First Ice Cores from Mars

A	report	from	the	NASA	Mars	Ice	Core	Working	Group

February	2021

Working Group Members:

● Mary	R.	Albert,	Dartmouth	College	(co-chair)

● Michelle	Koutnik,	University	of	Washington	(co-chair)

● Seth	Campbell,	University	of	Maine

● Laurel	Childress,	Texas	A&M	University

● T.J.	Fudge,	University	of	Washington

● Jack	Holt,	University	of	Arizona

● Aaron	Johnson,	Carnegie	Mellon

● Michael	Mellon,	Cornell	University	

● John	Priscu,	Montana	State	University

● Ted	Schuur,	Northern	Arizona	University

● Heidi	Smith,	Montana	State	University

● Michael	Sori,	Purdue	University

● Kris Zacny,	Honeybee	Robotics

NASA Observers:

● Mitchell	Schulte

● Catherine	Walker

Recommended bibliographic citation: 

Mars	Ice	Core	Working	Group	(2021),	First	Ice	Cores	from	Mars,	co-chairs:	M.R.	Albert	and	

M.	Koutnik,	74 p.	white	paper.	
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Table	of	Contents

Executive	Summary............................................................................................................................. 3

I.	Introduction ....................................................................................................................................... 3

II.	Ice	cores	from	Earth....................................................................................................................... 5

1.	Background.........................................................................................................................................................................5

2.	Example	past	and	future	high-priority	science	questions	for	life	(cryobiology)	and	climate	on	

Earth...........................................................................................................................................................................................6

3.	Evidence	of	life	and	climate	within	glacial	ice.....................................................................................................7

4.	Ice	core	drill-site	selection........................................................................................................................................12

5.	Handling	and	preservation	of	ice	cores	on	Earth	for	transport	and	storage ......................................16

6.	Initial	measurements	that	can	be	made	in	the	field	on	ice	cores	on	Earth..........................................20

7.	Core	allocation	and	measurements.......................................................................................................................21

III.	Ice	cores	from	Mars ....................................................................................................................24

1. High-priority	science...................................................................................................................................................24

2. Measurements	on	returned	samples....................................................................................................................37

3. Drill	site	selection	and	context	to	interpret	ice	core	records ....................................................................39

4. Initial	measurements	and	on-site	handling	of	the	ice	core ........................................................................41

5. Criteria	for	preserving	ice	cores	for	transport	and	storage .......................................................................42

IV.	Ice	core	drill	engineering	on	Earth	and	drilling	concepts	for	Mars............................44

V.	Requirements	from	science	for	engineering	an	ice	coring	drill	for	Mars ..................52

1.	Tradeoffs	between	optimal	cores/science	and	drilling	&	logistical	constraints...............................52

2.	Characteristics	of	Martian	ice	cores	and	their	potential	to	yield	scientific	results ..........................52

3.	Requirements	of	engineering	to	optimize	the	scientific	return	from	ice	coring	in	the	midlatitude	of	Mars...................................................................................................................................................................58

VI.	Other	enabling	technologies	for	in-situ	measurements	on	Mars................................60

VII.	Select	relevant	resources	and	organizations	that	may	have	related	experience	

and	technologies ................................................................................................................................61

VIII.	Recommendations....................................................................................................................62

References............................................................................................................................................65
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Executive	Summary

The	 NASA	 Mars	 Ice	 Core	 Working	 Group	 (NASA-MICWG)	 is	 an	 ad	 hoc	 interdisciplinary	

group	of	scientists	and	engineers	who	were	invited	by	NASA	Headquarters	 to	collaborate	

on	 four	 primary	 tasks:	 1)	 Define	 the	 key	 necessary	 characteristics	 of	 Martian	 ice	 cores	

crucial	 to	 support	 NASA’s	 research	 objectives,	 and	 relate	 those	 characteristics	 to	

anticipated	research;	2)	Describe	the	minimum	attributes	required	to	accomplish	mission	

goals;	3)	Provide	examples	of	how	similar	ice	cores	are	obtained	and	preserved	by	research	

teams	 on	 Earth;	 4)	 Identify	 relevant	 organizations	 that	 may	 have	 experience	 and	

technologies	 to	 assist	 NASA	 in	 developing	 the	 needed	 requirements.	 The	 NASA-MICWG	

held	 virtual	 meetings	 and	 email	 discussions	 over	 a	 period	 of	 five	 weeks;	 this	 report	

articulates	 the	 findings.	We	 found	 that	 the	potential	 to	significantly	advance	high-priority	

science	will	be	optimized	by	retrieving	a	continuous	ice	core	with	associated	borehole	and	

probe	measurements,	but	that	further	study	would	be	required	to	determine	whether	chips	

instead	 of	 a	 continuous	 core	 should	 be	 collected.	 Requirements	 for	 drill	 engineering	 to	

optimize	 the	 scientific	 return	 of	 the	 core(s)	 are	listed	in	 the	 report. We	 also	 recommend	

that	ground-based	imaging	of	the	subsurface	should	occur	to	confirm the	optimal	location	

before	drilling	commences.	

I.	Introduction

Subsurface	 ice	 sampling	 has	 been	 identified	 as	 the	 key	 science	 requirement	 by	 NASA	

planning	for	the	first	human	mission	to	Mars.	NASA	envisions	the	endeavor	to	significantly	

advance	 two	 major,	 and	 not	 mutually	 exclusive,	 science	 research	 themes:	 the	 Search for	

Life	and	Understanding	the	Evolution	of	Mars	Climate.	In	addition,	understanding	both	the	

characteristics	 of	 the	 subsurface	 ice	 and	 the	 surrounding	 geology	 will	 supply	 essential	

context	for	the	ice	core,	provide	new	geological	understanding,	and	contribute	to	planning	

future	in	 situ	 resource	 utilization	 (ISRU),	 where	 tapping	 the	 rich	 subsurface	ice	 deposits	

will	be	a	key	enabler	for	larger,	more	sustained	missions.	The	collection	of	perishable	Mars	

ice	core	samples	and	complex	nature	of	the	protection, preservation,	and	return	of	ice	cores	

will	place	significant	demands	on	 the	mission	concept,	operational	planning,	and	systems	

development.	As	such,	it	will	provide	a	central	focus	for	the	mission	architects	as	they	trade	

various	mission	approaches	and	element	designs	and	will	evolve	to	be	an	important	metric	

for	NASA	to	use	to	compare	and	contrast	competing	mission	design	concepts.	In	December	

2020,	NASA	invited	 a	 team	 of	 scientists	 and	 engineers	 to	 become	 the	 first	Mars	 Ice	 Core	

Working	Group,	and	asked	the	working	group	to	identify	potential	scientific	returns	of	ice	

cores	 from	mid-latitude	 regions	 on	Mars,	and	 to	 translate	 the	 objective	 of	meaningful	ice	

cores	into	engineering	requirements	for	mission	designers.	

Given	 assumptions	 that	 a	 mission	 to	 the Martian	 mid-latitudes	 would	 occur	 in	 the	 late	

2030s	with	a	short	surface	stay	of	~30	days,	and	with	two	crew	members	on	Mars	and	two	

crew	in	orbit,	the	Terms	of	Reference	(ToR)	requested	the	following	from	the	Mars	Ice	Core	

Working	Group:
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1) Define	 the	 key	 necessary	 characteristics	 of	 Martian	 ice	 cores	 crucial	 to	 support	

NASA’s	research	objectives.	Relate	those	characteristics	to	anticipated	research.

2) Describe	 the	minimum	 attributes	 required	 to	 accomplish	mission	 goals.	 Provide	 a	

range	 of	 attributes	 and	 requirements	 from	 which	 NASA	 can	 make	 an	 informed	

decision	on	mission	scope,	considering	practical	limitations	of	space	flight	missions	

such	 as	 technology	 and	 time.	 Provide	 scientific	 perspectives	 and	 information	 on	

activities	 relating	 to	 sample	 allocation;	 sample	 acquisition;	 ice	 core	 processing	

techniques;	infrastructure;	and	archiving	practices.

3) Provide	examples	of	how	similar	ice	cores	are	obtained	and	preserved	by	research	

teams	on	Earth,	with	an	emphasis	on	how	sites	of	interest	are	identified;	how	cores	

are	 taken;	 how	 they	 are	 preserved	 for	 transport;	 and	 what,	 if	 any,	 initial	

assessments	are	made	in	the	field.

4) Identify	relevant	organizations	that	may	have	experience	and	technologies	to	assist	

NASA	in	developing	the	needed	requirements.

The	 goal	 of	 this	 report	 is	 to	 provide	 high-level	 input	 to	 NASA	 on	 these	 four	 points	 in	

support	 of	 planning	 for	 the	 first	 ice	 cores	 from	 Mars.	 The	 scope	 of	 the	 report	 includes	

examples	from	terrestrial	ice	core	science	and	the	process	of	ice	core	drilling	and	analysis	

on	Earth	that	are	most	informative	to	Mars,	as	well	as	identifying	the	requirements	to	meet	

high-priority	Mars’	science	objectives.	An	interdisciplinary	team	of	scientists	and	engineers	

was	 necessary	 for	 this	 task,	 and	 the	 contents	 include	 outcomes	 from	 approximately	 one	

month	of	discussion	through	remote	meetings.
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II.	Ice	cores	from	Earth

1.	Background

Glaciers	 and	 ice	 sheets	 originate	 from	 snow	 that	 accumulates	 without	 experiencing	

significant	melt	over	very	long	periods	of	time.	This	process	results	in	a	natural	archive		of	

meteoric	ice	 that	records	local,	regional,	and/or	global	climate	conditions.	Water	isotopes	

reflect	 variations	in	 temperature	and	atmospheric	 pathways	 of	 the	water	 vapor	 before	it	

condensed	 as	 snowfall.	 Falling	 snow	 entrains	 dust,	 a	 variety	 of	 chemical	 species	 and	

microbes	that	provide	evidence	about	surface	conditions,	atmospheric	processes	and	how	

they	 have	 changed	 over	 time.	 Interstitial	 air	 in	 the	 firn	 eventually	 becomes	 trapped	 as	

bubbles	 in	 glacial	 ice,	 containing	 direct	 evidence	 of	 past	 atmospheric	 composition	 and	

associated	 biogeophysical	 processes	 on	 Earth.	 The	 layered	 nature	 of	 the	 ice	 is	 a	 direct	

result	 of	 the	depositional	process	 that	 originally	 formed	 the	glacier	 or	ice	 sheet,	and	it	is	

this	rich	natural	archive	that	has	enabled	the	discoveries	of	ice	core	science.		

														

Figure	 II-1. From	 Priscu	 et	 al.	 (2007).	 History	 of	 entrapped	 particles	 in	 glacial	 ice	 and	 the	 present-day	

distribution	of	glaciers.	(A)	Schematic	illustrating	the	range	of	source	environments	that	contribute	particles	to	

the	 atmosphere.	 	 (B)	 Advective	 currents,	 created	 by	 solar	 generated	infrared	 radiation,	inject	 surface	 derived	

aerosols	 high	in	 the	 atmosphere.	 	 Such	 aerosols	 (red	 dots)	may	 serve	 as	 primary	ice	 nuclei	in	 clouds	 and	 are	

subsequently	 precipitated	 in	 snowfall	 or	 rain.	 	 (C)	 In	 geographical	 locations	 where the	 annual	 temperature	

remains	 cold	 enough	 that	 snowfall	 accumulates	 annually,	 particles	 from	 the	 atmosphere	 are	 archived	 in	 a	

chronological	 sequence	 in	 firn	 and	 glacial	 ice.	 	 (D)	 Global	 locations	 of	 present-day	 ice	 sheets	 and	 mountain	

glaciers	 (in	 blue).	 	 Each	 glacial	 environment	 is	 unique,	 as	 the	 nearest	 ecosystems	 that	 would	 most	 likely	

contribute	 the	 majority	 of	 airborne	 biological	 particles	 are	 very	 different.	 Distribution	 data	 based	 in	 part	 on	

Satellite	Image	Atlas	of	Glaciers	of	the	World	(USGS,	2002,	Satellite	Image	Atlas	of	Glaciers	of	the	World).
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The	 stratigraphy	 of	 the	 ice	 resulting	 from	 the	

original	depositional	process	of	snowfall	is	evident	

even	after	the	snow	has	been	compacted	into	solid	

ice	much	deeper	in	the	ice	sheet,	as	seen	in	Figure	

II-2.	The	light	layers	resulted	 from	different	initial	

snow	crystal	types	and	the	dark	layer	is	ash	from	a	

major	volcanic	event.

Figure	 II-2. An	 ice	 core	 from	 Antarctica	 showing	 layering	

including	a	volcanic	ash layer	(Photo:	Heidi	Roop).

In	other	cold	areas	that	do	experience	snow	melt	but	where	ice	patches	survive	over	long	

times,	water	on	the	surface	of	an	ice	patch	adds	mass	upon	refreezing.	Very	old	patches	of	

ice	tens	of	meters	deep	may	include	bands	of	debris	or	deposited	organic	matter;	these	ice

patches	contain	evidence	of	life,	yet	melt	processes	obscure	much	of	the	evidence	of	climate	

history	within	 the	ice	(e.g.,	Chellman	et	al,	2021).	Thus,	understanding	 the	many	 forms	of	

evidence	within	a	massive	ice	body	depends	on	understanding	the	conditions	under	which	

the	 ice	 formed,	 compacted,	 and	 flowed.	 The	 search	 for	 clues	 about	 climate	 history	 that	

include	associated	evidence	 of	life	are	most	successful	in	locations	where	 the	 original	ice	

was	deposited	as	snow	and	where	ice	sheet	stratigraphy	is	preserved.

The	scientific	questions	posed	drive	selection	of	the	site	to	drill	an	ice	core.	In	the	following	

sections	we	provide examples	of	high-priority	science	drivers	(Sections	2	and	3),	describe	

how	sites	of	interest	are	identified	(Section	4),	describe	how	cores	are	drilled	and	how	ice	

core	samples	are	preserved	 for	 transport	(Section	5)	and	present	initial	assessments	 that	

may	be	made	in	 the	 field	 (Section	6),	as	well	as	discuss	aspects	of	ice	core	allocation	and	

measurement	strategies	to	maximize	the	use	of	ice	cores	on	Earth	(Section	7).

2.	Example	past	and	future	high-priority	science	questions	for	life	

(cryobiology)	and	climate	on	Earth	

Cryobiology: Twenty	years	ago	Earth’s	ice	sheets	were	thought	to	be	devoid	of	life.	Recent	

discoveries	of	microbial	life	in	the	ice	sheet	and	within	subglacial	lakes	below	the	ice	sheets	

has	 changed	 this	 view	 and	 shown	 that	 ice	 sheets	 and	 subglacial	 environments	 must	 be	

considered	 as	 part	 of	 Earth’s	 biosphere	 (Priscu	 and	 Christner	 2004;	 Boetius	 et	 al.,	 2015;	

Hawkings	 et	 al.	 2021).	 Recent	 studies	 in	 glacial	 ice	 have	 shown	 that	 bacterial	 densities,	

phylogenies,	and	organic	matter	signatures	reflect	past	climatic	history	(Miteva	et	al.	2009;	

Santibáñez	 et	 al.	 2016,	 2018;	 D’Andrilli	 et	 al.,	 2017).	 In	 addition	 to	 the	 presence	 of	

microorganisms	 within	 the	 ice	 itself,	 recent	 research	 has	 revealed	 the	 presence	 of	 a	

genetically	and	metabolically	diverse	microbial	ecosystem	beneath	the	ice	sheet	(Christner	

et	al.	2014;	Vick-Majors	et	al.	2020).	These	subglacial	ecosystems	have	been	isolated	from	

the	surface	for	hundreds	of	thousands	of	years	and	are	fueled	by	chemical	energy	and	relict	

organic	 matter	 deposited	 by	 past	 marine	 incursions.	 Two	 primary	 driving	 questions	
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include:	Are	microbes	reflective	of	depositional	events?	What	post-depositional	conditions	

support	and	maintain	life	in	these	entrapped	icy	habitats?				

Climate: There	 are	 a	multitude	 of	 questions	 regarding	 details	 of recent	 and	 past	 climate	

that	 drive	 the	 need	 to	 drill	 ice	 cores	 in	 specific	 locations.	 Ice	 cores	 have	 provided	

benchmark	 continuous	 climate	 records	 spanning	 hundreds	 of	 thousands	 of	 years	 and	

preserved	discontinuous	samples	for	at	least	several	million	years	(e.g.,	Brook	and	Buizert,	

2018).	 Paleoclimate	 records	 like	 ice	 cores	 reflect	 variations	 in	 solar	 radiation,	 especially	

those	related	to	ice	ages,	and	that	are	driven	by	Earth’s	orbital	variations	(Hays	et	al.,	1976;	

Laskar	 et	 al.,	 2004).	 These	 Milankovitch	 cycles	 on	 Earth	 are	 controlled	 by	 eccentricity	

(~100ka	and	~413ka	cycles),	obliquity	(~41ka	cycle),	and	precession	(~19-23ka	cycle).		

Two	 unique	 properties	 of	 the	massive	 polar	ice	 sheets	 are	 critical	 to	 their	 utility:	 1)	 the	

process	 of	 trapping	 air	 in	 bubbles	 in	 the	 near	 surface	 allows	 samples	 of	 the	 ancient	

atmosphere	 to	 be	 preserved	 for	 millions	 of	 years,	 and	 2)	 the	 continuous	 deposition	 of	

centimeters	 or	 more	 of	 ice	 each	 year	 provides	 sufficient	 resolution	 to	 identify	 abrupt	

changes	 in	 climate.	 For example,	 high	 snow	 accumulation	 rates	 in	 Central	 Greenland	

motivated	the	world’s	first	very	high	resolution,	continuous,	multi-proxy	ice	core	evidence	

that,	using	records	of	ice	stratigraphy,	density,	and	isotopic	and	chemical	records	answered	

the	question:	how	fast	can	climate	change?	The	GISP2	ice	core	demonstrated	that	the	local	

climate	can	change	abruptly	on	timescales	relevant	to	modern	society	and	discovered	that	

a	 10	 °C	 warming	 and	 doubling	 in	 accumulation	 rate	 could	 occur	 within	 a	 decade,	 which	

revolutionized	 climate	 science	 (Alley	 et	 al.,	 1993;	 Mayewski	 et	 al.,	 1993).	 The	 methane	

record	 further	 demonstrated	 that	 the	 abrupt	 changes	 were	 global	 in	 extent	 because	 the	

tropics	are	 the	primary	methane	source	(Chappellaz	et	al.,	1993).	And	 the	carbon	dioxide	

records	 spanning	 multiple	 glacial	 cycles	 have	 provided	 an	 unequivocal	 record	 of	 global	

temperature-CO2 coupling	 (Petit	 et	 al.,	 1999).	 An	 important	 question	 driving	 ice	 core	

climate	science	for	the	upcoming	Hercules	Dome	ice	core	(Steig	and	Neff,	2018)	is	whether	

the	West	Antarctic	Ice	Sheet	collapsed	during	the	last	interglacial	period,	and	what	the	rate	

of	 collapse	 implies	 for	 future	 sea	 level	 rise.	 The	 answer	 to	 this	 question	 is	 critical	 for	

planning	societal	response	to	current	climate	change.

3.		Evidence	of	life	and	climate	within	glacial	ice

Cryobiology: The	 science	 of	 understanding	 the	 global	 importance	 of	 microorganisms	

immured	in	glacial	ice	on	Earth	is	at	an	early	stage.	Recent	research	has	shown	that	glacial	

ice	 contains	 an	 important	 temporal	 record	 of	 microorganisms	 on	 our	 planet	 that	 reveal	

biogeochemical	 processes	 and	 habitat	 types	 that	 occurred	 during	 past	 glacial	 and	

interglacial	 periods	 (Santibáñez	 et	 al.	 2016,	 2018).	 This	 record	 also	 contains	 important	

information	on	microbial	evolution	and	physiology	(Priscu	et	al.	2008).	Work	on	the	Vostok	

ice	core	has	further	shown	the	presence	of	diverse	viral	particles	throughout	the	meteoric	

and	 accretion	 ice	 (Figure	 II-3	 and	 II-4;	 Priscu	 et	 al.,	 2007). We	 now	 know	 that	

microorganisms	 and	 associated	 nonliving	 organic	 matter	 are	 present	 and	 may	 be	

metabolically	 active	 in	 virtually	 all	 ice	 core	 samples	 examined	 for	 biological	 properties.	

Paleoclimate	studies	have	accurately	dated	layers	within	both	the	Antarctic	and	Greenland	
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Ice	 Sheets;	 investigating	 co-located	 evidence	 of	 life	 and	 climate	 provides	 an	 important	

stratigraphic	 timeline	 for	 these	microbial	ice	 repositories.	 In	general,	ice	cores	 from	nonpolar	 locations	 have	 been	 found	 to	 contain	 larger	 numbers	 and	 species	 of	 cultivable	

bacteria	 than	 samples	 from	 polar	ices.	This	 spatial	 trend	is	 presumably	 due	 to	 the	 closer	

proximity	 of	 terrestrial	 biological	 ecosystems	 and	 exposed	 landscape	 to	 these	 glacial	

environments,	 which	 provide	 a	 wide	 range	 of	 biological	 materials	 (i.e.,	 insects,	 plant	

fragments,	seeds,	pollen	grains,	fungal	spores	and	microorganisms)	that	create	an	influx	of	

airborne	biological	particles	that	can	become	entrapped	in	the	ice.	Studies	of	bacteria	from	

the	permanent	ice	covers	of	lakes	in	Taylor	Valley,	showed	that	the	organisms	were	closely	

associated	with	lithic	particles,	forming	distinct	ecosystems	within	the	ice	(Paerl	and	Priscu	

1998;	Priscu	et	al.	1998).

Figure	 II-3.	From	 Priscu	et	 al.	 (1999).	Scanning	electron	 (A-E)	 and	 atomic	force	 (F)	micrographs	 of	 particles	

within	an	ice	core	from	Vostok	accretion	ice	collected	3590	m	beneath	the	surface.	Arrows	denote	bacterial	cells;	

Image	“B”	is	a	magnification	of	the	area	outlined	in	image	“A”.
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Figure	II-4. From	Priscu	et	al.	(2007).	Viral	particles	observed	in	the	Vostok	ice	core	from	selected	depths	in	the	

glacial	and	accretion	ice.	All	images	were	obtained	by	transmission	electron	microscopy.

