Table Of ContentMoore on Mercury
Bythe same authorfrom Springer:
The AmateurAstronomer (12th Edition)
PatrickMoore
Astronomywith a Budget Telescope
PatrickMoore andJohn Watson
The Observer'sYear(2ndEdition)
PatrickMoore
The Sun in Eclipse
MichaelMaunderandPatrickMoore
Transit: When Planets Cross the Sun
MichaelMaunderandPatrickMoore
Eyeson the Universe: The Storyofthe Telescope
PatrickMoore
PatrickMoore's MillenniumYearbook
PatrickMoore andAllanChapman
Sir Patrick Moore
Moore on
Mercury
The Planet and the Missions
With 82Illustrations
~
Springer
Coverillustrations:Clockwisefrom bottomleft:BepiColombo(image courtesy
ofESA),Messenger(imagecourtesyofNASA)andMariner10(image courtesy
ofthe JetPropulsionLaboratory).Backgroundimage ofMercurycourtesyof
NASA.
BritishLibraryCataloguinginPublication Data
Moore,Patrick
MooreonMercury:theplanet andthemissions
1.SpaceflighttoMercury 2.Mercuryprobes 3.Mercury
(Planet)
I.Title
523.4'1
ISBN-13:9781846282577
ISBN-I0:1846282578
LibraryofCongressControl Number:2006931930
ISBN-I0:1-84628-257-8 Printedonacid-free paper
ISBN-13:978-1-84628-257-7
©Springer-VerlagLondonLimited2007
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Acknowledgements
My grateful thanks are due to Dr.David Rothery, of the Open
University,for his invaluable help when this book reached the
proofstage.
My thanks are also due to John Fletcher and Peter Paice for
theirphotographs,andto TonyWilmotforhis drawings- andto
NASA,JPL,the IAUand the LowellObservatoryfor allowing me
to use their material.
PatrickMoore
July2006
v
Contents
1 Lift-off . ... 1
2 ElusivePlanet 5
3 "Messengerofthe Gods". . . .13
4 Mercuryin theSolarSystem · 21
5 CrossingtheSun . · 27
6 Ghost Planet. . . . ... 37
7 Throughthe Telescope. . . 47
8 MappingMercury. · 55
9 Mariner 10.. . . · 65
10 CrateredWorld . 73
11 AroundMercury . 85
12 Returnto Mercury 105
13 Lifeon Mercury? . 115
14 ATrip to Mercury. 119
15 MercurianBase 125
Appendices
1 Data for Mercury. 131
2 PhenomenaofMercury . 133
Bibliography. . 135
Index..... . 137
vii
Lift-off
In the early hours of August the third, 2004,a group of people waited
expectantly at Cape Canaveral, in Florida.Most were scientists, though
some were reporters and invited onlookers. Allhad eyesturned toward
the launch pad,asafedistance away. In it wasatall rocket, carryingone of
the most interesting space-craft of the newcentury: Messenger,bound for
the little planetMercury.
Manyvehicles had been sent to otherworlds;some hadbeen successful,
others not, and certainly there had been major developments since 1957,
when Russia'sSputnik 1ushered in the SpaceAge.Sputnik was no larger
than a football, and carried little apart from the radio transmitter which
sent out the "bleep! bleep!" signals which will never be forgotten by
anybodywho heard them (as I did).Sincethen almost all the attention of
the space-planners had been focused on the Moon, Mars, Venus and the
occasional comet, and only one probe had been sent to Mercury.This was
Mariner 10,which had made threepasses ofthe planetin 1973-74before its
transmitting power gaveout. Mariner 10had been a great success,but it
had been able to imagelessthan halfofthe planet's surface,and wehad to
admitthatmany problems remainedunsolved,sothat ourin-depthknowl
edgeofMercurywasdecidedly sketchy.Messenger,itwashoped, wouldtell
us much more.
The last moments before launch were tense. Lift-off had already been
postponed once,mainly because of cloud-cover at Canaveral,but this time
allwentwell."Four... three ... two ... one ... Wehaveignition!"Therewas
Moore on Mercury:The Planet and the Missions
Figure 1.1.The launch ofMessengeratCapeCanaveral on August 3, 2004.Images
courtesyofNASA.
abrilliantburstoflight,followedafewseconds later byadeafeningroaras
the rocket rose from its pad - slowlyat first,then more and more rapidly.
Messenger was on its way. Soon it was lost to the view of the waiting
onlookers.Four minutesinto the journeythe firststage ofthe launcherfell
away,andthe motorofthe second stage ignited toputthe vehicleinto orbit
round the Earth.The onlookers breathed sighs of relief.After a 37-minute
"coast"phase, the Delta-2boosteragain firedfor three minutes.There was
abriefmanceuvre, and the probe separated from the rocket; henceforth it
2
lift-off
Figure 1.1. Continued
was on its own.The whole launch procedure had lasted for just under an
hour. The two solar panels were deployed, to generate power, and the
batteries were switched off.The five-thousand-million mile journey had
begun.
Messenger - acronym Mercury Surface Space Environment and
Geochemistry and Ranging - was in no particular hurry. Its Boeing-built
Delta-2launcherwasnot powerful enoughto send the probe directly from
Earth to Mercury,and it wasnecessaryto use the gravity-assist technique,
3
Moore on Mercury:ThePlanetand theMissions
involving one swing-by of the Earth, two of Venus,and three of Mercury
itselfbefore the probe finallysettles into Mercuryorbitin March 2011.Itis
rather like driving from Brighton to Bognor Regisand making detours to
Winchester and Hull,but there was no alternative, and the technique had
already been tested and found to be satisfactory. Oncein orbit, Messenger
wouldspendwelloverayearcollecting andtransmittingdata before being
deliberately crash-landedon the surface ofthe planet in 2015or 2016.This
would not be a controlled landing, because this part of the original
programme had to be abandoned on financial grounds. To President
George W.Bush,Messenger was much less important than the attack on
Iraq.
At least a great deal could be learned from observations made from
orbit,and thespace-plannerswereconfidentthat thefullprogrammecould
be carriedthrough,even though it did mean ratheralongwait.
Figure 1.2.TheEarthfrom Messenger.ImagecourtesyofNASA.
4
