Sky & Telescope - January 2021 - 40

Lunar Exploration

W WHAT NEUTRON SPECTROSCOPY DETECTS Cosmic rays constantly strike the Moon and liberate neutrons, which either get absorbed
or scattered by interactions with rocks before escaping to space. But the
neutrons lose a bit of energy if they glance off hydrogen atoms before
leaving - hydrogen that's very likely bound up in molecules of water. So
by recording these less-energetic "moderated" neutrons, scientists can
map the extent and abundance of water-ice deposits in the top meter or
so of the lunar surface.

Directly
escaping
neutrons

Moderated
neutrons

The rover will land in an "unbelievably cold" and "very
strange, never-seen-before region" that may have very little
resemblance to the Moon we think we know, says Andrews.
Already mission planners are sifting through thousands of
candidate landing sites and traverse patterns, factoring in
science needs, access to sunnier terrain, temperatures, sight
lines with Earth for communication, and obstacle avoidance.
We'll learn more about such mission needs from a smaller
rover called MoonRanger, under joint development by Carnegie Mellon University and CMUspinoff company Astrobotic. Set to arrive in
2022, it will test navigation, communications,
and mapping tools before VIPER lands.
This large-scale lunar exploration effort -
joined as well by China (S&T: June 2020, p. 34)
and other countries - would not be happening if not for the combined allure of scientific
discovery and natural resources.
The cache of water and other volatiles stored
at the lunar poles will provide valuable information about the creation and evolution of the
X WHERE'S THE ICE? These maps show the icefavorability index (IFI), a predictive assessment of which
regions near the lunar poles contain the most favorable
ice deposits for future mining operations. They apply
desired characteristics such as older crater ages, ice
stability closer to the surface, and higher areal fraction of
cold traps - but not ease of access. North pole on top.

terrestrial planets, including Earth, says Deutsch. "If we don't
have the opportunity to study these records in detail, we lose
access to the most accessible and potentially most complete
record of the processes that have delivered and modified volatiles in the inner solar system."
Understanding the timing and processes for the deposition
of surface and subsurface lunar water ice can also help us
understand impact rates over time, Cohen points out.
But although science is in many ways driving the lunar
revival, it might be economic activity and even settlements
that translate to further progress. Researchers are also studying which deposits would be best for in situ resource utilization, processed for crew consumption or rocket fuel.
"On Earth, we've learned a tremendous [amount] about
geologic processes and materials in the course
of exploring for resources," says Kevin Cannon
(Colorado School of Mines). "I think scientists
should welcome economic prospecting and
development of these ices, because it will result
in them getting more data, samples, and new
findings than they ever could have hoped for
with scientific exploration alone." Given that
there might be trillions of metric tons of ice
present, it won't be gone any time soon, he adds.
Somewhere, W. H. Pickering may be smiling.
There are no blizzards in Theophilus, but there
are places on the Moon locked in a kind of interplanetary winter. It's a season that heralds breakthroughs for our understanding of the Moon.

IFI+
Low

High

„ CHRISTOPHER COKINOS is coeditor of the
anthology Beyond Earth's Edge: The Poetry of
Spaceflight. He teaches at the University of Arizona and is writing a book about the Moon.

Where Is
the Ice?
NASA scientists
use four categories for where to
look for ice on
the Moon.

40

50 cm
100 cm

Surface region
Soils on the surface
where ice is expected
to be stable, such as
in permanently shadowed craters

JANUARY 2 021 * SK Y & TELESCOPE

Shallow region
Soils where ice
is expected to
be stable within
50 cm (20 in) of
the surface

Deep region
Soils where ice is
expected to be
stable at depths
of 50-100 cm
(20-40 in)

Dry region
Soils where
no ice is expected within
the top 100
cm (40 in)

NEU TRONS ESCA PING M OON: G REGG DINDER M A N / S&T, SOURCE:
LUN A H-M A P / A RIZON A STATE UNIV ERSIT Y; M OON M A PS: K E VIN
CA NNON & DA NIEL BRIT T / UNIV ERSIT Y OF CEN TR A L FLORIDA

