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Topic Review
Magnitude
In astronomy, magnitude is a unitless measure of the brightness of an object in a defined passband, often in the visible or infrared spectrum, but sometimes across all wavelengths. An imprecise but systematic determination of the magnitude of objects was introduced in ancient times by Hipparchus. The scale is logarithmic and defined such that a magnitude 1 star is exactly 100 times brighter than a magnitude 6 star. Thus each step of one magnitude is [math]\displaystyle{ \sqrt{100} \approx 2.512 }[/math] times brighter than the next faintest. The brighter an object appears, the lower the value of its magnitude, with the brightest objects reaching negative values. Astronomers use two different definitions of magnitude: apparent magnitude and absolute magnitude. The apparent magnitude (m) is the brightness of an object as it appears in the night sky from Earth. Apparent magnitude depends on an object's intrinsic luminosity, its distance, and the extinction reducing its brightness. The absolute magnitude (M) describes the intrinsic luminosity emitted by an object and is defined to be equal to the apparent magnitude that the object would have if it were placed at a certain distance from Earth, 10 parsecs for stars. A more complex definition of absolute magnitude is used for planets and small Solar System bodies, based on its brightness at one astronomical unit from the observer and the Sun. The Sun has an apparent magnitude of −27 and Sirius, the brightest visible star in the night sky, −1.46. Venus at its brightest is -5. The International Space Station (ISS) sometimes reaches a magnitude of −6.
  • 1.5K
  • 28 Sep 2022
Topic Review
Main-belt Comet
User:RMCD bot/subject notice Main-belt comets (MBCs) are bodies orbiting within the asteroid belt that have shown comet-like activity during part of their orbit. The Jet Propulsion Laboratory defines a main-belt asteroid as an asteroid with a semi-major axis (average distance from the Sun) of more than 2 AU but less than 3.2 AU, and a perihelion (closest approach distance to the Sun) of no less than 1.6 AU. David Jewitt from UCLA points out that these objects are most likely not comets with sublimating ice, but asteroids that exhibit dust activity, and hence he and others started calling these class of objects active asteroids. The first main-belt comet discovered is 7968 Elst–Pizarro. It was discovered in 1979 and was found to have a tail by Eric Elst and Guido Pizarro in 1996 and given the cometary designation 133P/Elst-Pizarro.
  • 440
  • 19 Oct 2022
Topic Review
Maintainance of the International Space Station
Since construction started, the International Space Station programme has had to deal with several maintenance issues, unexpected problems and failures. These incidents have affected the assembly timeline, led to periods of reduced capabilities of the station and in some cases could have forced the crew to abandon the space station for safety reasons, had these problems not been resolved.
  • 278
  • 18 Oct 2022
Topic Review
Mapping Imaging Spectrometer for Europa
The Mapping Imaging Spectrometer for Europa (MISE) is an imaging near infrared spectrometer on board the Europa Clipper mission to Jupiter's moon Europa. MISE will examine Europa's surface composition and relate it to the habitability of its internal water ocean.
  • 253
  • 01 Dec 2022
Topic Review
Marchywka Effect
The Marchywka effect refers to electrochemical cleaning of diamond using an electric field induced with remote electrodes.
  • 511
  • 25 Oct 2022
Topic Review
Mars (Planet)
Mars is the fourth planet from the Sun in our solar system and is named after Mars, the Roman god of war. Mars is also known as the "Red Planet" due to its reddish appearance when seen from Earth. The prefix areo-, from the Greek god of war, Ares, refers to Mars in the same way geo- refers to Earth. Until the first flyby of Mars by Mariner 4 in 1965, it was thought that Mars had channels of liquid water. Observations later showed that these channels do not exist. Still, of all the planets in our solar system other than Earth, Mars is the most likely to harbor liquid water, and perhaps life. Its rotational period and seasonal cycles are also similar to those of the Earth. It has the highest mountain in the solar system, Olympus Mons, the largest canyon in the solar system, Valles Marineris, and polar ice caps. Mars has two moons, Phobos and Deimos, which are small and oddly-shaped. These may be captured asteroids similar to 5261 Eureka, a Mars trojan asteroid. Mars can be seen from Earth by the naked eye. Its apparent magnitude reaches -2.9, a brightness surpassed only by Venus, the Moon, and the Sun. For much of the year, Jupiter may appear brighter to the naked eye than Mars. Mars is currently host to four orbiting spacecraft, more than any planet other than Earth. It is also home to the two Mars Exploration Rovers, Spirit and Opportunity.
  • 1.1K
  • 21 Nov 2022
Topic Review
Mars Helicopter Ingenuity
Ingenuity (also known as the Mars Helicopter) is a robotic helicopter that is planned to be used to test the technology to scout interesting targets on Mars, and help plan the best driving route for future Mars rovers. The small drone helicopter is planned for deployment in 2021 from the Perseverance rover as part of the Mars 2020 mission. It is expected to fly up to five times during its 30-day test campaign, early in the rover's mission, as it is primarily a technology demonstration. Each flight is planned to take no more than three minutes, at altitudes ranging from 3 to 10 m above the ground. It could potentially cover a distance of up to 300 metres (980 ft) per flight. It can use autonomous control and communicate with the Perseverance rover directly after each landing. If it works as expected, NASA could build on the design for future Mars aerial missions. MiMi Aung is the project lead. Other contributors include AeroVironment Inc., NASA Ames Research Center, and NASA Langley Research Center.
  • 705
  • 01 Dec 2022
Topic Review
Mars Multispectral Imager for Subsurface Studies
Mars Multispectral Imager for Subsurface Studies (MA-MISS) is a miniaturized imaging spectrometer designed to provide imaging and spectra by reflectance in the near-infrared (NIR) wavelength region and determine the mineral composition and stratigraphy. The instrument is part of the science payload on board the European Rosalind Franklin rover, tasked to search for biosignatures, and scheduled to land on Mars in spring 2023. MA-MISS is essentially inside a drill on the Rover, and will take measurements of the sub-surface directly. MA-MISS will help on the search for biosignatures by studying minerals and ices in situ before the collection of samples. The instrument is integrated within the Italian core drill system called DEEDRI, and it will be dedicated to in situ studies of the mineralogy inside the excavated holes in terms of visible and infrared spectral reflectance. The Principal Investigator is Maria Cristina De Sanctis, from the INAF (Istituto di Astrofisica Spaziale e Fisica Cosmica) in Italy.
  • 343
  • 16 Nov 2022
Topic Review
Masten Space Systems
Masten Space Systems was an aerospace manufacturer startup company in Mojave, California (formerly in Santa Clara, California) that is developing a line of vertical takeoff, vertical landing (VTVL) rockets, initially for uncrewed research sub-orbital spaceflights and eventually intended to support robotic orbital spaceflight launches. In 2020, NASA awarded Masten a contract for a lunar lander mission; NASA is to pay Masten US$75.9 million for Masten to build and launch a lander called XL-1 to take NASA and other customer payloads to the south pole of the Moon. Masten Mission One will be Masten's first space flight; it is scheduled for launch in November 2023. The company filed for Chapter 11 bankruptcy on 28 July 2022. The company would later be purchased by Astrobotic Technology on 11 September 2022.
  • 596
  • 26 Oct 2022
Topic Review
Materials and Applications of Smart Contact Lenses
Smart contact lenses (SCLs) have found applications in the continuous monitoring of ocular parameters, encompassing both physical characteristics, such as pressure and temperature, as well as chemical markers like glucose levels, protein content, and pH. These physiological indicators are intricately linked to human well-being, with noteworthy implications for health.
  • 356
  • 31 Oct 2023
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