Term
| What determines the space environmental effects on radio-wave signals? |
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Definition
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Term
| Name one space environmental effect on high-frequency communications. |
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Definition
| Controllability problems or disruption problems. |
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Term
| How can space environmental effects impact satellite communications? |
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Definition
| By intermittently interrupting SATCOM signals. |
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Term
| What causes space environmental effects to impact satellite communications? |
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Definition
| As UHF radio signals move through the ionosphere on their way to or from a satellite, extremely large electron density gradients within the ionosphere distort the signal sufficiently such that the signal is unrecognizable to a receiver. |
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Term
| How can space environmental effects impact GPS (single frequency) navigation signals? |
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Definition
| The performance (positional accuracy) of GPS single-frequency navigation systems is degraded. |
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Term
| What causes space environmental effects to impact single frequency GPSs? |
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Definition
| As a GPS signal moves through the ionosphere on its way down from a GPS satellite, the electrons slow down the signal. This slowing effect increases as the total number of electrons the signal passes through increases. Typically, four GPS signals from four satellites are used to compute a position. Since the total number of electrons each GPS signal moves through is different, the receiver computes a position that is not exact. |
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Term
| How can space environmental effects impact GPS (dual frequency) navigation signals? |
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Definition
| GPS dual-frequency receivers intermittently lose lock of GPS signals causing loss of positional accuracy. |
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Term
| What causes space environmental effects to impact dual frequency GPSs? |
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Definition
| Extremely large density gradients in the ionosphere distort the signal sufficiently such that the signal is unrecognizable to a receiver. |
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Term
| How is a GPS guided PGM affected by a large electron density gradient within the ionosphere? |
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Definition
| Positional accuracy and identification of specific objects are degraded. |
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Term
| Explain how an orbiting satellite is directly impacted by space environmental affects. |
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Definition
| Damage to on-board electronic components, false readings in satellite sensors, and anomalous behavior in satellite subsystems. |
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Term
| How can space environmental effects cause satellites to lose altitude? |
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Definition
| Heating of the thermosphere by the sun’s ultraviolet radiation or by enhanced electric currents in the magnetosphere expands atoms and molecules from lower altitudes upward into the orbit altitudes of satellites. These atoms and molecules increase frictional drag thus slowing their velocity and causing the satellites or space objects to lose altitude. |
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Term
| What type of communication system experiences direct radio frequency interference? |
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Definition
| Satellite communications. |
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Term
| At what speed do solar flare-enhanced X-rays, EUV, and radio waves reach earth? |
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Definition
| Speed of light (3×108 meters per second, or in about 8 minutes). |
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Term
| What are two examples of high-energy particles that result from the occurrence of a solar flare? |
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Definition
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Term
| Why is the prediction of solar proton and cosmic ray activity that affects earth so difficult? |
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Definition
| Not all solar flares produce high energy particles, the distance between earth and the sun is 93 million miles, and earth is a small target. |
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Term
| Over what regions of earth are the major impacts of proton activity felt? |
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Definition
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Term
| How long can ionospheric storms that are caused by electron and proton particle streams last? |
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Definition
| From a few hours to several days. |
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Term
| What is a short-wave fade? |
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Definition
| The absorption of HF radio waves by the ionosphere which results in radio signals not reaching their intended destination or fading. |
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Term
| What is the cause of a short-wave fade? |
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Definition
| HF radio signals being absorbed in the D-layer of the ionosphere and not reaching the F-layer where they can be refracted back toward earth. |
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Term
| What is a radio energy burst? |
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Definition
| A burst of energy from a solar flare on the sun that reaches earth’s upper atmosphere. |
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Term
| What is the cause of an absorption event? |
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Definition
| Enhanced ionization of atmospheric atoms and molecules caused by particle bombardment from space. |
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Term
| Describe ionospheric scintillation. |
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Definition
| The rapid, random variation in signal amplitude, phase, and/or polarization caused by small-scale irregularities in the electron density along a signal’s path. Scintillation is similar to the human eye observing the apparent twinkling effect when viewing a star or the heat shimmer over a hot road. |
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Term
| How can scintillation affect a GPS satellite? |
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Definition
| It can cause a GPS receiver to lose signal lock with a particular satellite |
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Term
| What effect can the TEC along the path of a GPS signal have? |
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Definition
| It can introduce a positioning error. |
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Term
| What sensors detect scintillation? |
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Definition
| Currently, C/NOFS allows the forecasting of scintillations, but no actual sensors currently exist to detect real-time scintillation. |
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Term
| Where in the atmosphere, statistically, is scintillation most severe? |
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Definition
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Term
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Definition
| Abnormal radar signal backscatter on poleward looking radars. |
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Term
| What effect can free electrons in the ionosphere have on missile detection and space track radars? |
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Definition
| They cause them to be bent or refracted, as well as slowed somewhat from the speed of light. |
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Term
| State the consequences of satellite drag. |
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Definition
| Inaccurate satellite locations hinder rapid acquisition of SATCOM links for commanding or data transmission; costly orbit maintenance maneuvers become necessary; de-orbit predictions become unreliable. |
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Term
| List the two space environmental parameters used by current models to predict the orbits of space objects. |
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Definition
