Airbags
Utilized to cushion the rovers’ impact on Mars during landing.
Approximate-true-color image
A Pancam image that has been processed to depict the Pancam team’s best estimate of the colors a person would see if they were on the martian surface.
APXS
Alpha Particle X-Ray Spectrometer, an instrument on the rovers’ arm to determine the elements present as well as their relative abundances in rocks, soils, and the atmosphere.
Athena Science Payload
The science instrument suite on each rover including Pancam, MiniTES, MI, APXS, MB, RAT and the Magnetic Properties experiment. The rovers also had engineering cameras (Navcam, Hazcam), which could be used for science.
Basalt
A dark-toned Mg (magnesium) and Fe (Iron) rich volcanic rock that is fine-grained, generally formed in effusive eruptions and which makes up much of the bedrock of Mars.
Bedrock
The solid rock found beneath soil or loose material.
Blueberries
Tiny (about the size of a BB) spherules of hematite that formed in rocks that were once saturated with water. They were observed across Meridiani Planum.
Calibration targets
Utilized to relate observations made by rover instruments to meaningful scientific values. The Pancam calibration target was in the shape of a sundial. Each rover’s Mini-TES instrument had two V-groove blackbody calibration targets with platinum temperature sensors. One was located on the rover deck and the other inside the PMA.
Carbonates
Minerals containing carbonate ions (CO32-) in their crystal structure. Carbonate minerals form in neutral pH conditions.
Clay
1) This term is commonly (but incorrectly) used in Mars science as a synonym of phyllosilicates. Clay minerals (e.g., kaolinites, illites, smectites (including montmorillonite), vermiculites, etc.) are phyllosilicates, but not all phyllosilicates are clay minerals (e.g., mica and serpentine are not clays). Clay minerals form through water-rock interactions. See also phyllosilicate. 2) Clay can also refer to grains smaller than 4 microns (0.004mm) regardless of composition.
Cleaning Event
When Martian wind removed dust from the rovers’ solar panels, temporarily increasing the rover’s ability to generate power.
Contact Science
Term used by the Mars Science Laboratory (MSL)/Curiosity rover team for the types of activities referred to as “IDD work” by the MER team. Equivalent to Mars2020/Perseverance rover “Proximity Science”.
Deep Space Network
An international network of large radio antennae that are used to communicate with spacecraft across the Solar System. There are DSN complexes in Australia, Spain, and the U.S.
Deimos
The smaller of the two moons of Mars. It’s a tiny “potato shaped” object, only about 15km by 12km by 11km in diameter, and has an orbital period of a bit over 30 hours.
Downlink
Data received on Earth from the rovers. Typically, the rovers sent data to an orbiter, which sent the data to the Deep Space Network (DSN) on Earth.
DSN
See Deep Space Network.
Dust
Tiny particles, much smaller than sand or soil, that cover the entire martian surface and can get lofted into and suspended in the air. Dust particles are about the size of the particles in cigarette smoke. In approximate-true-color images, dust is a rusty red color; in grayscale (Navcam) images it is often bright.
Dust Devil
A rotating column of air containing grains of martian dust (not sand!).
Dust Storm
When winds loft dust throughout the martian atmosphere, increasing the atmospheric opacity (Tau) and darkening the sky. Dust storms on Mars can be regional (equivalent to the size of countries or continents on Earth) or global. Because the dust is so fine, it can remain suspended in the atmosphere for weeks or months.
EDL
Entry, Descent and Landing; the phase of the mission when the spacecraft plunges through the atmosphere and lands on the surface.
False-color image
A Pancam image that has been processed to exaggerate spectral differences. If not everything in an image is the rusty red color of martian dust, it is likely a false-color image.
Filter Wheel
The Pancam instrument included a wheel of filters in front of each camera. By selecting specific filters for each camera, an observation could produce stereo red, stereo blue, approximate-true-color, false-color, or 13-filter spectroscopic images.
Goethite
A hydrated iron-bearing mineral with the formula Fe3+O(OH). Water is typically involved in its formation.
Gusev Crater
A ~150km diameter impact crater on Mars, nearly as large as the width of the state of Connecticut, that was the Spirit rover’s landing site.
Hazcam
Hazard Avoidance Camera. These pairs of cameras on the front and back of the rovers had fisheye lenses and were used for autonomous movement.
Hematite
An iron-bearing mineral with the formula Fe2O3. Water is sometimes but not always involved in its formation.
Hydrothermal
An environment of hot water heated by subsurface volcanic activity.
IDD
Instrument Deployment Device or the “arm” of the rover, with in-situ elements APXS, MB, MI and RAT.
