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80-531: The everyday tasks performed at the center during the life of the ISS include: The Payload Operations Center is staffed around the clock by three shifts of flight controllers. A total of eight flight controllers staff the Payload Operations Center front room. They are: The POD manages day-to-day operations of payloads on board the space station. This position is the single point-of-authority to

160-788: A band transponders. NSS 6 , launched in December 2002 and positioned at 95° East, contains only K u -band transponders with a footprint on Indonesia ( Sumatra , Java , Borneo , Celebes , Bali , Nusa Tenggara , Moluccas ). NSS 6 is intended to be replaced by SES-12 at the same location, which launched in June 2018 and carries 54 K u -band transponders. The IPSTAR 1 satellite, launched in 2004 also uses K u band footprints. Other satellites that provides K u band covers Indonesia are MEASAT-3b , JCSAT-4B , AsiaSat 5 , ST-2 , Chinasat 11, Koreasat 8/ABS-2 , SES-8 , Telkom-3S , and Nusantara Satu . Other ITU allocations have been made within

240-563: A medium with matter , their wavelength is decreased. Wavelengths of electromagnetic radiation, whatever medium they are traveling through, are usually quoted in terms of the vacuum wavelength , although this is not always explicitly stated. Generally, electromagnetic radiation is classified by wavelength into radio wave , microwave , infrared , visible light , ultraviolet , X-rays and gamma rays . The behavior of EM radiation depends on its wavelength. When EM radiation interacts with single atoms and molecules , its behavior also depends on

320-425: A radio receiver . Earth's atmosphere is mainly transparent to radio waves, except for layers of charged particles in the ionosphere which can reflect certain frequencies. Radio waves are extremely widely used to transmit information across distances in radio communication systems such as radio broadcasting , television , two way radios , mobile phones , communication satellites , and wireless networking . In

400-422: A radio wave photon that has a wavelength of 21.12 cm. Also, frequencies of 30 Hz and below can be produced by and are important in the study of certain stellar nebulae and frequencies as high as 2.9 × 10  Hz have been detected from astrophysical sources. The types of electromagnetic radiation are broadly classified into the following classes (regions, bands or types): This classification goes in

480-772: A television network's studio for editing and broadcasting . The band is split by the International Telecommunication Union (ITU) into multiple segments that vary by geographical region. NBC was the first television network to uplink a majority of its affiliate feeds via K u band in 1983. Some frequencies in this radio band are employed in radar guns used by law enforcement to detect vehicles speeding, especially in Europe. Segments in most of North and South America are represented by ITU Region 2 from 11.7 to 12.2 GHz ( Local Oscillator Frequency (LOF) 10.75 to 11.25 GHz), allocated to

560-446: A transmitter generates an alternating electric current which is applied to an antenna. The oscillating electrons in the antenna generate oscillating electric and magnetic fields that radiate away from the antenna as radio waves. In reception of radio waves, the oscillating electric and magnetic fields of a radio wave couple to the electrons in an antenna, pushing them back and forth, creating oscillating currents which are applied to

640-850: A dish of a given size. Position feedback accuracies are higher and the antenna may require a closed loop control system to maintain position under wind loading of the dish surface. ELF 3 Hz/100 Mm 30 Hz/10 Mm SLF 30 Hz/10 Mm 300 Hz/1 Mm ULF 300 Hz/1 Mm 3 kHz/100 km VLF 3 kHz/100 km 30 kHz/10 km LF 30 kHz/10 km 300 kHz/1 km MF 300 kHz/1 km 3 MHz/100 m HF 3 MHz/100 m 30 MHz/10 m VHF 30 MHz/10 m 300 MHz/1 m UHF 300 MHz/1 m 3 GHz/100 mm SHF 3 GHz/100 mm 30 GHz/10 mm EHF 30 GHz/10 mm 300 GHz/1 mm THF 300 GHz/1 mm 3 THz/0.1 mm Electromagnetic spectrum The electromagnetic spectrum

