Anomalous Long Term Effects in Astronauts' Central Nervous System (ALTEA) - 08.23.18

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
Anomalous Long Term Effects in Astronauts' Central Nervous System (ALTEA) integrates several diagnostic technologies to measure the effect of the exposure of crewmembers to cosmic radiation. It will improve the understanding of the impacts that radiation has on the human central nervous system functions, and will study the flashes from cosmic radiation that astronauts have reported since the Apollo flights. ALTEA will also provide an assessment of the radiation environment in the ISS.
Science Results for Everyone
Pirates saw green flashes at sunset; many space-flight crew members see light flashes at night during a mission. For space crew, these flashes  are thought to come from high-energy particles interacting with the eyes and brain. The Anomalous Long Term Effects of Astronauts (ALTEA) investigation measured the effect of exposure to radiation in space, particularly on the central nervous system. One part of the study relates the light flashes to the radiation passing through the spacecraft. This knowledge helps to more accurately determine the risk and  the specific type of radiation exposure of ISS crew members, and to develop ways to protect future crews.

The following content was provided by Livio Narici, Ph.D., and is maintained in a database by the ISS Program Science Office.
Experiment Details


Principal Investigator(s)
Livio Narici, Ph.D., University of Roma Tor Vergata and INFN-Roma2, Rome, Italy

Piergiorgio Picozza, Ph.D., University of Roma Tor Vergata, Rome, Italy
Walter G. Sannita, M.D., University of Genoa, Genoa, Italy

Italian Space Agency (ASI), Rome, Italy
Alenia Spazio - Laben, Milano, Italy

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
Italian Space Agency (ASI)

Research Benefits
Information Pending

ISS Expedition Duration
April 2006 - October 2007

Expeditions Assigned

Previous Missions
The predecessor of ALTEA, Alteino, was conducted aboard ISS in April of 2002 during a Soyuz taxi mission.

^ back to top

Experiment Description

Research Overview

  • Astronauts in orbit are exposed to cosmic radiation that is of sufficient frequency and intensity to cause effects on the central nervous system, such as the perception of flashes of light that have been reported since the days of Apollo. Radiation exposure represents one of the greatest risks to humans traveling on exploration missions beyond low Earth orbit (LEO).

  • The ALTEA experiment, developed by the Italian Space Agency (ASI), will measure details about the cosmic radiation passing through a crewmembers head, while measuring the brain activity and visual perception. Furthermore, ALTEA will measure the particle flux in the U.S. Lab on the International Space Station (ISS), being able to discriminate the type of particles, to measure their trajectories and the delivered energies.

  • This will provide in-depth information on the radiation experienced and its impact on the nervous systems and visual perception. ALTEA will also develop new risk parameters and possible countermeasures aimed at the functional central nervous system risks.

Long-duration space flights result in increased cosmic radiation exposure to astronauts. The ALTEA hardware is designed to measure particle radiation in the space environment, and determine how this radiation impacts the central nervous system (CNS) of the crew. The experiment is comprised of a helmet-shaped device holding 6 silicon particle detectors designed to measure cosmic radiation passing through the brain. The detectors measure the trajectory, energy, and species of individual ionizing particles. At the same time an electroencephalograph (EEG) will measure the brain activity of the crewmember to determine if radiation strikes cause changes in the electrophysiology of the brain in real time.

A common effect of radiation exposure that is reported by astronauts is the perception of light flashes. The actual mechanism of these light flashes is not understood. Earlier studies on the Mir space station suggest that both heavy nuclei and protons trigger abnormal CNS responses. (Casolino et al, 2003). A Visual Stimulator tests the astronaut's overall visual system, including dark adaptation stimuli to monitor visual status. . While not manned, the ALTEA hardware provides a continuous measure of the cosmic radiation in the ISS U.S. Laboratory, Destiny. The neurophysiological effects of cosmic radiation in long term space travel have never been explored with the depth of the ALTEA experiment. Data collected will help quantify risks to astronauts on future long-duration space missions and propose optimized countermeasures.

