Anomalous Long Term Effects in Astronauts' - Dosimetry (ALTEA-Dosi) - 05.13.15

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

ISS Science for Everyone

Science Objectives for Everyone
Anomalous Long Term Effects in Astronauts' - Dosimetry (ALTEA-Dosi) will operate in DOSI mode (unmanned) to provide an assessment of the radiation environment inside the International Space Station (ISS), U.S. Laboratory, Destiny.
Science Results for Everyone
Radiation may have given Peter Parker spidey senses, but it poses serious risks to astronauts. To protect future space explorers, scientists need a detailed characterization of the radiation environment in spacecraft and effectiveness of spacecraft shielding. This study assessed radiation inside the International Space Station, confirming that it is directional and that ionizing particle energy is affected by the amount of shielding in the station hull. Detailed, 3D measurements made of the components and total energy provide information about the qualities of space radiation and how it affects an area from different directions, which will help scientists design and interpret future experiments to help protect astronauts.

The following content was provided by Livio Narici, Ph.D., Tamra George, 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
Tamra George, Lockheed Martin, Houston, TX, United States

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

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

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
Human Exploration and Operations Mission Directorate (HEOMD)

Research Benefits
Information Pending

ISS Expedition Duration
April 2008 - September 2012

Expeditions Assigned

Previous ISS Missions
ALTEA collected dosimetry data during ISS Expeditions 13-15.

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Experiment Description

Research Overview

  • Radiation exposure represents one of the greatest risks to humans traveling on exploration missions beyond low Earth orbit (LEO).

  • Anomalous Long Term Effects in Astronauts' - Dosimetry (ALTEA-Dosi) will measure the particle flux in the U.S. Laboratory, Destiny on the International Space Station (ISS), being able to discriminate particle type and measure particle trajectory and deposited energy.

  • Comparison between data collected by ALTEA-Dosi, Intravehicular Charged Particle Directional Spectrometer (IVCPDS), and Extravhicular Charged Particle Directional Spectrometer (EVCPDS) will aid space agencies in understanding the radiation spectrum and radiation shielding characteristics of the Destiny.

Anomalous Long Term Effects in Astronauts' - Dosimetry (ALTEA-Dosi) will utilize the ALTEA hardware: a helmet-shaped device holding 6 silicon particle detectors designed to measure cosmic radiation passing through the detectors. The six identical silicon detector units (SDU) contain three sets of x-y plane silicon strip detectors. Each plane detector is 300 micrometers thick and divided into 64 strips. An event is recorded if at least all 3 x-plane detectors have signals above threshold, and these signals are the sum of the energy deposited in four adjacent strips. The geometry factor of each SDU is 250 cm-sr and is capable of measuring particle trajectory with an angular accuracy of 1.8 degrees and can resolve individual ionizing particles of charge 4 to 28 for energies above 25 MeV/n. In previous research, an electroencephalograph (EEG) measured the brain activity of the crewmember to determine if radiation strikes caused changes in the electrophysiology of the brain in real time. A Visual Stimulator performed tests of the crewmembers' overall visual system.

ALTEA-Dosi will continuously measure the cosmic radiation, without crewmember aid or wearing of the helmet, in the International Space Station (ISS) U.S. Laboratory, Destiny. The ALTEA-Dosi data will also be compared with data collected by Intravehicular Charged Particle Directional Spectrometer (IVCPDS), and Extravhicular Charged Particle Directional Spectrometer (EVCPDS) instruments. The IVCPDS and EVCPDS instruments measure the energy and species of individual ionizing particles of charge 1 to 10, where ALTEA-Dosi measures charge of 4 to 28; therefore, these data sets complement one another allowing for the measurement of the abundances of all ions that contribute significantly to crew radiation exposure.

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Space Applications
Outside the protection of Earth's atmosphere 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 measurements made by the ALTEA hardware will help scientists characterize the heavy ion radiation spectrum inside the ISS, and the measurements while the ISS is at high geomagnetic latitudes will give insight to the radiation environment outside the Earth's magnetosphere.