| F10 solar index and the geomagnetic Ap index. |
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Term
| Name the two observed impacts of geomagnetic storms on space track radars. |
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Definition
| Bearing and range errors and atmospheric drag. |
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Term
| What is a result of the protective shielding around a payload (satellite) being jettisoned too early? |
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Definition
| The payload is exposed to excessive frictional heating. |
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Term
| What impact do the Van Allen radiation belts have on geosynchronous and semisynchronous orbits? |
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Definition
| They affect orbiting spacecraft by exposing them to charged particles that can cause drag and electrical damage. |
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Term
| What can produce spacecraft charging? |
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Definition
| A spacecraft’s motion through a medium containing charged particles, directed particle bombardment, and solar illumination. |
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Term
| What are some impacts of spacecraft electrostatic discharging? |
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Definition
| Spurious circuit switching; degradation or failure of electronic components, thermal coatings, and solar cells; or false sensor readings. |
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Term
| What is a single event upset? |
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Definition
| An SEU is a random, unpredictable event and can occur any time during the 11–year solar cycle. Essentially, an SEU is caused by a single proton or cosmic ray depositing enough charge to cause an electrical upset in a circuit switch, spurious command or memory change or loss. This SEU can also cause serious physical damage to onboard computers or other components. |
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Term
| What causes satellite disorientation? |
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Definition
| Disorientation occurs primarily when solar activity is high and with geosynchronous or polar orbiting satellites. Essentially, high-energy protons and cosmic rays cause problems with a satellite’s orientation when they collide with one of its star sensors. The bright spot produced on the sensor may be falsely interpreted as a star. When computer software fails to find this false star in its star catalogue or incorrectly identifies it, the satellite can lose attitude lock with respect to earth. |
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Term
| What occurs during satellite disorientation? |
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Definition
| Directional communications antenna, sensors, and solar cell panels fail to see their intended targets. The result may be loss of communication with the satellite; loss of satellite power; and, in extreme cases, loss of the satellite due to drained batteries. |
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Term
| Identify the AFSPC unit that provides operational and staff support to Cheyenne Mountain |
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Definition
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Term
| Name the AFSPC unit that provides weather services for all DOD and civilian space and ballistic missile launches at the Western Range. |
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Definition
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Term
| Which AFSPC unit provides weather services for all DOD and civilian space and ballistic missile launches at the Eastern Range? |
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Definition
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Term
| List two responsibilities of the 2d Weather Squadron Space Weather Operations Center. |
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Definition
| Two of any of the following: provides space environmental forecasts, warnings, and anomaly assessments to enhance the capability of DOD forces; operate the worldwide Solar Electro-optical Network (SEON) and a product development center, 24 hours per day, and are responsible for collection, analysis, and dissemination of space environmental information required by high-priority space operations and systems for NORAD, NORTHCOM, AFSPC, other DOD agencies, and the intelligence community. SEON is the only network of its kind in the world that provides real-time, 24–hour observation and notification of solar radio and optical events. |
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Term
| Who is the focal point for weather and space environmental operations supporting AFSPC mission areas? |
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Definition
| 2d Weather Squadron Space Weather Operations Center. |
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Term
| What two agencies provide space environmental support in the United States? |
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Definition
| NOAA’s Space Weather Prediction Center (SWPC) in Boulder, Colorado and the 2d Weather Squadron Space Weather Operations Center. |
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Term
| From what agency do military customers receive space environmental support? |
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Definition
| 2d Weather Squadron Space Weather Operations Center. |
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Term
| What space vehicle provides energetic and geophysical data to SWPC? |
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Definition
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Term
| What happens to space environmental observational data after the 2d Weather Squadron Space Weather Operations Center or SWPC collect it? |
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Definition
| The data is quickly cross-fed between the two centers then analyzed and processed and used to produce alerts, analyses, forecasts, and environmental parameter specifications. |
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Term
| Explain the services provided by 2d Weather Squadron Space Weather Operations Center Space Weather Operations Center. |
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Definition
| Rapid warnings when a solar or geophysical event is observed as well as short-range and long-range forecasts of space environmental conditions. The branch also performs post-analysis assessments on specific radar, communications, or satellite anomalies, to help operators determine whether the environment contributed to a problem they experienced or whether the cause lies elsewhere. |
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Term
| How many solar optical and radio observatories does the USAF operate? |
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Definition
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Term
| Explain what an HF propagation product describes. |
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Definition
| HF communication propagation conditions on a global scale, both observed and forecasted for the next six hours. |
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Term
| What does a short-wave fade advisory describe? |
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Definition
| The HF frequencies that may become unusable during daylight conditions due to a sudden burst in the sun’s X-ray radiation that modifies the ionosphere. |
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Term
| What does a polar cap absorption event warning report describe? |
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Definition
| That HF communications north of about 50N latitude and south of 50S latitude may be seriously degraded or impossible due to a burst of protons from the sun that modify the ionosphere. |
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Term
| What is the application for the WOXX50 KGWC bulletin? |
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Definition
| Informing aircrews, tactical forces, and HF airways station operators of degraded conditions. |
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Term
| Which bulletin describes that a significant enhancement in the magnetosphere’s electric-current network (geomagnetic storming) has already started? |
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Definition
| WOXX54 KGWC, geomagnetic event warning report. |
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Term
| What is an application for the WOXX54 KGWC bulletin? |
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Definition
| Informing aircrews, tactical forces, mission planners, and HF airways operators of degraded HF communications conditions. |
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