^ back to top


Space Applications
Astronauts from Apollo missions onward have reported seeing unexplained light flashes (phosphenes), which were attributed to abnormal brain function caused by space radiation. Outside the protection of Earth's magnetic shield, ISS crewmembers are exposed to increased radiation, but the radiation environment is even more severe as exploration crews leave Earth's geomagnetic field and transit to other planets. The tests conducted using the ALTEA hardware will help scientists characterize how the heavy ion radiation of space impacts the brain and whether or not that radiation causes any temporary or permanent abnormalities in the brain function and the visual system in particular.

Earth Applications
Data provided from ALTEA can lead to further understanding of how radiation may affect brain function on Earth as well as in space. While the levels of heavy ion radiation are much higher in space that on Earth, any understanding into the way radiation may alter brain function is extremely useful to neuroscientists of these studies. Ion therapies to treat brain tumors will also benefit from the ALTEA results.

^ back to top


Operational Requirements and Protocols
Once the crewmember being tested has set up the experiment he or she then wears the ALTEA helmet for roughly 90 minutes, the time it takes for the ISS to completely orbit the Earth. ALTEA will require 6 of these tests.
A typical manned run of the experiment involves setting up the ALTEA hardware and performing calibrations before the ALTEA helmet is donned by the crewmember. The crewmember will then wear the helmet for 90 minutes while the sensors in the helmet are collecting EEG measurement. The unmanned run does not require crewtime after it is launched.

^ back to top

Decadal Survey Recommendations

Information Pending

^ back to top

Results/More Information

Since the Apollo flights to the moon, it has been known that most astronauts experience sudden visual light flashes during spaceflight. Described in early reports as occurring in darkness and typically before falling asleep, these light flashes are thought to originate as an effect of high-energy particles, abundant in space, interacting with the eye and/or the visual anatomy. The ALTEA project, active on ISS since August 2006 and currently investigating the ISS-US Lab radiation environment (ALTEA-DOSI, ALTEA-SHIELD/survey), has also been studying the risks of possible damage to the brain from particle radiation in space (ALTEA-CNSM). It is proposed that these interaction effects may go well beyond light flashes and could constitute a new kind of risk for longer space voyages. One study focus was on these abnormal visual perceptions and the impact on retinal and brain visual structures. ALTEA, with its 6 double detectors covering most of the astronaut’s head, permits a 3-dimensional reconstruction of the energy released in the brain by ionizing particles. In addition, ALTEA monitors the functional state of the optical pathway in order to interpret the biophysical mechanisms generating abnormal perceptions.  A survey was conducted in 2003 with 59 astronauts on the perception of light flashes, or "phosphenes", during missions. It was found that 80% of space explorers experience light flashes at some point (mainly before sleep when the eyes are night adjusted). As many as 20% of the respondents thought that light flashes sometimes disturbed their sleep. Light flashes are predominantly white, but other colors are mentioned, in particular yellow (10%). Most light flashes have an elongated shape, like stripes or comets, and are associated with a perception of motion. The motion is left-right or in-out, but never up-down, and about 8% of light flashes have a "blob" shape. There is a positive correlation between light flashes and radiation flux, and the majority of light flash in space is most likely produced by a direct interaction of an ion with the retina, although there is indirect indication that light flashes can result from interaction between particles and brain structures as well. 
Solar Particle Events (SPEs) could represent a high radiation hazard for the ISS crew. During most of the December 2006 SPE, the ALTEA detector collected continuous data inside the U.S. Lab module. Results indicate that a SPE significantly affects radiation energy levels in the ISS, producing a substantial increase of low energy radiation rate, which reaches the highest values in quite short periods. This confirms the need to consider SPEs in those biological processes for which radiation rate plays an important role. These results provide the first information for charged radiation risk assessment in space habitats during a SPE.

^ back to top

Results Publications

    Narici L.  Heavy Ions Light Flashes and Brain Functions: Recent Observations at Accelerators and in Spaceflight. New Journal of Physics. 2008 July 28; 10(7): 075010. DOI: 10.1088/1367-2630/10/7/075010.

    Larosa M, Agostini F, Casolino M, De Santis C, Di Fino L, La Tessa C, Narici L, Picozza P, Rinaldi A, Zaconte V.  Ion Rates in the International Space Station During the December 2006 Solar Particle Event. Journal of Physics G: Nuclear and Particle Physics. 2011; 38(9): 095102. DOI: 10.1088/0954-3899/38/9/095102.

