LSDA: Experiment - ALTEA

EXPERIMENT INFORMATION

Anomalous Long Term Effects in Astronauts' - Dosimetry (ALTEA_Dosi)

Principal Investigators

+ Narici, Livio

+ George, Tamra

Research Area:

Radiation biology

Species Studied

Scientific Name: Homo sapiens Species: Human

Study Type

+ International Space Station (ISS)

Description

OBJECTIVES:
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.

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 Extravehicular 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 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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APPROACH:
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.

RESULTS:
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 confirm 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).

Publications

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; 176(3): 397-406. [

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Keywords

Anisotropy

Radiation tolerance

Data Information

Data Availability

Archive is complete. No data sets are available for this experiment. Please Contact LSDA if you know of available data for this investigation.

Parameters

Galactic cosmic rays

Radiation measurement

Mission/Study Information

Mission	Launch/Start Date	Landing/End Date	Duration
Expedition 17	04/08/2008	10/23/2008	198 days
Expedition 18	10/12/2008	04/17/2009	187 days
Expedition 19	03/26/2009	10/11/2009	199 days
Expedition 20	05/27/2009	10/11/2009	137 days
Expedition 21	10/11/2009	12/01/2009	51 days
Expedition 22	11/30/2009	03/18/2010	109 days
Expedition 23	03/18/2010	06/01/2010	75 days
Expedition 24	06/01/2010	09/25/2010	117 days
Expedition 25	09/24/2010	11/25/2010	31 days
Expedition 26	11/26/2010	03/16/2011	111 days
Expedition 27	03/14/2011	05/23/2011	70 days
Expedition 28	05/23/2011	09/15/2011	115 days
Expedition 29	09/16/2011	11/21/2011	40 days
Expedition 30	11/14/2011	04/27/2012	166 days
Expedition 31	04/27/2012	07/01/2012	65 days
Expedition 32	07/01/2012	09/16/2012	78 days

Additional Information

Managing NASA Center

Johnson Space Center (JSC)

Responsible NASA Representative

Johnson Space Center LSDA Office
Project Manager: Jessica Keune

Institutional Support

National Aeronautics and Space Administration (NASA)

Italian Space Agency (ASI)

Similar Experiments or Analyses

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

+Anomalous Long Term Effects in Astronauts' Central Nervous System - Shield (ALTEA_Shield)

+Space Radiation Effects on the Central Nervous System (Alteino)