720-439: A few meters of water. One notable use is diagnostic X-ray imaging in medicine (a process known as radiography ). X-rays are useful as probes in high-energy physics. In astronomy, the accretion disks around neutron stars and black holes emit X-rays, enabling studies of these phenomena. X-rays are also emitted by stellar corona and are strongly emitted by some types of nebulae . However, X-ray telescopes must be placed outside

800-532: A heavy rain area usually gives poor results. This problem can be solved by using an appropriate link budget when designing the wireless communication link. Higher power can overcome the loss to rain fade . Measurements of rain attenuation in Indonesia have been done for satellite communication links in Padang, Cibinong, Surabaya and Bandung. The DAH Model for rain attenuation prediction is valid for Indonesia, as

880-588: A higher powered signal from the satellite to compensate. Therefore, the K u band satellites typically require considerably more power to transmit than the C-band satellites. Another weather-caused degradation called "snow fade" is not specific to the K u band. It is due to snow or ice accumulation on a dish significantly altering its focal point. The satellite operator's Earth station antenna requires more accurate position control when operating at K u band due to its much narrower beam focus compared to C band for

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960-636: A radio communication system, a radio frequency current is modulated with an information-bearing signal in a transmitter by varying either the amplitude, frequency or phase, and applied to an antenna. The radio waves carry the information across space to a receiver, where they are received by an antenna and the information extracted by demodulation in the receiver. Radio waves are also used for navigation in systems like Global Positioning System (GPS) and navigational beacons , and locating distant objects in radiolocation and radar . They are also used for remote control , and for industrial heating. The use of

1040-437: A wave nature or a particle nature with René Descartes , Robert Hooke and Christiaan Huygens favouring a wave description and Newton favouring a particle description. Huygens in particular had a well developed theory from which he was able to derive the laws of reflection and refraction. Around 1801, Thomas Young measured the wavelength of a light beam with his two-slit experiment thus conclusively demonstrating that light

1120-412: Is able to ionize atoms, causing chemical reactions. Longer-wavelength radiation such as visible light is nonionizing; the photons do not have sufficient energy to ionize atoms. Throughout most of the electromagnetic spectrum, spectroscopy can be used to separate waves of different frequencies, so that the intensity of the radiation can be measured as a function of frequency or wavelength. Spectroscopy

1200-449: Is also less vulnerable to rain fade than the K a band frequency spectrum. There are, however, some disadvantages of the K u band system. Around 10 GHz is the absorption peak due to orientation relaxation of molecules in liquid water. Above 10 GHz, Mie scattering takes over. The effect is a noticeable degradation, commonly known as rain fade , during heavy rain (100 mm/h). This problem can be mitigated by transmitting

1280-408: Is called fluorescence . UV fluorescence is used by forensics to detect any evidence like blood and urine, that is produced by a crime scene. Also UV fluorescence is used to detect counterfeit money and IDs, as they are laced with material that can glow under UV. At the middle range of UV, UV rays cannot ionize but can break chemical bonds, making molecules unusually reactive. Sunburn , for example,

1360-722: Is caused by the disruptive effects of middle range UV radiation on skin cells , which is the main cause of skin cancer . UV rays in the middle range can irreparably damage the complex DNA molecules in the cells producing thymine dimers making it a very potent mutagen . Due to skin cancer caused by UV, the sunscreen industry was invented to combat UV damage. Mid UV wavelengths are called UVB and UVB lights such as germicidal lamps are used to kill germs and also to sterilize water. The Sun emits UV radiation (about 10% of its total power), including extremely short wavelength UV that could potentially destroy most life on land (ocean water would provide some protection for life there). However, most of

1440-532: Is not harmless and does create oxygen radicals, mutations and skin damage. After UV come X-rays , which, like the upper ranges of UV are also ionizing. However, due to their higher energies, X-rays can also interact with matter by means of the Compton effect . Hard X-rays have shorter wavelengths than soft X-rays and as they can pass through many substances with little absorption, they can be used to 'see through' objects with 'thicknesses' less than that equivalent to

1520-407: Is responsible for command, control, data handling, communications and tracking for science payloads on the space station. The DMC manages the integrated high data rate ( K u -band ) communications link between the ground and the station. This position manages data system traffic, downlink video, assures ground data quality with NASA users, and assesses data system change requests. The DMC ensures that

