Communications blackout

Last updated

In telecommunications, communications blackouts are

Contents

Technical failures

Uptime being a key goal of most communications networks, power supplies and backup generators are typically used to ensure high-reliability power.

Wireless networks may be subject to radio jamming; wired networks can be physically severed. Network design can also play a role in maintaining communications reliability; depending on the constraints in building a fiber-optic network, a self-healing ring topology may be used.

Spacecraft reentry

The communications blackouts that affect spacecraft re-entering the Earth's atmosphere, which are also known as radio blackouts, ionization blackouts, or reentry blackouts, are caused by an envelope of ionized air around the craft, created by the heat from the compression of the atmosphere by the craft. The ionized air interferes with radio signals. For the Mercury, Gemini, and Apollo spacecraft, such communications blackouts lasted for several minutes. [1] Gemini 2, for example, endured such a blackout for four minutes, beginning at 9 minutes 5 seconds into the descent. [2]

For Apollo missions, the communications blackout was approximately three minutes long. [3] For Apollo 16, for example, pre-advisory data (PAD) for re-entry listed the expected times for re-entry communications blackout to be from 0 minutes 16 seconds after entry interface to 3 minutes 33 seconds after entry interface (a total of 3 minutes 17 seconds). [4] For the Apollo 13 mission, the blackout was much longer than normal because the flight path of the spacecraft was unexpectedly at a much shallower angle than normal. [4] According to the mission log maintained by Gene Kranz, the Apollo 13 re-entry blackout lasted around 6 minutes, beginning at 142:39 and ending at 142:45, and was 1 minute 27 seconds longer than had been predicted. [5]

Communications blackouts for re-entry are not solely confined to entry into Earth's atmosphere. They apply to entry into any atmosphere where such ionization occurs around a craft. The Mars Pathfinder endured a 30-second communications blackout as it entered Mars' atmosphere, for example. The Huygens probe endured a communications blackout as it entered the atmosphere of Titan. [1]

Until the creation of the Tracking and Data Relay Satellite System (TDRSS), the Space Shuttle endured a 30-minute blackout. The TDRSS allowed the Shuttle to communicate by relay with a Tracking and Data Relay Satellite during re-entry, through a "hole" in the ionized air envelope at the tail end of the craft, created by the Shuttle's shape. [1]

Space weather

Radio blackouts on Earth caused by solar flares are measured by the National Oceanic and Atmospheric Administration on a scale from 1 (minor) to 5 (extreme). [1] [6] [7]

Solar position

Communications can also be lost when the Sun is blocking or behind one station in the same line of sight; Sun outages periodically interrupt communications with geosynchronous satellites. It is also a common problem for interplanetary space missions.

See also

Related Research Articles

<span class="mw-page-title-main">Extravehicular activity</span> Activity done by an astronaut or cosmonaut outside a spacecraft

Extravehicular activity (EVA) is any activity done by an astronaut in outer space outside a spacecraft. In the absence of a breathable Earthlike atmosphere, the astronaut is completely reliant on a space suit for environmental support. EVA includes spacewalks and lunar or planetary surface exploration. In a stand-up EVA (SEVA), an astronaut stands through an open hatch but does not fully leave the spacecraft. EVAs have been conducted by the Soviet Union/Russia, the United States, Canada, the European Space Agency and China.

<span class="mw-page-title-main">Ionosphere</span> Ionized part of Earths upper atmosphere

The ionosphere is the ionized part of the upper atmosphere of Earth, from about 48 km (30 mi) to 965 km (600 mi) above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on Earth. It also affects GPS signals that travel through this layer.

<span class="mw-page-title-main">Project Mercury</span> Initial American crewed spaceflight program (1958–1963)

Project Mercury was the first human spaceflight program of the United States, running from 1958 through 1963. An early highlight of the Space Race, its goal was to put a man into Earth orbit and return him safely, ideally before the Soviet Union. Taken over from the US Air Force by the newly created civilian space agency NASA, it conducted 20 uncrewed developmental flights, and six successful flights by astronauts. The program, which took its name from Roman mythology, cost $2.57 billion. The astronauts were collectively known as the "Mercury Seven", and each spacecraft was given a name ending with a "7" by its pilot.

<span class="mw-page-title-main">Spacecraft</span> Vehicle or machine designed to fly in space

A spacecraft is a vehicle that is designed to fly in outer space and operate there. Spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, planetary exploration, and transportation of humans and cargo. All spacecraft except single-stage-to-orbit vehicles cannot get into space on their own, and require a launch vehicle.

<span class="mw-page-title-main">Atmospheric entry</span> Passage of an object through the gases of an atmosphere from outer space

Atmospheric entry is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet, or natural satellite. There are two main types of atmospheric entry: uncontrolled entry, such as the entry of astronomical objects, space debris, or bolides; and controlled entry of a spacecraft capable of being navigated or following a predetermined course. Technologies and procedures allowing the controlled atmospheric entry, descent, and landing of spacecraft are collectively termed as EDL.