Highlights	from	these	studies	follow:

● Prokaryotic	cells	and	organic	carbon:	The	ice	sheets	of	Greenland	and	Antarctica	

have	 been	 shown	 to	 contain	a	 combined	 total	 of	 4.4×1024 prokaryotic	 cells,	which	

equates	 to	 1.3×10-4 petagrams	 (Pg)	 of	 organic	 carbon.	 These	 cells	 represent	 a	

previously	 unrecognized	 carbon	 pool	 and	 approaches	 the	 values	 for	 bacterial	

carbon	contained	in	all	surface	freshwater	on	our	planet.

● Dissolved	 organic	 matter:	 The	 Greenland	 and	 Antarctic	 ice	 sheets	 have	 been	

estimated	to	contain	about	10	Pg	of	dissolved	organic	matter.	Microscopic	analysis	

has	 revealed	 that	 most	 of	 the	 cells	 and	 dissolved	 matter	 are	 concentrated	 within	

triple	junctions	(veins)	in	the	crystal	matrix	of	the	ice (Figure	II-5).	Vein	volume	in	

the	Greenland	and	Antarctic	ice	sheets	has	been	estimated	to	be	16.7	and	576	km3,	

respectively,	 representing	 habitable	 space	 which	 can	 support	 the	 metabolism	 of	

organisms	that	are	capable	of	growing	in	cold,	high	ionic	strength	solutions	with	low	

pH	(Barletta	et	al.,	2012).	In	Antarctic	near-surface	environments,	post-depositional	

organic	 matter processing	 has	 been	 demonstrated.	 Variations	 in	 organic	 matter	

composition	between	deep	Antarctic	ice	cores	have	been	shown	to	be	correlated	to	

specific	microbial	 communities	 based	 on	 their	metabolic	 capabilities;	 a	 concept	 of	

community	evolution	further	supported	by	studies	from	Antarctic	snow.	

● Fungi,	 bacteria,	 and	 viruses:	 Ancient	 microorganisms	 provide	 an	 unexplored	

frontier	 for	 the	 study	 of	microbial	 variability	 over	 at	least	 eight	 glacial	 cycles	 (~1	

million	years)	from	the	Greenland	and	Antarctic	ice	sheets.	Phylogenetic	diversity	of	

microorganisms	has	been	shown	to	vary	across	sampling	locations	and	is	generally	
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greater	in	 Arctic	 vs.	 Antarctic	 cores,	 which	is	 possibly	 attributed	 to	 differences	in	

deposition	rates	resulting	from	spatial	proximity	to	land	masses.	

● Microorganisms	 attached	 to	 dust:	 A	 positive	 correlation	 between	 dust	 and	

attached	 microorganisms	 in	 ice	 has	 been	 demonstrated	 from	 vertical	 ice	 profiles,	

which	 concluded	 that	 less	 dust	 and	 microbial	 species	 were	 deposited	 during	

warmer	 periods.	 While	 transport	 and	 deposition	 patterns	 of	 biotic	 and	 abiotic	

material	onto	ice	sheets	is	the	result	of	climate	induced	changes	at	the	source,	there	

is	evidence	for	in-situ	post-depositional	microbial	processing	of	organic	resources.	

● DNA	 from	microbes	 in	 ice:	Data	collected	 from	selected	habitats	 on	Earth	shows	

that	 microbial	 cells	 can	 be	 revived	 after	 extended	 entrapment	 in	 geological	

materials	 and	 that	 DNA	 can	 remain	 viable	 for	 several	 million	 years	 in	 icy	

environments	 providing	 a	 repository	 for	 maintaining	 stable	 DNA	 (Priscu	 et	 al.	

2007).	Perhaps	the	most	striking	example	of	a	microbial	ice	repository	is	the	ancient	

ice	collected	from	Beacon	Valley,	Antarctica.	Bacteria	immured	in	ice	in	the	Beacon	

Valley,	Antarctica,	estimated	to	be	~8	million	years	old,	were	shown	to	incorporate	

radiolabeled	 substrates	 and	 many	 could	 be cultured	 in	 nutrient-enriched	 ice	

meltwater	(Bidle	et	al.	2007).	16S	rDNA-based	community	reconstruction	suggested	

relatively	low	 bacterial	 sequence	 diversity	in	 the	ice	 but	metagenomic	analyses	 of	

community	DNA	 revealed	many	 diverse	 orthologs	 to	 extant	metabolic	 genes.	DNA	

degradation	 in	 Beacon	 Valley	 ice	 indicated	 an	 exponential	 decline	 of	 community	

DNA	size	with	a	half-life	of	about	1	million	years.

Collectively,	 these	 data	 show	 that	 ice	 cores	 represent	 ‘‘ice	 museums’’	 containing	 novel	

records	of	evolution,	habitat	variability,	and	climate	on	our	planet.	Future	ice-coring	efforts	

that	include	a	biological	component	will	lead	 to	new	biological	discoveries	and	provide	a	

more	 comprehensive	 view	 of	 past	 conditions	 on	 Earth.	 Such	 information	 will	 benefit	 all

sciences	 involved	 in	 deciphering	 the	 ice	 core	 record	 and	 will	 provide	 the	 necessary	

information	in	our	search	for	life	on	other	icy	worlds.	In	order	to	understand	life	in	ice	we	

must	understand	the	ice	itself.

																														

Figure	II-5.	 Modified	from	Barletta	et	al.	(2012). Triple	junction	from	the	GISP	2	core	at	a	depth	of	146.39	to	

146.46	m	(a)	and	from	the	Newall	Glacier	core	at	a	depth	of	7.75	to	7.774	m	(b).	Black	dot	represents	the	region	

of	 Raman	 laser	 focus.	 Micro-Raman	 spectroscopy	 was	 used	 to	 obtain	 the	 chemical	 composition	 of	 the	 liquid	

within	the	triple	junction	and	the	ice	crystal	itself.	Note	the	high	number	of	cells	attached	to	lithic	particles.
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Climate: Ice	cores	 from	glaciers	and	ice	sheets	have	played	a	critical	role	in	 transforming	

our	 understanding	 of	 past	 climate	 change	 from	 “what”	 happened,	 to	 “how”	 it	 happened.	

The	 temporal	 resolution	of	ice	core	 records	 varies	based	on	site	characteristics	including	

temperature	and	 snow	accumulation	 rate.	 Ice	 cores	 from	low	accumulation	 sites	 provide	

lower-resolution	evidence	of	changes	occurring	over	hundreds	of	 thousands	of	years	(e.g.	

Brook,	2013;	Brook	and	Buizert,	2018).		

Ice	cores	provide	sequential	records	of	environmental	conditions,	including:	

● Stable	 isotopes	 of	 water	 have	 long	 enabled	 reconstruction	 of	 past	 temperature	

patterns.

● Layer	thickness	and	modeling	of	 ice	 flow	thinning	have	enabled	reconstruction	

of	accumulation	patterns.	Patterns	of	atmospheric	circulation	can	be	inferred	 from	

multiple	ice	core	records	of	temperature	and	precipitation.

● Impurities	in	the	ice	record	non-local	climate	through	their	atmospheric	transport	

and	deposition	with	snow.	

● Methanosulfuric	acid can	be	linked	to	ocean	conditions	including	open	polynyas	in	

ice	cores	from	some	high	accumulation	sites.

● Dust size	 and	 composition	 provide	 information	 on	 wind	 strength	 and	 transport	

pathways.

● Black	 carbon	 and	 organic	 acids	 provide	 evidence	 of	 biomass	 burning	 through	

forest	fires.

● Many	additional	proxies indicate	climate	variations,	ranging	from	wind	strength	to	

sea	ice	extent.

● Gas	 composition	 measurements	 from	 bubbles	 in	 ice	 cores	 have	 provided	 the	

foundational	 records	 of	 past	 greenhouse	 gas	 records,	in	 particular	 carbon	 dioxide	

and	methane,	which	have	allowed	quantification	of	the	climate	feedbacks	associated	

with	orbital	cycles.	These	gases	are	globally	well	mixed	and	 thus	record	processes	

largely	unrelated	to	local	climate	conditions.

o Carbon	dioxide records	have	allowed	determination	of	the	iconic	records	of	

temperature	 and	 carbon	 dioxide	 co-varying	 for	 hundreds	 of	 thousands	 of	

years	 and	 have	 shown	 that	 the	 rate	 of	 anthropogenic	 emissions	 today	

exceeds	the	maximum	rate	from	natural	sources	by	an	order	of	magnitude.	

o Methane	 records	 showing abrupt	 increases,	 coincident	 with	 temperature	

increases	in	Greenland,	illustrate	the	global	nature	of	abrupt	climate	change	

and	 provide	 the	 benchmark	 record	 that	 allows	 confident	 interpretation	 of	

other	records,	such	as	cave	calcite	oxygen	isotope	records.

Evidence	within	permafrost	on	Earth

Permanently	 frozen	 ground	 provides	 a	 rich	 environment	 that	 supports	 cryobiology.	 The	

distribution	 of	ground	ice	in	 permafrost	is	 heterogeneous,	 such	 that	ice	 volume	in	a	 drill	

location	 can	 vary	widely	across	 1–10	m	 scale,	with	locations	 of	almost	 pure	ice	 (wedges,	

frozen	 groundwater)	 interspersed	 with	 frozen	 sediment	 or	 soil	 material.	 Stratigraphic	

records	 from	 accumulated	 layered	 sediment	 records	 can	 provide	information	 about	 past	

ecosystems	and	environment,	including:
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● Organic	matter: Radiocarbon	dating	of	organic	matter	within	permafrost	is	used	to	

indicate	age.

● Mineral	 grain	 size	 and	 composition is	 used	 to	 indicate	 the	 origin	 of	 dust/loess	

layers	in	cases	where	the	mineral	composition	of	the	source	area	is	known.

● Organic	 carbon,	 nitrogen,	 sulfur,	 and	 isotopes characterizes	 the	 local	

biogeochemical	environment.

● Pollen provides	direct	evidence	of	past	vegetation	communities.

● Macrofossils (testate	 amoebae,	 bones,	 teeth,	 insects)	 yield	 evidence	 of	 past	 local	

fauna.

● Stable	isotopes	of	water	indicate	relative	age	with	depth.

While	permafrost	 yields	information	about	cryobiology	within	its	local	habitat,	 the	water	

that	is	in	permafrost	is	a	product	of	meltwater	infiltration	and	thus	permafrost	cores	have	

not	been	used	with	a	primary	goal	of	investigating	past	climate.

4.	Ice	core	drill-site	selection	

Three	 critical	 tasks	 should	 be	 completed	 prior	 to	 and	in	 conjunction	 with	 an	ice	 drilling	

mission	on	Earth.	These	tasks	include:	

1) Site	 assessment	 and	 selection	 to	 assure	 the	 optimal	 drilling	 location	 based	 on	

mission	objectives

2) Local	 to	 regional	 characterization	 of	 the	 study	 region	 to	 place	 any	 core	 or	 other	

sampling	into	the	broader	context

3) An	assessment	of	borehole	properties	 for	comparison	 to	 the	core	and	surrounding	

terrain	observations

For	ice	core	science objectives	focused	on	cryobiology	and	climate,	we	describe	traditional	

site	 selection	 on	 Earth	along	with	 their	 preferred	assessments	and	 considerations	in	 this	

context.	It	is	worth	noting	that,	despite	the	fact	that	biology	can	help	elucidate	past	climate	

conditions,	 the	 best	 site	 for	assessing	 cryobiology	 from	an	ice	 core	is	 not	 necessarily	 the	

best	site	for	studying	climate,	and	vice	versa.	

Preferred	Ice	Core	Site	Characteristics

Ice	core	site	selection	on	Earth	is	initially	focused	on	finding	a	location	where	ice	that	is	the	

product	 of	 accumulated	 snowfall	 has	 experienced	 the	 least	 chemical	 and	 physical	

deformation	 or	 alteration	 since	 deposition.	 From	 a	 chemical	 perspective,	 this	 is	

traditionally	considered	 to	be	locations	where	minimal	surface	melt	and	diffusion	occurs.	

Surface	melt	and	meltwater	percolation	through	the	snowpack	and	 firn	enhance	diffusion	

of	chemicals,	 thereby	homogenizing	 the	properties	 of	interest	which	are	used	 for	climate	

reconstructions	 (e.g.,	 Campbell	 et	 al.,	 2012).	 This	 requirement	 generally	 requires	 polar	

sites	 at	 high	 elevations	 or	 high	 northern	 or	 southern	 latitudes	 with	 low	 annual	

temperatures.	It	precludes	low	elevation	or	temperate	glacier	sites	unless	the	annual	snow	

accumulation	 is	 so	 high	 that	 it	 limits	 diffusion	 into	 deposition	 from	 previous	 years	 (e.g.,	

Neff	 et	 al.,	 2012).	 	 One	 special	 scenario	 recently	 being	 considered	 on	 Earth	 includes	

elevations	where	some	melting	and	refreezing	occurs.		In	this	scenario,	the	melt	may	cause	

some	diffusion,	however	the	ice	lenses	within	snow	and	 firn	may	diminish	natural	mixing	
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processes	 prior	 to	 pore	 close	 off,	 therefore	 retaining	 the	 original	 chemical	 structure.	 A	

second	special	scenario	includes	polar	sites	with	low	accumulation	rates	and	temperatures.	

In	this	scenario,	the	natural compaction	of	snow	to	pore	close	off	can	occur	over	extended	

periods	 of	 time	 (>1000	 years)	 resulting	 in	 significant	 chemical	 mixing	 due	 to	 open	 pore	

spaces;	this	yields	a	lower-resolution	climate	record	such	as	from	the	Vostok	and	other	ice	

cores	from	East	Antarctica	(e.g.	Petit	et	al,	1999).

On	 Earth,	 ice	 deformation	 is	 critical	 to	 consider.	 We	 traditionally	 select	 sites	 to	 drill	 a	

vertical	ice	core	near	 the	highest	elevations	of	an	ice	mass	such	as	an	ice	divide	or	dome	

(e.g.,	Campbell	et	al.,	2013a;	Fischer	et	al.,	2013).	This	choice	is	made	because	 these	sites	

have	 surface	 and	 bed	 conformable	 stratigraphy	 (with	 some	 exceptions	 such	 as	 windderived	mega-dune	formation),	exhibit	minimal	horizontal	deformation,	and	are	dominated	

by	 vertical	 deformation.	 Each	 of	 these	 factors	 simplify	 local	 ice	 sheet	 evolution,	 which	

simplifies	 the	 ice-flow	 modeling	 required	 to	 interpret	 aspects	 of	 the	 ice	 core	 records,	

including	to	convert	measured	layer	thicknesses	to	past	accumulation	rates	by	accounting	

for	ice	deformation.	It	must	also	be	considered	if	the	regional	ice	sheet	geometry	and	basal	

flow	 conditions	 have	 been	 stable.	 It	is	 reasonable	 to	assume	 that	 the	ice	 divide	 has	 been	

stable	over	the	time	represented	by	shallow	ice	cores.	However,	ice-divide	migration,	basal	

conditions,	and	the	regional	flow	field	must	be	considered	at	ice	core	sites	with	longer-term	

records,	especially	in	Antarctica	or	Greenland.	Additional	assumptions	and	models	that	can	

account	 for	more	 complex	ice	 dynamics	may	 be	 required	 to	interpret	ice	 core	 records	at	

these	sites	that	are	not	at	a	stable	ice	divide.	

In	 areas	where	ice	 flows	 over	 terrain	 that	 brings	 very	 old	layers	 up	 close	 to	 the	 surface,	

horizontal	 surface	 coring	 across	 an	 ablated	 blue	 ice	 region	 that	 exposes	 a	 sequence	 of	

exposed	 stratigraphy	is	a	 specialized	 target	 on	Earth	due	 to	its	easy	access	 to	potentially	

old	ice	(e.g.,	Kerhl	et	al.,	2018;	Spaulding	et	al.,	2013;	Petrenko	et	al.,	2006).	While	access	to	

significant	stores	of	old	ice	is	relatively	easy	at	 these	sites,	 the	history	of	ice	deformation	

can	make	interpretation	of	the	chemical	and	biological	records	more	challenging.	

Another	 site	 of	 ice	 coring	 includes	 lateral	 glacier	 margins	 where	 cores	 are	 retrieved	 in	

conjunction	with	subglacial	bedrock	access.	Collection	of	subglacial	samples	can	be	used	for	

cosmogenic	 nuclide	 analysis	 to	 determine	 the	 timing	 of	 when	 ice	 cover	 was	 present,	

marking	past	ice	collapses	or	low	stands	(e.g.,	Spector	et	al.,	2018).	

Site	Assessment	Techniques

A	 range	 of	 techniques	are	 used	 for	ice	 core	 site	 selection	including	 satellite	and	airborne	

remote	sensing,	geodetics,	geophysics,	and	numerical	modeling.	

Satellite	 &	 Airborne	 Remote	 Sensing: The	 combination	 of	 satellite,	 airborne,	 and	

terrestrial-derived	 elevation	 and	 velocity	 fields	 provide	 large	 to	 local	 scale	 surveys,	

respectively,	of	Earth’s	ice	masses	to	locate	potential	domes,	flow	boundaries,	divides,	blue	

ice	areas,	lateral	margins,	or	other	potential	coring	targets	(for	example,	in	searching	for	a	

site	 to	drill	 for	 the	 oldest	ice	in	East	Antarctica;	Young	et	al.,	2017).	Remote	 sensing	also	

provides	observations	of	debris	cover,	stratigraphic	unconformities	exposed	at	the	surface,	

flow	banding,	surface	fracturing,	and	lateral	geomorphological	features	(or	lack	thereof	for	

each	 of	 these	 characteristics).	 These	 are	 qualitative	 and	 quantitative	 measures	 of	 the	
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deformation	field	and	history,	mass	balance,	and	stability,	all	useful	for	historical	context	of	

ice	flow	and	ice	sheet	boundary	conditions.		Airborne	radar	sounding	in	the	60	to	600	MHz	

range	 is	 frequently	 used	 in	 Antarctica	 to	 map	 horizontal	 and	 vertical	 stratigraphic	

continuity,	 extrapolate	 age-depth	 relationships	 from	 existing	ice	 core	 sites,	 and	 to	 detect	

basal	 melt/accretion	 at	 the	 tens	 to	 hundreds	 of	 kilometer	 scale,	 typically	 collected	 as	

gridded	data	sets.					

Ground-Based	Observations: Ground	Penetrating	Radar	(GPR)	between	1–900	MHz	range	

is	often	used	to	map	local	scale	(1–100	km)	distances,	in	smaller	or	confined	spaces	where	

airborne	radar	is	not	possible	(e.g.,	Campbell	et	al.,	2013a),	or	along	lateral	margins	in	high	

vertical	 resolution	 to characterize	 stratigraphic	 continuity	and	 refine	 specific	 coring	 sites	

from	preliminary	sites	selected	via	more	regional	assessments	(e.g.,	Schroeder	et	al.,	2020;	

example	of	radar-layer	evaluation	in	Figure	 II-6).		Concurrently,	installation	of	 temporary

GPS	units	in	a	grid	provides	higher-spatial	and	temporal	resolution	deformation	fields	than	

airborne	or	satellite	methods,	useful	for	future	flow	modeling	as	well	as	precision	core	site	

selection.		

Figure	 II-6. From	 Koutnik	 et	 al.	 (2016).	 a)	 Segment	 of	 a	 7 MHz	 radar	 echogram	 of	 the	 upper	 few	 hundred	

meters	 of	 the	West	Antarctic	ice	 sheet.	 b)	Segment	 of	 a	 1 MHz	 radar	echogram.	 (c)	Traced	layers	from	 7 MHz	

data	 (gray	layers)	 and	 the	 1 MHz	 data	 (black	layers)	 and	 the	 smoothed	 bed	 topography	 (solid	 gray	line).	The	

deepest	 imaged	 layer	 (black	 dash-dot)	 is	 known	 as	 “Old	 Faithful”,	 with	 an	 age	 ~17,650 kyr	 B.P.	 The	 dashed	

vertical	line	is	the	modern	ice-divide	position,	and	the	solid	vertical	line	is	the	WAIS	Divide	core site.	(d)	All	39	

radar-traced	layers	were	dated	using	the	WD2014	timescale.	Elevation	is	relative	to	the	deepest	bed	value	set	at	

zero,	and	elevations	above	the	bed	are	in	kilometers	of	ice-equivalent	values.

Autonomous	 Phase	 Sensitive	 Radar	 (ApRES)	is	 an	instrument	 (Nicholls	 et	 al.,	 2015)	 that	

provides	 vertical	 deformation	measurements	at	 the	millimeter	 scale.	These	are	 new	 data	

and	can	be	used	to	measure	vertical	velocity	in	the	ice	sheet	interior	and	improve ice-flow	

models	(e.g.,	Kingslake	et	al.,	2016).	Recent	use	of	terrestrial	interferometry	at	the	1-10	km	

range,	 as	 well	 as	 at	 the	 centimeter	 scale	 around	 ice	 core	 sites,	 can	 provide	 local	
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observations	 of	 horizontal	 deformation	 that	 can	 be	 used	 together	 with	 ApRES	

measurements	of	vertical	deformation.												

Where	it	is	relevant,	geological	and	geomorphological	observations	are	often	collected	near	

core	 sites	 in	 addition	 to	 on-ice	 observations.	 	 At	 core	 sites	 near	 bedrock	 exposures,	

nunataks,	 and	 lateral	 or	 terminal	 margins,	 geological	 and	 geomorphological	 mapping	 of	

moraines,	 erratics,	 sediment,	 lithic	 or	 clast	 deposits,	 coupled	 with	 cosmogenic	 nuclide	

dating	 (e.g.,	 beryllium-10),	 carbon-14,	 or	 other	 chemical	 techniques	 provide	 historical	

context	 of	 ice surface	 elevation	 change,	 flow	 pathways	 via	 interpretations	 of	 deposit	

provenance,	 and	 erosion	 history	 via	 micro-to-macro-scale	 sediment-to-clast	 analysis.	

Assessment	of	overburden	structure,	overburden	and	ice	mixing,	or	unconformities	within	

the	 overburden	 and	 sub-burden	 ice	 provide	 evidence	 of	 shearing	 (or	 potential	 advance	

deposition),	repeated	stages	of	advance	and	retreat,	or	surface	elevation	changes	over	time.	

In	areas	devoid	of	bedrock	exposures,	lithic	or	sediment	analyses	within	core	samples,	such	

as	 tephra	 or	 dust	 horizons	 also	 provide	 critical	 information	 such	 as	 absolute	 ages	 and	

atmospheric	circulation	processes,	particularly	if	provenance	can	be	determined.

