The Astromaterials Acquisition and Curation Office at NASA Johnson Space Center (JSC), in Houston, TX (henceforth Curation Office) manages the curation of extraterrestrial samples returned by NASA missions and shared collections from international partners, preserving their integrity for future scientific study while providing the samples to the international community in a fair and unbiased way. The Curation Office also curates flight and non-flight reference materials and other materials from spacecraft assembly (e.g., lubricants, paints and gases) of sample return missions that would have the potential to cross-contaminate a present or future NASA astromaterials collection

Calaway, M. J.

Fries, M. D.

Harrington, A. D.

McCubbin, F. M.

Mitchell, J. L.

Regberg, A. B.

Zeigler, R. A.

NASA Technical Reports Server

THE IMPORTANCE OF CONTAMINATION KNOWLEDGE IN CURATION – INSIGHTS INTO MARS 
SAMPLE RETURN. A. D. Harrington1, M. J. Calaway2, A. B. Regberg1, J. L. Mitchell1, M. D. Fries1, R. A. Zei-
gler1, and F. M. McCubbin1, 1Astromaterials Research and Exploration Sciences (ARES) Division, NASA Johnson 
Space Center, 2101 NASA Parkway Mail Code XI2, Houston TX 77058, Andrea.D.Harrington@NASA.gov, 
2Jacobs, NASA Johnson Space Center. 
 
Introduction: The Astromaterials Acquisition and 
Curation Office at NASA Johnson Space Center (JSC), 
in Houston, TX (henceforth Curation Office) manages 
the curation of extraterrestrial samples returned by 
NASA missions and shared collections from interna-
tional partners, preserving their integrity for future sci-
entific study while providing the samples to the inter-
national community in a fair and unbiased way. The 
Curation Office also curates flight and non-flight refer-
ence materials and other materials from spacecraft as-
sembly (e.g., lubricants, paints and gases) of sample 
return missions that would have the potential to cross-
contaminate a present or future NASA astromaterials 
collection. These materials are primarily collected dur-
ing the assembly, test, and launch operations (ATLO) 
phase and after flight during the recovery and curation 
phase. In addition, the Curation Office curates non-
flight, flight-like, and flown witness plates for sample 
return missions. These reference materials and witness 
plates provide the scientific community with the fun-
damental ability to reconstruct the contamina-
tion/alteration history of the sample collection through 
the course of the mission, with the overall goal of guid-
ing and strengthening the scientific conclusions drawn 
from the study of returned materials. The information 
gained from characterizing the physical, biological, 
inorganic, and organic chemical properties of reference 
materials and witness plates is defined as the Contami-
nation Knowledge (CK) of the sample collection. 
The Mars 2020 mission is the first step of a possi-
ble multi-mission campaign to return martian samples 
to Earth. By collecting and caching an array of drill 
core and regolith samples, along with the geologic con-
text provided by the in situ analyses, the Mars 2020 
mission will set the stage for future mission(s) to return 
the cached samples to Earth. Scientists will use these 
samples to better understand: 1) the geological pro-
cesses that formed Mars’ astrobiologically-relevant 
ancient environments and geologic diversity, 2) the 
habitability of Mars’ ancient environments and signs of 
past life (if present), and 3) the unique requirements for 
future human exploration of Mars [1]. 
Scientific investigations of returned samples are 
highly sensitive to terrestrial contamination, especially 
where studies of extant or extinct extraterrestrial life 
are concerned. The proper collection, storage, and 
cataloging of CK associated with the production and 
assembly of the spacecraft, rover, and sample and 
caching subsystem (SCS) will be vital to these investi-
gations. Without a well-constructed and curated CK 
collection, the baseline for contamination within the 
returned samples cannot be established. 
 
 
Fig. 1: Roles of CC versus PP versus CK 
Depiction of the main roles of Contamination Knowledge, 
Contamination Control, and Planetary Protection. 
 