<span class="mw-page-title-main">Space weather</span> Branch of space physics and aeronomy

Space weather is a branch of space physics and aeronomy, or heliophysics, concerned with the varying conditions within the Solar System and its heliosphere. This includes the effects of the solar wind, especially in the Earth's magnetosphere, ionosphere, thermosphere, and exosphere. Though physically distinct, space weather is analogous to the terrestrial weather of Earth's atmosphere. The term "space weather" was first used in the 1950s and popularized in the 1990s. Later, it prompted research into "space climate", the large-scale and long-term patterns of space weather.

<span class="mw-page-title-main">Soyuz (spacecraft)</span> Series of spacecraft designed for the Soviet space programme

Soyuz is a series of spacecraft which has been in service since the 1960s, having made more than 140 flights. It was designed for the Soviet space program by the Korolev Design Bureau. The Soyuz succeeded the Voskhod spacecraft and was originally built as part of the Soviet crewed lunar programs. It is launched on a Soyuz rocket from the Baikonur Cosmodrome in Kazakhstan. Between the 2011 retirement of the Space Shuttle and the 2020 demo flight of SpaceX Crew Dragon, the Soyuz served as the only means to ferry crew to or from the International Space Station, for which it remains heavily used. Although China did launch crewed Shenzhou flights during this time, none of them docked with the ISS.

<span class="mw-page-title-main">Gemini 3</span> 1965 American crewed space mission

Gemini 3 was the first crewed mission in NASA's Project Gemini and was the first time two American astronauts flew together into space. On March 23, 1965, astronauts Gus Grissom and John Young flew three low Earth orbits in their spacecraft, which they nicknamed Molly Brown. It was the first U.S. mission in which the crew fired thrusters to change the size and shape of their orbit, a key test of spacecraft maneuverability vital for planned flights to the Moon. It was also the final crewed flight controlled from Cape Kennedy Air Force Station in Florida, before mission control functions were moved to a new control center at the newly opened Manned Spacecraft Center in Houston, Texas.

<span class="mw-page-title-main">Gemini 1</span> First Gemini program spacelaunch

Gemini 1 was the first mission in NASA's Gemini program. An uncrewed test flight of the Gemini spacecraft, its main objectives were to test the structural integrity of the new spacecraft and modified Titan II launch vehicle. It was also the first test of the new tracking and communication systems for the Gemini program and provided training for the ground support crews for the first crewed missions.

<span class="mw-page-title-main">Gemini 11</span> 1966 NASA crewed spaceflight

Gemini 11 was the ninth crewed spaceflight mission of NASA's Project Gemini, which flew from September 12 to 15, 1966. It was the 17th crewed American flight and the 25th spaceflight to that time. Astronauts Charles "Pete" Conrad Jr. and Richard F. Gordon Jr. performed the first direct-ascent rendezvous with an Agena Target Vehicle, docking with it 1 hour 34 minutes after launch; used the Agena rocket engine to achieve a record high-apogee Earth orbit; and created a small amount of artificial gravity by spinning the two spacecraft connected by a tether. Gordon also performed two extra-vehicular activities for a total of 2 hours 41 minutes.

<span class="mw-page-title-main">Tracking and Data Relay Satellite System</span> Network of American communications satellites

The U.S. Tracking and Data Relay Satellite System (TDRSS) is a network of American communications satellites and ground stations used by NASA for space communications. The system was designed to replace an existing network of ground stations that had supported all of NASA's crewed flight missions. The prime design goal was to increase the time spacecraft were in communication with the ground and improve the amount of data that could be transferred. Many Tracking and Data Relay Satellites were launched in the 1980s and 1990s with the Space Shuttle and made use of the Inertial Upper Stage, a two-stage solid rocket booster developed for the shuttle. Other TDRS were launched by Atlas IIa and Atlas V rockets.

<span class="mw-page-title-main">Space capsule</span> Type of spacecraft

A space capsule is a spacecraft designed to transport cargo, scientific experiments, and/or astronauts to and from space. Capsules are distinguished from other spacecraft by the ability to survive reentry and return a payload to the Earth's surface from orbit, and are distinguished from other types of recoverable spacecraft by their blunt shape, not having wings and often containing little fuel other than what is necessary for a safe return. Capsule-based crewed spacecraft such as Soyuz or Orion are often supported by a service or adapter module, and sometimes augmented with an extra module for extended space operations. Capsules make up the majority of crewed spacecraft designs, although one crewed spaceplane, the Space Shuttle, has flown in orbit.

<span class="mw-page-title-main">Retrorocket</span> Rocket engine providing negative thrust used to slow the motion of an aerospace vehicle

A retrorocket is a rocket engine providing thrust opposing the motion of a vehicle, thereby causing it to decelerate. They have mostly been used in spacecraft, with more limited use in short-runway aircraft landing. New uses are emerging since 2010 for retro-thrust rockets in reusable launch systems.