In	addition,	shallow	core	sampling	is	often	completed	in	snow,	 firn,	and	ice,	prior	to	deep	

drilling	campaigns	in	order	to	estimate	the	retention	of	chemical	signatures	and	to	estimate	

a	 baseline	 of	 current	 atmospheric	 properties.	 Accumulation	 or	 ablation	 rate	may	 also	 be	

estimated	if	relative	or	absolute	chemical	markers	are	present	within	the	samples	that	can	

be	used	as	temporal	constraints.	

Numerical	 Modeling: Glaciological	 modeling,	 which	 includes	 applying	 thermal	 and	

mechanical	ice-flow	models,	is	a	critical	component	of	ice	core	site	selection	and	ice	core	

interpretation	on	Earth.	The	chronology	and	preservation	of	the	ice	depends	on	details	of	

ice	 flow	and	deformation,	basal	 temperature,	and	ice	sheet	and	climate	history.	While	 the	

vertical	velocity	field,	basal	boundary	conditions,	and	past	ice	sheet	geometry	and	climate	

conditions are	poorly	known,	ground-based	and	airborne	radar	data	can	provide	valuable	

constraints.	Numerical	models	 of	 varying	 complexity	 rely	 on	 geophysical	 observations	 of	

bed	 topography	 (and	 ice	 thickness),	 and	 may	 also	 assimilate	 englacial	 stratigraphy,	

borehole	 temperature	 measurements,	 ice	 fabric	 and	 microstructure	 observations,	 and	

available	constraints	 on	ice	deformation	and	ice	physical	properties	in	 reconstructing	ice	

evolution	(e.g.,	Licciulli	et	al.,	2020,	Kerhl	et	al.,	2018;	Koutnik	et	al.,	2016;	Waddington	et	

al.,	2007;	Hindmarsh	et	al.,	2006).	Models	provide	spatial	and	temporal	information	about	

ice	temperature,	ice	flow,	and	ice	age.	Models	are	necessary	to	extrapolate	the	age	scale	to	

the	bottom	of	the	ice	sheet	for	the	deep	ice	cores.

Permafrost	and	Massive	Ice	Deposits

In	addition	to	glaciological	ice	coring,	ice-rich	permafrost	or	massive	ice	deposits	beneath	

and	within	sediment	have	been	studied	as	potential	paleoclimate	or	paleo-environmental	

records	 on	 Earth	 (e.g.	Van	Huissteden	et	at.,	 2003;	Schirrmeister	et	al.,	 2001).	 	However,	

permafrost	 structure	 is	 a	 less	 straightforward	 environment	 because	 deposits	 can	 be	

vertically	or	horizontally	stratified	depending	on	environmental	and	geological	conditions	

and	ice	content	within	sediment	can	vary	widely	depending	on	water	sources,	subsurface	

pore	 space,	 and	 atmospheric	 thermal	 fluctuations.	 Interpretations	 of	 ice	 relative	 to	
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subsurface	 water	 or	 stratified	 sedimentary	 deposits	 generally	 relies	 on	 phase	 responses,	

comparisons	 in	 scattering,	 and	 surface evidence	 of	 permafrost	 or	 such	 as	 ice	 wedge	

polygons.	 	 Massive	 ice	 units	 can	 nearly	 replace	 subsurface	 sediments	 over	 time	 through	

water	 flow	 and	 successive	 refreezing	 events	 (e.g.	 Campbell	 et	 al.,	 2018).	 	 Massive	 ice	

provides	 clearly	 visible	 GPR	 targets	 within	 subsurface	 sediments	 due	 to	 less	 scattering	

relative	to	sediments.	Near-surface	permafrost	or	massive	ice	are	most	commonly	imaged	

with	100-400	MHz	GPR	frequencies	and	penetration	depth	is	limited	by	highly	attenuative	

sediments	relative	to	ice	(e.g.	Campbell	et	al.,	2021).	

Figure	 II-7. From	 Campbell	 et	 al.	 (2018).	 Left:	 200	 MHz	 GPR	 profile	 (top)	 and	 interpretation	 (bottom)	 of	 a	

massive	ice	feature.	Note	the	clear	and	speckle-free	massive	ice	relative	to	the	surrounding	geology	and	buried	

utilities	(U).	Right:	photo	of	excavated	massive	ice	displaced	within	GPR	profile.

5.	Handling	and	preservation	of	ice	cores	on	Earth	for	transport	and	

storage

Handling	 of	 ice	 core	 segments	 retrieved	 from	 drilling	 operations	 is	 a	 manual	 operation	

requiring	great	care.	Methods	to	ensure	that	the	ice	cores	resist	cracking	and	are	kept	free	

from	contamination	during	the	handling	have	been	developed,	and	drill	teams	are	trained	

in	the	procedures.

Drilling	operations	should	use	clean	techniques	(e.g.,	sterile	drill,	clean	clothing)	to	obtain	

intact	 core	with	little	 occurrence	 of	microfracture.	Once	extracted,	 care	must	 be	 taken	 to	

ensure	 that	 the	 ice	 cores	 are	 properly	 preserved	 in	 order	 to	 ensure	 accurate	 scientific	

measurements.	The	 primary	 concerns	 for	 the	integrity	 of	 the	ice	 core	are	 contamination,	

melt	 loss,	 fracture,	 release	 of	 trapped	 gasses,	 grain	 evolution	 via	 vapor	 diffusion,	 and	

chemical	or	biological	changes.	In	addition,	the	handling	of	the	cores	must	take	into	account	

transportation	 and	 logistics	 at	 every	 stage	 in	 the	 recovery	 process.	 Souney	 et	 al.	 (2014)	

documented	the	core	handling	and	processing	procedures	for	the	WAIS	Divide	ice	core.

Certain	ice	cores	require	more	involved	handling	procedures.	For	ice	cores	to	be	analyzed	

for	 particularly	 diffusive	 gases,	 such	 as	 He,	 samples	 are	 cut	 in	 the	 field	 and	 placed	 in	

vacuum	 sealed	 containers.	Samples	may	also	 need	 to	 be	 shielded	 from	 radiation,	 such	as	

14C	of	CO	or	CO2.	Ensuring	that	the	cores	are	stored	at	a	cold	enough	temperature	is	one	key	

consideration.	Cores	are	typically	stored	at	or	below	-20	°C,	with	the	NSF	Ice	Core	Facility	

long	term	storage	at	-36	°C.	This	sub-freezing	temperature	is	needed	in	order	to	minimize	
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melt	 loss,	 gas	 diffusion,	 chemical	 and	 biological	 reactions,	 as	 well	 as	 to	 create	 a	 buffer	

below	freezing	to	protect	the	core	if	briefly	exposed	to	warmer	temperatures.	In	addition	to	

ensuring	a	low	temperature,	it	is	important	to	minimize	the	change	in	core	temperature	in	

order	to	avoid	fractures	that	can	disrupt	the	sample	and	let	in	contamination.	

		 				

Figure	 II-8. West	Antarctic	 Ice	Sheet	 (WAIS)	Divide	 drill	 site.	 Left:	On	 site	freezer	units	 that	keep	ice	 at	-26C.	

Right:	Core	sections	in	core	trays,	where	the	core	diameter	is	122	mm	(4.8	inches).

Logistics	 challenges	 exist	 in	 maintaining	 boxes	 of	 ice	 cores	 at	 constant	 low	 temperature	

from	 the	 time	of	drilling	in	 the	 field	 to	 transport	via	air,	sea,	and	land	 to	 the	 final	storage	

location.	 Instances	 of	ice	 cores	 experiencing	 too-warm	 conditions	 have	 occurred.	 Even	if	

melting	doesn’t	occur,	the	movement	of	ice	via	vapor	exchange	can	impact	the	stratigraphy	

of	the	core	and	prevent	robust	interpretation.	

			

Figure	II-9. Left:	Cores	wrapped	for	transport	to	keep	at	consistently	cold	temperature.	Right:	Cores	at	the	NSF	

Ice	Core	Facility	(Photo:	Peter	Rejcek).	
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Methods	of	decontamination	of	ice	cores	on	Earth

Core	 contamination	 can	 come	 from	 the	 mission	 itself,	 drilling	 technology,	 handling	 ice	

cores	 in	 the	 field,	 in	 transit,	 and	 in	 the	 laboratory.	 Contaminant	 sources	 include	 the	

environment	 (e.g.,	 collection,	 laboratory	 personnel,	 tools,	 reagents,	 and	 air)	 during	 the	

processing	 of	 ice	 including	 ice	 sampling,	 concentrating	 cells,	 and	 DNA	 extraction	 and	

sequencing.		Except	at	core	breaks,	contamination	is	generally	confined	to	the	outer	regions	

of	 the	 core	 with	 the	 potential	 for	 contamination	 decreasing	 toward	 the	 center.	

Consequently,	sampling	from	the	inner	portions	of	the	core	provides	the	cleanest	ice.

Experiments	 to	 address	 biological	 contamination	 on	 cores	 of	 Vostok	 meteoric	 and	

accretion	ice	obtained	using	hydrocarbon	drilling	fluid	showed	that	the	outer	portion	of	the	

core	had	up	to	three	orders	of	magnitude	greater	bacterial	density	as	the	inner	portion	of	

the	 core	 (Christner	 et	 al.	 2005).	 The	 extreme	 gradients	 that	 exist between	 the	 outer	 and	

inner	 portion	 of	 the	 cores	 makes	 contamination	 a	 very	 relevant	 aspect	 of	 geobiological	

investigations	of	ice	cores,	particularly	when	the	actual	numbers	of	bacterial	cells	are	low.	

Although	various	protocols	to	eliminate	microbial	contamination	have	been	developed	in	a	

number	of	laboratories,	proving	that	a	positive	result	is	not	an	artifact	is	very	difficult.	To	

address	 this	 issue	 and	 the	 inherent	 concern	 it	 raises	 for	 the	 integrity	 of	 future	

microbiological	 investigations,	 a	 method	 to	 monitor	 decontamination	 procedures	 for	

biological	 work	 with	 ice	 cores	 was	 developed	 where	 	 each	 core	 is	 contaminated	 by	

“painting”	the	outer	surface	with	a	known	bacterial	species,	a	target	DNA	sequence,	and	a	

fluorescent	molecule	(Table	II-1).		

Table II-1. Tracers	used	for	monitoring	ice	core	sampling.	From	Christner	et	al.	(2005).	

Tracer Specifics [applied] Rationale Detection	limit

Cell Serratia	marcescens 5	x	107 cells ~105 cells/ml	

observed	on	core	

exteriors

1	cfu/ml

Macromolecule 4.3kb	DNA	plasmid:	

pTOPO-ITSNaegleriaa

Mol.	wt.	~2.6	x	106

1	ng

(2.2	x	108

molecules)

If	~105 cells/ml	on	

exterior,	105-106

rDNA	copies

500	molecules/ml/	

round	of	PCR

(Theoretical)

Molecule Rhodamine	6G:

Mol	wt.	479.0

0.1	ml	of	1000	ppm	

rhodamine	6G	

solution

DOC	values	2	log	

higher	on	core	

exterior,	so	use	3	log	

detection	sensitivity	

for	dye

0.5	ppb	rhodamine	6G

aPlasmid	DNA	is	pCRII-TOPO	vector	(Invitrogen)	containing	~400	nucleotide	cloned	DNA	insert	(Pélandakis	et	

al.	2000)	that	would	not	be	expected	to	be	present	in	the	sample.	cfu	=	colony	forming	units	of	S.	marcescens	on	

defined	media.
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Following	 this	 intentional	 contamination,	 the	 outer	 1	 cm	 from	 the	 core	 was	 aseptically	

removed	 by	 physical	 scraping	 in	 a	 particle	 free	 environment	 (class	 100	 clean	 room	 or

better)	followed	by	washing	with	ethanol	and	sterile,	particle-free	deionized	water.	Results	

from	these	experiments	have	demonstrated	that	most	cores	are	contamination	free	once	at	

least	 1	 cm	 of	 the	 ice	 radius	 is	 removed	 (Figure	 II-11).	 These	 decontamination	 protocols	

provide	 a	 direct	method	 to	 verify	 the	 authenticity	 of	 results	 obtained	 and	 eliminate	 core	

samples	that	fail	to	pass	our	monitoring	procedure.

Figure	II-10. From	Christner	et	al.	(2005).	Schematic	illustrating	

the	 removal	 of	 ice	 core	 veneers	 during	 each	 step	 of	 the	

decontamination	 procedure.	This	includes	 that	 5	mm	is	 scraped,	

then	 5	 mm	 was	 removed	 by	 washing,	 and	 then	 5	 mm	 was	

removed	by	melting.

Figure	II-11. From	Christner	et	al.	(2005).	

All	images	are	from	a	Vostok	meteoric	ice	

core	 collected	 1577	 m	 below	 the	 surface.	

Epifluorescence	images	of	DNA-containing	

prokaryotic	 cells	 (gold	 dots)	 in	 successive	

samples	 collected	 from	 the	 outer	 0.47	 cm	

(A)	and	after	0.57	cm	(B)	and	0.82	cm	(C)	

of	 the	 original	 core	 radius	 was	 removed	

from	 the	 ice	 core.	 Scanning	 electron	

micrographs	of	bacterial	contaminants	on	

the	 outer	 portion	 of	 the	 core	 showing	

extensive	 contamination	 by	 large	 rodshaped	cells	(D,	E).		All	images	are	from	a	

Vostok	meteoric	ice	core	collected	1577	m	

below	the	surface.

Sampling	 of	 the	 inner	 portions	 of	 an	 ice	 core	 can	 also	 be	 achieved	 along	 with	 chemical	

analysis	 when	 high	 resolution	 measurements	 are	 obtained	 using	 a	 closed,	 continuously	

melting	 system	 to	 measure	 geochemistry	 and	 particle	 abundance	 (e.g.,	 McConnell	 et	 al.	

2002);	 see	Section	 7.	These	 systems	 typically	 consist	 of	a	 titanium	 or	 ceramic	 concentric	

melting	 head	 that	 differentially	 melts	 selected	 portions	 of	 a	 core	 section	 and	 directs	 the	
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melt	 to	various	analytical	instruments.	Such	melting	systems	have	been	used	successfully	

to	 resolve	 small	 time-scale	 measurements	 of	 gases,	 black	 carbon,	 a	 host	 of	 geochemical	

constituents,	dissolved	organic	carbon	and	bacteria.	Measurements	on	the	inner	portions	of	

the	core	minimizes	contamination	and	allows	a	wide	variety	of	measurements	to	be	made	

on	a	relatively	small	sample.

6.	Initial	measurements	that	can	be	made	in	the	field	on	ice	cores	on	Earth

Measurements	on	the	cores

As	ice	 cores	are	 removed	 from	 the	 drill,	measurements	 of	 core	 density,	length,	 diameter,	

and	 notes	 on	 condition	 of	 the	 core	 are	 manually	 recorded	 before	 the	 cores	 are	 put	 into	

sleeves	or	tubes	to	be	packed	in	boxes	for	transport.	

Borehole	measurements

Initial	 signatures	 of	 organic	 matter	 within	 the	 borehole	 can	 be	 made	 using	 deep-UV	

spectroscopy	 of	 the	 borehole	 sidewalls.	 Deep-UV	 techniques	 have	 been	 demonstrated	 to	

distinguish	microbes	in	situ	in	non-ice	environments	based	on	 their	 fluorescence	spectra,	

and	 field	 deep-UV	 fluorescence	 instruments	 have	 been	 deployed	 to	 study	 deep	 marine	

biospheres,	 successfully	 detecting	 microbe-like	 signatures	 (Eschelman	 et	 al.	 2019).	 This	

technology	forms	the	basis	for	the	SHERLOC	instrument	on	the	Mars	2020	rover.	Deep-UV	

spectrometers	 have	 recently	 been	 incorporated	 into	 an	 ice	 coring	 drill	 to	 make	 high	

resolution	spatial	measurements	in	a	borehole	at	Summit	Station,	Greenland	(Malaska	et	al.	

2020;	Figure	II-12).	

The	 deep-UV/drill	 system	 revealed	 diverse	 spectral	 signatures	 in	 the	 Summit	 borehole.	

Most	 hotspots	 were	 less	 than	 20	 mm	 in	 diameter	 and	 were	 clearly	 isolated	 from	 other	

hotspots.	 The	 spectral	 signatures	were	 consistent	with	 organic	matter	 fluorescence	 from	

microbes,	 lignins,	 fused-ring	 aromatic	 molecules,	 including	 polycyclic	 aromatic	

hydrocarbons,	and	biologically	derived	materials	such	as	fulvic	acids.

Additional	borehole	measurements	include	core	imaging	and	borehole	televiewing/optical	

stratigraphy	ensures	 that	 the	 proper	 stratigraphy	 of	 the	 core	is	 preserved,	and	 serves	as	

backup	 stratigraphic	 data.	 Borehole	 temperature	 measurements	 provide	 temperature	

estimates	at	different	depths,	including	near	the	bed,	which	can	help	to	constrain	the	heat	

flux	entering	the	base	of	the	ice	and	the	rate	of	basal-ice	melting.	
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Figure	 II-12. From	Malaska	 et	 al.	(2020).	 Image	 and	 schematic	 of	 operations	 showing	in-borehole	 operation	

and	 data	flow.	 (A)	 Image	 of	WATSON	 drill	instrument	in	 drill	 tent	 at	Summit	Station,	Greenland.	The	 upright	

silver	tube	at	the	center	is	the	WATSON	instrument.	Optical	window	at	lower	center	in	image.	The	rest	of	the	drill	

is	inside	the	borehole	at	lower	center	in	image.	(B)	Cutaway	schematic	showing	drill-instrument	combination	in	

the	 ice	 borehole.	 The	 WATSON	 instrument	 is	 indicated	 by	 a	 blue	 rectangle	 in	 the	 schematic.	 The	 laser	

illumination	(not	to	scale)	is	indicated	as	a	purple	beam	penetrating	into	ice	and	hitting	a	target.	During	a	point	

cloud	 measurement,	 the	 instrument	 is	 moved	 vertically	 as	 the	 laser	 is	 illuminated	 along	 the	 length of	 the	

borehole.	 During	 a	 map,	 the	 instrument	 is	 stationary,	 and	 the	 laser	 beam	 is	 moved	 by	 a	 series	 of	 internal	

windows	 to	 build	 up	 a	 raster	map	 product.	 (C)	 Graphic	 of	 a	map	 product	 showing	 a	 portion	 of	 the	 borehole.	

Green	squares	indicate	pixels	of	interest.	(D)	Cartoon	simulating	a	spectral	response	extracted	from	one	of	 the	

map	pixels.

7.	Core	allocation	and	measurements

Once	the	ice	core	is	in	the	laboratory,	it	is	cut	into	meter-long	sticks	of	ice	that	are	sent	to	

various	laboratories	for	measurements.	Figure	II-13	shows	the	cut	plan	for	the	WAIS	Divide	

ice	core	and	the	South	Pole	Ice	Core.

For	multi-investigator	group	projects	on	Earth,	the	division	of	ice	core	samples	is	carefully	

coordinated	 among	 project	 participants	 to achieve	 an	 efficient	 use	 of	 the	 limited	 ice.	 A	

significant	portion	of	the	core	is	reserved	as	an	archive	to	allow	investigations	in	the	future	

when	new	techniques	are	available	and	new	questions	arise.	The	face	between	the	top	and	

bottom	 slabs	 is	 used	 for optical	 and	 electrical	 imaging	 of	 the	 core.	 The	 top	 slab	 is	 used	

primarily	for	continuous	sticks	for	chemistry,	water	isotopes	and	dissolved	and	particulate	

organic	matter	that	will	be	melted	as	part	of	Continuous	Flow	Analysis	systems	(CFA),	and	

these	 analysis	 streams	 are	 described	 in	 Figure	 II-14.	 The	 gases	 and	 physical	 properties	

pieces	 from	 the	lower	 slab	 are	 cut	into	 discrete	 pieces.	 These	 samples	 typically	 range	in	

length	 from	5	cm	 to	20	cm	depending	 on	 the	measurement,	and	are	 sampled	 from	every	

few meters	to	each	meter	based	on	the	depth-age	relationship	to	yield	a	desired	temporal	

frequency.		
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Figure	II-13. a)	Cut	plan	for	the	WAIS	Divide	ice	core	with	a	core	diameter	of	12.2	cm	(Credit:	Joe Souney).	b)

From	Souney	et	al.	(2014). Cut	plan	for	 the	South	Pole	 Ice	Core	with	a	core	diameter	of	9.8	cm.	For	 the	SP	ice	

core,	the	sticks	cut	from	the	top	slab	are	for	continuous	flow	measurements.	The	Gases/Phys	Prop	portion	is	cut	

into	discrete	pieces,	typically	5	to	20	m	in	length.

In	ice	core	projects	where	smaller-diameter	cores	(~	3”)	are	drilled	for	a	single	investigator	

or	small	team,	sticks	of	core	are	not	always	available	to	be	archived.	In	some	cases	much	of	

the	 core	 is	 processed	 using	 one	 CFA	 device	 to	 yield	 a	 range	 of	 chemical	 and	 isotopic	

measurements	that	ensures	co-located	measurements.	In	this	case	the	resulting	CFA	data	is	

coordinated	between	the	investigators	for	data	interpretation,	rather	than	sending	sticks	of	

the	original	core	to	separate	labs	for	measurements.	

Figure	II-14. From	McConnell	et	al.	(2017).	Example	of	an	ice	core	Continuous	Flow	Analysis	system.
Mars Ice Core Working Group – First Ice Cores from Mars

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Continuous	 flow	 analysis	 is	 an	 efficient	 technique	 for	 making	 multiple	 chemical	 and	

isotopic	measurements	on	a	stick	of	ice.	CFA	refers	to	measurements	where	sticks	of	ice	are	

melted	at	a	constant	rate,	providing	a	steady	stream	of	water	and	air	for	instruments.	CFA	

typically	requires	what	we	have	termed	“continuous”	ice	because	each	break	or	penetrating	

fracture	needs	 to	be	individually	cleaned	and	 thus	cores	with	lots	of	breaks	and	 fractures	

are	 more	 easily	 analyzed	 as	 discrete	 samples.	 Many	 different	 parameters,	 such	 as	 the	

elemental	composition,	dust	and	black	carbon	counts,	bacteria,	and	atmospheric	methane,	

can	be	analyzed	as	shown	in	 the	diagram	below. This	allows	high	depth	resolution	of	 the	

measurements	 and	 reduces	 the	 ice	 loss	 from	 cutting	 individual	 samples.	 Additionally,	

discrete	samples	of	water	can	be	stored	for	use	by	others.	On	typical	Earth	ice	core	projects,	

the	chemistry	and	water	isotopes	are	measured	on	separate	CFA	systems	because	the	flow	

rate	cannot	be	optimized	for	both.			
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III.	Ice	cores	from	Mars	

1.High-priority	science

High-amplitude	 obliquity	 variations	 on	 a	 planet	 with	 relatively	 simple	 climate	 dynamics	

make	 Mars	 an	 ideal	 laboratory	 from	 which	 to	 learn	 about	 the	 relationship	 between	

planetary	climate	and	orbital	cycles.	Mars	is	also	a	high-priority	environment	in	the	search	

for	evidence	of	life	beyond	Earth,	one	of	the	highest	priority	goals	in	planetary	exploration.	