CC versus PP versus CK: As with all missions, 
minimizing the amount of contamination on the space-
craft is important. However, the contamination stand-
ards for the Mars 2020 mission are even more stringent 
since Mars is “a body deemed by scientific opinion to 
be of significant interest to the process of chemical 
evolution and/or the origin of life (Category V; Re-
stricted Earth-Return) [2].” Contamination Control 
(CC) and Planetary Protection (PP) are tasked with 
ensuring the spacecraft contamination standards are 
met (Figure 1). Unlike CC and PP, CK is exclusively 
concerned with preserving reference materials and wit-
ness plates for study by future scientists upon sample 
return. Although data collected for CC and PP purpos-
es is complementary to CK, they are two separate data 
sets with distinct objectives. A robust collection of CK 
is necessary to allow the martian material in a returned 
sample to be distinguished from terrestrial contamina-
tion.  
Lessons Learned from Recent Sample Return 
Missions: Although always treated as CK, OSIRIS-
REx is the first sample return mission to explicitly dif-
ferentiate curated witness materials from CC and group 
them with reference materials. This change in nomen-
clature is due to the disparate purposes of the witness 
materials, the increasing complexity of the sample re-
turn missions, and the need to ensure an adequate CK 
https://ntrs.nasa.gov/search.jsp?R=20180002582 2019-08-29T18:14:01+00:00Z
collection. The necessity of CK to mission success is 
demonstrated by the last two NASA sample return mis-
sions: Genesis and Stardust. In their own ways, these 
missions demonstrate that as long as proper controls 
are in place (e.g., CK), the presence of contamination 
will not hinder a well-designed scientific investigation.  
Genesis. Genesis was launched in 2001 to collect 
solar wind at the Earth-Sun Lagrange Point, L1. On 
September 8, 2004, a hard landing at the Utah Test and 
Training Range (UTTR) resulted in a breach of the 
science canister which exposed samples to contamina-
tion from the spacecraft and UTTR lacustrine envi-
ronment. In addition, unknown contamination adhered 
to the samples during the mission at L1 from the com-
bination of spacecraft outgassing and solar irradiation 
damage. The CK enabled scientists and curation ex-
perts to make great strides in identifying and quantify-
ing the degree of sample contamination, decontaminat-
ing each sample, extracting solar wind elemental signa-
tures, and creating correction models for the composi-
tion of the sun, thereby allowing the primary science of 
the mission to be completed despite the non-nominal 
landing.  
Stardust. Launched in 1999 and returned to UTTR 
in 2006 (nominal landing), Stardust was designed to 
collect dust from comet Wild 2 and interstellar space. 
After successfully returning to Earth, scientists found 
that the aerogel designed to capture the dust particles 
contained amino acids. After extensive study utilizing 
both non-flight and flown CK, scientists determined 
that the amino acids found within the comet-exposed 
aerogel were primarily from Wild 2, with only trace 
amounts of organic contamination from the aerogel 
itself [3-5]. This finding would not be possible without 
adequate CK. 
The Unique CK of Mars 2020: The classification 
of Mars sample return as Category V Restricted Earth 
Return not only adds more CC and PP constraints, it 
also broadens the scope of required CK to include bio-
logical witness materials. Unlike other collections, 
which only require storage in an inert ultra-pure nitro-
gen gaseous environment, the biological CK for Mars 
2020 will also require samples to be frozen. 
Planning for evolving technology. Technological 
advancements to instrumentation are continually pro-
gressing with greater precision and accuracy for sample 
measurements, especially in the field of microbiology. 
The Curation Office must ensure that an array of CK 
samples are available to scientists once the samples 
cached by Mars 2020 are returned to Earth. Some of 
the types of biological CK samples the Curation Office 
requires include:  
1.) Un-analyzed swabs and wipes in sterile contain-
ers stored at ≤ -80°C. 
2.) All recirculation filters from the clean rooms 
used for rover and rover hardware assembly and 
all filters from the laminar flow benches used to 
assemble sample intimate hardware. Packaged in 
sterile Teflon bags and frozen at -80°C. 
3.) Witness plates collecting airborne contamination 
within the assembly cleanrooms stored at ≤ -
80°C. 
Collecting and curating unanalyzed samples will 
minimize the possibility that current analysis and ex-
traction techniques destroy or alter the samples or oth-
erwise inhibit yet to be developed measurements. It has 
been Curation Office policy since the Apollo missions 
to preserve as many pristine samples as possible for 
future scientific research [6,7].  
Temperature Constraints. To date, there have not 
been any conclusive studies indicating the most effec-
tive long-term storage for microbiological samples. 
Cryogenic temperatures (below the glass transition 
point for water < -137 °C) are the standard for biologi-
cal preservation. However, some short-term studies 
indicate that -80°C is preferential since cryogenic tem-
peratures actually break down some biological materi-
al, limiting analyses of DNA [8]. Therefore, subsets of 
CK biological witness materials will be cataloged and 
stored at either -80 °C or cryogenically. 
Conclusions: Although CK is required to be col-
lected for all stages of the Mars sample return cam-
paign, the CK for the Mars 2020 mission is the most 
critical for understanding contamination in the returned 
samples given the intimacy between the samples and 
the Mars 2020 hardware. Rigorous collection of CK 
and derived blanks for all possible contamination 
sources and pathways particularly those in the SCS, is 
essential for mission success. Without adequate CK 
data, the baseline for contamination within the returned 
samples cannot be established. 
References: [1] http://mars.nasa.gov/mars2020/ 
mission/science/goals/. [2] https://planetaryprotection.n 
asa.gov/categories. [3] Sandford S.A. et al. (2010) Me-
teoritics & Planet. Sci., 45, Nr3, 406-433. [4] Glavin 
D. P. et al. (2008) Meteoritics & Planet. Sci., 43, Nr ½, 
399-413. [5] Elsila J.E. et al. (2009) Meteoritics & 
Planet. Sci., 44, 9, 1323-1330. [6]. NASA 1965 Sum-
mer Conference on Lunar Exploration and Science, 
Falmouth, Massachusetts, 421. [7] Allen C. et al. 
(2011), Chemie der Erde – Geochemistry, 71, 1–20. 
[8] Smittle R. B. et al. (1972) Applied Microbiology, 
24, 4, 551-554. 


The Importance of Contamination Knowledge in Curation - Insights into Mars Sample Return

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