Galactic cosmic-ray protons



Sky & Telescope - January 2021

Table of Contents for the Digital Edition of Sky & Telescope - January 2021

Contents
Sky & Telescope - January 2021 - Cover1
Sky & Telescope - January 2021 - Cover2
Sky & Telescope - January 2021 - 1
Sky & Telescope - January 2021 - Contents
Sky & Telescope - January 2021 - 3
Sky & Telescope - January 2021 - 4
Sky & Telescope - January 2021 - 5
Sky & Telescope - January 2021 - 6
Sky & Telescope - January 2021 - 7
Sky & Telescope - January 2021 - 8
Sky & Telescope - January 2021 - 9
Sky & Telescope - January 2021 - 10
Sky & Telescope - January 2021 - 11
Sky & Telescope - January 2021 - 12
Sky & Telescope - January 2021 - 13
Sky & Telescope - January 2021 - 14
Sky & Telescope - January 2021 - 15
Sky & Telescope - January 2021 - 16
Sky & Telescope - January 2021 - 17
Sky & Telescope - January 2021 - 18
Sky & Telescope - January 2021 - 19
Sky & Telescope - January 2021 - 20
Sky & Telescope - January 2021 - 21
Sky & Telescope - January 2021 - 22
Sky & Telescope - January 2021 - 23
Sky & Telescope - January 2021 - 24
Sky & Telescope - January 2021 - 25
Sky & Telescope - January 2021 - 26
Sky & Telescope - January 2021 - 27
Sky & Telescope - January 2021 - 28
Sky & Telescope - January 2021 - 29
Sky & Telescope - January 2021 - 30
Sky & Telescope - January 2021 - 31
Sky & Telescope - January 2021 - 32
Sky & Telescope - January 2021 - 33
Sky & Telescope - January 2021 - 34
Sky & Telescope - January 2021 - 35
Sky & Telescope - January 2021 - 36
Sky & Telescope - January 2021 - 37
Sky & Telescope - January 2021 - 38
Sky & Telescope - January 2021 - 39
Sky & Telescope - January 2021 - 40
Sky & Telescope - January 2021 - 41
Sky & Telescope - January 2021 - 42
Sky & Telescope - January 2021 - 43
Sky & Telescope - January 2021 - 44
Sky & Telescope - January 2021 - 45
Sky & Telescope - January 2021 - 46
Sky & Telescope - January 2021 - 47
Sky & Telescope - January 2021 - 48
Sky & Telescope - January 2021 - 49
Sky & Telescope - January 2021 - 50
Sky & Telescope - January 2021 - 51
Sky & Telescope - January 2021 - 52
Sky & Telescope - January 2021 - 53
Sky & Telescope - January 2021 - 54
Sky & Telescope - January 2021 - 55
Sky & Telescope - January 2021 - 56
Sky & Telescope - January 2021 - 57
Sky & Telescope - January 2021 - 58
Sky & Telescope - January 2021 - 59
Sky & Telescope - January 2021 - 60
Sky & Telescope - January 2021 - 61
Sky & Telescope - January 2021 - 62
Sky & Telescope - January 2021 - 63
Sky & Telescope - January 2021 - 64
Sky & Telescope - January 2021 - 65
Sky & Telescope - January 2021 - 66
Sky & Telescope - January 2021 - 67
Sky & Telescope - January 2021 - 68
Sky & Telescope - January 2021 - 69
Sky & Telescope - January 2021 - 70
Sky & Telescope - January 2021 - 71
Sky & Telescope - January 2021 - 72
Sky & Telescope - January 2021 - 73
Sky & Telescope - January 2021 - 74
Sky & Telescope - January 2021 - 75
Sky & Telescope - January 2021 - 76
Sky & Telescope - January 2021 - 77
Sky & Telescope - January 2021 - 78
Sky & Telescope - January 2021 - 79
Sky & Telescope - January 2021 - 80
Sky & Telescope - January 2021 - 81
Sky & Telescope - January 2021 - 82
Sky & Telescope - January 2021 - 83
Sky & Telescope - January 2021 - 84
Sky & Telescope - January 2021 - Cover3
Sky & Telescope - January 2021 - Cover4
Sky & Telescope - January 2021 - SA1
Sky & Telescope - January 2021 - SA2