    Zaconte V, Casolino M, Di Fino L, La Tessa C, Larosa M, Narici L, Picozza P.  High Energy Radiation Fluences in the ISS-USLab: Ion Discrimination and Particle Abundances. Radiation Measurements. 2010 February; 45(2): 168–172. DOI: 10.1016/j.radmeas.2010.01.020.

    La Tessa C, Di Fino L, Larosa M, Narici L, Picozza P, Zaconte V.  Estimate of the Space Station Shielding Thickness at a USLab Site Using ALTEA Measurements and Fragmentation Cross Sections. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms. 2009 October 1; 267(9): 3383-3387. DOI: 10.1016/j.nimb.2009.06.107.

    Narici L, Belli F, Bidoli V, Casolino M, De Pascale MP, Di Fino L, Furano G, Modena I, Morselli A, Picozza P, Reali E, Rinaldi A, Ruggieri D, Sparvoli R, Zaconte V, Sannita WG, Carozzo S, Licoccia S, Romagnoli P, Traversa E, Cotronei V, Vazquez M, Miller J, Salnitskii VP, Shevchenko OI, Petrov VP, Trukhanov KA, Galper A, Khodarovich A, Korotkov MP, Popov AN, Vavilov N, Avdeev S, Boezio M, Bonvicini W, Vacchi A, Zampa N, Mazzenga G, Ricci M, Spillantini P, Castellini G, Vittori R, Carlson P, Fuglesang C, Schardt D.  The ALTEA/ALTEINO projects: studying functional effects of microgravity and cosmic radiation. Advances in Space Research. 2004; 33(8): 1352 - 1357. DOI: 10.1016/j.asr.2003.09.052. PMID: 15803627.

^ back to top

Ground Based Results Publications

    Zaconte V, Belli F, Bidoli V, Casolino M, Di Fino L, Narici L, Picozza P, Rinaldi A, Sannita WG, Finetti N, Nurzia G, Rantucci E, Scrimaglio R, Segreto E, Schardt D.  ALTEA: The Instrument calibration. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms. 2008 May; 266(9): 2070-2078. DOI: 10.1016/j.nimb.2008.02.072.

^ back to top

ISS Patents

^ back to top

Related Publications

^ back to top

Related Websites

^ back to top


image Flight Model ALTEA helmet and detectors, the front one panel removed and put on a side for seeing the visual simulator at KSC. Image courtesy of Unione Astrofili Italiana.
+ View Larger Image

image Astronaut, Bill MacArthur wearing the ALTEA helmet during baseline data collection at JSC. Image courtesy of Unione Astrofili Italiana.
+ View Larger Image

image NASA Image: ISS013E65565 - ALTEA helmet inside the U.S. Laboratory of ISS during Expedition 13.
+ View Larger Image

image NASA Image: ISS013E65567 - ISS Science Officer, Jeff Williams, in the U.S. Laboratory of ISS next to the ALTEA helmet during Expedition 13.
+ View Larger Image

image Screen shot of Expedition 13 ISS Science Officer, Jeff Williams, using the ALTEA helmet during one of the 90 minute sessions.
+ View Larger Image

image STS-116/12A.1 ESA Astronaut Christer Fuglesang performs the ALTEA investigation. In this image, Fuglesang's head is located in the ALTEA helmet.
+ View Larger Image

image NASA Image: ISS014E16195 - Astronaut Sunita Williams, Expeditions 14 and 15 Flight Engineer, receives assistance from Astronaut Michael Lopez-Alegria, Expedition 14 Commander, in donning a sensor studded cap as she prepares to calibrate equipment for the Anomalous Long Term Effects in Astronauts' Central Nervous System (ALTEA) experiment in the Destiny laboratory module.
+ View Larger Image

image NASA Image: ISS014E16208 - Astronaut Sunita Williams, Expeditions 14 and 15 Flight Engineer, wears the Anomalous Long Term Effects in Astronauts' Central Nervous System (ALTEA) experiment helmet while conducting the experiment in the Destiny laboratory module.
+ View Larger Image

image NASA Image: ISS032E005613 - View of Anomalous Long Term Effect on Astronauts (ALTEA) hardware.
+ View Larger Image