Understanding	 the	 fundamental	 processes	 of	 Mars’	 climate	 is	 a	 necessary	 step	 toward	

understanding	the	nature	and	temporal	evolution	of	habitable	space	on	Mars	and	if	extinct	

and/or	 extant	 life	 is	 present.	 While	 it	 is	 understood	 that	 variations	 in	 Mars’	 orbit	 and	

obliquity	drive	changes	in	Mars’	climate	 (e.g.,	Laskar	et	al.,	2002),	 fundamental	questions	

remain	 about	 past	 climate	 conditions	 and	 how	mid-latitude	ice	 was	 deposited,	modified,	

and	buried.	Water	ice	is	currently	unstable	on	the	surface	in	the	mid-latitudes,	but	a	cover	

of	 permafrost,	 regolith,	 dust	 and/or	 debris	 maintains	 the	 stability	 of	 water	 ice	 in	 many	

subsurface	locations.	

The	geographic	distribution	of	subsurface	ice-rich	deposits	in	the	mid-latitudes	of	Mars	has	

been	mapped	using	multiple	datasets	and	with	numerous	methods.	For	example,	the	Mars	

Odyssey	 Neutron	 Spectrometer	 (MONS)	 instrument	 measured	 the	 concentration	 of	

hydrogen	in	the	top	few	centimeters	of	the	ice	table,	found	at	depths	less	than	1	m,	and	high	

concentrations	are	found	in	the	higher	latitudes	(e.g.,	Boynton	et	al.,	2002;	Diez	et	al.,	2008;	

Pathare	et	al.,	2018).	SHAllow	RADar	(SHARAD)	soundings	from	the	Mars	Reconnaissance	

Orbiter	 (MRO)	 have	 been	 used	 to	 constrain	 the	ice	 content	 of	lobate	 debris	aprons	 to	 be	

>80%	 ice	 (Holt	 et	 al.,	 2008;	 Petersen	 et	 al.,	 2018),	 and	 an	 inventory	 of	 such	 features	

indicates	 an	 equivalent	 global	 ice	 layer	 of	 up	 to	 2.6	 m	 (Levy	 et	 al.,	 2014).	 	 Radar	

observations	 in	 combination	 with	 high-resolution	 imagery	 has	 also	 identified	 significant	

stores	of	buried	massive	ice	in	the	northern	plains	(e.g.,	Bramson	et	al.,	2015;	Stuurman	et	

al.,	 2016).	 In	 select	 locations	 between	 45–70°	 S	 and	 45–65°	 N,	 vertical	 scarps	 directly	

expose	water	ice	deposits	up	to	~100	m	thick	just	below	the	surface	(Dundas	et	al.,	2018;	

Dundas	 et	 al.,	 2021;	 Figure	 III-10).	Monitoring	with	 the	High	 Resolution	 Imaging	 Science	

Experiment	 (HiRISE)	 camera	 has	 detected	 numerous	 small,	 fresh craters	– newly	 formed	

during	 the	lifetime	 of	MRO	 – that	 directly	 excavate	 and	 expose	 shallow	ice	 (Byrne	 et	 al.,	

2009;	Dundas	et	al.,	2014;	Dundas	et	al.,	2021).	In	addition	to	local	investigations,	detailed	

regional	 “ice	 consistency	 maps”	 of	 the	 Northern Hemisphere	 of	 Mars	 were	 recently	

produced	 by	 the	Mars	Subsurface	Water	 Ice	Mapping	 (SWIM)	 project	 (e.g.,	Morgan	et	al.,	

2021;	 Figure	 III-1).	 These	 maps	 show	 which	 locations	 are	 most	 likely	 to	 have	 shallow	

subsurface	ice	based	 on	how	many	different	datasets	 (e.g.,	 thermal,	 radar)	are	consistent	

with	 an	 icy	 interpretation	 at	 that	 location.	 	 Existing	 data	 make	 a	 compelling	 case	 for	 ice	

stores	within	 the	upper	 few	meters	below	 the	surface	and	extending	 tens	 to	hundreds	of	

meters	 below	 the	 surface	 at	many	mid-latitude	locations,	 but	 they	 do	 not	 resolve	 ~5–20	

meters	 below	 the	 surface.	 New	 data	 that	 constrain	 the	 upper	 tens	 of	 meters	 below	 the	

subsurface	 and	 provide	 constraints	 on	where	ice	is	located	in	 the	 shallowest	 subsurface,	

the	depth	to	the	ice,	and	the	thickness	of	the	ice	deposit	where	it	is	shallow	enough	will	be	

valuable	to	an	ice	coring	mission.		This	report	assumes that	prior	to	the	ice	core	mission,	a	

different	mission	will	have	returned	the	highest	resolution	possible	radar	images	of	the	top	
Mars Ice Core Working Group – First Ice Cores from Mars

25

20 meters	 of	 potential	 ice	 coring	 areas	 to	 inform	 drill	 site	 selection	 and	 to	 aid	

interpretation	of	eventual	measurements.

Because	 buried	ice	is	widespread	in	 the	Martian	mid-latitudes,	 the	 drilling	 target	 of	a	 10	

meter	 core	 that	 is	 primarily	 ice	 (but	 may	 contain	 dust,	 rocks,	 or	 soil	 debris)	 could	 be	

obtained	 from	 ground	 ice	 deposits	 where	 meters-thick	 ice	 in	 excess	 of	 the	 pore	 space	

(excess	 ice)	 occurs	 and	 from	 ice-rich	 glacial-type	 deposits	 (lobate	 debris	 aprons).	 To	

address	the	high-priority	science	highlighted	here,	we	indicate	where	the	science	questions	

apply	to	drilling	in	ground	ice	or	in	glacial	ice.	Both	environments	should	be	considered	as	

targets	 for	 drilling	 a	 core	 that	 is	 primarily	 composed	 of	 ice	 and	 that	 represents	 a	

stratigraphic	sequence.	We	also	indicate	what	science	questions	and	measurements	rely	on	

a	 high-quality	 continuous	ice	 core,	 compared	 to	 core	 fractures or	 pieces,	 or	 to	 collecting	

only	core	chips	(see	Section	V	and	VIII).	

															

Figure	III-1. From	Morgan	et	al.	(2021). Purple	shading	is	studied	region	in	the	northern	hemisphere,	and	grey	

shading	shows	the	estimated	areal	extent	of	theoretical	3 m	ice	stability.	b)	Map	of	composite	ice	consistency	(Ci).	

Bluer	pixels	are	consistent	with	presence	of	ice	and	redder	pixels	are consistent	with	absence	of	ice.

Motivation	 for	 drilling	 in	 glacial-ice	 environments: Lobate	 debris	 aprons	 on	 Mars	

(Figure	III-2)	are	up	to	hundreds	of	meters	thick	deposits	of	most	likely	meteoric	ice	in	the	

mid-latitudes,	and	 this	ice	should	record	past	climate	conditions	similar	 to	ice	cores	 from	

glaciers	and	ice	sheets	on	Earth.	There	is	recent	evidence	that	individual	glaciers	on	Mars	

indeed	 record	 multiple	 episodes	 of	 accumulation	 linked	 to	 orbital	 forcing	 (Levy	 et	 al.,	

2021).	 	 Meteoric	 ice	 on	 Earth	 contains	 an	 important	 reservoir	 of	 information	 on	 past	

climatic	 events,	 extending	 back at	 least	 one	 million	 years	 as	 a	 continuous	 record,	 and	

multiple	million	year	old	discontinuous	records	have	been	found	so	far.	Paleoclimatologists	

have	used	this	information	to	determine	past	climate	changes,	and	recent	work	on	a	deep	

ice	 core	 from	 West	 Antarctica	 has	 shown	 that	 polar	 ice	 cores	 provide	 archives	 of	

prokaryotic	cells	and	other	meteoric	constituents	over	time	(Santibáñez	et	al.,	2018).	These	

ice	 cores	 allowed	 for	 the	 examination	 of	 historical	 ecological	 forces	 shaping	 microbial	

communities	 on time	 scales	 at	 which	 climatic	 and	 environmental	 processes	 occur.	 Data	

from	this	ice	core	conclusively	showed	that	airborne	Antarctic	prokaryotic	concentrations	

from	ice	cores	are	sensitive	 to	large-scale	changes	in	mean	climate	states	and	millennialscale variations.	As	such,	meteoric	ice	contains	an	important	record	of	microorganisms	on	
Mars Ice Core Working Group – First Ice Cores from Mars

26

our	planet	that	theoretically	could	be	used	to	assess	biogeochemical	processes	and	habitat	

types	that	occurred	during	past	glacial	and	interglacial	periods.	Investigations on	Mars	are	

similarly	motivated	by	questions	about	cryobiology	and	climate.	

					

Figure	III-2. Left:	Lobate	debris	apron	at	~41°	S,		103°	E	shown	in	perspective	false	color	from	HRSC	image	0451	

(Credit:	ESA/DLR/FU	Berlin).	The	diameter	of	the	apron	is	~50	km.	Right:	SHARAD	radar	profile	along	a	lobate	

debris	apron	(Credit:	Eric	Petersen).

Figure	 III-3. From	 Priscu	 et	 al.	

(1998).	 A)	 A	 sediment	 aggregate	

and	associated	freezing	front	bubble	

pattern	 from	 2	 m	 beneath	 the	

surface	of	the	permanent	ice	cover	of	

Lake	 Bonney.	 B)	 Confocal	 laser	

photomicrographs	 showing	

microorganisms	 associated	 with	 a	

sediment	 particle,	 with	 enlarged	

views	 of	 two	 species	 of	

cyanobacteria	 (blue,	 DAPI-stained	

bacteria;	 red,	 chlorophyll	

autofluorescence;	 gray,	 sediment	

particle).	 Scale	 bars,	 10	 μm.	 C)	

Microautoradiograph	 of	 sediment	

particles	 bound	 by	 cyanobacterial	

filaments	 (dark	 regions	 denote	 sites	

of	 active	 14CO2 accumulation,	

indicative	 of	 photosynthetic	

activity).	Scale	bar,	100	μm.

Motivation	for	drilling	in	ground-ice	environments:	Collecting	ice	cores	from	ground	ice	

is	 also	 motivated	 by	 high-priority	 questions	 in	 both	 biology	 and	 climate. In	 regards	 to	

biology,	habitable	space	and	associated	life	in	Earth’s	icy	environments	are	often	associated	

with	lithic	material.	Lithic	matter,	particularly	near	the	surface,	has	been	shown	to	provide	

permanent	or	transient	films	or	inclusion	of	liquid	water	that	can	enhance	the	weathering	
Mars Ice Core Working Group – First Ice Cores from Mars

27

process	 of	 important	 life	 sustaining	 minerals	 and	 associated	 free	 energy	 couples.	 These	

relationships	have	been	shown	 to	support	a	seasonally	active	microbial	ecosystem	within	

the	permanent	ice	covers	of	lakes	in	the	McMurdo	Dry	Valleys	(Figures III-3,	III-4,	and	III-5)	

and	entrained	in	cryoconite holes	(Smith	et	al.	2016;	Foreman	et	al.,	2007;	Figures	III-7	and	

III-8).

Figure	 III-4. Lake	 ice	 aggregate	 during	 late	 winter	 before	 liquid	 water	

formation.	The	photograph	was	taken	at	an	ice	depth	of	2m	from	a	3.5m	deep	

trench	cut	into	the	ice	cover	of	Lake	Bonney,	Antarctic	Dry	Valleys.	The	bubbles	

are	 a	 result	 of	 gas	 exsolution	 that	 occurs	 as	 the	water	 occlusions	freeze	from	

the	 top	 down	 during	 autumn	 and	 early	 winter.	 Scale	 bar	 2	 cm	 (Credit:	 John	

Priscu).

			

Figure	 III-5. From	 Priscu	et	 al.	 (1998).	Vertical	 profiles	 of	 selected	 constituents	 (A-D)	in	 the	lake	ice	 cover	 of	

Lake	Bonney.	 	 Individual	 points	 represent	 the	mean	from	ice	 core	 sections	 approximately	 14	 cm	long	 (10	 cm	

diameter)	except	in	(D)	where	points	represent	the	mean	from	approximately	30	cm	long	core	sections.		DIN	=	

NH4+ +	NO3-,	SRP	 =	 soluble	 reactive	 phosphorus, DOC	– dissolved	 organic	 carbon,	 Primary	 productivity	 =	light	

mediated	photosynthetic	activity,	Bacterial	activity	(TdR)	represents	 the	rate	of	incorporation	of	 3H-thymidine	

into	bacterial	cells.
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The	4	 to	20	m	 thick	permanent	ice	covers	of	Antarctic	lakes	in	 the	McMurdo	Dry	Valleys	

develop	 liquid	 water	 inclusions	 in	 response	 to	 solar	 heating	 of	 internal	 aeolian-derived	

sediments.	 These	 sediments	 typically	 reach	 their	 depth	 of	 downward	melting	 about	 2	m	

below	the	ice	surface.	The	ice	sediment	particles	serve as	nutrient	(inorganic	and	organic)–

enriched	 microzones	 for	 the	 establishment	 of	 a	 physiologically	 and	 ecologically	 complex	

microbial	 consortium	 capable	 of	 contemporaneous	 photosynthesis,	 atmospheric	 nitrogen	

fixation,	 and	 decomposition.	 The	 consortium	 is capable	 of	 physically	 and	 chemically	

establishing	 and	 modifying	 a	 relatively	 nutrient- and	 organic	 matter–enriched	 microbial	

“oasis”	 embedded	 in	 the	 lake	 ice	 cover.	 The	 habitat	 in	 the	 Antarctic	 lake	 ice	 cover	 may	

serve	as	a	model	environment	for	past	life on	Mars. Although	Mars	may	have	had	extensive	

liquid	water	at	one	 time,	it	rapidly	cooled,	and	ice	would	have	become,	as	it	is	 today,	 the	

dominant	 form	 of	 water	 on	 the	 surface.	 While	 lake	 ice	 environments	 are	 not	 found	 on	

modern	Mars,	they	could	be	an	analogue	for	crater	lake	environments	on	early	Mars	(e.g.,	

McKay	et	al.,	2017).	 In	addition,	solar	heating	of	 the	ground	surface during	high-obliquity	

periods	of	Amazonian	Mars could	have	resulted	in	subsurface	melt	layers	similar	to	those	

that	exist	in	the	permanent	ice	covers	in	the	McMurdo	Dry	Valley	lakes.

Figure	III-6. From	Priscu	and	Christner	(2004).	The	cryoconite	hole	environment	in	the	McMurdo	Dry	Valleys.	In	

summer,	sediment	collects	on	glacial	surfaces	and	exposure	to	solar	irradiation	produces	melt	pools	within	the	

ice	 (A),	 which	 may	 subsequently	 freeze	 on	 the	 surface,	 and	 completely	 freeze	 during	 the	 winter	 (B).	 The	

cryoconite	hole	illustrated	 (C)	was	located	on	 the	Canada	glacier	and	was	completely	frozen	when	sampled	in	

January	2001. (D)	A	comparison	of	cores	retrieved	from	the	cryoconite	hole	(left)	with	a	core	from	the	adjacent	

glacial	 ice.	 Note	 the	 dense	 layer	 of	 sediment	 and	 organic	 material	 present	 within	 the	 bottom	 5	 cm	 of	 the	

cryoconite	hole	core.
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Cryoconite	 holes	 are	 depressions	 on	 glacial	 surfaces	 that	 have	 a	 characteristic	 sediment	

layer	 and	 melt	 to	 an	 equilibrium	 depth	 (Figures III-6,	 III-7,	 and	 III-8).	 In	 the	 Antarctic	

McMurdo	 Dry	 Valleys	 these	 entombed	 habitats	 harbor	 active	 microbial	 assemblages	

predominantly	associated	with	lithic	material	and	on	average	 remain	entombed	 (isolated	

from	atmospheric	 conditions)	 over	decadal	 timescales.	Previously,	 cryoconites	 have	 been	

studied	as	analogs	to	Mars.	It	has	been	shown	that	microbial	activity	significantly	decreases	

with	increased	distances	from	other	organisms	and	lithic	material	(Figure	III-8).

				

Figure	 III-7. Left:	 From	 Foreman	 et	 al.	 (2007)	 showing	 a	 cryconite	 hole	 and	 core	 section	 through	 the	 hole.	

Cryconite	 hole	 diameter	 is	 on	 the	 order	 100	 cm.	 Right:	 From	 Smith	 et	 al.	 (2016).	 Confocal	 scanning	 laser	

Microscopy	 images	 of	 cryoconite	 particles	 and	 associated	 microbial	 cells	 (A-C,E)	 and	 biofilm	 matrix	 (D)	 and	

control	sediment	(F).

Figure	 III-8. From	 Smith	 et	 al.	 (2016).

Analyzed	 aggregate	 of	 microbial	 cells	 from	

an	Antarctic	cryoconite	 hole.	Representative	

nanoSIMS	 isotope	 ratio	 images	 of	 an	

analysed	 Oscillatoria	 sp.	 filament	 for	 a	 the	

13C/12C	ratio	(B)	the	15N/14N	ratio	(C)	the	

epifluorescence	 overlay	 used	 to	 confirm	 cell	

identification	 of	 hybridised	 Bacteroidetes	

cells	 (green),	 DAPI	 stained	 (blue)	 and	 an	

autofluorescent	 filament	 (red).	 (D)	

NanoSIMS	analysis	of	13C	and	15N	enrichment	

measurements	 atom	 %	 (AT%)	 for	

Bacteroidetes	sp.	cells	based	on	proximity	to	

filamentous	 cells	 and	 particles.	 Showing	 a	

decrease	in	activity	with	increased	distance.
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In	addition	to	the	goals	related	to	biology	described	above,	collection	of	cores	from	ground	

ice	 is	 motivated	 by	 a	 number	 of	 outstanding	 questions	 related	 to	 the	 Martian	 climate.	

Ground	 ice	 in	 the	 shallow	 subsurface	 is	 widespread	 on	 Mars	 (e.g.,	 Morgan	 et	 al.,	 2021),	

including	in	many	mid-latitude	regions	that	are	likely	to	be	the	first	sites	visited	by	human	

explorers.	 	 This	 ground	 ice	 includes	 pore-filling	 ice,	 which	 refers	 to	 ice	 condensed	 from	

water	 vapor	in	 the	atmosphere	 that	 diffuses	into	 the	 regolith.	 	 Theoretical	models	 of	 the	

stability	 and	 dynamics	 of	 pre-filling	 ground	 ice	 (e.g.,	 Mellon	 et	 al.,	 2009)	 correlate	

extremely	well	with	observations	(e.g.,	Boynton	et	al.,	2002;	Byrne	et	al.,	2009;	Dundas	et	

al.,	2014),	including	the	ice	observed	at	the	Phoenix	landing	site	(Figure	III-9).

Excess	ice	(ice	in	excess	of	pore	space)	is	also	observed	in	some	mid-latitude	regions,	and	

evidence	 for	 excess	 ice	 in	 different	 locations	 is	 increasing (e.g.,	 Bramson	 et	 al.,	 2015;	

Stuurman	et	al.,	2016;	Dundas	et	al.,	2018;	Pathare	et	al.,	2018;	Morgan	et	al.,	2021).		While	

the	 formation	 of	 mid-latitude	 excess	 ice	 in	 the	 past	 is	 predicted	 by	 some	 models	 (e.g.,	

Madeleine	et	al.,	2009),	its	persistence	and	age	are	less	well	understood.		In	particular,	for	

depths	 deeper	 than	 several	 meters,	the	 minimum	 age	 of	 the	 excess ice	 is	 thought	 to	 be	

much	 more than	 recent obliquity	 cycles	 on	 Mars	 (Viola	 et	 al.,	 2015).	 This	 requires	 a	

mechanism for	this ice	to	persist	during	times	when	mid-latitude	ice	is	unstable.						Possible	

mechanisms to	 preserve	 ground	 ice could	 include	 protective	 sublimation	 lags	 (e.g.,	

Bramson	et	al.,	2017)	or	high	water	vapor	content	in	the	lower	atmosphere	(e.g.,	Tamppari	

and	 Lemmon,	 2020).	 	Excess	ice at	 shallow	 depths	is	 periodically	 unstable	as	 recently	as	

100,000	 years,	 and	 shallow	 enough	 to	 be	 lost	 and	 reform	 on	 1000	 year time	 scales.	

Ultimately,	the	age	and	persistence	of	excess	ice	is	important	in	understanding	mid-latitude	

climate, but	our	knowledge	of	these subjects	is	currently	limited,	which	motivates the	need	

to	collect	ice	cores.		

Figure	 III-9. From	 Mellon	 et	 al.	

(2009).	 Phoenix	 Lander	 images	 of	

subsurface	 exposures.	 Left: small	

patch	 of	 99%	 pure	water	ice	 (trench	

is	 ~15	 cm	 wide).	 Right:	 pore-filling	

ice-rich	soil	(trench	is	~23	cm	wide).

Broad	motivation	to	understand	Mars’	climate	history:	Climate	questions	that	motivate	

the	 collection	 of	 ice	 cores	 extend	 beyond	 mid-latitude-specific	 climate	 and	 include	

outstanding	 questions	 about	 Martian	 climate	 in	 general.	 Consider	 the	 extensive	 Martian	

polar	layered	deposits	(PLDs),	large	water	ice	sheets at	the	north	and	south	poles	of	Mars.	