Earth Applications
Previous research data provided from the ALTEA investigation 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 than 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.

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Operational Requirements
ALTEA-Dosi will obtain accurate measurements of the radiation environment inside the ISS to study the particle fluxes, in relation with the known fluxes outside the station. ALTEA-Dosi does not require crew time after it is unstowed

Operational Protocols
ALTEA-Dosi requires positioning of the helmet tilted at 90 degrees and to switch on/off via the protocol from the laptop. At the beginning of each ALTEA-Dosi measurement the crewmember will start the automatic set-up/calibration procedure and the Dosi session. At the end the crewmember will stop the Dosi measurement. During the measurement the data collected by the particle detectors needed to study energy, trajectory, and type of the cosmic particles will be sent to Earth in real time via automated telemetry.

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Results/More Information

In addition to measuring the radiation exposure on a crewmember’s head, the Anomalous Long Term Effects in Astronauts' Central Nervous System (ALTEA) hardware can also provide an assessment of the radiation environment in the ISS. Since June 1st 2009, a new analysis technique has been employed by researchers to make use of the 3-dimensional capability of the ALTEA space radiation detector to measure both the direction of radiation particle flow and its linear energy transfer (LET) rate inside the Space Station.

The radiation field in low-Earth orbit (LEO) is a combination of galactic cosmic rays (GCR), trapped ions (in the South Atlantic Anomaly, SAA) and radiation due to solar events. It penetrates the International Space Station (ISS) through the vessel hull as well as through the uneven shielding due to the many racks, experimental devices, etc. on the walls. Results from this study further confirms that the radiation environment inside the Space Station is directional and the energy of ionizing particles is affected by the amount of shielding these particles encountered on their path. High-LET particles show a minimum along the longitudinal axis (most shielded) and a maximum perpendicular to the cylindrical hull of the ISS. However, the sum of the energy from light ions and the fragments produced by heavier ions appears to be independent of direction, and the average radiation dose rate measured by ALTEA is similar to those previously measured by the Tissue Equivalent Proportional Counter (TEPC) and the Columbia Resin #39 (CR-39) detectors. Researchers are planning to move the ALTEA unit to another ISS site for more survey.

Detailed measurement of the angular components and total energy of space radiation is relevant in helping scientists to design radiation experiments and interpret results by providing information about the different quality of radiation impinging on the same spot from different directions. Recent calculations show that space radiation may exceed recommended risk levels for long voyages outside the protection of the Earth’s magnetic shield and atmosphere, and the major goal of space radiation research is to enable the human exploration of space within acceptable radiation risks. This requires a detailed characterization of the space environment in which the astronauts are living and are expected to live (Di Fino et al., 2011).

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Results Publications

    Di Fino L, Agostini F, Larosa M, Narici L, Zaconte V.  The ALTEA experiment onboard the International Space Station. Journal of Physics: Conference Series. 2012 October 1; 383: 012006. DOI: 10.1088/1742-6596/383/1/012006.

    Di Fino L, Casolino M, De Santis C, Larosa M, La Tessa C, Narici L, Picozza P, Zaconte V.  Heavy-Ion Anisotropy Measured by ALTEA in the International Space Station. Radiation Research. 2011 September; 176(3): 397-406. DOI: 10.1667/RR2179.1. PMID: 21561339.

    Zaconte V, Casolino M, De Santis C, Di Fino L, La Tessa C, Larosa M, Narici L, Picozza P.  The radiation environment in the ISS-USLab measured by ALTEA: Spectra and relative nuclear abundances in the polar, equatorial and SAA regions. Advances in Space Research. 2010 09/15/2010; 46(6): 797-799. DOI: 10.1016/j.asr.2010.02.032.

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Ground Based Results Publications

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ISS Patents

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Related Publications

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Related Websites

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image NASA Image: ISS013E65565 - ALTEA helmet inside the U.S. Laboratory of ISS during Expedition 13.
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image NASA Image: ISS014E16208 - Astronaut Sunita Williams, Expedition 14 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.
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