Sky & Telescope - January 2021 - SA3
Sky & Telescope - January 2021 - SA4
Sky & Telescope - January 2021 - SA5
Sky & Telescope - January 2021 - SA6
Sky & Telescope - January 2021 - SA7
Sky & Telescope - January 2021 - SA8
Sky & Telescope - January 2021 - SA9
https://www.nxtbook.com/nxtbooks/aas/st_202103
https://www.nxtbook.com/nxtbooks/aas/st_202102
https://www.nxtbook.com/nxtbooks/aas/st_202101
https://www.nxtbook.com/nxtbooks/aas/skywatch_2021
https://www.nxtbook.com/nxtbooks/aas/st_202012
https://www.nxtbook.com/nxtbooks/aas/st_202011
https://www.nxtbook.com/nxtbooks/aas/st_202010
https://www.nxtbook.com/nxtbooks/aas/st_202009
https://www.nxtbook.com/nxtbooks/aas/st_202008
https://www.nxtbook.com/nxtbooks/aas/st_202007
https://www.nxtbook.com/nxtbooks/aas/st_202006
https://www.nxtbook.com/nxtbooks/aas/st_202005
https://www.nxtbook.com/nxtbooks/aas/st_202004
https://www.nxtbook.com/nxtbooks/aas/st_202003
https://www.nxtbook.com/nxtbooks/aas/st_202002
https://www.nxtbook.com/nxtbooks/aas/st_202001
https://www.nxtbook.com/nxtbooks/aas/st_201912
https://www.nxtbook.com/nxtbooks/aas/st_201911
https://www.nxtbook.com/nxtbooks/aas/st_201910
https://www.nxtbook.com/nxtbooks/aas/st_201909
https://www.nxtbook.com/nxtbooks/aas/st_201908
https://www.nxtbook.com/nxtbooks/aas/st_201907
https://www.nxtbook.com/nxtbooks/aas/st_201906
https://www.nxtbook.com/nxtbooks/aas/st_201905
https://www.nxtbook.com/nxtbooks/aas/st_201904
https://www.nxtbook.com/nxtbooks/aas/st_201903
https://www.nxtbook.com/nxtbooks/aas/st_201902
https://www.nxtbook.com/nxtbooks/aas/st_201901
https://www.nxtbook.com/nxtbooks/aas/st_201812
https://www.nxtbook.com/nxtbooks/aas/st_201811
https://www.nxtbook.com/nxtbooks/aas/st_201810
https://www.nxtbook.com/nxtbooks/aas/st_201809
https://www.nxtbook.com/nxtbooks/aas/st_201808
https://www.nxtbook.com/nxtbooks/aas/st_201807
https://www.nxtbook.com/nxtbooks/aas/st_201806
https://www.nxtbook.com/nxtbooks/aas/st_201805
https://www.nxtbook.com/nxtbooks/aas/st_201804
https://www.nxtbook.com/nxtbooks/aas/st_201803
https://www.nxtbook.com/nxtbooks/aas/st_201802
https://www.nxtbook.com/nxtbooks/aas/st_201801
https://www.nxtbook.com/nxtbooks/aas/st_201712
https://www.nxtbook.com/nxtbooks/aas/st_201711
https://www.nxtbook.com/nxtbooks/aas/st_201710
https://www.nxtbook.com/nxtbooks/aas/st_201709
https://www.nxtbook.com/nxtbooks/aas/st_201708
https://www.nxtbook.com/nxtbooks/aas/st_201707
https://www.nxtbook.com/nxtbooks/aas/st_201706
https://www.nxtbook.com/nxtbooks/aas/st_201705
https://www.nxtbook.com/nxtbooks/aas/st_201704
https://www.nxtbook.com/nxtbooks/aas/st_201703
https://www.nxtbook.com/nxtbooks/aas/st_201702
https://www.nxtbook.com/nxtbooks/aas/st_201701
https://www.nxtbook.com/nxtbooks/aas/st_201612
https://www.nxtbook.com/nxtbooks/aas/st_201611
https://www.nxtbook.com/nxtbooks/newtrack/st_201612
https://www.nxtbook.com/nxtbooks/aas/st_201610
https://www.nxtbook.com/nxtbooks/aas/st_201609
https://www.nxtbook.com/nxtbooks/aas/st_201608
https://www.nxtbook.com/nxtbooks/aas/st_201607
https://www.nxtbook.com/nxtbooks/aas/st_201606
https://www.nxtbook.com/nxtbooks/aas/st_201605
https://www.nxtbook.com/nxtbooks/aas/st_201604
https://www.nxtbook.com/nxtbooks/aas/st_201603
https://www.nxtbook.com/nxtbooks/aas/st_201602
https://www.nxtbook.com/nxtbooks/aas/st_201601
https://www.nxtbook.com/nxtbooks/aas/st_201512
