The Fine-Resolution Epithermal Neutron Detector (FREND) is a
neutron detector
Neutron detection is the effective detection of neutrons entering a well-positioned detector. There are two key aspects to effective neutron detection: hardware and software. Detection hardware refers to the kind of neutron detector used (the most ...
that is part of the instrument payload on board the
Trace Gas Orbiter
The ExoMars Trace Gas Orbiter (TGO or ExoMars Orbiter) is a collaborative project between the European Space Agency (ESA) and the Russian Roscosmos agency that sent an atmospheric research orbiter and the ''Schiaparelli'' demonstration lander ...
(TGO), launched to
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
in March 2016. This instrument is currently mapping
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...
levels to a maximum depth of beneath the Martian surface, thus revealing shallow water ice distribution. This instrument has an improved resolution of 7.5 times over the one Russia contributed to NASA's ''
2001 Mars Odyssey
''2001 Mars Odyssey'' is a robotic spacecraft orbiting the planet Mars. The project was developed by NASA, and contracted out to Lockheed Martin, with an expected cost for the entire mission of US$297 million. Its mission is to use spectr ...
'' orbiter.
Overview
FREND can provide information while orbiting Mars on the presence of hydrogen, in the form of
water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...
or
hydrated minerals in the top of the Martian surface.
FREND also features a
dosimeter
A radiation dosimeter is a device that measures dose uptake of external ionizing radiation. It is worn by the person being monitored when used as a personal dosimeter, and is a record of the radiation dose received. Modern electronic personal dos ...
to monitor the radiation environment along its orbit around Mars.
Objectives
The main science objective of the instrument is to carry out high spatial resolution mapping of epithermal and fast neutron fluxes from the Martian surface. FREND will work in synergy and complement orbital and ground data as measured the Dynamic Albedo of Neutrons
The Dynamic Albedo of Neutrons (DAN) instrument is an experiment mounted on the Mars Science Laboratory ''Curiosity'' rover. It is a pulsed sealed-tube neutron source and detector used to measure hydrogen or ice and water at or near the Martian s ...
(DAN) instrument on the ''Curiosity'' rover, the ADRON-RM
ADRON-RM (Autonomous Detector of Radiation of Neutrons Onboard Rover at Mars) is a Neutron spectroscopy, neutron spectrometer to search for Water on Mars#Ground ice, subsurface water ice and Mineral hydration, hydrated minerals. This analyser is ...
instrument on the ''Rosalind Franklin'' rover and the ADRON-EM on the Kazachok
The ExoMars ''Kazachok'' ( rus, Казачок; formerly ExoMars 2020 Surface Platform) was a planned robotic Mars lander led by Roscosmos, part of the ExoMars 2022 joint mission with the European Space Agency. ''Kazachok'' translates as "Littl ...
.
The second goal of FREND is to use its dosimeter
A radiation dosimeter is a device that measures dose uptake of external ionizing radiation. It is worn by the person being monitored when used as a personal dosimeter, and is a record of the radiation dose received. Modern electronic personal dos ...
to measure the radiation dose at the TGO orbit from energetic particles of galactic cosmic ray
Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own ...
s and solar flare
A solar flare is an intense localized eruption of electromagnetic radiation in the Sun's atmosphere. Flares occur in active regions and are often, but not always, accompanied by coronal mass ejections, solar particle events, and other solar phe ...
s. The data will be used to estimate exposure levels of spacecraft and maintain radiation safety of crewed interplanetary flights.
Principle and development
Cosmic ray
Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own ...
s are sufficiently energetic to break apart atoms in the top one or two metres of Mars' surface, releasing high-energy neutrons, which can be measured by FREND instrument. The distribution of neutron velocities measured reveals the hydrogen content, which are a good indicator of hydrogen abundance —water or hydrated minerals— in the shallow subsurface of Mars.
