:''APXS is also an abbreviation for APache eXtenSion tool, an extension for
Apache
The Apache () are a group of culturally related Native American tribes in the Southwestern United States, which include the Chiricahua, Jicarilla, Lipan, Mescalero, Mimbreño, Ndendahe (Bedonkohe or Mogollon and Nednhi or Carrizaleño an ...
web servers.''
An alpha particle X-ray spectrometer (APXS) is a
spectrometer
A spectrometer () is a scientific instrument used to separate and measure spectral components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomenon where the ...
that analyses the chemical element composition of a sample from scattered
alpha particle
Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay, but may also be produce ...
s and fluorescent
X-ray
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...
s after a sample is irradiated with alpha particles and X-rays from radioactive sources. This method of analysing the elemental composition of a sample is most often used on space missions, which require low weight, small size, and minimal power consumption. Other methods (e.g.
mass spectrometry
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a ''mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is use ...
) are faster, and do not require the use of radioactive materials, but require larger equipment with greater power requirements. A variation is the alpha proton X-ray spectrometer, such as on the
Pathfinder mission, which also detects
protons
A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...
.
Over the years several modified versions of this type of instrument such as APS (without X-ray spectrometer) or APXS have been flown:
Surveyor 5-7,
Mars Pathfinder
''Mars Pathfinder'' (''MESUR Pathfinder'') is an American robotic spacecraft that landed a base station with a roving probe on Mars in 1997. It consisted of a lander, renamed the Carl Sagan Memorial Station, and a lightweight, wheeled robot ...
,
Mars 96
Mars 96 (sometimes called Mars-8) was a failed Mars mission launched in 1996 to investigate Mars by the Russian Space Forces and not directly related to the Soviet Mars probe program of the same name. After failure of the second fourth-stage bu ...
,
Mars Exploration Rover
NASA's Mars Exploration Rover (MER) mission was a robotic space mission involving two Mars rovers, ''Spirit (rover), Spirit'' and ''Opportunity (rover), Opportunity'', exploring the planet Mars. It began in 2003 with the launch of the two rover ...
,
Phobos,
[
] Mars Science Laboratory
Mars Science Laboratory (MSL) is a robotic spacecraft, robotic space probe mission to Mars launched by NASA on November 26, 2011, which successfully landed ''Curiosity (rover), Curiosity'', a Mars rover, in Gale (crater), Gale Crater on August ...
and the
Philae comet lander.
[
] APS/APXS devices will be included on several upcoming missions including the
Chandrayaan-2
Chandrayaan-2 (, ; ) is the second lunar exploration mission developed by the Indian Space Research Organisation (ISRO), after Chandrayaan-1. It consists of a lunar orbiter, and also included the ''Vikram'' lander, and the ''Pragyan'' lunar ...
lunar rover
A lunar rover or Moon rover is a space exploration vehicle designed to move across the surface of the Moon. The Apollo Program's Lunar Roving Vehicle was driven on the Moon by members of three American crews, Apollo 15, 16, and 17. Other rov ...
.
Sources
Several forms of radiation are used in APXS. They include
alpha particles
Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay, but may also be prod ...
,
protons
A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...
, and
X-ray
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...
s. Alpha particles, protons, and X-rays are emitted during the radioactive decay of unstable atoms. A common source of alpha particles is
curium-244
Curium (96Cm) is an artificial element with an atomic number of 96. Because it is an artificial element, a standard atomic weight cannot be given, and it has no stable isotopes. The first isotope synthesized was 242Cm in 1944, which has 146 ne ...
. It emits particles with an energy of 5.8
MeV
In physics, an electronvolt (symbol eV, also written electron-volt and electron volt) is the measure of an amount of kinetic energy gained by a single electron accelerating from rest through an Voltage, electric potential difference of one volt i ...
. X-rays of 14 and 18 keV are emitted in the decay of
plutonium-240
Plutonium-240 ( or Pu-240) is an isotope of plutonium formed when plutonium-239 captures a neutron. The detection of its spontaneous fission led to its discovery in 1944 at Los Alamos and had important consequences for the Manhattan Project.