These	PLDs	 (see,	e.g.,	 review	in	Byrne,	2009)	have	 been	 the	 subject	 of	many	 studies	 that	

have	sought	to	address	questions	about	global	Martian	climate.	In	particular,	the	plentiful	

exposures	of	layered	stratigraphic	ice	(Figure	 III-10)	have	been	considered	as	“virtual	ice	
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cores”,	with	many	studies	(e.g.,	Laskar	et	al.,	2002,	Milkovich	and	Head,	2005,	Becerra	et	al.,	

2019)	attempting	to	use	patterns	observed	in	the	ice	exposures	with	remote	sensing	data	

from	 orbiting	 spacecraft	 to	 test	 the	 long-standing	 hypothesis	 that	 Martian	 climate	 is	

strongly	 controlled	 by	 variations	in	 the	 planet’s	 spin	 and	 orbit	 (e.g.,	Murray	 et	 al.,	 1973;	

Cutts	 and	 Lewis,	 1982).	 These	 studies	 have	 made	 valuable	 progress,	 but	 the	 confident	

detection	of	such	an	orbital	signal	in	Martian	ice	from	remote	sensing	data	alone	is	debated	

(e.g.,	Perron	and	Huybers,	2009).	Ultimately,	independent	age	constraints	– such	as	 those	

that	 can	 come	 from	 study	 of	 ice	 core	 samples	 – will	 be	 needed	 (Sori	 et	 al.,	 2014) to	

definitively	test	this	important	hypothesis.	The	orbital	forcing	of	Martian	climate	is	thought	

to	 be	 a	 global	 phenomenon,	 so	 physical	 collection	 and	 dating	 of	 mid-latitude	 ice	 cores	

(similar	stratigraphic	ice	exists	in	the	mid-latitudes,	Figure	III-10) can	be	used	to	study	it,	

including	 study	 of	 hypothesized	 links	 and	 exchanges	 between	 polar	 and	 mid-latitude	

reservoirs	(e.g.,	Head	et	al.,	2003).

				

Figure	 III-10. Left: Modified	from	 Sori	 et	 al.	 (2014). Example	 of	 a	 stratigraphic	 sequence	from	 the	 northern	

polar	layered	deposits	on	Mars,	corrected	for	topography,	from	Mars	Orbiter	Camera	(MOC)	Image	#M0001754.		

Vertical	 scale	 indicates	 vertical	 depth	 within	 the	 sequence,	 horizontal	 scale	 indicates	 distance	 along	 outcrop.	

Right:	From	Dundas	et	al.	(2018).	Enhanced	color	image	of	a	mid-latitude	ice	cliff	nearly	100	m	high	exposing	a	

deposit	of	nearly	pure	ice	(blue	shading);	NASA/JPL/University	of	Arizona/USGS.

We	emphasize	 that	 the	biology	and	climate	motivations	 for	collecting	ice	cores	are	linked	

together.	In	addition	to	ice	core	collection,	a	local	radar	survey	in	order	to	pick	the	drill	site	

(see	Section	III.3),	as	well	as	sampling	from	the	surface	to	depth	at	the	target	ice	core	site,	

would	answer	questions	about	the	distribution	of	ice	that	have	implications	for	the	climate	

controls	on	habitability.

Goals	and	Objectives

A	 human-led	 scientific	 mission	 to	 the	 mid-latitudes	 of	 Mars	 would	 transform	 our	

understanding	of	past	and	present	conditions	and processes	related	to	life	and	climate,	as	
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well	 as	 contribute	 to	 understanding	 Mars’	 geological	 history	 and	 further	 support	 human	

exploration.	 NASA	 goals	 and	 priorities	 have	 been	 defined	 by	 the	 planetary	 science	

community	and	are	 thoroughly	discussed	in	 the	Planetary	Science	Decadal	Survey	(Vision	

and	 Voyages	 for	 Planetary	 Science	 in	 the	 Decade	 2013–2022;	 NRC,	 2013)	 and	 the	 Mars	

Exploration	 Program	 Analysis	 Group	 Goals	 Document	 (MEPAG,	 2020).	 In	 addition,	 white	

papers	submitted	 for	 the	development	 for	 the	2023–2032	Decadal	Survey	and	 the	report	

from	 the	 Ice	 and	 Climate	 Evolution	 Science	 Analysis	 Group	 (ICE-SAG,	 2019)	 also	 define	

high-priority	science	areas.

The	Mars	 Ice	 Core	Working	Group	 has	adopted	 the	 first	 two	MEPAG	 science	goals	as	 the	

overarching	goals related	 to	 the	majority	of	 the	science	objectives	and	questions	detailed	

here.	These	goals	can	be	addressed	from	new	in	situ	measurements	and	core	samples	that	

are	 primarily	ice	 	 collected	 by	 a	 ground	 crew	 and	 returned	 to	 Earth.	 The	 first	 two	 goals	

from	MEPAG	(2020)	include	(I)	Determine	if	Mars	ever	supported,	or	still	supports,	life	and	

(II)	Understanding	the	processes	and	history	of	climate	on	Mars.	In-situ	measurements	and	

returned	sample	measurements	associated	with	the	first	ice	coring	effort	on	Mars will	also	

bring	new	understanding	related	 to	aspects	of	MEPAG	Goals	 (III)	and	 (IV),	 to	understand	

Mars’	as	a	geological	system	and	to	support	human	exploration.

Related	 to	 these	 goals,	 the	 Mars	 Ice	 Core	 Working	 Group	 has	 defined	 the	 highest	

priority	objectives	that	could	be	addressed	with	the	first	ice	cores	from	Mars:

1. Determine	 the	nature	and	 temporal	evolution	of	habitable	space	in	 the	subsurface	

ice	environment

2. Determine	 if	 extinct	 or	 extant	 life	 is	 present	 and	 evaluate	 phylogenetic	 and	

metabolic	relationships

3. Assess	the	potential	to	preserve	biosignatures

4. Determine	the	ice	stratigraphy	and	age	of	ice	in	the	core

5. Determine	the	lithic	stratigraphy	and	age	of	lithic	matter	in	the	core

6. Characterize	climate	processes	on	Mars	and	the	relationship	between orbital	cycles	

and	climate	conditions

7. Characterize	the	geographic	distribution	and	history	of	subsurface	ice	near	the	core	

site

8. Determine	the	context	for	interpreting	the	biological	and	climate	records	in	the	core

The	 following	subsections	discuss	questions	 that	can	be	answered	with	 the	 first	ice	cores	

from	 Mars	 and	 describe	 measurements	 and	 protocols	 to	 maximize	 the	 scientific	 return	

from	 an	 ice-coring	 mission.	 Addressing	 the	 science	 questions	 presented	 here	 requires	

various	measurements	 on	 the	 core,	which	 put	 requirements	 on	 the	 characteristics	 of	 the	

core,	 as	 well	 as	 requirements	 on	 how	 the	 core	 is	 handled	 and	 stored.	 In	 addition,	 local	

measurements	 from	 the	 region	 near	 the	 core	 site	 provide	 necessary	 context	 to	interpret	

the	biological	and	climate	records	in	the	core.
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Compelling	science	questions	that	can	be	addressed	with	returned	samples

Linkages	 between	 life,	 climate,	 and	 geology: Much	 of	 Mars’	 science	 is	 “cross	 cutting”	

(MEPAG,	 2020),	 and	 high-priority	 science	 related	 to	 life,	 climate,	 and	 geology	 are	

inextricably	 linked.	 For	 example,	 a	 major	 discovery	 related	 to	 the	 presence	 of	 extant	 or	

extinct	life	on	Mars	would	require	consistent	discoveries	about	past	climate	and	the	water	

cycle,	as	well	as	discoveries	about	geological	and	geochemical	conditions	conducive	to	life.	

Cryobiology: Fundamental	questions	about	the	nature	and	temporal	evolution	of	habitable	

space	in	 the	 subsurface	 environment	include	 understanding	if	 the	 physical	 and	 chemical	

properties	 of	 icy	 environments	 can	 support	 life.	 Liquid	 water	 is	 critical	 to	 life,	 and	

questions	 about	 the	 physical	 and	 temporal	 distribution	 of	 subsurface	 liquid	 water	 are	 a	

priority.	High	priority	is	 to	address:	 Is	“ancient”	or	“modern”	DNA	present?	Are	organism	

“skeletons”	or	fossil	remnants	present?	Are	metabolically	active	organisms	present?

Table	III-1. Questions	related	to	Objectives	1-3.	Color	indicates	if	addressing	the	question	requires	a	continuous	

ice	core	(dark	blue),	or	if	fractures	or pieces of	core/chips	are	acceptable	(light	blue).	

Stratigraphy:	 Measuring	 ice	 stratigraphy,	 lithic	 stratigraphy,	 and	 age	 of	 the	 ice	 are	

fundamental	analyses.	The	ice	stratigraphy	allows	investigation	of	whether	samples	of	past	

atmosphere	 are	 preserved,	 and	 if	 clathrate	 hydrates	 are	 present.	 A	 core	 in	 ground	 ice	

would	provide	ground	 truth	on	 the	subsurface	ice	concentration	with	depth,	as	well	as	if	

unique	 thermal	 or	 depositional	 structures	 are	 present,	 if	 sediments	 are	 fractionated	

according	 to	 size	 and	 density,	 and	 if	 there	 is	 dissolved	 and	 particulate	 organic	 matter	

associated	 with	 sediment	 stratigraphy.	 For	 glacial	ice,	 the	ice	 stratigraphy	 would	 further	
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34

reveal	 any	 density	 variations,	 the	 frequency	 and	 thickness	 of	 dust	layers	in	 the	 core,	 the	

layer-thickness	profile	of	ice	layers,	and	if	cells	are	associated	with	dust	layers,	clathrates,	

and/or	bubbles.	The	lithic	stratigraphy	will	define	what	constitutes	a	layer.	In	addition,	the	

presence	of	dust,	volcanic	ash	(if	observed),	and	the	lithic	grain	distribution	provide	direct	

constraints	on	atmospheric	and	geologic	processes.

Table	III-2. Questions	related	to	Objectives	4-5.	Color	indicates	if	addressing	the	question	requires	a	continuous	

ice	core	(dark	blue),	or	if	fractures	or	pieces	of	core/chips	are	acceptable	(light	blue).	

Climate: Climate	 on	 Mars	 has	 long	 been	 hypothesized	 to	 be	 strongly	 controlled	 by	

variations	in	 the	planet’s	spin	and	orbit	(e.g.,	Murray	et	al.,	1973;	Cutts	and	Lewis,	1982).	

However,	 confident	 identification	 of	 this	 orbital	 signal	 in	 icy	 stratigraphy	 has	 remained

debated	(e.g.,	Laskar	et	al.,	2002;	Perron	and	Huybers,	2009),	as	have	the	exact	sensitivity	

of	stratigraphy	 to	orbital	cycles	and	many	ice	characteristics	including	accumulation	rate,	
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35

age,	 deformational	 history,	 and	 more.	 	 Laboratory	 analysis	 of	 returned ice	 core	 samples	

would	 be	 a	 game	 changer	 in	 addressing	 these	 climate	 questions.	 	 For	 example:	 (1)	

Constraints	on	age	and	accumulation	rate	of	mid-latitude	ground	ice	cores	would	allow	for	

determination	 of	 the	 relationship	 of	 mid-latitude	 ice	 to	 other	 Martian	 water	 reservoirs,	

including	 the	 polar	 layered	 deposits	 (e.g.,	 Bramson	 et	 al.,	 2017).	 	 (2)	 In	 glacial-type	

deposits,	 these	 same	constraints	would	allow	 for	 testing	 of	hypotheses	 on	 the	number	 of	

glacial	 transitions	recorded	(e.g.,	Levy	et	al.,	2021).		(3)	Chemical	analysis	of	atmospheric	

samples,	if	present,	could	allow	for	the	quantification	of	carbon	dioxide’s	relationship	with	

orbital	cycles	(e.g.,	Buhler	et	al.,	2020).		(4)	Identification	of	impact	sediments	or	volcanic	

ash,	 which	 have	 been	 putatively	 identified	 in	 the	 polar	 deposits	 (e.g.,	 Sinha	 and	 Horgan,	

2021),	would	represent	a	lithic	source	that	is	unlikely	to	be	strongly	controlled	by	obliquity	

and	 would	 be	 important	 to	 consider	 in	 addition	 to	 the	 likely	 more	 prevalent	

atmospherically	deposited dust.		

Table	 III-3. Questions	related	 to	Objectives	6.	Color	indicates	if	addressing	 the	question	requires	a	continuous	

ice	core	(dark	blue),	or	if	fractures	or	pieces	of	core/chips	are	acceptable	(light	blue).	

Geology,	 geochemistry,	 glaciology,	 and	 geomorphology: Characterizing	 the	 subsurface	

ice	distribution	is	necessary	for	drill-site	selection,	but	also	addresses	high-priority	science.	

The	geographic	distribution	of	ice,	as	well	as	the	geology	and	geochemistry	in	the	vicinity	of	

the	drill	site contribute	necessary	context	to	interpret	the	biological	and	climate	records	for	
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36

ice	 cores.	 Mapping	 and	 dating	 glaciological	 and	 geomorphological	 landforms,	 spanning	

periglacial,	 glacial,	 and	 paraglacial	 environments,	 as	 well	 analyses	 focused	 on	 past	 and	

present	processes	driving	ice	and	organic	evolution	provide	further	context	for	the	ice	core	

records.	

Table	III-4. Questions	related	to	Objectives	7	and	8.	Addressing	these	questions	requires	in-situ	measurements	in	

combination	with	cores	and/or	chips.	Color	indicates	if	addressing	 the	question	requires	a	continuous	ice	core	

(dark	blue),	or	if	fractures	or	pieces	of	core/chips	are	acceptable	(light	blue).

Comparative	 planetology: Ice	 cores	 from	 Earth	 are	 distinctly	 rich	 records	 of	 Earth’s	

history.	Ice	cores	from	Mars	would	provide	similarly	rich	records	for	Mars’	history,	but	also	

make	 it	 possible	 to	 understand	 the	 history	 of	 terrestrial	 planets	 more	 generally	 by	

comparing	 Earth	 and	 Mars.	 Indeed,	 terrestrial	 analogue	 studies	 have	 advanced	 our	

understanding	 of	 geological,	 geomorphological,	 glaciological,	 biological,	 and	 chemical	

processes	on	Mars.		Simpler	climate	dynamics	on	Mars	(e.g.,	lack	of	current	oceans)	allow	

us	 to	 evaluate	 the	 relationship	 between	 orbital	 cycles	 and	 climate,	 which	 may	 apply	 to	

other	planetary	bodies,	and	especially	as	we	continue	to	learn	about	the	other	ice	sheets	of	

the	solar	system	(including	the	nitrogen	ice	sheets	of	Pluto	(Stern	et	al.,	2015)	and	Triton	
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(Moore	and	Spencer,	1990)).	 In	general,	questions	related	 to	life	and	climate	in	our	solar	

system	 are	 fundamental	 to	 understanding	 the	 evolution	 of	 terrestrial	 planets	 and	

exoplanets.	 Comparative	 planetology	 is	 a	 way	 to	 move	 beyond	 solar	 system	 exploration,	

toward	the	explanation	of	how	planetary	systems	work	(e.g.,	Glassmeier,	2020).	

Solar	storm	events: Ice	records	are	unique	in	how	they	preserve	specifics	of	the	hydrologic	

cycle	during	snow	deposition,	past	atmospheric	composition,	and	can	record	climate	events	

on	seasonal	to	millennial	timescales.	Ice	cores	records	of	10Be	show	correlation	with	solar	

activity	 	 (Vonmoose	 and	 others,	 2006),	 and	 it	 has	 recently	 been	 confirmed	 that	 extreme	

solar	 storms	 can	 lead	 to	 increased	 atmospheric	 production	 of	 cosmogenic	 radionuclides	

(O’Hare	et	al.,	2019),	and	evidence	of	14C,	10Be	and	36Cl	increases	in	ice	core	records	have	

been	linked	to	extreme	solar	storms	from	~660	BC	(O’Hare	et	al.,	2019),	as	well	as	775	and		

993	 BC	 (Mekhaldi	 et	 al.,	 2015).	However	 recent	 studies	 have	 strongly	 stated	 that	 nitrate	

spikes	in	ice	cores	are	not	proxies	for	solar	storms	(e.g.,	Duderstadt	et	al.,	2016;	Mekhaldi	et	

al.,	2017).	Even	 for	 the	most	extreme	solar	storms	 (including	years	775,	994,	1859,	1956	

BC),	 ice	 cores	 from	 Antarctica	 and	 from	 Greenland	 do	 not	 record	 a	 coincident	 global	

increase	 in	 nitrate,	 and	 the	 nitrate	 spikes	 that	 are	 observed	 are	 likely	 associated	 with	

biomass	 burning	 (Mekhaldi	 et	 al.,	 2017).	 These	 studies	 highlight	 the	importance	 of	 highresolution	 analyses	 (annual to	 multi-year	 resolution)	 of	 multiple	 radionuclides	 from	 ice	

cores	and	the	possibility	 for	a	comparison	between	ice	core	records	 from	Earth	and	highresolution	ice	cores	from	Mars.	

2. Measurements	on	returned	samples

Section	 V	 and	 Table	 V-2	 discuss	 the	 continuity,	 quality,	 and	 quantity	 of	 the	 returned	

samples	required	to	enable	specific	measurements.	We	distinguish	between	three	primary	

types	 of	 ice	 core	 samples,	 where	 the	 core	 is	 retrieved	 in	 lengths	 of	 approximately	 one	

meter:

1) Continuous: ice	core	is	in	five	or	fewer	pieces	per	meter	with	relatively	few	cracks	

penetrating	into	the	interior	of	the	core

2) Fractures:	 ice	 core	 is	 in	 six	 or	 more	 pieces	 per	 meter	 with	 frequent	 cracks	

penetrating	 into	 the	 interior.	 The	 pieces	 and	 cracks	 are	 tight	 fitting	 such	 that	 the	

stratigraphic	order	is	preserved	at	the	mm	and	longer	length	scales

3) Pieces: ice	 core	 is	 broken	 into	 pieces	 and	 stratigraphic	 order	 is	 uncertain	 at	 cm	

length	scales	and	shorter

4) Chips:	 chips	 are	 small	 ice	 shards	 and	 dust	 with	 maximum	 dimension	 6	 mm,	 as	

would	be	generated	 from	an	ice	drill	 that	shaves	ice	into	chips	but	does	not	drill	a	

core	(see	section	IV	for	further	description).

All	 ice	 samples	 from	 Mars	 will	 have	 scientific	 value,	 but	 the	 extent	 to	 which	 our	 highpriority	objectives	and	questions	can	be	addressed	will	depend	on	the	characteristics	of	ice	

cores	recovered	from	Mars.	Section	V	discusses	trade-offs	between	core	characteristics	and	

the	 measurements	 that	 will	 be	 possible	 to	 make,	 as	 well	 as	 discusses	 estimates	 for	 the	
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38

quantity	 of	 core	 required	 to	 make	 certain	 measurements	 based	 on	 contemporary	

technology.	

Indicators	of	life

Multiple	lines	 of	 evidence	will	 be	 required	 to	 determine	 unequivocally	if	life	 does	 or	 did	

exist	on	Mars.	Past	reports	from	Viking	tracer	release	experiments	and	Martian	meteorites	

(Allan	 Hills	 84001)	 have	 yet	 to	 be	 verified	 owing	 to	 the	 lack	 of	 corroborating	 data.	 The	

analysis	 of	Martian	ice	in	 an	 earth-based	laboratory	 setting	 will	 allow	 scientists	 to	 use	 a	

multifaceted	approach	to	verify	results. At	a	minimum,	these	measurements	must	contain	

experiments	 to	 both	 observe	 the	 presence	 of	 cellular	 matter	 (e.g.,	 electron	 and	 optical	

microscopic	 analysis,	 multidimensional	 fluorescence),	 determine	 its	 phylogenetic	

character,	and	identify	the	presence	of	metabolic	activity.	Ideally,	such	measurements	must	

also	be	made	on	parallel	control	samples	to	ensure	that	the	results	are	not	contaminants;	

for	biological	studies,	controls	are	as	important	as	the	actual	samples	themselves.	For	this	

reason,	 Mars	 2020	 incorporated	 a	 number	 of	 control	 cores	 to	 examine	 contamination	 at	

various	points	in	the	mission.

In	 addition	 to	 measurements	 and	 experiments	 focused	 directly	 on	 biology,	 a	 suite	 of	

chemical	and	physical	determinations	must	also	be	included	 to	interpret	and	corroborate	

the	 biological	 data.	 These	 measurements	 should	 include,	 but	 not	 be	 limited	 to,	

geochemistry,	 crystal	 structure,	 bubble	 structure,	 lithic	 matter,	 and	 the	 temporal	

stratigraphy	 of	 the	 ice.	 Data	 from	 intact	 ice	 cores	 together	 with	 ice	 chips	 and	 shavings	

should	 be	 incorporated	 into	 the	 suite	 of	 measurements.	 If	 we	 are	 to	 understand	 life	 in	

Martian	ice	we	must	understand	the	ice	itself	and	its	potential	to	serve	as	a	habitat.	Finally,	

it	is	imperative	that	stringent	sampling	and	decontamination	protocols	be	applied	to	both	

the	control	and	actual	ice	samples	from	Mars.

Indicators	of	climate

Measurements	 that	 provide	 constraints	 on	 Mars’	 climate	 include	 ice	 chemistry,	 stable	

isotopes,	trapped	gases	(if	preserved),	ionic	content,	material	properties	of	the	ice	(density,	

crystal/grain	 structure,	 bubble	 distribution),	 and	 electrical	 properties.	 Decimeter-scale	

analysis	of	ice	stratigraphy	over	 the	meters-long	core,	as	well	as	 the	lithic	stratigraphy	of	

the	overburden,	will	reveal	the	frequency	and	thickness	of	dust	layers.

Stable	isotopes,	including	the	ratio	of	18O	to	16O,	the	ratio	of	Deuterium	to	Hydrogen	(D/H),	

and	isotopes	of	trace	gases	(e.g.,	N,	Ar,	Kr),	all	fractionate	over	time,	largely	by	loss	to	space,	

during	 time	 spent	in	 the	atmosphere.	Water	 stable-isotope	 records	 from	a	Mars’	ice	 core	

are	particularly	important	to	constraining	the	history	of	water	on	Mars.	The	D/H	ratio	has	

changed	over	Martian	history	due	to	 fractionation	loss	to	space,	and	to	a	lesser	degree	by	

sequestering	in	ice	reservoirs (e.g.,	Alsaeed	and	Jakosky,	2019;	Vos	et	al.,	2019).	Profiles	of	

D/H	 from	mid-latitude	ice	cores	can	be	compared	 to	 the	current	atmospheric	 value	or	 to	

polar	ice,	which	would	reveal	relative	ages	of	these	reservoirs	and	their	exchange	history.	
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Measurement	of	ice	age

Ice	cores	on	Earth	are	dated	with	a	variety	of	methods.	Relatively	young	ice,	<60,000	years,	

has	been	dated	by	counting	annual	layers	 of	ice	deposition	 (Svensson	et	al.,	2008),	while	

older	ice		with	continuous	stratigraphy	has	been	dated	by	 tuning	different	records	 to	 the	

known	 variations	 in	 Earth’s	 orbit	 (Parrenin	 et	 al.,	 2007).	 Increasingly,	 ages	 are	 being	

determined	by	radiometric	methods:	cosmogenic	81Kr	in	 the	 trapped	gas	has	a	half	life	of	

230,000	 years	 (Buizert	 et	 al.,	 2014);	 and	 the	 234U/238U	 ratio	 is	 useful	 on	 timescales	 of	

hundreds	of	 thousands	of	years	 (Aciego	et	al.,	2011).	The	amount	of	 40Ar,	relative	 to	 36Ar	

and	38Ar,	has	been	used	on	timescales	of	millions	of	years,	as	40Ar	has	accumulated	in	the	

atmosphere	as	40K	has	decayed	and	outgassed	(Yan	et	al.,	2020).		

