CHAPTER 23: SEASONS, ECLIPSES AND LUNAR PHASES
ACTIVITY 3: COMPREHENSION 1 Read this article and answer the questions that follow.
MOON’S WATER IS USEFUL RESOURCE, SAYS NASA
There are patches of water-rich soil that could help astronauts survive on the Moon, according to NASA.
The impact caused by a rocket and a probe crashing into a lunar crater, carried out as part of an experiment, kicked up rock and dust, revealing chemical compounds and more water than anyone had imagined. Approximately 155 kg of water vapour and water-ice were blown out of the crater. The researchers’ analysis suggests the lunar regolith, or soil, at the impact site contains 5.6% by weight of water-ice. It’s in the form of water-ice grains. If you took just the 10 km region around the impact site and were to say that it had 5% water, this would be equivalent to about a billion gallons of water.
The spacecraft targeted the Cabeus crater at the Moon’s southern pole. This crater is so deep and dark that the odds of finding ice were thought to be very good. The rocket stage went in first, followed a few minutes later by the LCROSS probe, which gathered imagery and other data just before it too slammed into the surface. Another spacecraft, NASA’s Lunar Reconnaissance Orbiter (LRO), was passing close by. It was also able to study the plume of material ejected into sunlight more than 15 km above the rim of Cabeus.
Instruments on the spacecraft have determined that as much as 20% of this dust plume was made up of compounds such as methane, ammonia, hydrogen gas,
carbon dioxide and carbon monoxide. The instruments also saw relatively large amounts of some metals, such as sodium and mercury. There was even a signature of silver, but this was tiny. Scientists say the water and mix of compounds could be left over from comet or asteroid impacts, but they reckon a number of complex chemical and physical processes also helped to create and move these substances around the Moon. We’ve discovered things we just didn’t expect. And just as the Earth holds its clues to the past climates in the ices at its poles, the Moon also holds clues to past impacts and perhaps even the last stages of lunar volcanism.
The water-ice is not uniformly distributed across the southern pole. It is held in pockets, like in Cabeus, to be found in shadows where temperatures fall to –244°C. Under such conditions, ices will stay fixed for billions of years. Research indicates there is probably water-ice even in areas which receive some sunlight through the year, provided it is buried in the soil. This could help future human visitors as a potential resource: rather than having to brave the cold and dark conditions inside permanent shadow, they could land much more easily in areas where the sunlight is shining at least for part of the year and then dig a small distance below the surface to access the ice.
Adapted from: BBC News report by Jonathan Amos, science correspondent, 22 October 2010
a. What percentage of the lunar regolith was water? b. How much water could be in the area surrounding the impact? c. What was the name of the crater the probe crashed into? d. Name three other compounds detected during the mission.
e. What is one possible source for these compounds?
f. What are the lowest temperatures these craters can reach?
UNIT 6: RELATIONSHIPS
109
EARTH AND SPACE
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