240 ...
. The
Mars Exploration Rover
NASA's Mars Exploration Rover (MER) mission was a robotic space mission involving two Mars rovers, ''Spirit (rover), Spirit'' and ''Opportunity (rover), Opportunity'', exploring the planet Mars. It began in 2003 with the launch of the two rover ...
s' Athena payload uses curium-244 with a source strength of approximately .
Alpha particles
![Pathfinder01](https://upload.wikimedia.org/wikipedia/commons/e/e5/Pathfinder01.jpg)
Some of the alpha particles of a defined energy are backscattered to the detector if they collide with an atomic nucleus. The physical laws for
Rutherford backscattering
Rutherford backscattering spectrometry (RBS) is an analytical technique used in materials science. Sometimes referred to as high-energy ion scattering (HEIS) spectrometry, RBS is used to determine the structure and composition of materials by mea ...
in an angle close to 180° are
conservation of energy
In physics and chemistry, the law of conservation of energy states that the total energy of an isolated system remains constant; it is said to be ''conserved'' over time. This law, first proposed and tested by Émilie du Châtelet, means th ...
and conservation of
linear momentum
In Newtonian mechanics, momentum (more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. If is an object's mass and ...
. This makes it possible to calculate the mass of the nucleus hit by the alpha particle.
Light elements absorb more energy of the alpha particle, while alpha particles are reflected by heavy nuclei nearly with the same energy. The energy spectrum of the scattered alpha particle shows peaks from 25% up to nearly 100% of the initial alpha particles. This spectrum makes it possible to determine the composition of the sample, especially for the lighter elements. The low backscattering rate makes prolonged irradiation necessary, approximately 10 hours.
Protons
Some of the alpha particles are absorbed by the atomic nuclei. The
lpha,protonprocess produces protons of a defined energy which are detected.
Sodium
Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...
,
magnesium
Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...
,
silicon
Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic tab ...
,
aluminium
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
and
sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
can be detected by this method. This method was only used in the Mars Pathfinder APXS. For the
Mars Exploration Rover
NASA's Mars Exploration Rover (MER) mission was a robotic space mission involving two Mars rovers, ''Spirit (rover), Spirit'' and ''Opportunity (rover), Opportunity'', exploring the planet Mars. It began in 2003 with the launch of the two rover ...
s the proton detector was replaced by a second alpha particle sensor. So it is also called alpha particle X-ray spectrometer.
X-ray
The alpha particles are also able to eject electrons from the inner shell (K- and L-shell) of an atom. These vacancies are filled by electrons from outer shells, which results in the emission of a characteristic X-ray. This process is termed
particle-induced X-ray emission
Particle-induced X-ray emission or proton-induced X-ray emission (PIXE) is a technique used for determining the elemental composition of a material or a sample. When a material is exposed to an ion beam, atomic interactions occur that give off EM ...
and is relatively easy to detect and has its best sensitivity and resolution for the heavier elements.
Specific instruments
*''Alpha-X'', for DAS lander on Phobos 1 and Phobos 2.
[
*''ALPHA'', for Mars 96 landers. Collaboration between Germany, Russia, and USA.
*''Alpha Proton X-Ray Spectrometer'', for ]Mars Pathfinder
''Mars Pathfinder'' (''MESUR Pathfinder'') is an American robotic spacecraft that landed a base station with a roving probe on Mars in 1997. It consisted of a lander, renamed the Carl Sagan Memorial Station, and a lightweight, wheeled robot ...
by the Max Planck Institute
Max or MAX may refer to:
Animals
* Max (dog) (1983–2013), at one time purported to be the world's oldest living dog
* Max (English Springer Spaniel), the first pet dog to win the PDSA Order of Merit (animal equivalent of OBE)
* Max (gorilla) (1 ...
and the University of Chicago
The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park neighborhood. The University of Chicago is consistently ranked among the b ...
