C/NOFS, or Communications/Navigation Outage Forecasting System was a

USAF The United States Air Force (USAF) is the Aerial warfare, air military branch, service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part ...

satellite developed by the

Air Force Research Laboratory The Air Force Research Laboratory (AFRL) is a scientific research organization operated by the United States Air Force Materiel Command dedicated to leading the discovery, development, and integration of aerospace warfighting technologies, pl ...

(AFRL) Space Vehicles Directorate to investigate and forecast scintillations in the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...

ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to 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 ...

. It was launched by an

Orbital Sciences Corporation Orbital Sciences Corporation (commonly referred to as Orbital) was an American company specializing in the design, manufacture, and launch of small- and medium- class space and launch vehicle systems for commercial, military and other governmen ...

Pegasus-XL Pegasus is an air-launched launch vehicle developed by Orbital Sciences Corporation (OSC) and now built and launched by Northrop Grumman. Capable of carrying small payloads of up to into low Earth orbit, Pegasus first flew in 1990 and remai ...

launch vehicle A launch vehicle or carrier rocket is a rocket designed to carry a payload ( spacecraft or satellites) from the Earth's surface to outer space. Most launch vehicles operate from a launch pads, supported by a launch control center and sys ...

at 17:02:48 UTC on 16 April 2008 and decayed on 28 November 2015. The satellite, which was operated by the

Space Test Program The Space Test Program (STP) is the primary provider of spaceflight for the United States Department of Defense (DoD) space science and technology community. STP is managed by a group within the Advanced Systems and Development Directorate, a d ...

(STP), allowed the U.S. military to predict the effects of ionospheric activity on signals from communication and navigation satellites, outages of which could potentially cause problems in battlefield situations. C/NOFS had a three-axis stabilisation system, and was equipped with seven sensors. It was placed into a

low Earth orbit A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never m ...

with

orbital inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Ea ...

of 13.00°, a

perigee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any el ...

of and an

apogee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any el ...

of . It carried the CINDI experiment for

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...

. Launch was originally scheduled for 2003, but was delayed due to a number of issues.

Scientific instruments on board

The spacecraft payload consists of the following instruments: * CERTO: the Coherent Electromagnetic Radio Tomography experiment is a radio beacon that will provide plasma density profiles and information on phase and amplitude scintillation of radio signals. CERTO is provided by the

Naval Research Laboratory The United States Naval Research Laboratory (NRL) is the corporate research laboratory for the United States Navy and the United States Marine Corps. It was founded in 1923 and conducts basic scientific research, applied research, technologic ...

(NRL). Principal investigator: Paul Bernhardt. * CORISS: the C/NOFS Occultation Receiver for Ionospheric Sensing and Specification (CORISS) instrument is a

GPS The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sy ...

dual-frequency receiver designed to measure line-of-sight TEC. CORISS is provided by

The Aerospace Corporation The Aerospace Corporation is an American nonprofit corporation that operates a federally funded research and development center (FFRDC) in El Segundo, California. The corporation provides technical guidance and advice on all aspects of space mi ...

. Principal investigator: Paul Straus. * Ion Velocity Meter (IVM): consists of a pair of sensors designed to measure the in situ ion velocity vector, ion temperature, and ion composition. The IVM is provided by the William B. Hanson Center for Space Sciences at the University of Texas at Dallas. IVM is a component of the CINDI package funded by NASA.

Principal investigator In many countries, the term principal investigator (PI) refers to the holder of an independent grant and the lead researcher for the grant project, usually in the sciences, such as a laboratory study or a clinical trial. The phrase is also often u ...

: Dr. Roderick A. Heelis. * Neutral Wind Meter (NWM): a two sensor package designed to measure the neutral wind velocity. NWM is provided by the William B. Hanson Center for Space Sciences at the University of Texas at Dallas. Like IVM, NWM is a component of the CINDI package funded by NASA. Principal investigator: Greg Earle. * Ram Wind Sensor (RWS): measures the ram component of the neutral wind by ionizing a fraction of the incoming neutral gas then performing retarding potential analysis on those ions. * Cross Track Sensor (CTS): is a hollow hemispherical dome divided into four independent chambers with a miniaturized Bayard-Alpert

hot filament ionization gauge The hot-filament ionization gauge, sometimes called a hot-filament gauge or hot-cathode gauge, is the most widely used low-pressure (vacuum) measuring device for the region from 10−3 to 10−10 Torr. It is a triode, with the filament being th ...

in each chamber. Four small holes in the dome allow the neutral gas to stream into the chambers. The pressure in any chamber will depend on the arrival angle of the neutral wind. * Planar Langmuir Probe (PLP): a two sensor package consisting an ion trap designed to measure ion density fluctuations and a

Langmuir probe A Langmuir probe is a device used to determine the electron temperature, electron density, and electric potential of a plasma. It works by inserting one or more electrodes into a plasma, with a constant or time-varying electric potential between ...