1600-505: Is responsible for managing all ground commanding of U. S. payload systems and experiments on board the International Space Station. The PRO manages the command system, receives and sends command files to the mass storage device and configures the system to allow flight controllers in the Payload Operations Center and remote users to send commands to their equipment on the space station. The Data Management Coordinator

1680-429: Is responsible for troubleshooting ground system issues as the ground system expert. Marshall GC leads troubleshooting of real time commanding, telemetry, communication, and facility issues. Other duties that Marshall GC perform are coordinating payload video restrictions, space-to-ground enablement, space-to-ground restrictions, and ground system maintenance. If payload developers have any ground system issues, Marshall GC

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1760-450: Is the ITU model. The DAH model has become an ITU recommendation since 2001 (Recommendation No. ITU-R P.618-7). This model can create a 99.7% available link so that K u -band can be applied in Indonesia. Use of the K u -band for satellite communications in tropical regions like Indonesia is becoming more frequent. Several satellites above Indonesia have K u -band transponders , and even K

1840-539: Is the full range of electromagnetic radiation , organized by frequency or wavelength . The spectrum is divided into separate bands, with different names for the electromagnetic waves within each band. From low to high frequency these are: radio waves , microwaves , infrared , visible light , ultraviolet , X-rays , and gamma rays . The electromagnetic waves in each of these bands have different characteristics, such as how they are produced, how they interact with matter, and their practical applications. Radio waves, at

1920-494: Is the part of the EM spectrum the human eye is the most sensitive to. Visible light (and near-infrared light) is typically absorbed and emitted by electrons in molecules and atoms that move from one energy level to another. This action allows the chemical mechanisms that underlie human vision and plant photosynthesis. The light that excites the human visual system is a very small portion of the electromagnetic spectrum. A rainbow shows

2000-458: Is the real time coordinator to resolve such issues. As the ground system expert, Marshall GC is the HOSC interface for Backup Control Center (BCC) operations. The Timeline Change Officer (TCO) serves as the real-time expert on all NASA payload planning-related information for the International Space Station. Coordinating with NASA control centers, International Partners, and NASA Payload Developers,

2080-451: Is too long for ordinary dioxygen in air to absorb. This leaves less than 3% of sunlight at sea level in UV, with all of this remainder at the lower energies. The remainder is UV-A, along with some UV-B. The very lowest energy range of UV between 315 nm and visible light (called UV-A) is not blocked well by the atmosphere, but does not cause sunburn and does less biological damage. However, it

2160-427: Is used to study the interactions of electromagnetic waves with matter. Humans have always been aware of visible light and radiant heat but for most of history it was not known that these phenomena were connected or were representatives of a more extensive principle. The ancient Greeks recognized that light traveled in straight lines and studied some of its properties, including reflection and refraction . Light

2240-737: The Astra satellites. The 11.7 to 12.5 GHz segment is allocated to the BSS ( broadcasting satellite service ). Australia is part of ITU Region 3 and the Australian regulatory environment provides a class license that covers downlinking from 11.70 GHz to 12.75 GHz and uplinking from 14.0 GHz to 14.5 GHz. The ITU has categorized Indonesia as Region P, countries with very high rain precipitation. This statement has made many people unsure about using K u -band (11 – 18 GHz) in Indonesia. Using frequencies higher than 10 GHz in

2320-587: The Rayleigh criterion , the diameter of a parabolic dish required to create a radiation pattern with a given angular beamwidth ( gain ) is proportional to the wavelength , and thus inversely proportional to the frequency. At 12 GHz a 1-meter dish is capable of focusing on one satellite while sufficiently rejecting the signal from another satellite only 2 degrees away. This is important because satellites in FSS (Fixed Satellite Service) service (11.7-12.2 GHz in

2400-508: The microwave range of frequencies from 12 to 18  gigahertz (GHz). The symbol is short for "K-under" (originally German : Kurz-unten ), because it is the lower part of the original NATO K band , which was split into three bands (K u , K , and K a ) because of the presence of the atmospheric water vapor resonance peak at 22.24 GHz, (1.35 cm) which made the center unusable for long range transmission. In radar applications, it ranges from 12 to 18  GHz according to

