View source for Tanpopo mission

{{short description|2015–18 ISS astrobiology experiment}}
[[File:Japanese Experiment Module exterior - cropped.jpg|thumb|upright=1.3|The Japanese [[Kibo (ISS module)|Kibo module]] (left) and the Exposed Facility Unit (right)]]

The '''Tanpopo mission''' is an orbital [[astrobiology]] experiment investigating the potential interplanetary transfer of [[life]], [[organic compound]]s, and possible terrestrial particles in the low Earth orbit. The purpose is to assess the [[panspermia]] hypothesis and the possibility of natural interplanetary transport of microbial life as well as prebiotic organic compounds.

The collection and exposure phase took place from May 2015 through February 2018 utilizing the Exposed Facility located on the exterior of Kibo, the [[Kibo (ISS module)|Japanese Experimental Module]] of the [[International Space Station]].<ref>[http://spaceref.com/international-space-station/nasa-iss-on-orbit-status-13-may-2015.html NASA ISS On-Orbit Status 13 May 2015]</ref> The mission, designed and performed by Japan, used ultra-low density silica gel ([[aerogel]]) to collect [[cosmic dust]] by,<ref>{{cite journal|last1=Tabata |first1=M |last2=Imai |first2=E |last3= Yano|first3= H|last4= Hashimoto|first4= H|last5=Kawai |first5= H|display-authors=etal|date= 2014|title=Design of a Silica-aerogel-based Cosmic Dust Collector for the Tanpopo Mission Aboard the International Space Station |journal= Transactions of the Japan Society for Aeronautical and Space Sciences, Aerospace Technology Japan |volume= 12|issue= ISTS 29|pages= Pk_29–Pk_34 |doi= 10.2322/tastj.12.Pk_29|arxiv=1406.3160|bibcode=2014JSAST..12.Pk29T |s2cid=118448985 }}</ref> which is being analyzed for amino acid-related compounds and microorganisms following their return to Earth.<ref name="prelim2017">[https://repository.exst.jaxa.jp/dspace/bitstream/a-is/609841/1/SA6000060153.pdf Current State of Organics Exposure Experiments In the Tanpopo Mission] (PDF). K. Kobayashi, H. Mita, H. Y. Kebukawa, K. Nakagawa, E. Imai, H. Yano, H. Hashimoto, S. Yokobori, A. Yamagishi. JAXA. January 2017.</ref> The last samples were retrieved in February 2018 and analyses are ongoing.<ref name="Expedition Duration"/> The principal investigator is Akihiko Yamagishi, who heads a team of researchers from 26 universities and institutions in Japan, including [[JAXA]].

==Mission==
[[File:Dandelion in the wind.jpg|thumb|Dandelion seeds spread by the wind]]
The capture and exposure experiments in the Tanpopo mission were designed to confirm the hypothesis that extraterrestrial [[organic compound]]s played important roles in the generation of the first terrestrial life, as well as examination of the hypothesis of panspermia. If the Tanpopo mission can detect microbes at the higher altitude of [[low Earth orbit]] (400&nbsp;km), it will support the possible interplanetary migration of terrestrial life.<ref>[https://www.researchgate.net/publication/241270775_Microbe_space_exposure_experiment_at_International_Space_Station_(ISS)_proposed_in_Tanpopo_mission Microbe space exposure experiment at International Space Station (ISS) proposed in "Tanpopo" mission]. Research Gate, July 2010.</ref><ref>[https://www.hou.usra.edu/meetings/lpsc2017/pdf/3040.pdf In-orbit operation and initial sample analysis and curation results for the first year collection samples of the Tanpopo project]. H. Yano, S. Sasaki, J. Imani, D. Horikawa, A. Yamagishi8, et al. ''Lunar and Planetary Science XLVIII'' (2017)</ref> The mission was named after the plant [[dandelion]] (Tanpopo) because the plant's seeds evoke the image of seeds of lifeforms spreading out through space.

The Tanpopo mission exposures took place at the Exposed Facility located on the exterior of the Kibo module of the ISS from May 2015 through February 2018.<ref name="Expedition Duration"/> It collected [[cosmic dust]] and exposed dehydrated [[microorganism]]s outside the International Space Station while orbiting {{convert|400|km|mi|abbr=on}} above the Earth. These experiments will test some aspects of panspermia, a [[hypothesis]] for an [[Astrobiology|exogenesis]] origin of life distributed by [[meteoroids]], [[asteroids]], [[comets]] and [[cosmic dust]].<ref name="Conference2014">"[http://www.hou.usra.edu/meetings/lpsc2014/pdf/2934.pdf Tanpopo Experiment for Astrobiology Exposure and Micrometeoroid Capture Onboard the ISS-JEM Exposed Facility]." (PDF) H. Yano, A. Yamagishi,  H. Hashimoto1, S. Yokobori, K. Kobayashi, H. Yabuta, H. Mita, M. Tabata H., Kawai, M. Higashide, K. Okudaira, S. Sasaki, E. Imai, Y. Kawaguchi, Y. Uchibori11, S. Kodaira and the Tanpopo Project Team. 45th Lunar and Planetary Science Conference (2014).</ref> This mission will also test if terrestrial microbes (e.g., aerosols embedding microbial colonies) may be present, even temporarily and in [[Freeze-drying|freeze-dried]] form in the low Earth orbit altitudes.<ref name="Conference2014"/>