https://www.nxtbook.com/nxtbooks/aas/st_201511
https://www.nxtbook.com/nxtbooks/aas/st_201510
https://www.nxtbook.com/nxtbooks/aas/st_201509
https://www.nxtbook.com/nxtbooks/aas/st_201508
https://www.nxtbook.com/nxtbooks/aas/st_201507
https://www.nxtbook.com/nxtbooks/aas/st_201506
https://www.nxtbook.com/nxtbooks/aas/st_201505
https://www.nxtbook.com/nxtbooks/aas/st_201504
https://www.nxtbook.com/nxtbooks/aas/st_201503
https://www.nxtbook.com/nxtbooks/aas/st_201502
https://www.nxtbook.com/nxtbooks/aas/st_201501
https://www.nxtbook.com/nxtbooks/aas/st_201412
https://www.nxtbook.com/nxtbooks/aas/st_201411
https://www.nxtbook.com/nxtbooks/aas/st_201410
https://www.nxtbook.com/nxtbooks/aas/st_201409
https://www.nxtbook.com/nxtbooks/aas/st_201408
https://www.nxtbook.com/nxtbooks/aas/st_201407
https://www.nxtbook.com/nxtbooks/aas/st_201406
https://www.nxtbook.com/nxtbooks/aas/st_mars
https://www.nxtbook.com/nxtbooks/aas/st_201405
https://www.nxtbook.com/nxtbooks/aas/st_201404
https://www.nxtbook.com/nxtbooks/aas/st_201403
https://www.nxtbook.com/nxtbooks/aas/st_201402
https://www.nxtbook.com/nxtbooks/aas/st_201401
https://www.nxtbook.com/nxtbooks/aas/st_201312
https://www.nxtbook.com/nxtbooks/aas/st_201311
https://www.nxtbook.com/nxtbooks/aas/st_201310
https://www.nxtbook.com/nxtbooks/aas/st_201309
https://www.nxtbook.com/nxtbooks/aas/st_201308
https://www.nxtbook.com/nxtbooks/aas/st_201307
https://www.nxtbook.com/nxtbooks/aas/st_201306
https://www.nxtbook.com/nxtbooks/aas/st_201305
https://www.nxtbook.com/nxtbooks/aas/st_201304
https://www.nxtbook.com/nxtbooks/aas/st_201303
https://www.nxtbook.com/nxtbooks/aas/st_201302
https://www.nxtbook.com/nxtbooks/aas/st_201301
https://www.nxtbook.com/nxtbooks/aas/st_201212
https://www.nxtbook.com/nxtbooks/aas/st_201211
https://www.nxtbook.com/nxtbooks/aas/st_201210
https://www.nxtbook.com/nxtbooks/aas/st_201209
https://www.nxtbook.com/nxtbooks/aas/st_201208
https://www.nxtbook.com/nxtbooks/aas/st_201207
https://www.nxtbook.com/nxtbooks/aas/st_201206
https://www.nxtbook.com/nxtbooks/aas/st_201205
https://www.nxtbook.com/nxtbooks/aas/st_201204
https://www.nxtbook.com/nxtbooks/aas/st_201203
https://www.nxtbook.com/nxtbooks/aas/st_201202
https://www.nxtbook.com/nxtbooks/aas/st_201201
https://www.nxtbook.com/nxtbooks/aas/st_201112
https://www.nxtbook.com/nxtbooks/aas/st_201111
https://www.nxtbook.com/nxtbooks/aas/st_201110
https://www.nxtbook.com/nxtbooks/aas/st_201109
https://www.nxtbook.com/nxtbooks/aas/st_201108
https://www.nxtbook.com/nxtbooks/aas/st_201107
https://www.nxtbook.com/nxtbooks/aas/st_201106
https://www.nxtbook.com/nxtbooks/aas/st_201105
https://www.nxtbook.com/nxtbooks/aas/st_201104
https://www.nxtbook.com/nxtbooks/aas/st_201103
https://www.nxtbook.com/nxtbooks/aas/st_201102
https://www.nxtbook.com/nxtbooks/aas/st_201101
https://www.nxtbook.com/nxtbooks/aas/st_201012
https://www.nxtbook.com/nxtbooks/aas/st_201011
https://www.nxtbook.com/nxtbooks/aas/st_201010
https://www.nxtbook.com/nxtbooks/aas/st_201009
https://www.nxtbook.com/nxtbooks/aas/st_201008
https://www.nxtbook.com/nxtbooks/aas/st_201007
https://www.nxtbook.com/nxtbooks/aas/st_201006
https://www.nxtbook.com/nxtbooks/aas/st_201005
https://www.nxtbook.com/nxtbooks/aas/st_201004
https://www.nxtbook.com/nxtbooks/aas/st_201003
https://www.nxtbook.com/nxtbooks/aas/st_201002
https://www.nxtbook.com/nxtbooks/aas/st_201001
https://www.nxtbookmedia.com