The	techniques	needed	to	date	ice	cores	from	Mars	are	not	yet	known	in	part	because	there	

is	a	large	range	in	the	possible	age	of	the	ice,	ranging	from	hundreds	of	thousands	of	years	

if	deposited	during	a	recent	obliquity	cycle	to	hundreds	of	millions	of	years	if	the	ice	is	from	

an	earlier	climate	period.	The	techniques	used	on	Earth	will	be	useful	if	the	ice	is	relatively	

young,	or	to	place	a	minimum	age	constraint.	Thus,	additional	dating	techniques	relating	to	

losses	to	space	will	need	to	be	developed	if	the	ice	proves	to	be	older.	Relative	dating	of	the	

ice	may	be	possible	based	on	how	D/H	from	mid-latitude	ice	is	similar	to	or	differs	from	the	

current	 atmosphere	 and	 from	 the	 polar	 ice	 reservoirs.	 If	 volcanic	 ash	 exists	 in	 the	 ice,	

radiogenic	dating	of	the	ash	could	provide	valuable	age	constraints.

Permafrost	and	regolith/debris/dust	samples	

Dry	soil	may	overlie	all	forms	of	ground	ice,	and	pore-filling	ice	may	overlie	massive	buried	

ice	deposits.	Surface	and	subsurface	samples	should	be	collected	for	geological	context	and	

to	 address	 high-priority	 science	 (see	 Table	 III-4).	 If	 permafrost	 is	 present,	 a	 core	 or	 an	

intact	stratigraphic	sequence	should	be	collected.	Subsurface	samples	provide	information	

at	 depths poorly	 resolved	 by	 satellite	 remote	 sensing,	 and	 provide	 in-situ	 validation	 for	

remote	 data	 sets.	 Similar	 to	 measurements	 made	 on	 samples	 from	 Earth,	 measurements	

from	samples	on	Mars	could	include:	organic	matter,	mineral	grain	size	and	composition,	

organic	 carbon,	 nitrogen,	 sulfur,	 and	 isotopes,	 as	 well	 as	 pollen,	 macrofossils,	 and	 stable	

isotopes	of	water.

3. Drill	site	selection	and	context	to	interpret	ice	core	records

Prior	to	choosing	the	specific	drill	site	on	Mars:	

1) Satellite	 remote	 sensing	 of	 subsurface	 structure	 from	 0	 to	 20	 meters	 below	 the	

surface	 will	 be	 critical	 in	 order	 to	 map	 the	 depth	 to	 ice,	 ice-deposit	 thickness,	

horizontal	 distribution	 of	 ice,	 and	 observable	 vertical	 or	 horizontal	 structures	

within	 target	ice-rich	 deposits,	and	 ultimately,	 select	 the	 final	 rough	 (~1	 km	 x	 ~1	

km)	drill	site.					
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2) Once	the	ground	crew	has	reached	the	target	region,	on-site	ground	surveys	would	

be	 conducted	 to	 pick	 the	 specific	 core	 site(s)	 within	 the	 satellite-selected	 region.

Ground	 surveys	 should	 consider	 safety,	 topography,	 overburden	 (debris)	 cover,	

lateral	 extent	 of	 a	 relatively	 smooth	 working	 surface,	 and	 subsurface	 or	 surfaceexposed	stratigraphic	features	being	targeted	from	the	satellite	platform.	Given	the	

slow	deformation	rates,	the	application	of	techniques	to	measure	deformation	fields	

such	as	those	commonly	used	on	Earth	are	not	warranted	or	recommended	in	this	

case.	 However,	 assessment	 of	 stratigraphic	 horizons	 within	 satellite	 and	 groundbased	 geophysical	 observations	 should	 be	 relied	 upon	 to	 select	 a	 core	 site	 where	

surface	conformable	stratigraphy	exists.								

3) Short	cores	or	samples	should	be	collected	from	the	overburden	layer	to	the	top	of	

the	ice	layer,	which	may	include	sampling	permafrost,	regolith,	debris,	and/or	dust.	

Satellite	remote	sensing	on	Earth

In	 comparison	 to	 radar	 remote	 sensing	 on	 Earth,	 the	 most	 closely	 applicable	 airborne	

platforms	 relative	 to	 a	 proposed	 NASA	 Mars	 Ice	 Mapper	 may	 be	 the	 Center	 for	 Remote	

Sensing	of	 Ice	Sheets	 (CReSIS)	VHF	150	 to	600	MHz	Ultra-Wideband	(UWB)	Radar	which	

has	a	50	cm	vertical	resolution	depth	range	and	reaches	1 km	in	Polar	ice,	operating	at	peak	

transmit	 power	 (400	 W).	 	 CReSIS	 also	 operates	 a	 Snow	 radar	 operating	 at	 2	 to	 18	 GHz	

which	 provides	 2	 to	 4	 cm	 resolution	 in	 snow	 and	 40	 m	 depth	 penetration	 at	 1	 W	 peak	

transmit	 power.	 However,	 much	 shallower	 penetration	 depths	 associated	 with	 higher	

scattering	and	attenuation	rates	will	likely	occur	over	debris-covered	ice	and	within	debrisrich	 ice.	 In	 support	 of	 Mars	 Ice	 Mapper	 system	 design	 we	 recommend	 a	 comprehensive	

modeling	 effort	 tied	 to	 surface	 roughness	 and	 geological	 composition	 at	 high	 spatial	

resolution	using	existing	data	to	determine	conservative	penetration	depths	in	the	types	of	

environments	where	subsurface	ice	is	likely	present	within	a	few	to	ten	meters	below	the	

surface.	 	 Terrestrial	 analog	 studies	 with comparable	 systems	 over	 buried	 ice	 would	 be	

highly	beneficial	for	this.		

Local	ground	penetrating	radar	survey

Standard	 ground	 survey	 ground	 penetrating	 radar	 (GPR)	 systems	 operate	 between	 2	 to	

900	MHz	 for	deep	 to	 shallow	applications	 respectively,	and	generally	have	a	much	lower	

power	source	 than	airborne	systems.		Most	commercial	impulse	radar	units	in	 the	100	 to

900	MHz	range	are	used	for	on	ground	surveys	to	reach	80	m	to	15	m,	respectively,	in	polar	

snow,	 firn,	 and	 ice	 studies.	 	 Critical	 consideration	 should	 be	 given	 to	 high	 stacking	 and	

sampling	rates	per	trace	to	improve	signal-to-noise	ratios.	Stacking	depends	on	the	system	

and	survey	goals	but	can	range	 from	one	 to	over	2000	pulses	stacked	per	resulting	 trace.	

For	Mars,	ground	acquisitions	may	have	poor	ground	coupling	due	to	debris	cover	resulting	

in	 surface	 scattering	 and	 high	 attenuation	 rates.	 	 Ideally	 a site	 will	 be	 selected	 that	 has	

small	(pebble	or	smaller)	surface	debris	where	a	GPR	could	be	towed	manually	or	by	rover.	

It	 may	 be	 possible	 to	 mount	 the	 GPR	 to	 a	 rover	 above	 the	 ground	 surface	 for	 smoother	

acquisitions.	 Drone-based	 GPR	is	in	 the	 experimental	 stage	 but	 shows	 some	 promise	 for	

shallow	mapping.		The	local	survey	should	be	tens	of	meters	to	multiple	kilometers	in	scale,	

depending	 on	 what	 is	 known	 about	 the	 target	 region	 from	 satellite	 data.	 Survey	 wheels	
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which	 trigger	impulses	 and	 a	 high-precision	 GPS	 are	 generally	linked	 to	 GPR	 surveys	 on	

Earth	 to	 distance	 normalize	 data	 for	 post-collection	 processing	 and	 place	 data	 within	

geospatial	 context.	 	 Given	 the	 critical	 nature	 of	 georeferencing	 and	 distance-normalizing	

geophysical	 data	 for	 post	 processing,	 these	 or	 other	 techniques	 should	 be	 considered.	 	 If	

possible,	grid	GPR	data	should	be	collected	around	the	drill	site(s)	because	this	will	provide	

a	 three-dimensional	 understanding	 of	 subsurface	 structure.	 	 For	 example,	 in	 twodimensions,	stratigraphic	features	can	only	be	assessed	for	apparent	dip,	whereas	a	threedimensional	 grid	 provides	 the	 opportunity	 to	 quantify	 true	 dip	 of	 subsurface	 horizons.		

Lastly,	 observations	 made	 from	 Mars	 Ice	 Mapper	 should	 be	 repeated	 by	 ground-based	

surveys	along	a	given	segment	near	the	selected	core	site(s).	This	repeat	survey	would:	1)	

tie	local	scale	ground	observations	to	more	regional	observations,	2)		provide	comparisons	

of	attenuation,	off-nadir	responses	 from	 terrain,	or	other	geophysical	observations	which	

may	be	challenging	to	interpret	solely	from	only	one	survey	method,	and	3)	ground-based	

surveys	 can	 provide	 both	 higher	 vertical	 resolution	 and	 better	 penetration	 depth	 to	

elucidate	subsurface	structure,	thereby	helping	to	understand	satellite	observations	across	

broader	regions.						

			

Permafrost	Surveys

It	is	likely	that	any	selected	drill	sites	are	located	at	or	near	buried	ice-rich	soils	or	massive	

ice	deposits	which	are	 traditionally	classified	as	permafrost	on	Earth.	 In	 this	instance,	insitu	 GPR	 surveying	 strategies	 should	 remain	 the	 same	 as	 above.	 However,	 there	 may	 be	

additional	 challenges	 to	 surveying	ice-rich	 debris	 versus	 cleaner	ice.	Namely,	attenuation	

rates	will	likely	be	higher	within	debris-rich	ice	versus	cleaner	ice	and	greater	thickness	of	

debris	 cover	 will	 also	 minimize	 penetration	 into	 subsurface	 ice.	 Given	 this	 limitation,	 a	

lower	 frequency	 (200	 MHz)	 system	 would	 likely	 be	 warranted	 over	 permafrost	 terrain.		

Additionally,	permafrost	 subsurface	 stratigraphic	 units	are	 often	 far	less	 continuous	 than	

units	visible	within	glacier	ice,	therefore,	local	surveys	to	place	features	into	lateral	context	

will	likely	be	on	 the	order	of	 tens	 to	hundreds	of	meters	instead	of	 the	km	scale.	Shallow	

core	sampling	into	the	subsurface	to	confirm	GPR	observations,	if	possible,	are	a	traditional	

method	 used	 on	 Earth	 which	 should	 be	 considered	 on	 Mars,	 particularly	 if	 coring	 was	

completed	solely	with	an	auger	device	to	assure	rapid	access.		Core	site	selection	ideally	is	

located,	 as	 with	 glaciological	 coring,	 in	 sites	 where	 subsurface	 structure	 is	 surface	

conformable,	or	relatively	consistent	laterally,	in	space,	relative	to	the	specific	drill	site.	Any	

core	 samples	 that	 are	 acquired	 to	 ground-truth	 GPR	 profiles	 should	 be	 assessed	 as	

discussed	 elsewhere	 in	 this	 report.	 However,	 at	 a	 minimum,	 auger	 depth	 to	 each visible	

stratigraphic	 horizon	 should	 be	 recorded	along	with	 other	 classical	 sedimentary	analysis	

(e.g.	lithology,	grain	size,	shape,	color,	etc.).						

4. Initial	measurements	and	on-site	handling	of	the	ice	core

Given	 stringent	 clean	 handling	 protocols,	 as	 well	 as	 the	 assumption	 that	 drilled	 cores	

should	 be	 kept	 at	 similar	 temperature	 and	 pressure	 conditions,	we	 expect	 that	Mars’	ice	

cores	will	be	sealed	 from	within	the	drill	before	it	is	brought	to	the	surface.	On	Earth,	the	
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42

minimum	on-site	measurements	include	basic	core	logging	of	the	length,	diameter,	weight,	

and	 condition	 of	 the	 core.	 Photographs	 to	 assess	 any	 loss	 of	 stratigraphic	 order	 during	

transport	can	also	be	useful.	The	on-site	handling	can	also	be	kept	to	a	minimum	to	avoid	

contamination,	particularly	if	the	ice	is	fractured.	Keeping	the	ice	at	a	constant	temperature	

during	handling	is	also	important	to	avoid	thermal	shock	introducing	fractures.	

5. Criteria	for	preserving	ice	cores	for	transport	and	storage

Once	drilling	is	complete, care	must	be	taken	for	the	preservation	and	clean	handling	of	ice	

cores	at	every	step	along	the	way,	including:	

1) Extraction	to	the	Martian	surface

2) On-site	preparation	for	storage	and	transit

3) Storage	during	the	remainder	of	the	mission	on	the	Martian	surface

4) Launch	and	return	trip	to	Earth

5) Landing	and	initial	storage	on	Earth	and	ultimately	archival	storage

Critical	 factors	 for	 core	 handling	 and	 storage	 include	 temperature,	 pressure,	 radiation,	

vibration	and	contamination	protocols.

Minimum	criteria	to	preserve	biological	and	climate	records

During	transport	and	storage	cores	must	remain	below	-20°C,	and	ideally	below	-36°C,		to	

minimize	 gas	 diffusion,	 chemical	 and	 biological	 reactions,	 and	 to	 provide	 a	 temperature	

buffer	 for	 storage	 transitions	 when	 the	 ice	 may	 be	 exposed	 to	 warmer	 temperatures.	

Minimizing	fluctuations	in	temperature	during	transport	and	storage	is	required	to	reduce	

fractures	forming	in	core	pieces.	Sample	material,	particularly	cores,	should	be	maintained	

at	 pressures	 equivalent	 to	 extraction	 at	 the	 Martian	 surface.	 This	 includes	 transport	 to	

Earth,	initial	and	archival	storage.

All	ice	samples	(cores,	chips,	shavings)	should	be	collected	and	handled	using	established	

clean	 protocols	 for	 collecting	 samples	 from	 sensitive	 regions	 of	 Mars	 (e.g.,	 Chyba	 et	 al.,	

2005).	Decontamination	protocols	for	the	cores	should	follow	established	protocols	for	ice	

cores	 on	 Earth	 (Section	 II.5),	 but	 are	 unlikely	 feasible	 on	 the	 Martian	 surface	 and	 thus	

should	be	integrated	into	post-mission	research.	Decontamination	of	chips	and	shavings	is	

difficult	 and	 there	 is	 currently	 no	 established	 protocol.	 However,	 results	 from	 chips	 and	

shavings	can	be	compared	to	cleaned	cores	for	corroboration.	

Considerations	for	handling	and	transportation	of	Mars	ice	cores

In	addition	to	the	considerations	for	handling	ice	cores	on	Earth,	discussed	in	Section	II.5,	

further	 issues	 will	 arise	 with	 the	 handling	 of	 Mars	 ice	 cores.	 During	 extraction	 and	

processing	on	site,	 the	exposure	 to	Martian	atmospheric	conditions	should	be	minimized.	

Ice	on	Mars	has	a	sublimation	rate	on	 the	order	of	1	mm/h	(Chittenden	et	al.,	2008),	and	
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therefore	must	be	sealed	and	placed	in	a	controlled	storage	container	soon	after	extraction.	

Rapid	shifts	in	temperature	and	pressure	can	crack	the	ice,	and	contamination	protocols	in	

place	for	Mars	2020	should	be	followed.

In	 addition,	 many	 of	 the	 handling	 procedures	 developed	 on	 Earth	 are	 manual	 processes	

that	will	be	more	difficult	on	Mars	for	astronauts	in	space	suits.	If	possible,	robotic	storage	

of	cores	in	hermetically	sealed	tubes	immediately	upon	extraction	from	the	drill	would	be	

ideal. During	 the	 return	 trip,	 the	 ice	 cores	 will	 be	 exposed	 to	 higher	 accelerations,	

vibrations,	and	radiation	levels	 than	a	 typical	 terrestrial	ice	core	 transported	 from a	 field	

site	to	storage	or	laboratory	facility.	Appropriate	storage	and	protection	units	will	need	to	

be	designed	and	 tested	 to	ensure	 that	 they	maintain	 the	integrity	 of	 the	ice	samples	 (see	

also	Section	V.3).

Short-term	and	archival	storage	considerations	on	Earth

All	ice	samples	(cores,	pieces,	and	chips)	should	be	returned	to	Earth	following	at	least	the	

basic	 protocols	 developed	 for	 returned	 Mars	 2020	 sediment	 core	 samples.	 This	 includes	

the	 storage	 of	 contamination	 references.	 The	 NASA	 Johnson	 Space Center	 (JSC),	

Astromaterials	 Acquisition	 and	 Curation	 Office	 in	 Houston,	 TX	 manages	 the	 curation	 of	

extraterrestrial	 samples	 returned	 by	 NASA	 missions	 (and	 international	 partners)	 and	

protects	the	integrity	of	these	samples	for	future	scientific	study	(e.g.,	Allen	et	al.,	2011).	As	

part	 of	 sample	 return	 missions,	 the	 Curation	 Office	 also	 curates	 flight	 and	 non-flight	

reference	 materials	 and	 space	 exposed	 hardware	 (any	 materials)	 that	 would	 have	 the	

potential	to	contaminate	a	present	or	future	NASA	astromaterials	collection.

Samples	 from	 an	 ice-coring	 mission	 would	 include	 ice	 core	 samples,	 as	 well	 as	 surface	

samples	(permafrost,	regolith,	dust,	debris).	Advances	in	the	process	and	capacity	for	cold	

curation	of	astromaterials,	including	ice	cores	that	require	cold	temperature	and	biological	

containment,	is	in	progress,	and	the	importance	of	contamination	knowledge	is	recognized	

in	 order	 to	 maximize	 the	 science	 return	 from	 missions	 where	 samples	 are	 collected	

(McCubbin	et	al.,	2019).	

Figure	III-11. Left:	From	Allen	et	al.	(2011).	Apollo	astronaut	collecting	a	soil	sample	(SESC;	NASA	photo	AS12-

49-7278).	 Right:	 From	 McCubbin	 et	 al.	 (2019),	 indicating	 the	 joint	 challenges	 related	 to	 cold	 curation	 and	

biological	 containment	faced	 by	 astromaterials	 storage	 when	 collecting	 ice	 cores,	 as	 well	 as	 how	 capabilities	

need	to	connect.	
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IV.	Ice	core	drill	engineering	on	Earth	and	drilling	concepts	for	Mars									

Drilling	 an	 ice	 core	 tens	 of	 meters	 deep	 in	 a	 glacier	 or	 ice	 sheet	 on	 Earth	 is	 easily	

accomplished	 using	 either	 a	 hand	 auger	 or	 a	 light	 weight	 cable	 suspended	

electromechanical	drill.	Ice	coring	programs	in	many	nations	have	various	versions	of	these	

drills;	in	the	U.S.	Ice	Drilling	Program,	the	Badger-Eclipse	drill	is	a	workhorse	successfully	

used	 both	 in	 the	 Arctic	 and	 Antarctic.	 It	 is	 an	 easily	 transportable	 cable	 suspended	

electromechanical	drill	that	retrieves	81	mm	(3.2”)	diameter	ice	cores	to	depths	up	to	300	

m.	 	 Drills	 of	 this	 type,	 which	 core	 the	 ice	 and	 do	 not	 involve	 percussive	 impact,	 reliably

produce	high-quality,	uniform	cores	in	clean	ice,	or	ice	with	a	minimal	amount	of	enclosed	

dust.	

Figure	IV-1. Left:	IDP	driller	Lou	Albershardt	operates	the	Badger-Eclipse	Drill	at	Thwaites	Glacier,	Antarctica,	

during	 the	 2010-2011	 summer	 field	 season.	(Photo:	 Howard	 Conway).	 Right:	 Eclipse	 drill	 deployed	 at	 Taylor	

Glacier,	Antarctica	in	2004-2005	season.	(Photo:	Michelle	Koutnik).

However,	 cable-suspended	 drills	are	 not	 capable	 of	 drilling	 through	 rock,	 thick	 hardened	

soil,	or	composite	mixtures	of	ice	and	rock.		At	sites	that	may	contain	various	bands	of	rock,	

debris,	 rock/ice	 mixtures,	 or	 where	 massive	 ice	 exists	 but	 it	 may	 include	 thick	 bands	 of	

stones,	 hardened	 soil,	 or	 rock/ice	mixtures	 the	 drill	 string	 should	 be	made	 of	 pipes.	 The	

pipes	 are	 capable	 of	 delivering	 sufficient	 torque	 and	 weight	 on	 bit	 to	 drill	 through	 solid	

rock	and	rock/ice	composites;	on	Earth	all	drills	of	this	type	require	use	of	a	drilling	fluid.		

The	U.S.	 Ice	Drilling	 Program	 (IDP)	 has	 adapted	 several	 commercial	 rock	 coring	 drills	 to	

drill	rock/ice	composites,	as	described	in	Albert	and	others	(2021).	Designed	for	recovery	

of	meters	of	rock	beneath	hundreds	of	meters	of	ice,	or	recovery	of	mixed	rock/ice	cores,	

the	Agile	Sub-Ice	Geological	Drill	(ASIG)	(Kuhl	and	others,	2020)	has	been	successfully	used	

in	Antarctica,	as	shown	in	Fig	IV-2.	The	core	retrieved	from	the	ASIG	drill	has	a	diameter	of	

33.4	mm.	Specification	and	additional	photos	can	be	seen	at:

https://icedrill.org/equipment/agile-sub-ice-geological-drill
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45

Figure	 IV-2. IDP	 drillers	 Clayton	 Armstrong	 (at	 left)	 and	 Mike	

Jayred	(at	right)	operating	the	ASIG	Drill	at	Pirrit	Hills,	Antarctica,	

during	the 2016-2017	summer	field	season	(Photo:	Tanner	Kuhl).

