Commercial Generic Bioprocessing Apparatus Science Insert - 06: Ants in Space (CSI-06) - 07.12.17

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ISS Science for Everyone

Science Objectives for Everyone
Commercial Generic Bioprocessing Apparatus Science Insert – 06: Ants in Space (CSI-06) compares behavior differences in groups of ants living in normal gravity and microgravity conditions. It measures how the interactions among ants in a group depend on the number of ants in a given area. These interactions may be important in determining group behavior. Cameras record ants living on the International Space Station, and software analyzes their movement patterns and interaction rates. Students in grades K-12 observe the videos in near real-time as the ISS experiment and conduct their own classroom experiments as part of a related curriculum.
Science Results for Everyone
Ants on a spaceship! The way that ant colonies collectively search for resources using local cues has potential applications such as designing search and rescue operations using robots. Ants in microgravity searched less efficiently, perhaps due to difficulty holding onto the surface and getting dislodged. At any time, about seven percent of the ants in space were free floating and do not have a "foothold" on the surface. This may have interfered with each individual ant’s ability to assess the density of ants in an area and adjust its search path accordingly. To what extent this affected collective search behavior is not yet known.

The following content was provided by Stefanie Countryman, M.B.A., and is maintained in a database by the ISS Program Science Office.
Experiment Details

OpNom: Ants in Space

Principal Investigator(s)
Deborah Gordon, Ph.D., Stanford University, Stanford, CA, United States

Michael Greene, University of Colorado-Denver, Denver, CO, United States
Stefanie Countryman, M.B.A., BioServe Space Technologies, Boulder, CO, United States

BioServe Space Technologies, University of Colorado, Boulder, CO, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
National Laboratory Education (NLE)

Research Benefits
Earth Benefits, Scientific Discovery

ISS Expedition Duration
September 2013 - September 2014

Expeditions Assigned

Previous Missions
Space Technology and Research Students (STARSTM), a similar investigation was performed on STS-93 and STS-107. CSI-01 began on ISS Expedition 14 and completed during ISS Expedition 15. CSI-02 was performed during ISS Expeditions 15 - 17. CSI-03 began operation during Expedition 18 and was completed during Expedition 19.

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Experiment Description

Research Overview

  • Commercial Generic Bioprocessing Apparatus Science Insert - 06: Ants in Space (CSI-06) compares how the interaction rate of a group of ants depends on density, the number of ants per unit area, in normal gravity and microgravity conditions.

  • The investigation houses eight ant habitats containing three areas: nest area, Forage Area 1 and Forage Area 2.  Each area is separated by a sealed “door.”

  • Approximately 100 Tetramorium caespitum or pavement ants are launched in the nest area of each habitat.  Once the habitats are on the International Space Station (ISS) a crew member “activates” the experiment by releasing the ants from the nest area into Forage Area 1 by lowering a barrier door.  Once the ants have thoroughly explored Forage Area 1 (approximately 25 minutes), Forage Area 2 is opened. 

  • Ground controls are conducted on a slight offset from the spaceflight experiment. 

  • The ants’ movements are videotaped using the HD video cameras on board the ISS and a similar HD camera for the ground controls.

  • Analyses of movement patterns and interaction rates captured on video are completed using a tracking software program.


Ant colonies operate without central control. No one ant directs the behavior of a group of ants and no ant decides what another ant should do. Instead ants use only whatever information they pick up nearby, and in the aggregate, the combination of responses to local cues produces the coordinated behavior of the colony. Such distributed algorithms are now being used to coordinate the behavior of swarms of robots as well as other complex human problems.

How do ants evaluate group density? Studies of different species suggest that they use interaction rate. The rate at which each ant meets other ants is a measure of how many other ants are moving around the same area. Ants need to evaluate group density in many different situations. One example is the search problem. If you asked a group of people to find a needle in a haystack, they might come up with a plan for dividing up the haystack and having each person search part of it. The ants can’t do that. Instead the ants must find a way to cover the ground so that if there is something out there to find, some ant will eventually get close enough to find it.

One way that ants solve the search problem is to adjust their paths to density. When there are many ants in a small space, each ant can move at random, because a random walk tends to go round and round the same place. But when density is low, and there are few ants, each one has to walk a straighter path to cover enough ground to search the area thoroughly. Argentine ants adjust their path shape in this way. (Gordon 1995)

Commercial Generic Bioprocessing Apparatus Science Insert - 06: Ants in Space (CSI-06)  compares how the interaction rate of a group of ants (Tetramorium caespitum) changes as a result of density, the number of ants per unit area, in normal gravity and microgravity conditions.

The ants are kept in a small container divided into a humid nest area and a foraging area. The foraging area is divided into a smaller and larger part separated by a sealing door.

During transport to the International Space Station (ISS), the ants are in the nest area.Once the ant habitats are on board the ISS, a crewmember opens the door between the nest area and Forage Area 1.  Over a 25 minute period, the ants spread out over the forage area.  .  The initial foray into Forage Area 1 is the high density condition of the experiment.   The ant interactions and path shape are monitored on video, for this 25 minute period of time. After 25 minutes the crewmember opens the door to Forage Area 2, which begins the low density condition of the experiment.  The video continues for another 30 minutes at which time the experiment is considered complete.  The experiment examines how the interaction rate and path shape change once density is decreased.