FREND uses inherited technology developed by the Russian Space Research Institute
The Russian Space Research Institute (russian: Институт космических исследований Российской академии наук, Space Research Institute of the Russian Academy of Sciences, SRI RAS, Russian abbreviat ...
and flown on the High Energy Neutron Detector (HEND) on ''Mars Odyssey
''2001 Mars Odyssey'' is a robotic spacecraft orbiting the planet Mars. The project was developed by NASA, and contracted out to Lockheed Martin, with an expected cost for the entire mission of US$297 million. Its mission is to use spectro ...
''; the Mercury Gamma and Neutron Spectrometer (MGNS) on ''BepiColombo
BepiColombo is a joint mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) to the planet Mercury. The mission comprises two satellites launched together: the Mercury Planetary Orbiter (MPO) and ''Mio'' ...
''; the Lunar Exploration Neutron Detector (LEND) on the ''Lunar Reconnaissance Orbiter
The Lunar Reconnaissance Orbiter (LRO) is a NASA robotic spacecraft currently orbiting the Moon in an eccentric polar mapping orbit. Data collected by LRO have been described as essential for planning NASA's future human and robotic missions t ...
'', and Dynamic Albedo of Neutrons
The Dynamic Albedo of Neutrons (DAN) instrument is an experiment mounted on the Mars Science Laboratory ''Curiosity'' rover. It is a pulsed sealed-tube neutron source and detector used to measure hydrogen or ice and water at or near the Martian s ...
(DAN) on ''Curiosity'' rover.
This instrument's key components are four detectors containing Helium-3
Helium-3 (3He see also helion) is a light, stable isotope of helium with two protons and one neutron (the most common isotope, helium-4, having two protons and two neutrons in contrast). Other than protium (ordinary hydrogen), helium-3 is the ...
for neutrons with energies from 0.4 keV to 500 keV, and a stilbene-based scintillator
A scintillator is a material that exhibits scintillation, the property of luminescence, when excited by ionizing radiation. Luminescent materials, when struck by an incoming particle, absorb its energy and scintillate (i.e. re-emit the absorbed ...
for high-energy neutrons up to 10 MeV. Each of the four 3He detectors counts neutrons independently for increased reliability. All five detectors are encased within a collimator
A collimator is a device which narrows a beam of particles or waves. To narrow can mean either to cause the directions of motion to become more aligned in a specific direction (i.e., make collimated light or parallel rays), or to cause the spati ...
that improves the resolution 7.5 times over the one Russia contributed to NASA's ''Mars Odyssey'' orbiter.
The Principal Investigator is Igor G. Mitrofanov, from the Russian Space Research Institute
The Russian Space Research Institute (russian: Институт космических исследований Российской академии наук, Space Research Institute of the Russian Academy of Sciences, SRI RAS, Russian abbreviat ...
(IKI). Mitrofanov is also the PI for ExoMars' ADRON-RM
ADRON-RM (Autonomous Detector of Radiation of Neutrons Onboard Rover at Mars) is a Neutron spectroscopy, neutron spectrometer to search for Water on Mars#Ground ice, subsurface water ice and Mineral hydration, hydrated minerals. This analyser is ...
and ADRON-EM neutron detector instruments.
See also
* Astrobiology
Astrobiology, and the related field of exobiology, is an interdisciplinary scientific field that studies the origins, early evolution, distribution, and future of life in the universe. Astrobiology is the multidisciplinary field that investig ...
* Life on Mars
The possibility of life on Mars is a subject of interest in astrobiology due to the planet's proximity and similarities to Earth. To date, no proof of past or present life has been found on Mars. Cumulative evidence suggests that during the ...
* Water on Mars
Almost all water on Mars today exists as ice, though it also exists in small quantities as vapor in the atmosphere. What was thought to be low-volume liquid brines in shallow Martian soil, also called recurrent slope lineae, may be grains of f ...
References
{{Use British English, date=July 2018
ExoMars
Mars imagers
Astrobiology
Space science experiments