A	lighter	weight	drill	that	is	useful	for	retrieving	meters	of	rock core	from	beneath	meters	

of	ice,	including	retrieval	of	mixed	rock/ice	composite	cores	is	the	IDP	ice-enabled	Winkie	

Drill	 (Boeckmann	and	 others,	 2020)	 shown	in	 Figure	 IV-3.	The	 diameter	 of	 the	 retrieved	

rock,	ice,	or	rock/ice	composite	core	is	39	mm.	This	drill	has	retrieved	high	quality	rock/ice	

composite	 cores	 from	 Ong	 Valley,	 Antarctica;	 a	 composite	 core	 is	 shown	 in	 Figure	 IV-4.	

Further	 description	 and	 photos	 are	 available	 at https://icedrill.org/equipment/winkiedrill.

Figure	 IV-3. The	 Winkie	 Drill	 in	 Ong	

Valley,	 Antarctica,	 during	 the	 2017-2018

Antarctic	 field	 season (Photo:	 Dan	

Morgan).
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46

Fig	IV-4. Composite	ice/rock	core	drilled	with	the	ice-enabled	Winkie	drill	in	Ong	Valley.

WATSON	(Wireline	Analysis	Tool	 for	Subsurface	Observation	of	Northern-ice	

sheets)

Figure	IV-5. A)	WATSON	and	drill	being	deployed	at	Summit,	Greenland.	B)	WATSON	entering	the	borehole.	C)

Schematic	 showing	WATSON	mounted	 to	 the	 drill.	The	inset	 shows	 a	 small	 nano	 drill	 that	 can	 be	 deployed	 to	

take	targeted	samples	of	the	borehole	sidewall.	D)	Expanded	view	of	the	deep	UV	system.
Mars Ice Core Working Group – First Ice Cores from Mars

47

WATSON	 is	 an	 autonomous	 ice	 drill	 coupled	 to	 a	 targeted	 deep-UV	 fluorescence/Raman	

mapping	 spectrometer.	 The	 drill	 has	 been	 used	 to	 successfully	 core	 and	 identify	 organic	

matter	 within	 the	 borehole	 sidewalls	 (Eschelman	 et	 al.	 2019,	 Malaska	 et	 al.	 2020).	 The	

WATSON	wireline	deep	drill	is	 the	most	advanced	planetary	drilling	system	developed	 to	

date.	 The	 WATSON	 drill	 is	 based	 on	 traditional	 wireline	 architectures	 used	 yearly	 in	

Antarctica	 for	recovering	ice	cores.	However,	as	opposed	 to	 the	Antarctic	drills	which	are	

human-operated,	 the	WATSON	drilling	system	is	 fully robotic,	except	 for	a	winch	system.	

The	 drill	 system	 consists	 of	 three	 major	 parts:	 a	 surface	 subsystem	 which	 includes	 a	

deployment	 tower	with	a	drum	 for	a	 tether,	 the	 tether,	and	a	probe	also	 referred	 to	as	a	

drill	 that	 is	 attached	 to	 one	 end	 of	 the	 tether	 (Figure	 IV-5).	 Plans	 are	 underway	 to	

incorporate	a	Nano	Drill	for	targeted	sidewall	drilling.

Concepts	for	drilling	ice	cores	on	Mars

Masses	of	ice	 that	are	meters	or	greater	in	 thickness	are	 thought	 to	exist	beneath	surface	

debris	in	some	areas,	and	within	the	ground	in	lesser	thicknesses	within	permafrost	areas.	

Based	on	observations	of	other	ice	on	Mars	and	theoretical	studies	of	ice	accumulation	and	

sublimation,	it	is	likely	 that	even	within	 the	meters-thick	ice	buried	under	surface	debris,	

the	ice	may	embed	thick	layers	of	dust	or	debris	that	had	been	deposited	earlier.	

The	requirement	 for	 the	drilling	system	includes	 the	ability	 to penetrate	several	different	

types	of	layers:	loose	regolith,	rocks,	ice	cemented	ground,	and	ice	with	various	fractions	of	

particles	and	rocks.	Nominally,	 there	are	 three	drilling	options:	 the	cable-suspended	drill,	

wireline	drill,	 and	 coiled	tubing	drill as	 shown	in	 Table	 IV-1.	 All	 these	 options	 are	 being	

used	 on	 Earth	 every	 day,	 and	in	 turn	 there	is	 a	 significant	 body	 of	 published	 knowledge	

related	to	their	limitations	and	benefits	(Bar-Cohen	and	Zacny,	2009;	Bar-Cohen	and	Zacny,	

2020).	

Cable-suspended	drills are	used	traditionally	in	terrestrial	ice	coring	tasks.	The	drill	with	

all	the	required	motors	and	sensors	is	housed	inside	a	tube,	which	is	suspended	by	a	cable.	

To	drill,	the	system	is	lowered	into	the	borehole	to	drill	a	section	of	the	hole	(nominally	a	

few	meter	core),	upon	which	the	drill	is	retracted	using	the	cable	to	the	surface.	The	core	is	

removed	 and	 the	 drill	 is	 lowered	 back	 into	 the	 same	 hole.	 This	 approach	 is	 ideal	 if	 the	

borehole	is	 stable,	which	is	 true	in	Antarctic	and	Greenland	ice, for	example.	However,	if	

the	borehole	is	unstable	(e.g.	it	has	loose	regolith,	rocks	etc.)	 there	is	a	significant	chance	

the	drill	would	get	stuck	by	debris	falling	on	top	of	it.	A	potential	solution	is	using	a	casing	

with	bi-center	bit,	to	cut	a	larger	diameter	hole	that	would	accommodate	the	casing	and	the	

drill.				

The	 wireline	 drill uses	 a	 traditional jointed pipe	 (as	 used	 in	 the	 oil	 and	 gas	 industry)	

approach	 to	drilling.	 It	has	pipes	 that	are	screwed	 together	 to	advance	 the	drill	down.	To	

capture	a	core	sample,	the	hollow	pipe	has	a	coring	section	that	can	be	lowered	down	and	

pulled	 out	 using	 a	 wire.	 As	 such,	 the	 pipes	 stay	 inside	 a	 hole	 (and	 prevent	 borehole	

collapse),	while	a	separate	wire	with	a	coring	section	is	used	to	remove	the	cores.	
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48

Table	IV-1. Three	types	of	drilling	approaches	that	can	be	considered	for	core	capture.		

Cable Suspended Wireline Coiled Tubing

Complexity Low High Medium

Mass Low High Medium

Drilling fluid No Yes (Gas) Yes (Gas)

Terrestrial use Ice coring Oil and gas Oil and gas

Formations it 

can penetrate

Ice Any Any

Borehole 

stability

Needs casing which 

would drive complexity

Not a problem Not a problem

Downhole 

instruments?

Yes No Yes

Example of 

planetary 

system

WATSON: 111 m in 

Greenland 

AutoGopher2: 7 m in 

gypsum

Planetary Deep Drill: 14 

m in gypsum

MARTE: 8 m in rock quarry

SCAD: 10 m in rock quarry

RedWater: 1 m in ice 

- limited by height of 

freezer. Designed for 

25 m.

TRL 5 4 4

Reference Mellerowicz et al., 

(2018); Badescu at el., 

(2018); Zacny et al., 

(2013; 2016)

Bar-Cohen and Zacny (2009)

Paulsen et al. (2006)

Bar-Cohen and 

Zacny (2020)

Zacny et al. (2018)
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49

Coiled	 Tubing	 drilling is	 nominally	 used	 to	 drill	 a	 hole,	 and	 not	 a	 core,	 but	 could	 be	

adapted	 to	 drill	 a	 core.	 Unlike	 in	 the	 Jointed	 Pipe	 approach	 where	 each	 pipe	 is	 straight,	

Coiled	Tubing	has	a	continuous	‘pipe’	that’s	wrapped	around	a	drum	(this	is	similar	to	how	

a	tape	measure	works,	except	that	it	is	a	tube	and	not	a	strip).	To	advance	the	drill	forward,	

a	set	of	rollers	is	used	to	pull	the	tube	down	while	making	it	straight.	The	drilling	system,	

motors	and	the	drill	bit,	are	mounted	at	the	end	of	the	‘pipe’.	To	capture	the	core,	a	coring	

bit	is	lowered	into	the	borehole	and	once	the	core	is	captured,	the	drum	is	spun	in	reverse	

to	 coil	 the	 tubing	 back.	 Coiled	 Tubing	 prevents	 borehole	 collapse	 because	 the	 tubing	 is	

always	in	the	hole	while	the	drill	operation	occurs.		

Over the	past	two	decades,	several	planetary	prototypes	have	been	developed	and	tested	in	

the	laboratory	and/or	in	the	field.	In	particular,	Cable	Suspended	drills	such	as	AutoGopher	

(Badescu	 et	 al.,	 2018)	 and	 Planetary	 Deep	 Drill	 (Zacny	 et	 al.,	 2016)	 have	 been	 tested	 in	

gypsum	quarry	to	7	m	and	14	m	depth,	respectively.	WATSON,	with	an	integrated	deep-UV	

/	Raman	spectrometer	was	tested	to	111	m	depth	in	Greenland’s	Summit	(Mellerowicz	et	

al.,	 2018,	 Malaska	 et	 al.	 2020).	 Figure	 IV-6	 shows	 WATSON	 drill	 tests	 in	 Greenland	 and	

possible	 implementation	 on	 a	 Mars	 Curiosity-size	 rover.	WATSON	 incorporates	 borehole	

instrumentation	 enabling	 in-situ	 detection	 of	 biological	 material	 and	 associated	 organics	

distributed	in	the	ice.	Such	measurements	will	provide	an	immediate understanding	of	the	

geochemical	 and	 physical	 features	 that	 drive	 the	 distribution	 of	 organic	 matter.	 In	 situ	

borehole	measurements	provide	spatial	information	that	can	be	used	to	target	sampling	in	

returned	 ice	 cores	 minimizing	 contamination	 and	 loss	 of	 native	 material	 from	 effects	 of	

dilution	 from	 bulk	 analysis.	 In	 situ	 borehole	measurements	 will	 also	 provide	 a	means	 to	

handle/process	 smaller	 cores;	 enabling	 spectral	 and	 single-cell	 resolution	 chemical	

imaging	analyses	previously	unavailable.

Figure IV-6. Left:	 Wireline	 drill,	 WATSON,	 being	 tested	 in	 Greenland.	 Right:	 WATSON	 implementation	 on	

Curiosity	size	rover.
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50

A	wireline	system	called	SCAD,	was	laboratory	tested	to	over	2	m	depth	in	rock	(Bar-Cohen	

and	Zacny,	2009).	The	MARTE	coring	drill	was	tested	to	8	m	in	limestone	quarry	(Paulsen	

et	al.,	2006).	Figure	IV-7	shows	MARTE	and	SCAD	systems.

Figure	IV-7. Left:	MARTE	coring	drill	with	sample	analysis	system.	Right:	SCAD	coring	system.

			 					

Figure	IV-8. Left:	Coiled	Tubing	drill,	RedWater, being	tested	in	a	freezer.	Right:	RedWater	implementation	on	

NASA	All-Terrain	Hex-Limbed	Extra-Terrestrial	Explorer	(ATHLETE)	rover.
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A	Coiled	Tubing	drill	such	as	RedWater	 (Zacny	et	al.,	2018)	is	currently	being	 tested	in	a	

freezer	- it	has	successfully	drilled	in	ice	to	1	m	depth;	the	depth	being	limited	by	the	height	

of	 the	 freezer.	RedWater	is	 being	 developed	 for	water	extraction	 on	Mars,	with	a	goal	 to	

drill	through	20	m	of	overburden	 followed	by	5	m	in	ice.	Once	in	ice,	the	drill	would	melt	

and	 pump	 water	 to	 the	 surface.	 Figure	 IV-8 shows	 RedWater	 tests	 in	 a	 freezer	 and	

implementation	 on	 the	 NASA	 All-Terrain	 Hex-Limbed	 Extra-Terrestrial	 Explorer	

(ATHLETE) rover.
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V.	Requirements	from	science	for	engineering	an	ice	coring	drill	for	

Mars

1.	Tradeoffs	between	optimal	cores/science	and	drilling	&	logistical	

constraints

There	are	important	 tradeoffs	between	 the	scientific	needs	of	amount	and	quality	of	core	

and	 the	 logistical	 feasibility	 of	 drilling	 and	 retrieving	 the	 core	 on	 Mars.	 The	 very	 high	

quality	 cores	 (free	 from	gouges	 or	 cracks)	 resulting	 from	 deep	ice	 core	 drilling	 on	Earth,	

such	as	in	 the	South	Pole	ice	core,	have	core	diameters	of	98	mm.	These	cores	have	good	

core	strength	(outside	of	the	brittle	zone)	and	can	survive	drilling	and handling,	and	they	

also	yield	enough	ice	to	support	a	robust	set	of	scientific	measurements.	A	mission	to	Mars	

would	not	have	logistics	capability	to	return	multiple	meters	of	98	mm	core.	Thus	smallerdiameter	cores	will	be	considered	in	this	section.		

2.	Characteristics	of	Martian	ice	cores	and	their	potential	to	yield	scientific	

results

A	76	mm	diameter core	can	be	drilled	with	excellent	core	quality,	and	the	core	diameter	is	

sufficiently	strong	to	maintain	its	integrity	through	the	drilling/packing/shipping	process.	

A	76	mm core	also	can	support	a	meaningful	set	of	scientific	measurements,	 for	example	

cryobiology,	stratigraphy,	density,	chemistry,	and	isotopes.

Ice	core	with	50	mm diameter	would	be	valuable	for	investigating	cryobiology,	along	with	

water	isotopes	and	chemistry,	even	if	 the	core	was	not	entirely	intact	but	had	 significant	

contiguous	pieces.	Full	cores	would	not	likely	result	 from	the	drilling	process,	rather	core	

pieces	 of	 varying	 lengths	 between	 approximately 6	 to 15	 mm would	 result	 that	 may	

challenge	stratigraphic	analysis	and	lead	to	lower	resolution	in	most	measurements.

If	 the	 drilling	 does	 not	 provide	 core,	 but	 instead	 results	 in	 only	 chips	 with	 a	 maximum	

diameter	approximately	6	mm,	cryobiology	measurements	would	be	possible	only	at	low	

resolution	 and	 decontamination	 procedures	 would	 be	 very	 challenging,	 but	 very	 lowresolution	measurements	of	water	isotopes	and	chemistry	would	be	possible.	A	drill	 that	

produces	chips	could	be	augmented	with	a	sidewall	corer	 to	capture	smaller	cores	(e.g.	2	

cm	in	diameter	and	5	cm	long)	at	target	locations.	These	locations	could	be	selected	using	

co-located	 instruments,	 such	 as	 Raman	 /	 deep	 UV.	 See	 Table	 V-2	 for	 a	 summary	 of	 how	

measurements	relate	to	core/sample	characteristics.

If	 the	 drill	 produces	 water	 that	 is	 refrozen	 for	 the	 return	 trip	 to	 earth,	 some	 aspects	 of	

cryobiology	may	be	observable,	but	evidence	of	the	habitability	near	the	biological	samples	

would	be	lost.
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Engineering	challenges	associated	with	core	diameter	for	drilling	on	Mars

In	consideration	of	engineering	aspects	of	a	drill	for	use	on	Mars,	Table	V-1	below	indicates	

the	level	of	engineering	and	logistics	difficulty	for	3”	core	(similar	to	the	Badger-Eclipse	ice	

coring	drill),	2”	core	(similar	to	the	core	from	a	rock	core	drill),	or	only	chips	(chips	have	a	

max	diameter	of	approximately	6	mm).	

Table	V-1.	Challenges	for	drill	engineering	as	a	function	of	core	diameter.

Metric Core retrieval: 

Good quality

Core retrieval: 

Poor quality

Chips retrieval

Core diameter Needs to be >100 mm Needs to be > 50 mm N/A

Borehole diameter >100 mm >76 mm ~50 mm

Drill mass / volume / 

power

Very high High Low

Drill complexity Very high

- Need different bits for 

regolith / rock and ice

- Need complex bottom 

hole assembly or different 

rigs for drilling through 

regolith / rock and then 

ice

High

- May use same bits for 

regolith / rock and ice

but core quality will be 

compromised

- Need complex bottom 

hole assembly or 

different rigs for drilling 

through regolith/rock 

and then ice

Low

Sample handling - Need individual core 

tubes

- Cores remain in 

sampling tubes –

manipulate tubes

- Need individual core 

tubes

- Cores remain in 

sampling tubes –

manipulate tubes

Chips packaged and 

sealed in individual 

containers (e.g., 

every 20cm)

					Planetary 

Protection/Containme

nt Control

Very complex Very complex Easier

A	drill	that	produces	only	chips	has	the	least	complexity	and	easier	sample	handling	than	a	

drill	that	produces	core,	however	retrieving	only	chips	severely	limits	the	scientific	value	of	

the	material.	A	drill	that	retrieves	3”	cores	will	require	a	very	high	amount	of	power,	a	lot	of	

drilling	 complexity,	 more	 steps	 in	 core	 handling,	 and	 very	 complex	 Planetary	

Protection/Containment	 Control	 (PP/CC),	 yet	 the	 core	 from	 such	 a	 drill	 could	 include	 a	

scientifically-rich	return.		A	drill	 that	retrieves	broken	2”	cores	requires	a	high	amount	of	
Mars Ice Core Working Group – First Ice Cores from Mars

54

power	 and	 is	 complex.	 Because	 of	 the	 smaller	 diameter,	 the	 core	 could	 be	 broken.	 If	

rock/regolith	bits	are	used,	the	core	quality	would	be	lower,	as	well.	The	science	value	of	a	

broken	2”	core	is	not	as	high	as	a	3”	core,	but it	is	significantly	better	than	retrieving	only	

chips.	Note	that	in	this	case	automation	of	the	placement	of	the	core	or	core	pieces	into	a	

hermetically	 sealed	 tube	 should	 be	 considered	 to	 maintain	 biological	 integrity	 of	 the	

samples.

Figure	V-1. Eccentric	tube	core	breakoff	approach	is	a	robust	method	of	breaking	and	retaining	a	core.	

A	critical	aspect	of	coring	is	core	break-off	and	retention.	This	is	a	non-trivial	operation	and	

it	has	to	work	with	good	quality	and	poor	quality	(broken	up)	cores.	Traditional	ice	coring	

systems	use	so-called	‘dogs’	- a	set	of	three	blades	that	pinch	the	core,	create	a	small	notch,	

and	break	the	core	in	tension	as	the	core	drill	is	being	retracted.	Dogs	do	not	always	work	-

if	ice	is	 too	 hard,	 they	may	 slide;	if	ice	is	 broken	 up,	ice	 chips	 will	 fall	 down	 to	 the	 hole	

bottom.	

A	 more	 robust	 (but	 also	 more	 complex)	 approach	 is	 to	 use	 an	 eccentric	 core	 breakoff	

system	 (Myrick	 2003;	 Zacny	et	al.,	 2011).	 In	 this	approach,	 the	bit	and	 the	breakoff	tube	

each	 have	 bores	which	 are	 slightly	 offset	 from	 center	 by	 the	 same	 distance	 (Figure	 V-1).	

The	breakoff	tube	is	installed	 within	 the	 offset	 bore	inside	 of	 the	bit.	 During	 the	 drilling	

process,	 the	 two	 tubes	are	aligned	such	 that	 the	 thru	bore	of	 the	breakoff	tube	is	aligned	

with	the	drilling	axis.	When	core	breakoff	is	desired,	the	breakoff	tube	is	rotated	relative	to	
Mars Ice Core Working Group – First Ice Cores from Mars

55

the	bit,	which	gradually	shifts	the	central	axis	of	the	breakoff	tube.	This	pushes	the	entire	

portion	of	the	core	within	the	bit	to	one	side,	shearing	it	at	the	base.	This	technology	results	

in	the	narrowest	possible	kerf	(annular	groove	cut	by	the	bit	or	the	width	of	a	cut),	which	

enables	low	weight	on	bit	(WOB),	power,	drilling	time	and	energy	compared	to	other	core	

breakoff	mechanisms.	This	core break	off	approach	is	also	robust	to	broken	up	cores	and	a	

small	step	at	the	bit,	helps	to	retain	the	core.	This	technology	has	been	implemented	on	the	

Mars	Perseverance	rover	mission.	

Figure	 V-2	 illustrates	 what	 measurements	 are	 possible	 to	 address	 high-priority	 science	

questions	as	a	function	of	core	quality,	where	some	measurements	require	continuous	ice	

core	 (ice	 core	 is	 in	 five	 or	 fewer	 pieces	 per	 meter	 with	 relatively	 few	 cracks)	 and	 other	

measurements	 can	 be	made	 on	fractures (ice	 core	is	in	 six	 or	more	 pieces	with	 frequent	

cracks)	or	pieces	of	core	(fractured core and	stratigraphic	order	is	uncertain	at	the	cm	scale	

and	 shorter),	 as	 well	 as	 on	 chips	 (6	 mm	 in	 diameter	 maximum).	 The	 resolution	 of	 the	

measurements	and	the	utility	of	the	measurements	to	address	science	questions	increases	

with	 the	 quality	 of	 the	 core.	While	 obtaining pieces	 of	ice	 core	 or	 only	 chips	is	easier	 for	

drill	 engineering	 and	 logistics,	 decontamination	 procedures	 become	 increasingly	 more	

difficult	as	the	core	quality	goes	down.

Figure	V-2. Measurements	that	could	be	conducted	on	continuous	ice	cores	or	on	fractures	or	pieces	of	ice	core,	

as	well	as	on	chips,	in	order	to	address	high-priority	science.	Some	measurements	are	only	possible	on	continuous	

ice	cores,	and	the	measurements	possible	on	fractures	or	pieces	of	ice	core and	chips	will	be	lower	resolution.
Mars Ice Core Working Group – First Ice Cores from Mars

56

Scientific	requirements	related	to	drilling	on	Mars

The	 choice	 of	 drill	 and	 characteristics	 of	 the	 recovered	 cores	 determines	 what	

measurements	can	be	made.	Figure	V-2	groups	all	of	 the	measurements	identified	by	 the	

Working	 Group	 that	 could	 be	 used	 to	 address	 the	 high-priority	 science	 questions.	 All	

measurements	 can	 be	 conducted	 on	 continuous	 ice	 core	 samples,	 but	 only	 certain	

measurements	 can	 be	 collected	 on	 fractures	 or	 pieces	 of	 core,	 or	 only	 core	 chips.	 The	

resolution	 decreases	as	 the	 core	 quality	 decreases,	and	 the	 challenge	 of	 decontamination	

increases	as	the	core	quality	decreases.

