2.3 Missions to the Moon

David A. Rothery Teach Yourself Planets, Chapter 6, pp. 66–75, Hodder Education, 2000, 2003.

Copyright © David Rothery

The Moon was the first extraterrestrial target for space missions. Probes have been directed towards it since almost the very dawn of the space age (see below), and it was the main focus of the 1960s–1970s ‘space race’ between the USA and the then Soviet Union. In the end, only NASA attempted to put people on the Moon, and the six suc
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2.1 The Moon

David A. Rothery Teach Yourself Planets, Chapter 6, pp. 66–75, Hodder Education, 2000, 2003.

Copyright © David Rothery

In this chapter you will learn:

  • about the nearest planetary body to the Earth

  • about the long record of impact cratering on its surface, and about the ancient eruptions that flooded many low-lying areas.

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1 Observing the Moon

Activity 1

0 hours 30 minutes

Try to make out features on the surface of the Moon, even if you have no optical aid available. If you have the use of a pair of binoculars you will probably
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Learning outcomes

After studying this unit you will be able to:

  • retrieve, evaluate and interpret data and information about the Moon, so that (for example) using a close-up picture of the Moon's surface you could identify the types of feature visible and recognise the processes responsible for creating them;

  • interpret simple tables;

  • express, manipulate and compare very small numbers.


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Acknowledgements

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9 Unit summary

You have learned about the following concepts in this unit:

  • Each type of atom contains a characteristic number of protons in a central nucleus and an equal number of electrons in layers surrounding the nucleus.

  • Elements are substances that consist of only one type of atom. Compounds contain two or more elements combined together. There are two kinds of bond between atoms: covalent and ionic.

  • Molecules are the smallest
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7 Ions and ionic bonding

This section returns to bonding – the way in which atoms are joined to each other. You have already met one type of bonding involving covalent bonds, which is found in molecules. However, this is not the only bonding found in compounds. In this section you will look at ionic bonding and the ionic compounds that contain such bonding. What is the main difference between the covalent compounds you met in Author(s): The Open University

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2.3 The irreversible Universe

‘Science owes more to the steam engine than the steam engine owes to Science.’

L.J. Henderson (1917)

From the time of Newton until the end of the nineteenth century the development of physics consisted essentially of the refinement and extension of the mechanical view of the Universe. There were many stages in this process but one of the most interesting came towards its end with the re
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2.2.2 Energy and conservation

Newtonian mechanics is concerned with explaining motion, yet it contains within it the much simpler idea that some things never change. Take the concept of mass, for example, which appears throughout Newtonian mechanics, including the law of gravitation. In Newtonian mechanics, mass is conserved. This means that the mass of the Universe is constant and the mass of any specified collection of particles is constant, no matter how much rearrangement occurs within the system. A chemist might take
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2.3.1 Applying the principles

Trying to use ‘guiding principles’ of this type does not make assessment straightforward. For example, such principles can't be rigidly applied in an abstract way, reflecting absolutes such as what is ‘right’ or ‘wrong'; their operation depends on context.

We can explore this further by attempting to apply the third of these principles. Justice might be considered to involve directing the benefits of a new technology to those who need it most. At the same time, the role of pol
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Introduction

This unit is the first in a series of three on Animals at the extreme. It is concerned with the integration of behaviour anatomy, physiology and biochemistry in diverse vertebrates that live in deserts. Once you have completed this unit, you will be all the more able to appreciate the linked units that follow, Animals at the extreme: hibernation and torpor and Animals at the extreme: the polar environment. These units build on and develop some of the science you will stud
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6.3 Metabolic regulation and the midbrain

As you found in the last section, the physiological evidence points to the likelihood that different components of regulation may be regulated separately. The hypothalamus, which appears to be central to the depression and recovery of body temperature during entry to torpor and arousal, is not the only player in the control of metabolic processes underlying non-behavioural thermogenesis. In many respects, the initiation of thermogenesis is the prime event in the reactivation of a cold body: t
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6.2 The hypothalamus as central regulator

Research in the past 30–40 years has established that the hypothalamus, which lies below the thalamus and above the optic nerve chiasma and the pituitary gland in the brain, fulfils all of the functions listed above, at least in part. The main function of the hypothalamus is homeostasis. Factors such as blood pressure, body temperature, fluid and electrolyte balance, and body weight are held to constant values called the set-points. Although set-points can vary over time, from day to
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5.7 Summary

BMR is regulated independently of T b at least in hibernating mammals. Entry into hibernation is characterized by a gradual fall in RQ, which indicates a switch from carbohydrate to lipid metabolism for energy provision (through the phosphorylation of pyruvate dehydrogenase, the inhibitor of mitochondrial fatty acid uptake). There is evidence that some other vertebrates, such as hibernating frogs, may continue to use carbohydrate catabolism or activate gluconeogenic pathways
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5.5 Energy budgeting – the benefits of hibernation and torpor

Studies performed on ground squirrels in the wild and in the laboratory have allowed estimates to be made of energy expenditure in hibernating and euthermic animals over similar periods (Wang, 1987). The average time spent by Richardson's ground squirrel in a periodic arousal in the wild is about 10 hours and the frequency of arousal decreases during November-March, when animals are spending more than 90% of their time in torpor. Monthly total oxygen consumption in January is about 35% of tha
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5.4 Inspiratory drive

The supply of oxygen to tissues such as the heart, liver and WAT is, under euthermic conditions, invariably linked to and dependent upon local blood flow and pulmonary function. However, as we have already seen, under conditions in which blood flow is reduced to a trickle, the control of energy supply switches to local adaptations in the capillaries and tissue cells, including the oxygen affinity of erythrocyte haemoglobin, the supply and metabolism of respiratory fuels and the rate of protei
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5.3 Mitochondrial adaptations

During the winter months, whilst hibernating vertebrates maintain a very low metabolic rate, major reorganization of mitochondrial metabolism occurs. The phenomenon has been studied in some detail in frogs which, although not hibernators in the true sense, can endure very low water temperatures under the conditions of profound hypoxia that exist when they lie dormant for long periods below the surface. In contrast to normoxic conditions, the muscle mitochondria of dormant frogs depress their
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4.4 Cell survival mechanisms

Physical damage is not the only danger that faces cells recovering from low temperatures in the absence of oxygen (due to a 90% drop in blood flow to the brain) and energy supplies. A universal sign of recovery from such conditions is the production of reactive oxygen species (ROS) (Box 4). The electron transfer chain that participates in the formation of water from oxygen in mitochondrial respiration can also be used in the production of the free radical superoxide, sometimes called ‘singl
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4.2 Arresting protein synthesis

The regulation of T b in hibernators has traditionally been viewed as the fundamental physiological process in hibernation. But recently, questions have been raised about whether thermal changes initiate or simply accompany metabolic depression. Is the metabolic inactivity of animal tissues during bouts of torpor or in hibernation, the cause or the result of hypothermia? A common-sense view is that temperature directly influences metabolism by regulating enzyme activity. Evi
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