IDD work
Term for the direct measurement of surface properties made by instruments on the arm (IDD) of either Spirit or Opportunity. Equivalent to “Contact Science” with the Mars Science Laboratory (MSL)/Curiosity rover and “proximity science” with the Mars2020/Perseverance rover.
In Situ
A type of MER observation with a payload element that touched (or, in the case of the MI, came within millimeters of) martian rocks and soils. Literal meaning is “in place”. The MER in situ instruments were APXS, MB, MI, and RAT.
Magnet Arrays
An experiment on each rover consisting of magnets that collected magnetic grains from airborne dust particles.
Mössbauer Spectrometer
See MB.
MB
The Mössbauer Spectrometer determined the abundance and composition of iron-bearing minerals in an in situ target observation.
MER
Mars Exploration Rover. Can refer to the rovers themselves, or to the Mars Exploration Rover mission.
Meridiani Planum
A large, mostly flat plain near the equator of Mars that was the Opportunity rover’s landing site.
MI
Microscopic Imager for close-up views of rocks and soils on Mars. The rovers’ equivalent of a geologist’s handlens. The MI had a resolution of 30 microns per pixel.
Mini-TES
The Miniature Thermal Emission Spectrometer, an infrared spectrometer that was one of the rovers’ remote sensing instruments. It was located on the PMA and in the WEB, and was used to detect the composition of rocks and soils from a distance based on their thermal emission spectra.
Navcam
A pair of stereo, greyscale, navigation cameras that were mounted on the PMA. Navcam had a wider field of view than Pancam, and was part of the Engineering Payload.
Newberries
BB-sized spherules that likely formed in water on Mars. Found at Endeavour Crater.
Noachian Period
The oldest of the three main geological epochs on Mars. The Noachian lasted from ~4.1 to ~3.7 Ga (billion years ago). It was followed by the Hesperian and then the Amazonian.
Outcrop
Bedrock that is easily visible as it protrudes from the surface.
Pancam
The Panoramic high resolution stereo camera sat atop the PMA. The two Pancam “eyes” each had approximately the same resolution as 20/20 vision. Pancam typically acquired 1024x1024 pixel images, though subframe images were sometimes acquired. Pancam’s CCD arrays were greyscale, but false-color, approximate true color, and multispectral images could be produced by using the filter wheels that were directly in front of each camera.
pH
Measures the acidity of a solution. Acidic solutions have a lower pH than neutral and basic/alkaline solutions.
Phobos
The larger of the two moons of Mars. It’s a small “potato shaped” object, about 27km by 22km by 18km in diameter, and has an orbital period of only 7 hours and 39 minutes.
Phyllosilicates
Hydrated silicate minerals in which the silica tetrahedra in the crystal structure are arranged in sheets. Clay minerals are phyllosilicates, but not all phyllosilicates are clay minerals (e.g., mica and serpentine are phyllosilicates but not clays). See also clay.
PMA
The Pancam Mast Assembly stood up from the deck as the “head” and “neck” of each rover.
Proximity Science
The term used by the Mars2020/Perseverance rover team for observations of objects near the rover. Equivalent to what MER called “IDD work” and the MSL/Curiosity team call “Contact Science”.
RAT
The Rock Abrasion Tool exposed fresh rock surfaces for study by rover instruments. Similar to a drill, the instrument could brush the surface of or grind into rocks and consolidated soils.
Remote Sensing
Acquiring scientific data from a distance (as opposed to in situ). Pancam stereo and multispectral imaging and Mini-TES thermal infrared spectroscopy are the primary MER remote sensing datasets. Other (non-MER) examples of remote sensing include radar ranging, synthetic aperture radar (SAR), ground-penetrating radar (GPR), laser altimetry, and gamma ray neutron spectroscopy.
Smectites
A group of clay phyllosilicate minerals that have H2O in their crystal structure and form in water with neutral pH. The minerals saponite, montmorillonite, and nontranite are smectites.
Sol
A martian day (24 hours and 39 minutes). The length of the MER mission is measured in sols.
Solar Arrays
Solar panels that cover the deck of each rover to collect sunlight for power.
Spectra
Plural of “spectrum,” a chart or graph that can help scientists understand the composition of an item that is being studied by a spectroscopic instrument. There are many types of spectra
Sulfates
Minerals that contain the SO42- ion.
Tau
Atmospheric opacity. In MER operations, the word Tau was also the term for an image of the Sun used to estimate atmospheric opacity. A low tau indicates clear air, while (on Mars) a high tau typically indicates dust suspended in the atmosphere.
Uplink
Transmission from Earth to the rovers. These transmissions were generally instructions sent to the rovers from Earth.
WEB
The Warm Electronics Box inside the body of the rover, which protected temperature-sensitive components.