2480-869: The radio spectrum is strictly regulated by governments, coordinated by the International Telecommunication Union (ITU) which allocates frequencies to different users for different uses. Microwaves are radio waves of short wavelength , from about 10 centimeters to one millimeter, in the SHF and EHF frequency bands. Microwave energy is produced with klystron and magnetron tubes, and with solid state devices such as Gunn and IMPATT diodes . Although they are emitted and absorbed by short antennas, they are also absorbed by polar molecules , coupling to vibrational and rotational modes, resulting in bulk heating. Unlike higher frequency waves such as infrared and visible light which are absorbed mainly at surfaces, microwaves can penetrate into materials and deposit their energy below

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2560-537: The visible spectrum and the X-ray range. The UV wavelength spectrum ranges from 399 nm to 10 nm and is divided into 3 sections: UVA, UVB, and UVC. UV is the lowest energy range energetic enough to ionize atoms, separating electrons from them, and thus causing chemical reactions . UV, X-rays, and gamma rays are thus collectively called ionizing radiation ; exposure to them can damage living tissue. UV can also cause substances to glow with visible light; this

2640-456: The > 10 MeV region)—which is of higher energy than any nuclear gamma ray—is not called X-ray or gamma ray, but instead by the generic term of "high-energy photons". The region of the spectrum where a particular observed electromagnetic radiation falls is reference frame -dependent (due to the Doppler shift for light), so EM radiation that one observer would say is in one region of

2720-650: The 7.6 eV (1.22 aJ) nuclear transition of thorium-229m ), and, despite being one million-fold less energetic than some muonic X-rays, the emitted photons are still called gamma rays due to their nuclear origin. The convention that EM radiation that is known to come from the nucleus is always called "gamma ray" radiation is the only convention that is universally respected, however. Many astronomical gamma ray sources (such as gamma ray bursts ) are known to be too energetic (in both intensity and wavelength) to be of nuclear origin. Quite often, in high-energy physics and in medical radiotherapy , very high energy EMR (in

2800-476: The Earth's atmosphere to see astronomical X-rays, since the great depth of the atmosphere of Earth is opaque to X-rays (with areal density of 1000 g/cm ), equivalent to 10 meters thickness of water. This is an amount sufficient to block almost all astronomical X-rays (and also astronomical gamma rays—see below). After hard X-rays come gamma rays , which were discovered by Paul Ulrich Villard in 1900. These are

2880-563: The FSS ( fixed satellite service ), uplink from 14.0 to 14.5 GHz. There are more than 22 FSS K u band satellites orbiting over North America, each carrying 12 to 48 transponders , 20 to 120 watts per transponder, and requiring a 0.8-m to 1.5-m antenna for clear reception. The 12.2 to 12.7 GHz (LOF 11.25 to 11.75 GHz) segment is allocated to the BSS ( broadcasting satellite service ). BSS (DBS direct broadcast satellites ) normally carry 16 to 32 transponders of 27  MHz bandwidth running at 100 to 240 watts of power, allowing

2960-659: The International Space Station Mission Control Center Flight Director in Houston for all of NASA's payload operations. The POD oversees team members responsible for managing payload mission planning, ground commanding of space station payloads, communications with the crew, use of the payload support system, the video system and the data systems. The POD ensures compliance with established safety requirements, flight rules and payload regulations. The POD also leads

3040-466: The K u band to the fixed service (microwave towers), radio astronomy service, space research service, mobile service, mobile satellite service, radiolocation service (radar), amateur radio service , and radionavigation. However, not all of these services are actually operating in this band and others are only minor users. Compared with C-band , K u band is not similarly restricted in power to avoid interference with terrestrial microwave systems, and

3120-478: The Sun's damaging UV wavelengths are absorbed by the atmosphere before they reach the surface. The higher energy (shortest wavelength) ranges of UV (called "vacuum UV") are absorbed by nitrogen and, at longer wavelengths, by simple diatomic oxygen in the air. Most of the UV in the mid-range of energy is blocked by the ozone layer, which absorbs strongly in the important 200–315 nm range, the lower energy part of which