[[Image:Stardust Dust Collector with aerogel.jpg|right|thumbnail|Stardust Sample Collection (SSC) tray with [[aerogel]] blocks from the [[Stardust (spacecraft)|Stardust]] mission]]
Three key microorganisms include ''Deinococcus'' species:  ''[[Deinococcus radiodurans|D. radiodurans]]'', ''D. aerius'' and ''D. aetherius''.<ref>{{cite journal | last1 = Kawaguchi | first1 = Y. | last2 = Yang | first2 = Y. | last3 = Kawashiri | first3 = N. | last4 = Shiraishi | first4 = K. | last5 = Takasu | first5 = M. | last6 = Narumi | first6 = I. | last7 = Satoh | first7 = K. | last8 = Hashimoto | first8 = H. | last9 = Nakagawa | first9 = K. | last10 = Tanigawa | first10 = Y. | last11 = Momoki | first11 = Y.H. | last12 = Tanabe | first12 = M. | last13 = Sugino | first13 = T. | last14 = Takahashi | first14 = Y. | last15 = Shimizu | first15 = Y. | last16 = Yoshida | first16 = S. | last17 = Kobayashi | first17 = K. | last18 = Yokobori | first18 = S. | last19 = Yamagishi | first19 = A. | year = 2013 | title = The possible interplanetary transfer of microbes: assessing the viability of Deinococcus spp. under the ISS Environmental conditions for performing exposure experiments of microbes in the Tanpopo mission | journal = Orig Life Evol Biosph | volume = 43 | issue = 4–5| pages = 411–28 | doi = 10.1007/s11084-013-9346-1 | pmid = 24132659 | bibcode = 2013OLEB...43..411K | s2cid = 15967438 }}</ref> Containers holding [[yeast]] and other microbes were also placed outside the Kibo module to examine whether microbes can survive being exposed to the harsh cold environment of [[outer space]]. Also, by evaluating retrieved samples of exposed terrestrial microbes and astronomical organic analogs on the exposure panels, they can investigate their survival and any alterations in the duration of interplanetary transport.

Researchers also aim to capture [[organic compounds]] and prebiotic organic compounds — such as [[aminoacids]] — drifting in space.<ref name="Yomiuri"/>  The mission collected [[cosmic dust]] and other particles for three years by using a two-layer [[aerogel]] ultra-low density silica gel collector with a density of {{convert|0.01|g/cc|abbr=on}} for the upper layer and ~{{convert|0.03|g/cc|abbr=on}} for the base layer.<ref name="Conference2014"/> Some of the aerogel collectors were replaced every one to two years through February 2018.<ref name="Yomiuri">[http://the-japan-news.com/news/article/0002066967 Tanpopo mission to search space for origins of life]. ''The Japan News'', April 16, 2015.</ref><ref name="Expedition Duration">[https://www.nasa.gov/mission_pages/station/research/experiments/2201.html Tanpopo - Expedition Duration]. Published by NASA.</ref>

The official ISS experiment code name is "Astrobiology Japan" representing "Astrobiology exposure and micrometeoroid capture experiments".<ref>{{Cite journal |last1=Cottin |first1=Hervé |last2=Kotler |first2=Julia Michelle |last3=Billi |first3=Daniela |last4=Cockell |first4=Charles |last5=Demets |first5=René |last6=Ehrenfreund |first6=Pascale |last7=Elsaesser |first7=Andreas |last8=d’Hendecourt |first8=Louis |last9=van Loon |first9=Jack J. W. A. |last10=Martins |first10=Zita |last11=Onofri |first11=Silvano |last12=Quinn |first12=Richard C. |last13=Rabbow |first13=Elke |last14=Rettberg |first14=Petra |last15=Ricco |first15=Antonio J. |date=2017 |title=Space as a Tool for Astrobiology: Review and Recommendations for Experimentations in Earth Orbit and Beyond |journal=Space Science Reviews |language=en |volume=209 |issue=1 |pages=83–181 |doi=10.1007/s11214-017-0365-5 |issn=1572-9672 |doi-access=free}}</ref>

==Objectives==

The objectives of Tanpopo lie in following 6 topics:<ref>[https://www.nasa.gov/mission_pages/station/research/experiments/2201.html Astrobiology Exposure and Micrometeoroid Capture Experiments (Tanpopo)]. 18 October 2017. Hideyuki Watanabe. JAXA. Published by NASA.</ref>
#Sources of organic compounds to the surface of Earth<ref name="Yuko2016"/> 
#Organic compounds on micrometeorites are being exposed to the space environment before return to Earth for analyses
#Possibility for terrestrial microbe detection at the ISS orbital altitude due to the processes of volcanic eruptions, thunderstorms, meteorite impacts, and electromagnetic fields around the Earth
#Survival of some species of microbes in the space environment
#Capture of artificial micro-particles (space debris) by aerogel
#Two aerogel densities to capture particles moving at high velocity