.[Mars Pathfinder Instrument Descriptions – NASA]
/ref>
*''Alpha Particle X-ray Spectrometer'', for ''Spirit'' (MER-A) and ''Opportunity'' (MER-B) Mars Exploration Rovers
NASA's Mars Exploration Rover (MER) mission was a robotic space mission involving two Mars rovers, ''Spirit'' and ''Opportunity'', exploring the planet Mars. It began in 2003 with the launch of the two rovers to explore the Martian surface and ...
.
*''Alpha Particle X-ray Spectrometer'', for ''Curiosity'' (MSL). The principal investigator for ''Curiosity''s APXS is Ralf Gellert, a physicist at the University of Guelph
, mottoeng = "to learn the reasons of realities"
, established = May 8, 1964 ()As constituents: OAC: (1874) Macdonald Institute: (1903) OVC: (1922)
, type = Public university
, chancellor ...
in Ontario
Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...
, Canada. It was developed and funded by the Canadian Space Agency
The Canadian Space Agency (CSA; french: Agence spatiale canadienne, ASC) is the national space agency of Canada, established in 1990 by the ''Canadian Space Agency Act''.
The president is Lisa Campbell, who took the position on September 3, 2020 ...
, with operations also supported by Guelph and United States' space administration.NASA – Alpha Particle X-ray Spectrometer (APXS)
/ref>
*''Alpha Particle X-ray Spectrometer'', for Philae
; ar, فيلة; cop, ⲡⲓⲗⲁⲕ
, alternate_name =
, image = File:File, Asuán, Egipto, 2022-04-01, DD 93.jpg
, alt =
, caption = The temple of Isis from Philae at its current location on Agilkia Island in Lake Nasse ...
, the European Space Agency
, owners =
, headquarters = Paris, Île-de-France, France
, coordinates =
, spaceport = Guiana Space Centre
, seal = File:ESA emblem seal.png
, seal_size = 130px
, image = Views in the Main Control Room (1205 ...
's lander attached to ''Rosetta'', to study the comet 67P/Churyumov–Gerasimenko
67P/Churyumov–Gerasimenko (abbreviated as 67P or 67P/C–G) is a Jupiter-family comet, originally from the Kuiper belt, with a current orbital period of 6.45 years, a rotation period of approximately 12.4 hours and a maximum velocity of . Chu ...
.[http://www.uni-mainz.de/, Johannes Gutenberg Universität Mainz]
Alpha particle x-ray spectrometer developed in Mainz to be used on comet Churyumov–Gerasimenko
10 April 2014
Gallery
Image:PIA18602-MarsCuriosityRover-BonanzaKingRock-20140817.jpg, " Bonanza King" rock on Mars – cleaned with " Dust Removal Tool" (17 August 2014).
Image:PIA18477-MarsCuriosityRover-BonanzaKingRock-Drill-20140911.jpg, " Bonanza King" rock on Mars – dusted and initially drilled (11 September 2014).
Image:PIA18478-MarsCuriosityRover-Bonanz-KingRock-Drill-LightColorVein-20140911.jpg, " Bonanza King" rock on Mars – drilling stopped due to loose rock (11 September 2014).
Image:PIA18479-MarsCuriosityRover-BonanzaKingRock-APXS-Graph-20140911.png, " Bonanza King" rock on Mars – APXS analysis (''Curiosity
Curiosity (from Latin '' cūriōsitās'', from ''cūriōsus'' "careful, diligent, curious", akin to ''cura'' "care") is a quality related to inquisitive thinking such as exploration, investigation, and learning, evident by observation in humans ...
'' rover; 11 September 2014).
References
External links
*
*
{{DEFAULTSORT:Alpha Particle X-Ray Spectrometer
Mars Pathfinder
Mars Science Laboratory instruments
Science and technology in Canada
Canadian inventions
Space program of Canada
Mars Exploration Rover mission
X-ray spectroscopy
Spacecraft instruments
University of Guelph
Space science experiments