3200-460: The TCO bridges the gap between long range planning and execution of the plan on board by the crew. The TCO team supports real-time operations seven days a week, twenty-four hours per day; in addition, short term planning operations are supported five days a week, eight hours per day. Ku-band The K u band ( / ˌ k eɪ ˈ j uː / ) is the portion of the electromagnetic spectrum in

3280-520: The U.S.) are only 2 degrees apart. At 4 GHz (C-band) a 3-meter dish is required to achieve this narrow angular resolution. Note the inverse linear correlation between dish size and frequency. For K u satellites in DBS (Direct Broadcast Satellite) service (12.2-12.7 GHz in the U.S.) dishes much smaller than 1-meter can be used because those satellites are spaced 9 degrees apart. As power levels on both C and K u band satellites have increased over

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3360-504: The amount of energy per quantum (photon) it carries. Spectroscopy can detect a much wider region of the EM spectrum than the visible wavelength range of 400  nm to 700 nm in a vacuum. A common laboratory spectroscope can detect wavelengths from 2 nm to 2500 nm. Detailed information about the physical properties of objects, gases, or even stars can be obtained from this type of device. Spectroscopes are widely used in astrophysics . For example, many hydrogen atoms emit

3440-496: The antenna's actual receiving element, mounted in front of the dish (and pointed back towards its face); if the waves are more intense, fewer of them need to be collected to achieve the same intensity at the receiving element. A major attraction of the band over lower frequency microwave bands is that the shorter wavelengths allow sufficient angular resolution to separate the signals of different communication satellites to be achieved with smaller terrestrial parabolic antennas . From

3520-844: The chemical mechanisms responsible for photosynthesis and the working of the visual system . The distinction between X-rays and gamma rays is partly based on sources: the photons generated from nuclear decay or other nuclear and subnuclear/particle process are always termed gamma rays, whereas X-rays are generated by electronic transitions involving highly energetic inner atomic electrons. In general, nuclear transitions are much more energetic than electronic transitions, so gamma rays are more energetic than X-rays, but exceptions exist. By analogy to electronic transitions, muonic atom transitions are also said to produce X-rays, even though their energy may exceed 6 megaelectronvolts (0.96 pJ), whereas there are many (77 known to be less than 10 keV (1.6 fJ)) low-energy nuclear transitions ( e.g. ,

3600-545: The configuration of systems resources to all NASA payload racks. When a new payload is installed, the PRO configures the rack interfaces to properly support the payload. For existing payloads, the PRO configures the EXPRESS racks to power payloads on or off, monitors the health and status of both the payload and the rack and if necessary, coordinates troubleshooting of the payload support structure and payload interfaces. The PRO also

3680-633: The crew about their experiments, and for managing payload conferences. Additionally, the PAYCOM reviews requests for changes to payload activity to assess their impact on the crew. The POIC Stowage console position is responsible for tracking the stowage locations of payload hardware, tools, and items on the International Space Station. This console position develops products that ensure the ISS crew knows where to locate every item they need for their day to day experiments, and helps maintain an inventory database for accurate tracking of those items. They also support

3760-541: The crew by helping them locate missing items. When the crew calls down and reports an item lost, the POIC Stowage console conducts investigations using video, imagery, and many other resources to come up with alternate search locations. The Stowage Team maintains a high level of situational awareness and knowledge of the current layout of station to ensure the crew can always find what they need to perform payload ops successfully. The Marshall GC (Marshall Ground Control)

3840-471: The current science timeline, payload hardware assets and resources required for science such as crew time and electrical power. The OC also is responsible for evaluating requests by scientists for changes to the experiment timeline, and then implementing changes to the science operations plan on board. The PRO is responsible for the configuration of ExPRESS payload racks in the International Space Station's US Lab, JEM, and Columbus modules, and for coordinating