The experiment is conducted with ants from two different colonies.  Each colony has four replicates for a total of eight samples.  There are matching ground controls.  The investigation seeks to answer the following questions: does the relation of density and interaction rate change when ants have less control over their movement (microgravity)? Does path shape differ in microgravity? Results from this experiment could provide insight into how ants regulate interaction in normal conditions. Additionally, very little is known about how ants control path shape and results could provide some clues about how ants generate a random walk or a straighter path.   Finally, the results could help to elucidate how ants coordinate their behavior and may have applications in other systems that rely on distributed algorithms, such as robots deployed for search and rescue operations.

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Space Applications
The investigation brings information about life science research being conducted by the space program to students in grades K-12, generating interest in science, technology, engineering and mathematics (STEM) fields. Results from CSI-06 could also provide insight into ant behavior or swarm intelligence, or how the simple actions of individuals add up to the complex behavior of a group.  Understanding swarm intelligence helps create mathematical procedures for solving complex human problems, such as routing trucks, scheduling airlines, or telecommunications efficiency. 

Earth Applications

Ant colonies do not have centralized leaders; instead, ants coordinate their behavior according to cues from nearby ants. This behavior is being used to design computer programs that can control swarms of robots. CSI-06 investigates whether microgravity alters the behavior of ants in a colony. The investigation also provides an opportunity for educators and students in grades K-12 to participate in life science experiments operating on the International Space Station.

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Operational Requirements and Protocols

There are eight samples each within a different Ant Habitat.  Four samples are activated at one time for a total of two activation periods.  Each experiment lasts between 50 and 70 minutes.  The HD video data is downlinked as soon as possible following video recording of the two experiment activations.  The Ant Habitats are returned to Earth on board a future SpaceX mission..  The ants live their life out on board the ISS.  Crew time is required to activate the experiments and set-up video recording of the experiment and to downlink the video recording once completed.

The Ant Habitats are soft stowed in the dark in ambient conditions until activated on board the ISS.  The crew sets up the area where the Ant Habitats are videotaped.  Ambient light within the ISS is used for the recording.  The crew activates four Ant Habitats at one time.  While the experiment operates (50-70 minutes) the crew is not required to monitor the ants other than to release them from the nest area into Forage Area 1 and then to open Forage Area 2 following saturation of Forage Area 1 with ants.  

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Decadal Survey Recommendations

Information Pending

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Results/More Information

Because ants perceive only locally, mostly by chemical and contact cues, their colonies operate without central control to collectively search for resources and to monitor the colony’s environment. Examining how ants in diverse environments solve the problem of collective search can give insights on how different forms of collective behavior evolve. Solutions to the problem of collective search are currently of much interest in robotics, for example, to design ways that robots can use local information to perform search and rescue operations. An experiment conducted on the International Space Station (ISS) examined how ants (Tetramoriumcaespitum) perform collective search in space. Analysis shows that the ants did not perform collective search as effectively in microgravity as they did in the ground controls. When the area to be searched is expanded in their ISS habitat, they did not thoroughly search the new area. The ants did not spread out or spread out much less than they did on Earth, so more regions were never, or very rarely, visited by ants and the mean number of ant visits to each part of the search area was lower. Space ants traverse less ground and take more convoluted paths when the area to be searched expanded. It appears that the difficulty of holding onto the surface interfered with the ants’ ability to search collectively. Ants frequently lost contact with the surface, but showed a remarkable ability to regain contact. In space, the relation of number of ants and the local density of ants in any one area may have been obscured by the fact that at any time, about 7% of the ants were not in contact with the surface and landed somewhere else, disrupting the relation between population density and encounter with each others. This disruption may have interfered with each ant’s ability to assess local density and to adjust its path shape accordingly. It is not known how much the collective search behavior of ants in microgravity was due to unreliable information about local density, and there was no clear relation of path shape and density either on Earth or in Space.

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Results Publications

    Countryman S, Stumpe MC, Crow SP, Adler FR, Greene M, Vonshak M, Gordon D.  Collective search by ants in microgravity. Frontiers in Ecology and Evolution. 2015 March 30; 3(25): 10 pp. DOI: 10.3389/fevo.2015.00025.

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Ground Based Results Publications

    Goulart C, Rupert M, Hoehn A.  Habitat Development in Support of Small Scale Biological and Biochemical Space Experiments. International Conference on Environmental Systems, Vancouver, Canada; 2002

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ISS Patents

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Related Publications

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Related Websites
BioEd Online
Butterfly Pavilion
BioServe Space Technologies
Monarch Watch
NIH BioMed-ISS Meeting Video Presentation, 2009—CSI-06
NIH BioMed-ISS Meeting, 2009—CSI-06
Orions Quest: Authentic Research for Today's Youth

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image NASA Image: ISS038E029155 - Close-up view of an Ants in Space ant forage habitat.
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image NASA Image: ISS038E029056 - Image of ant habitat on board the ISS.
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NASA Image: ISS038E029065 - NASA astronaut Rick Mastracchio uses a video camera to photograph the Ant Forage Habitat.

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image NASA Image: ISS038E029077 - NASA astronaut Mike Hopkins uses a video camera to photograph the Ant Forage Habitat.
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