Queensland in Australia, Sicily and the Galapagos islands. Underground networks of tubes can reach up to 65 kilometres. Space missions have also observed chains of collapsed pits and "skylights" on the moon and Mars that have been interpreted as evidence of lava tubes. Recently the NASA GRAIL mission provided detailed gravity data for the moon that suggested the presence of enormous subsurface voids related to lava tubes below the lunar maria, plains of basalt formed in volcanic eruptions early in the moon's history. 
  
 Now, researchers from the University of Padova and the University of Bologna in Italy have carried out the first systematic comparison of lava tube candidates on the Earth, moon and Mars, based on high-resolution Digital Terrain Models (DTM) created from data from spacecraft instrumentation. 
  
 ESA Astronauts training in terrestrial lava tubes in Lanzarote during the PANGEA 2016 course. Credit: ESA/L. Ricci "The comparison of terrestrial, lunar and martian examples shows that, as you might expect, gravity has a big effect on the size of lava tubes. On Earth, they can be up to thirty metres across. In the lower gravity environment of Mars, we see evidence for lava tubes that are 250 metres in width. On the moon, these tunnels could be a kilometre or more across and many hundreds of kilometres in length," says Dr Riccardo Pozzobon, of the University of Padova. "These results have important implications for habitability and human exploration of the moon but also for the search of extraterrestrial life on Mars. Lava tubes are environments shielded from cosmic radiation and protected from micrometeorites flux, potentially providing safe habitats for future human missions. They are also, potentially, large enough for quite significant human settlements – you could fit most of the historic city centre of Riga into a lunar lava tube." 
  
 The work by Pozzobon and colleagues is already being used in the European Space Agency's astronaut training programme. The teams lead a planetary geology training course called PANGAEA for the European Space Agency's astronauts and engineers. The PANGAEA project has included a field trip and a test campaign in lava tubes in the Canary Island to familiarise the astronauts with geological research they could carry out during future missions to the moon or Mars, as well as to test technical and operational systems. In particular, PANGAEA has focused on using laser technologies to characterise the Corona lava tube, an 8-kilometre long tunnel on Lanzarote. 
  
 However, analysis of lava tubes with DEMs requires that a collapse or a puncture from a meteorite reveals the presence of the hidden tunnel. Conventional remote sensing instruments cannot detect and characterise the lava tubes, as they cannot acquire measurements beneath the surface. 
  
 Checking the mineral composition of some weathered rocks with the HaloSpec Spectrometer during ESA astronaut PANGEA training course in terrestrial lava tubes in Lanzarote. Credit: ESA/L. Ricci 
  
 In a separate talk at EPSC, Leonardo Carrer and colleagues of the University of Trento presented a concept for a radar system specifically designed to detect lava tubes on the moon from orbit. The radar probes beneath the lunar surface with low frequency electromagnetic waves and measures the reflected signals. This radar instrument could determine accurately the physical composition, size and shape of the caves and obtain a global map of their location. 
  
 "The studies we have developed show that a multi- frequency sounding system is the best option for detecting lava tubes of very different dimensions. The electromagnetic simulations show that lava tubes have unique electromagnetic signatures, which can be detected from orbit irrespective of their orientation to the radar movement direction. Therefore, a mission carrying this instrument would enable a crucial step towards finding safe habitats on the moon for human colonisation," says Carrer. 
  
 Artist’s impression of the radar instrument to probe for lava tubes beneath the lunar surface. Credit: NASA/U. Trento Artist’s impression of the radar instrument to probe for lava tubes beneath the lunar surface. Credit: NASA/U. Trento 
  
 Explore further: Data from GRAIL spacecraft suggest moon may have large lava tubes |||||
Output:
Thanks to a study in Geophysical Research Letters, we now know where the first human settlement on the moon could be built—a massive lava tube potentially extending miles below the surface. Astronauts haven't been able to spend more than three days on the moon—which lacks Earth's atmosphere and magnetic field—because spacesuits offer minimal protection from radiation, extreme temperatures, and meteorites, according to a press release. A lava tube, on the other hand... "It's important to know where and how big lunar lava tubes are if we're ever going to construct a lunar base," says a researcher at JAXA, Japan's space agency. Researchers at JAXA and Purdue University combined radar data from the SELENE spacecraft and gravitational data from GRAIL to locate what they believe are a number of intact lava tubes—formed when flowing lava forms a crust before draining away—in the Marius Hills area of the moon, the Houston Chronicle reports. Marius Hills is the moon's biggest volcanic dome field. According to Phys.org, Italian researchers recently presented findings that lava tubes on the moon could be massive compared to their counterparts on Earth due to lower gravity, stating the "results have important implications for habitability and human exploration of the moon." One model from the new study shows a lunar lava tube could be large enough to encompass the entire city of Philadelphia. (Russia and the US are building a moon base.)