3920-555: The data system is properly configured to support payload operations. The DMC also is responsible for managing video coverage of research activity on the station. The DMC monitors, configures and coordinates the use of the video system. The PAYCOM, using the call sign, "Huntsville," is the prime communicator with the International Space Station astronaut crew on payload matters. The PAYCOM is responsible for enabling researchers around-the-world to talk directly with

4000-436: The electromagnetic spectrum covers the range from roughly 300 GHz to 400 THz (1 mm – 750 nm). It can be divided into three parts: Above infrared in frequency comes visible light . The Sun emits its peak power in the visible region, although integrating the entire emission power spectrum through all wavelengths shows that the Sun emits slightly more infrared than visible light. By definition, visible light

4080-809: The electromagnetic spectrum was filled in with the discovery of gamma rays . In 1900, Paul Villard was studying the radioactive emissions of radium when he identified a new type of radiation that he at first thought consisted of particles similar to known alpha and beta particles , but with the power of being far more penetrating than either. However, in 1910, British physicist William Henry Bragg demonstrated that gamma rays are electromagnetic radiation, not particles, and in 1914, Ernest Rutherford (who had named them gamma rays in 1903 when he realized that they were fundamentally different from charged alpha and beta particles) and Edward Andrade measured their wavelengths, and found that gamma rays were similar to X-rays, but with shorter wavelengths. The wave-particle debate

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4160-445: The eyes, this results in visual perception of the scene. The brain's visual system processes the multitude of reflected frequencies into different shades and hues, and through this insufficiently understood psychophysical phenomenon, most people perceive a bowl of fruit. At most wavelengths, however, the information carried by electromagnetic radiation is not directly detected by human senses. Natural sources produce EM radiation across

4240-407: The field. Analyzing the speed of these theoretical waves, Maxwell realized that they must travel at a speed that was about the known speed of light . This startling coincidence in value led Maxwell to make the inference that light itself is a type of electromagnetic wave. Maxwell's equations predicted an infinite range of frequencies of electromagnetic waves , all traveling at the speed of light. This

4320-403: The following three physical properties: the frequency f , wavelength λ , or photon energy E . Frequencies observed in astronomy range from 2.4 × 10  Hz (1 GeV gamma rays) down to the local plasma frequency of the ionized interstellar medium (~1 kHz). Wavelength is inversely proportional to the wave frequency, so gamma rays have very short wavelengths that are fractions of

4400-605: The formal definition of radar frequency band nomenclature in IEEE Standard 521–2002. K u band is primarily used for satellite communications , most notably the downlink used by direct broadcast satellites to broadcast satellite television , and for specific applications such as NASA 's Tracking Data Relay Satellite used for International Space Station (ISS) communications and SpaceX Starlink satellites. K u band satellites are also used for backhauls and particularly for satellite from remote locations back to

4480-570: The increasing order of wavelength, which is characteristic of the type of radiation. There are no precisely defined boundaries between the bands of the electromagnetic spectrum; rather they fade into each other like the bands in a rainbow (which is the sub-spectrum of visible light). Radiation of each frequency and wavelength (or in each band) has a mix of properties of the two regions of the spectrum that bound it. For example, red light resembles infrared radiation in that it can excite and add energy to some chemical bonds and indeed must do so to power

4560-425: The low end of the band the atmosphere is mainly transparent, at the upper end of the band absorption of microwaves by atmospheric gases limits practical propagation distances to a few kilometers. Terahertz radiation or sub-millimeter radiation is a region of the spectrum from about 100 GHz to 30 terahertz (THz) between microwaves and far infrared which can be regarded as belonging to either band. Until recently,

4640-525: The low-frequency end of the spectrum, have the lowest photon energy and the longest wavelengths—thousands of kilometers , or more. They can be emitted and received by antennas , and pass through the atmosphere, foliage, and most building materials. Gamma rays, at the high-frequency end of the spectrum, have the highest photon energies and the shortest wavelengths—much smaller than an atomic nucleus . Gamma rays, X-rays, and extreme ultraviolet rays are called ionizing radiation because their high photon energy