<span class="mw-page-title-main">Reentry capsule</span> Part of a space capsule

A reentry capsule is the portion of a space capsule which returns to Earth following a spaceflight. The shape is determined partly by aerodynamics; a capsule is aerodynamically stable falling blunt end first, which allows only the blunt end to require a heat shield for atmospheric entry. A crewed capsule contains the spacecraft's instrument panel, limited storage space, and seats for crew members. Because a capsule shape has little aerodynamic lift, the final descent is via parachute, either coming to rest on land, at sea, or by active capture by an aircraft. In contrast, the development of spaceplane reentry vehicles attempts to provide a more flexible reentry profile.

<span class="mw-page-title-main">Tracking and data relay satellite</span> American communications satellite

A tracking and data relay satellite (TDRS) is a type of communications satellite that forms part of the Tracking and Data Relay Satellite System (TDRSS) used by NASA and other United States government agencies for communications to and from independent "User Platforms" such as satellites, balloons, aircraft, the International Space Station, and remote bases like the Amundsen-Scott South Pole Station. This system was designed to replace an existing worldwide network of ground stations that had supported all of NASA's crewed flight missions and uncrewed satellites in low-Earth orbits. The primary system design goal was to increase the amount of time that these spacecraft were in communication with the ground and improve the amount of data that could be transferred. These TDRSS satellites are all designed and built to be launched to and function in geosynchronous orbit, 35,786 km (22,236 mi) above the surface of the Earth.

<span class="mw-page-title-main">Flight controller</span> Person who aids in spaceflight activities

Flight controllers are personnel who aid space flight by working in such Mission Control Centers as NASA's Mission Control Center or ESA's European Space Operations Centre. Flight controllers work at computer consoles and use telemetry to monitor various technical aspects of a space mission in real-time. Each controller is an expert in a specific area and constantly communicates with additional experts in the "back room". The flight director, who leads the flight controllers, monitors the activities of a team of flight controllers, and has overall responsibility for success and safety.

<span class="mw-page-title-main">ARGOS (satellite)</span>

The Advanced Research and Global Observation Satellite (ARGOS) was launched on 23 February 1999 carrying nine payloads for research and development missions by nine separate researchers. The mission terminated on 31 July 2003.

The Manned Space Flight Network was a set of tracking stations built to support the American Mercury, Gemini, Apollo, and Skylab space programs.

<span class="mw-page-title-main">Ionospheric Connection Explorer</span> NASA satellite of the Explorer program

Ionospheric Connection Explorer (ICON) is a satellite designed to investigate changes in the ionosphere of Earth, the dynamic region high in our atmosphere where terrestrial weather from below meets space weather from above. ICON studies the interaction between Earth's weather systems and space weather driven by the Sun, and how this interaction drives turbulence in the upper atmosphere. It is hoped that a better understanding of this dynamic will mitigate its effects on communications, GPS signals, and technology in general. It is part of NASA's Explorer program and is operated by University of California, Berkeley's Space Sciences Laboratory.

<span class="mw-page-title-main">Solar particle event</span> Solar phenomenon

In solar physics, a solar particle event (SPE), also known as a solar energetic particle (SEP) event or solar radiation storm, is a solar phenomenon which occurs when particles emitted by the Sun, mostly protons, become accelerated either in the Sun's atmosphere during a solar flare or in interplanetary space by a coronal mass ejection shock. Other nuclei such as helium and HZE ions may also be accelerated during the event. These particles can penetrate the Earth's magnetic field and cause partial ionization of the ionosphere. Energetic protons are a significant radiation hazard to spacecraft and astronauts.

References

  1. 1 2 3 4 Lucy Rogers (2008). It's only rocket science: an introduction in plain English. Astronomers' universe: Springer eBooks collection. Springer. pp. 159–162. ISBN   978-0-387-75378-2.
  2. David Shayler (2001). "Gemini 2". Gemini: steps to the moon. Springer-Praxis books in astronomy and space sciences. Springer. p. 183. ISBN   978-1-85233-405-5.
  3. Neville Warren (2004). Excel HSC physics. Pascal Press. p. 23. ISBN   978-1-74125-077-0.
  4. 1 2 W. David Woods (2008). How Apollo Flew to the Moon. Springer Praxis Books in Space Exploration. Springer. pp.  354, 366. ISBN   9780387716756.
  5. Joe Pappalardo (2007-05-01). "Did Ron Howard exaggerate the reentry scene in the movie Apollo 13?". Air & Space . Smithsonian Institution. Archived from the original on 2009-07-29. Retrieved 2009-08-13.
  6. "NOAA Space Weather Scales".
  7. "Solar Flares (Radio Blackouts) | NOAA / NWS Space Weather Prediction Center". www.swpc.noaa.gov. Retrieved 11 November 2021.

Further reading