Sample	 quantity	 is	 also	 a	 consideration	 with	 respect	 to	 the	 number	 and	 quality	 of	

measurements	 that	 are	 possible.	 Table	 V-2	 includes	 estimates	 of	 the	 amount	 of	

core/sample	 required	 based	 on	 contemporary	 technology.	 If	 there	 is	 sufficient	 core	

continuity	and	quality,	some	measurements	may	be	combined	as	part	of	a	Continuous	Flow	

Analysis	(CFA)	system	in	order	to	maximize	the	number	of	measurements	that	can	be	made	

on	the	same	sample	(see	Section	II.7).

Table	V-2. There	are	at	least	34	measurements	that	may	be	made	on	the	first	ice	cores	from	Mars.	Amount	of	the	

ice	 sample	 for	 each	 measurement	 is	 estimated	 to	 the	 best	 of	 our	 knowledge	 based	 on	 contemporary	

measurement	technology.	

Measurement on the returned 

core/sample

Amount of 

core/sample

Condition of the ice 

core

Possible to 

measure on 

chips without a 

core?

(Estimate based on 

contemporary 

technology)

(Continuous, 

Fractures, or Pieces)

(chips are 6mm 

maximum)

Detection and spatial distribution of 

organic matter ~ 0.5 g Continuous No

Cellular mass and distribution ~10 ml melted Continuous No

Sediment mass and distribution -- Continuous No

Gases 1000g Continuous No

Radiometric dating (gas) 500g (U); 5000g (Kr) Continuous No

Grain structure ~ 0.5 g Continuous; Fractures No

Scanning Electron Microscope 

imaging of triple junctions and grain 

boundaries with ice and different T

~ 0.5 g Continuous; Fractures No

Electrical conductivity

Non-destructive, but 

smooth surface may be 

needed requiring 

polishing

Continuous; Fractures* No
Mars Ice Core Working Group – First Ice Cores from Mars

57

Visual layer identification and 

microscopy

Non-destructive, but 

smooth surface may be 

needed requiring 

polishing

Continuous; Fractures* No

Material properties of the ice 

(density, crystal/grain structure, 

bubble distribution)

Requires thin sections Continuous; Fractures* No

Frequency and thickness of 

debris/dust layers

non-destructive, but 

smooth surface may be 

needed requiring 

polishing

Continuous; Fractures* No

Core impurity and salt 

concentrations Variable Continuous**; Fractures; Pieces* At low resolution

Chemistry of the ice 3g Continuous**; 

Fractures; Pieces* At low resolution

Water (ice) Stable isotopes 0.1g D/H and O18/O16; 

1g O17/O16

Continuous**; 

Fractures; Pieces* At low resolution

Microbial redox couples 5 ml melted Continuous**; 

Fractures; Pieces* At low resolution

Amino acid racemization ~10 ml melted Continuous**; 

Fractures; Pieces* At low resolution

Stable isotope composition of 

particulates and dissolved organic 

matter

Variable Continuous**; 

Fractures; Pieces* At low resolution

Scanning Electron Microscope 

imaging of cellular material ~10 ml melted Continuous**; Fractures; Pieces* At low resolution

Epiflurescence microscopy and flow 

cytometry using select metabolic 

stains (DNA, Redox, live/dead)

~10 ml melted Continuous**; 

Fractures; Pieces* At low resolution

Genomic and proteomic data for 

phylogeny and metabolic diversity

Depends on how many 

cells are observed (106-

108 DNA containing 

cells)

Continuous**; 

Fractures; Pieces* At low resolution

Metabolic activity using tritiated and 

14C-labeled (radiolabeled) 

substrates (amino acids, sugars, 

metabolic intermediates)

50 ml melted Continuous**; 

Fractures; Pieces* At low resolution

Respiration of radiolabeled 14C 

substrates

Can be incorporated 

into the metabolic 

activity expts

Continuous**; 

Fractures; Pieces* At low resolution

Selected aerobic and anaerobic 

culturing of heterotrophs and 

chemoautotrophs, methanogens, 

methanotrophs, etc.

~10 ml melted Continuous**; 

Fractures; Pieces* At low resolution

Biosignatures (gases, lipids, 

polysaccharides, PAHs aliphatic 

and aromatic compounds)

Variable Continuous**; 

Fractures; Pieces* At low resolution
Mars Ice Core Working Group – First Ice Cores from Mars

58

Organic matter quality ~20 ml Continuous**; 

Fractures; Pieces* At low resolution

Determination of metabolic free 

energy based on geomchemical 

measurements

~20 ml Continuous**; 

Fractures; Pieces* At low resolution

Metabolic potential of cells to repair 

damage induced by the oxidation 

potential of the habitat

Can combine with 

metaboilic rate 

experiments

Continuous**; 

Fractures; Pieces* At low resolution

Major ion concentration Variable Continuous**; 

Fractures; Pieces* At low resolution

Cosmogenic nuclides One example: 5 g for 

10Be

Continuous; Fractures; 

Pieces* At low resolution

Exposure age of lithic fragments 10 g quartz for 10Be, 

30g quartz for 26Al All Yes

Physical properties of dust/tephra 1mg All Yes

Composition 1mg All Yes

Minerology of sediment particles 1mg All Yes

Physical and chemical properties of 

the regolith surface Variable -- At low resolution

*	Utility of records increases with core quality

**	Measurement	on	a	continuous	core	can	be	combined	in	a	Continuous	Flow	Analysis	(CFA)	system	to	maximize	

the	number	of	measurements	on	the	ice	samples

A	drill	that	incorporates	borehole	instrumentation	will	enable	in-situ	detection	of	biological	

material	and	associated	organics	distributed	in	the	ice.	Such	measurements	will	provide	an	

immediate	 understanding	 of	 the	 geochemical	 and	 physical	 features	 that	 drive	 	 the	

distribution	 of	 organic	 matter.	 In	 addition,	 borehole	 measurements	 will	 provide	 spatial	

information	 that	 can	 be	 used	 to	 target	 sampling	 in	 returned	 ice	 cores	 minimizing	

contamination	and	loss	of	native	material	from	effects	of	dilution	from	bulk	analysis.	It	will	

also	 provide	 a	 means	 to	 handle/process	 smaller cores;	 enabling	 spectral	 and	 single-cell	

resolution	chemical	imaging	analyses	previously	unavailable.

3.	Requirements	of	engineering	to	optimize	the	scientific	return	from	ice	

coring	in	the	mid-latitude	of	Mars

The	 following	 requirements	 assume	 that	 the	 ice	 core	 will	 be	 retrieved	 from	 the	 midlatitudes	beneath	a	debris	overburden,	and	that	the	core	returned	is	up	to	10	meters	long.	

This	 ten	 meters	 of	 material	 may	 include	 bands	 of	 ice	 and	 dust/debris/rock/cemented

ground,	and	it	also	should	be	assumed	 that	 the	drill	will	encounter	mixtures	of	ice,	rocks	

and	debris.	
Mars Ice Core Working Group – First Ice Cores from Mars

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The	requirements	of	engineering	to	optimize	the	scientific	return	from	ice	cores	include:

1. We	have	assumed	that	prior	to	the	mission	to	drill	the	ice	core,	a	mission	will	return	

the	 highest	 resolution	 possible	 radar	images	 of	 the	 top	 20	meters	 of	 potential	ice	

core	sites;	 these	will	inform	site	selection	as	well	as	aid	interpretation	of	eventual	

measurements	from	the	core.

2. Ground-based	imaging	of	the	subsurface	will	occur	at	the	site	to	characterize	the	site	

and	select	an	optimal	location	before	drilling	commences.

3. A	 key	 requirement	 for	 the	 drilling	 system	 on	 Mars	 is	 the	 ability	 of	 the	 drill	 to	

penetrate	 several	 different	 types	 of	 layers:	 loose	 regolith, rocks,	 ice	 cemented	

ground,	and	ice	with	various	fractions	of	particles	and	rocks.

4. If	a	 drilling	 fluid	 (e.g.	 compressed	gas)	is	 used,	its	 chemical	 composition	must	 not	

contaminate	the	samples	for	biological	investigations.

5. Retrieval	of	continuous	core	will	optimize	the	scientific	return.

6. Analysis	 of	 potential	 scientific	 findings	 from	 ice	 that	 has	 not	 been	 retrieved	 from	

coring	but	instead	from	chipping	the	ice	(a	chip	has	maximum	length	6	mm)	should	

be	carefully	considered	before	designing	a	drill	for	retrieving	chips	of	ice	from	Mars.

7. Robotic	drilling	and	core	handling	should	be	used	to	the	greatest	extent	possible.

8. If	 possible,	 replicate	 coring	 should	 be	 included	 with	 drill	 design	 to	 retrieve	

additional	ice	from	depths	where	ice	probes	have	detected	signs of	life	or	significant	

events.

9. The	core	should	be	maintained	at	its	original	temperature	and	pressure	at	all	times	

through	the	handling	on	Mars,	transport	to	Earth,	and	storage	in	a	facility	on	Earth.

10. Borehole	 logging	 and	 on	 site	 measurements	 from	 melt	 probes	 should	 be	 used	 to	

replicate	 or	 augment	 data	 from	 the	 core.	 Borehole	 instrumentation	 such	 as	 that	

included	 in	 the	WATSON	 drill	 (described	 above)	 could	 target	 organic	 matter	 “hot	

spots”	which	can	 then	be	sites	 of	horizontal	drilling.	Small	 targeted	sidewall	cores	

would	reduce	the	size	of	core	necessary	for	detection	of	analytes	of	interest.

11. If	 possible,	 a	 robotic	 method	 for	 placing	 ice	 cores	 in	 hermetically	 sealed	 tubes	

according	 to	 the	 Mars	 2020	 protocol	 immediately	 upon	 removal	 from	 the	 drill	

should	be designed	and	built	in	connection	with	drill	development.

12. Appropriate	storage	and	protection	units	should	be	designed	and	 tested	 to	ensure	

that	 they	maintain	 the	integrity	 of	 the	ice	samples	after	drilling,	during	 the	 return	

flight,	and	when	storing	in	an	archival	facility	on	Earth.

13. Improve	methods	of	core	measurement	and	analysis	to	reduce	the	required	quantity	

and	 quality	 sample	 beyond	 current	 capabilities	 that	 were	 identified	 in	 Table	 V-2	

above.

14. Include	plans	for	borehole	instrumentation	into	drill	design	planning.
Mars Ice Core Working Group – First Ice Cores from Mars

60

VI.	Other	enabling	technologies	for	in-situ	measurements	on	Mars

Targeted	side-wall	cores

Borehole	 instrumentation	 such	 as	 that	 included	 in	 the	 WATSON	 drill	 (described	 above)	

could	target	organic	matter	“hot	spots”	which	can	then	be	sites	of	horizontal	drilling.	Small	

targeted	sidewall	cores	would	reduce	the	size	of	core	necessary	for	detection	of	analytes	of	

interest.

Thermal	melt	probe

Melt	 probes	 descend	 vertically	 through	 nearly	 pure	 ice	 using	 electrical	 power	 supplied	

from	 the	 surface,	 conducted	 along	 wires	 that	 pay	 out	 from	 within	 the	 probe	 as	 the	melt	

hole	 above	 refreezes.	 They	 could	 also	 be	 deployed	 into	 a	 low-impurity	 ice	 mass	 from	 a	

borehole	 that	 was	 drilled	 through	 debris.	 Advances	 in	 the	 probe	 technology	 have	 now	

made	 high-voltage	 operation	 reliable,	 specifically	 with	 recent	 developments	 of	 the	 Ice	

Diver	thermal	probe	led	by	Dale	Winebrenner	(University	of	Washington	- Applied	Physics	

Laboratory).	The	University	of	Washington	Ice	Diver	is	170	cm	long	with	a	diameter	of	6.5	

cm,	uses	pendulum	steering	to	maintain	vertical	travel,	and	carries	1100	m	of	spooled	wire.	

Two	 field	 tests	 (July	 2013	 and	 July	 2014)	 were	 conducted	 at	 an	 ablation-zone	 site	 in	

southwest	 Greenland	 (1000	 m	 elevation,	 near-surface	 ice	 temperature	 -15°C)	 and	

demonstrated	its	 potential.	Using	 higher	 power	 the	 probe	was	 capable	 of	 descending	 6.6	

m/hr.	The	Ice	Diver	includes	thermistors,	but	the	Ice	Diver	technology	could	be	adapted	to	

host	other	instruments.	A	desirable	configuration	is	 to	integrate	a	dust	logger	 (Bay	et	al.,	

2001),	which	shines	light	into	the	ice	surrounding	a	borehole.	The	reflected	signal	precisely	

tracks	 impurity	 layers	 through	 absorption	 and	 scattering	 and	 is	 a	 sensitive	 tracer	 of	

continental	mineral	dust	and	volcanic	ash.	Additional	configurations	could	include	that	the	

Ice	Diver	hosts	a	laser	spectrometer	for	measuring	water	isotopes	and	gases.	In	a	different	

application	of	the	probe,	Ice	Diver	could	also	be	modified	to	return	water	and	gas	samples	

to	the	surface.	Thermal	melt	probes	work	well	in	low	impurity	ice	but	drilling	efficiency	is	

hampered	greatly	in	sediment	laden	ice.	Additional	information	can	be	found	at:	

https://apl.uw.edu/project/project.php?id=ice_diver
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61

VII.	Select	relevant	resources	and	organizations	that	may	have	related	

experience	and	technologies

The	Terms	 of	Reference	 for	 this report	 requested	 that	 the	Mars	 Ice	 Core	Working	Group

identify	 other	 organizations	 and	 resources	 that	 may	 have	 insights	 or	 specialized	

capabilities	 that	 could	 be	 useful	 in	 planning	 or	 instrument	 testing	 for	 engineering	 drills	

capable	of	ice	coring	on	Mars.	Highly	specialized	and	relevant	scientific	expertise	exists	at	

many	universities	across	the	U.S.	and	beyond;	we	do	not	attempt	to	list	those	here. A	list	of	

select	 relevant	 resources	 and	 organizations	 that	 may	 have	 related	 experience	 and	

technologies	includes:

1) U.S.	Ice	Drilling	Program:	https://icedrill.org/

2) Ice	Drilling	Program	Ice	Core	Working	Group:	https://icedrill.org/about/scienceadvisory-board/working-groups#icwg

3) National	Science	Foundation	Ice	Core	Facility: https://icecores.org/

4) Juneau	Icefield	Research	Program	(test	site):	https://juneauicefield.org/

5) Honeybee	Robotics:	www.honeybeerobotics.com

6) Mars	Exploration	Program	Analysis	Group	(MEPAG):	https://mepag.jpl.nasa.gov/

7) Astromaterials	Acquisition	&	Curation	Office:	https://curator.jsc.nasa.gov/

8) Astromaterials	Research	& Exploration	Science:	https://ares.jsc.nasa.gov/

9) NASA	Jet	Propulsion	Laboratory	
Mars Ice Core Working Group – First Ice Cores from Mars

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VIII.	Recommendations

Research	prior	to	the	Mars	ice	core	mission

We	 assume	 that	 a	 satellite	 radar	mission	 capable	 of	imaging	 the	 upper	 20	meters	 of	 the	

subsurface	will	have	 occurred	 prior	 to	 the	ice	 coring	mission. High-resolution	imagery	is	

also	valuable.

• All	available	 data	 should	 be	analyzed	 to	 characterize	and understand	 processes	in	

the	upper 20	m	of	several	potential	drill	sites.	Based	on	these	analyses,	targeting	a	

site	to	drill	in	ground	ice	or	in	glacial	ice,	or	both,	must	be	determined.

Key	characteristics	of	Martian	ice	cores	crucial	to	NASA’s	research	objectives

NASA	will	need	to	evaluate	the	tradeoffs	between	1)	collecting	a	high	quality	ice	core	with	

diameter	between	50	to 76	mm that	is	optimized	for	scientific	return	but	at	the	expense	of	

requiring	 a	 relatively	 complex	 and	 logistically	 difficult	 drill,	 versus	 2)	 collecting	 6	 mm	

diameter	 ice	 chips	 that	 support	 less	 of	 the	 high-priority	 science	 objectives	 but	 can	 be	

achieved	with	a	non-coring drill	 that	is	logistically	easy	by	needing	 to	only	grind	 through	

ice	to	produce	chips.

Minimum	attributes	of	a	mission	that	minimizes	logistics	through	deployment	of	a	chip	drill:

• Sample	acquisition: Deploy	a	drill	that	collects	only	chips	(defined	as	<6mm).	

• Ice	chips	processing: Retain	stratigraphic	order	of	the	chips	and	seal	immediately	to	

avoid	 sublimation	 and	 contamination.	 Follow	 sample	 handling	 procedures	

established	for	Mars	2020	to	minimize	contamination.	

• Sample	allocation:	TBD	by	scientists chosen	by	NASA.	

• Archiving	practices:	Follow	Mars	2020	protocol.

Range	 of	 attributes	 of	 a	mission	 that	maximizes	 scientific	 return	 through	 deployment	 of	 an	

ice-coring	drill:

• Sample	acquisition: Deploy	an	ice	coring	drill	that	collects	a	76	mm	diameter	ice	core	

(preferable)	 or	 50	 mm	 diameter	fragmented ice	 core.	 If	 a	 drilling	 fluid	 is	 used,	 it	

must	preserve	the	integrity	of	biological	samples	in	the	ice.	

• Ice	 core	 processing: Immediately	 upon	 removal	 from	 the	 drill,	 place	 cores	 in	

hermetically	sealed	bags	in	1-m	increments,	and	store	according	 to	 the	Mars	2020	

protocol.

• Sample	allocation:	TBD	by	scientists	chosen	by	NASA.

• Archiving	practices:	TBD	by	scientists	chosen	by	NASA.

Number	of	ice	cores	and	quantity	of	ice	core	collected

For	a	core-collection	mission:	

• A	continuous	ice	core	(in	five	or	fewer	pieces	per	meter	with	relatively	few	cracks)	

collected	and/or	stored	in	meter-long	increments	is	ideal.
Mars Ice Core Working Group – First Ice Cores from Mars

63

• Collect	 at	least	 50	 cm	 of	 debris/dust/regolith	 or	 permafrost	 from	 the	 overburden	

layer	 as	 a	 core	 sample;	 if	 the	 overburden	 layer	 is	 multiple	 meters	 thick	 then	

additional	samples	may	be	warranted.

• Collect	10	meters	of	core	 that	is	predominantly	ice	but	may	contain	 thick	bands	of	

ice	mixed	with	rocks,	regolith	and	other	debris.

• Borehole	instrumentation	 can be	 used	 to	 target	locations	 for	 horizontal	 drilling	 to	

collect	small,	targeted	sidewall	cores	(for	example,	using	the	WATSON	drill).

• Collect	multiple	cores	from	the	same	local	site	for	at	least	two	reasons:	

○ As	 control	 cores	 for	 all	 measurements	 in	 order	 to	 rigorously	 examine	

contamination,	as	well	as for	 corroboration.	Controls	are	equally	important	

samples,	and	for	these	reasons	were	incorporated	as	part	of	Mars	2020.

○ To	maximize	the	number	and	type	of	measurements	that	can	be	made	on	the	

limited	ice	recovered.

• If	 possible,	 replicate	 coring	 should	 be	 designed	 with	 the	 drill	 so	 that	 borehole	

instrumentation, such	 as	 that	 included	 in	 the	 WATSON	 drill, for	 example, could	

target	organic	matter	“hot	spots”	which	can	then	be	sites	of	horizontal	drilling.	Small	

targeted	 sidewall	 cores	 would	 reduce	 the	 size	 of	 core	 necessary	 for	 detection	 of	

analytes	of	interest.

For	a	chip-collection	mission:

• Depending	on	the	site	characteristics,	collect	multiple	surface	samples.

• Collect	multiple	chip	cores,	ideally	from	both	ground	ice	and	glacial	ice.

• Design	 a	 measurement	 plan	 that	 integrates	 chip	 coring	 and	 borehole	

instrumentation,	 as	 well	 as	 possibly	 sidewall	 (horizontal)	 drilling,	 in	 order	 to	

maximize	scientific	return.

Ice	core	site	selection	and	in-situ	measurements

• Soon	 after	 the	 Mars	 ice	 core	 mission	 lands,	 a	 high-resolution	 ground-penetrating	

survey	around	the	chosen	ice	core	drill	site	should	be	conducted	to	provide	context	

for	ice	core	interpretation.

• Ambient	air	 temperature	and	chemical	composition measured	over	site	occupancy	

time.

• Borehole	temperature	profile	after	drilling	is	finished.

• Consider	 melt	 probe	 autonomous	 measurements	 of	 ice	 temperature	 and	 water	

isotope	profile	if	thick	undisturbed	ice	exists	at	a	location	within	5	m	of	the	ice	core	

borehole.

Additional	data	collection	to	support	drill-site	selection	and	sample	interpretation

• Surface	 samples	 through	 the	 overburden	 layer	 and	 at	 the	 interface	 between	 the	

overburden	and	the	ice-rich	deposit	should	be	collected.

• Additional	 samples of	 permafrost,	 regolith,	 debris,	 rock,	 and	 dust	 from	 the	 region	

near	 the	 drill	 site	 should	 be	 collected,	 with	 a	 plan	 determined	 based	 on	

characteristics	of	the	target	site.
Mars Ice Core Working Group – First Ice Cores from Mars

64

Ice	core	archive

• In	addition	to	storing	samples	according	to	protocols	for	cold	curation	and	biological	

containment,	including	 storage	 of	 contamination	 references,	 some	 samples	 should	

remain	 archived	 for	 future	 use.	 Archiving	 material	 is	 a	 valuable	 practice	 for	

terrestrial	ice	cores	and	lunar	samples,	and	allows	new	technologies	to	be	applied	in	

future	investigations.

Technology	development

• As	determined	by	NASA	after	science-logistics	tradeoffs,	create	either	a	chip	drill,	or	

a	2”	(or	3”)	coiled	tubing	or	jointed	pipe	ice	coring	drill.	

• Development	 of	 lateral	 coring	 capability	 off	 of	 the	 main	 borehole,	 for	 retrieval	 of	

material	at	depths	that	probes	have	indicated	are	scientifically	very	significant.

• Development	 of	 an	 autonomous	 ice	 probe	 that	 measures	 temperature	 and	 water	

isotopes	as	it	melts	down	through	the	ice.

• Measurement	 techniques	 should	 try	 to	 use	 the	 least	 amount	 of	 ice	 possible,	

including	scientific	measurement	capabilities	on	ice	chips,	which	may	require	new	

measurement	technologies.

• Temperature	probes	and	deep-UV	spectroscopy	should	be	developed	in	association	

with	the	drill	development		to	optimize	scientific	return.
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