4720-708: The most energetic photons , having no defined lower limit to their wavelength. In astronomy they are valuable for studying high-energy objects or regions, however as with X-rays this can only be done with telescopes outside the Earth's atmosphere. Gamma rays are used experimentally by physicists for their penetrating ability and are produced by a number of radioisotopes . They are used for irradiation of foods and seeds for sterilization, and in medicine they are occasionally used in radiation cancer therapy . More commonly, gamma rays are used for diagnostic imaging in nuclear medicine , an example being PET scans . The wavelength of gamma rays can be measured with high accuracy through

4800-550: The optical (visible) part of the electromagnetic spectrum; infrared (if it could be seen) would be located just beyond the red side of the rainbow whilst ultraviolet would appear just beyond the opposite violet end. Electromagnetic radiation with a wavelength between 380 nm and 760 nm (400–790 terahertz) is detected by the human eye and perceived as visible light. Other wavelengths, especially near infrared (longer than 760 nm) and ultraviolet (shorter than 380 nm) are also sometimes referred to as light, especially when

4880-412: The power of its uplinks and downlinks can be increased. This higher power also translates into smaller receiving dishes and points out a generalization between a satellite's transmission and a dish's size. As the power increases, the size of an antenna's dish will decrease. This is because the purpose of the dish element of the antenna is to collect the incident waves over an area and focus them all onto

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4960-531: The properties of microwaves . These new types of waves paved the way for inventions such as the wireless telegraph and the radio . In 1895, Wilhelm Röntgen noticed a new type of radiation emitted during an experiment with an evacuated tube subjected to a high voltage . He called this radiation " x-rays " and found that they were able to travel through parts of the human body but were reflected or stopped by denser matter such as bones. Before long, many uses were found for this radiography . The last portion of

5040-522: The range was rarely studied and few sources existed for microwave energy in the so-called terahertz gap , but applications such as imaging and communications are now appearing. Scientists are also looking to apply terahertz technology in the armed forces, where high-frequency waves might be directed at enemy troops to incapacitate their electronic equipment. Terahertz radiation is strongly absorbed by atmospheric gases, making this frequency range useless for long-distance communication. The infrared part of

5120-506: The review and approval of all change requests to the timeline. The Operations Controller leads a team that is responsible for maintaining the daily payload work assignments; ensuring scheduled research activities are accomplished safely and on time, and managing and tracking available resources. The OC leads resolution of NASA payload anomalies, and monitors troubleshooting of on board systems to identify possible impacts to payload operations. The position assesses change requests for impacts to

5200-436: The size of atoms , whereas wavelengths on the opposite end of the spectrum can be indefinitely long. Photon energy is directly proportional to the wave frequency, so gamma ray photons have the highest energy (around a billion electron volts ), while radio wave photons have very low energy (around a femtoelectronvolt ). These relations are illustrated by the following equations: where: Whenever electromagnetic waves travel in

5280-402: The spectrum could appear to an observer moving at a substantial fraction of the speed of light with respect to the first to be in another part of the spectrum. For example, consider the cosmic microwave background . It was produced when matter and radiation decoupled, by the de- excitation of hydrogen atoms to the ground state . These photons were from Lyman series transitions, putting them in

5360-399: The spectrum, and technology can also manipulate a broad range of wavelengths. Optical fiber transmits light that, although not necessarily in the visible part of the spectrum (it is usually infrared), can carry information. The modulation is similar to that used with radio waves. Next in frequency comes ultraviolet (UV). In frequency (and thus energy), UV rays sit between the violet end of

5440-498: The spectrum, as though these were different types of radiation. Thus, although these "different kinds" of electromagnetic radiation form a quantitatively continuous spectrum of frequencies and wavelengths, the spectrum remains divided for practical reasons arising from these qualitative interaction differences. Radio waves are emitted and received by antennas , which consist of conductors such as metal rod resonators . In artificial generation of radio waves, an electronic device called

5520-422: The spectrum, noticed what he called "chemical rays" (invisible light rays that induced certain chemical reactions). These behaved similarly to visible violet light rays, but were beyond them in the spectrum. They were later renamed ultraviolet radiation. The study of electromagnetism began in 1820 when Hans Christian Ørsted discovered that electric currents produce magnetic fields ( Oersted's law ). Light