==Analyses==
The aerogels were placed and retrieved by using the robotic arm outside Kibo. The first year samples were returned to Earth in mid-2016,<ref name="Yuko2016">{{cite journal |title=Investigation of the Interplanetary Transfer of Microbes in the Tanpopo Mission at the Exposed Facility of the International Space Station |journal=Astrobiology |date=13 May 2016 |last=Kawaguchi |first=Yuko |volume=16 |issue=5 |pages=363–376 |doi=10.1089/ast.2015.1415 |display-authors=etal |pmid=27176813|bibcode=2016AsBio..16..363K }}</ref> panels from the second year were brought back in late 2017, and the last set ended exposure in February 2018.<ref name="Expedition Duration"/> The last aerogels were placed inside the 'landing & return capsule' in early 2018 and ejected toward Earth for retrieval.<ref name="Conference2014"/> After retrieving the aerogels, scientists are  investigating the captured microparticles and tracks formed, followed by microbiological, organochemical and mineralogical analyses. Particles potentially containing microbes will be used for [[PCR amplification]] of [[rRNA]] genes followed by [[DNA sequencing]].<ref>[http://www.dlr.de/me/en/Portaldata/25/Resources/dokumente/institut_me/institutsseminar/abstracts_2014/abstract_kawaguchi_y_09102014.pdf Tanpopo mission: Astrobiology exposure and capture experiments of microbes and micrometeoroid]. (PDF) Yuko Kawaguchi. 2014.</ref>

Early mission results from the first sample show evidence that some clumps of microorganism can survive for at least one year in space.<ref name="AGU2017">[http://blogs.agu.org/geospace/2017/05/19/early-tanpopo-mission-results-show-microbes-can-survive-space/ Early Tanpopo mission results show microbes can survive in space]. American Geophysical Union - Geospace. Larry O'Hanlon. 19 May 2017.</ref>  This may support the idea that clumps greater than 0.5 millimeters of microorganisms could be one way for life to spread from planet to planet.<ref name="AGU2017"/>  It was also noted that [[glycine]]'s decomposition was less than expected, while [[hydantoin]]'s recovery was much lower than glycine.<ref name="prelim2017"/>

In August 2020, scientists reported that [[bacteria]] from Earth, particularly ''[[Deinococcus radiodurans]]'' bacteria, which is highly resistant to [[environmental hazard]]s, were found to survive for three years in [[outer space]], based on studies conducted on the International Space Station. These findings support the notion of panspermia, the hypothesis that [[life]] exists throughout the [[Universe]], distributed in various ways, including [[space dust]], [[meteoroid]]s, [[asteroid]]s, [[comet]]s, [[Minor planet|planetoid]]s or [[Contamination|contaminated]] [[spacecraft]].<ref name="CNN-20200826">{{cite news |last=Strickland |first=Ashley |title=Bacteria from Earth can survive in space and could endure the trip to Mars, according to new study |url=https://www.cnn.com/2020/08/26/world/earth-mars-bacteria-space-scn/index.html |date=26 August 2020 |work=[[CNN News]] |access-date=26 August 2020 }}</ref><ref name="FM-20200826">{{cite journal |author=Kawaguchi, Yuko |display-authors=et al. |title=DNA Damage and Survival Time Course of Deinococcal Cell Pellets During 3 Years of Exposure to Outer Space |date=26 August 2020 |journal=[[Frontiers in Microbiology]] |volume=11 |page=2050 |doi=10.3389/fmicb.2020.02050 |pmid=32983036 |pmc=7479814 |doi-access=free }}</ref>

==See also==
{{Portal|Astronomy|Biology|Spaceflight}}
*{{annotated link|Astrobiology}}
*{{annotated link|Bion (satellite)|Bion}}
*{{annotated link|BIOPAN}}
*{{annotated link|Biosatellite program}}
*{{annotated link|EXPOSE}}
*{{annotated link|List of microorganisms tested in outer space}}
*{{annotated link|O/OREOS}}
*{{annotated link|OREOcube}}
*{{annotated link|Stardust (spacecraft)|Stardust}} mission

==References==
{{reflist}}

==External links==
*[http://www.mpi-hd.mpg.de/cosmicdust/ Cosmic Dust Group]

{{Astrobiology}}
{{Japanese space program}}
{{Molecules detected in outer space}}

[[Category:Astrobiology space missions]]
[[Category:Origin of life]]
[[Category:Cosmic dust]]
[[Category:Sample return missions]]
[[Category:Space exposure experiments]]
[[Category:Space science experiments]]
[[Category:Space-flown life]]