5600-503: The surface. This effect is used to heat food in microwave ovens , and for industrial heating and medical diathermy . Microwaves are the main wavelengths used in radar , and are used for satellite communication , and wireless networking technologies such as Wi-Fi . The copper cables ( transmission lines ) which are used to carry lower-frequency radio waves to antennas have excessive power losses at microwave frequencies, and metal pipes called waveguides are used to carry them. Although at

5680-471: The ultraviolet (UV) part of the electromagnetic spectrum. Now this radiation has undergone enough cosmological red shift to put it into the microwave region of the spectrum for observers moving slowly (compared to the speed of light) with respect to the cosmos. Electromagnetic radiation interacts with matter in different ways across the spectrum. These types of interaction are so different that historically different names have been applied to different parts of

5760-454: The use of receiver antennas as small as 18 inches (450 mm). Segments in those regions are represented by ITU Region 1, and they are the 11.45 to 11.7 and 12.5 to 12.75 GHz bands are allocated to the FSS ( fixed satellite service , uplink 14.0 to 14.5 GHz). In Europe K u band is used from 10.7 to 12.75 GHz (LOF Low 9.75 GHz, LOF High 10.6 GHz) for direct broadcast satellite services such as those carried by

5840-421: The visibility to humans is not relevant. White light is a combination of lights of different wavelengths in the visible spectrum. Passing white light through a prism splits it up into the several colours of light observed in the visible spectrum between 400 nm and 780 nm. If radiation having a frequency in the visible region of the EM spectrum reflects off an object, say, a bowl of fruit, and then strikes

5920-431: The waves and was able to infer (by measuring their wavelength and multiplying it by their frequency) that they traveled at the speed of light. Hertz also demonstrated that the new radiation could be both reflected and refracted by various dielectric media , in the same manner as light. For example, Hertz was able to focus the waves using a lens made of tree resin . In a later experiment, Hertz similarly produced and measured

6000-403: The years, dish beam-width has become much more critical than gain. The K u band also offers a user more flexibility. A smaller dish size and a K u band system's freedom from terrestrial operations simplifies finding a suitable dish site. For the end users K u band is generally cheaper and enables smaller antennas (both because of the higher frequency and a more focused beam). K u band

6080-415: Was a wave. In 1800, William Herschel discovered infrared radiation. He was studying the temperature of different colours by moving a thermometer through light split by a prism. He noticed that the highest temperature was beyond red. He theorized that this temperature change was due to "calorific rays", a type of light ray that could not be seen. The next year, Johann Ritter , working at the other end of

6160-423: Was first linked to electromagnetism in 1845, when Michael Faraday noticed that the polarization of light traveling through a transparent material responded to a magnetic field (see Faraday effect ). During the 1860s, James Clerk Maxwell developed four partial differential equations ( Maxwell's equations ) for the electromagnetic field . Two of these equations predicted the possibility and behavior of waves in

6240-442: Was intensively studied from the beginning of the 17th century leading to the invention of important instruments like the telescope and microscope . Isaac Newton was the first to use the term spectrum for the range of colours that white light could be split into with a prism . Starting in 1666, Newton showed that these colours were intrinsic to light and could be recombined into white light. A debate arose over whether light had

6320-578: Was rekindled in 1901 when Max Planck discovered that light is absorbed only in discrete " quanta ", now called photons , implying that light has a particle nature. This idea was made explicit by Albert Einstein in 1905, but never accepted by Planck and many other contemporaries. The modern position of science is that electromagnetic radiation has both a wave and a particle nature, the wave-particle duality . The contradictions arising from this position are still being debated by scientists and philosophers. Electromagnetic waves are typically described by any of

6400-507: Was the first indication of the existence of the entire electromagnetic spectrum. Maxwell's predicted waves included waves at very low frequencies compared to infrared, which in theory might be created by oscillating charges in an ordinary electrical circuit of a certain type. Attempting to prove Maxwell's equations and detect such low frequency electromagnetic radiation, in 1886, the physicist Heinrich Hertz built an apparatus to generate and detect what are now called radio waves . Hertz found

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