. PLP is provided by the Air Force Research Laboratory. Principal investigator: Patrick Roddy, formerly Donald Hunton. * Vector Electric Field Instrument (VEFI): is a collection of instruments including 6 electric field booms, a 3-axis

magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, ...

, a spherical

, and a

lightning detector A lightning detector is a device that detects lightning produced by thunderstorms. There are three primary types of detectors: ''ground-based'' systems using multiple antennas, ''mobile systems'' using a direction and a sense antenna in the same l ...

. VEFI is provided by NASA

Goddard Space Flight Center The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory located approximately northeast of Washington, D.C. in Greenbelt, Maryland, United States. Established on May 1, 1959 as NASA's first space flight center, GSFC empl ...

(GSFC) with funding from the Air Force Research Laboratory. Principal investigator: Dr. Robert F. Pfaff.

Experiments

C/NOFS Occultation Receiver for Ionospheric Sensing and Specification (CORISS)

The C/NOFS Occultation Receiver for Ionospheric Sensing and Specification (CORISS) is a

Global Positioning System The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite ...

(GPS) dual-frequency receiver that measures the total

electron The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have n ...

content (TEC) along the line-of-sight from C/NOFS to GPS satellite. TEC measurement can help to constrain C/NOFS ionospheric models. Limb profiles of TEC obtained during occultations can be inverted to produce vertical profiles of electron density. It may be also possible to measure

L-band The L band is the Institute of Electrical and Electronics Engineers (IEEE) designation for the range of frequencies in the radio spectrum from 1 to 2 gigahertz (GHz). This is at the top end of the ultra high frequency (UHF) band, at the lowe ...

scintillations caused by electron density irregularities.

Coherent Electromagnetic Radio Tomography (CERTO)

The Coherent Electromagnetic Radio Tomography (CERTO) is a tri-band (150, 400, 1067 MHz)

radio beacon In navigation, a radio beacon or radiobeacon is a kind of beacon, a device that marks a fixed location and allows direction-finding equipment to find relative bearing. But instead of employing visible light, radio beacons transmit electromagne ...

that permits direct measurement of ionospheric scintillation parameters at several frequencies by ground receivers. CERTO measurements can also be used for tomographic reconstruction of electron density profiles.

Coupled Ion-Neutral Dynamics Investigation (CINDI)

The Coupled Ion-Neutral Dynamics Investigation (CINDI) payload is funded by NASA as an Explorer Mission of Opportunity. CINDI consists of two instruments: the Ion Velocity Meter (IVM) and the Neutral Wind Meter (NWM). The IVM instrument includes an ion drift meter and a retarding potential analyzer. IVM measure the ion drift vector, the ion temperature, and the major ion composition with a spatial resolution of about along the satellite track; the ion drift meter also provides vertical and horizontal ion drift components at resolution. The NWM consists of a cross track wind sensor and a ram wind sensor providing a direct measure of the neutral wind vector with a spatial resolution of about along the satellite track.

Planar Langmuir Probe (PLP)

The Planar Langmuir Probe (PLP) is a dual-disk probe designed to provide in situ measurements of plasma density and density fluctuations. Low time-resolution density measurements are intended as inputs for background ionosphere models and high time-resolution density irregularity measurements to specify disturbance conditions. PLP also monitors the spacecraft surface potential.

Vector Electric Field Instrument (VEFI)

The Vector Electric Field Instrument (VEFI) consists primarily of three orthogonal tip-to-tip double probe antennas. It measures the

alternating current Alternating current (AC) is an electric current which periodically reverses direction and changes its magnitude continuously with time in contrast to direct current (DC) which flows only in one direction. Alternating current is the form in whic ...

(AC) and

Direct current Direct current (DC) is one-directional flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or ev ...

(DC)

electric field An electric field (sometimes E-field) is the physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field ...

s related to plasma drift and irregularity development. The VEFI instrument package also includes a

fluxgate magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, o ...

, an optical lightning detector and a fixed-bias Langmuir probe.

Scientific data

C/NOFS science data is now available online for general use. VEFI and PLP data are available through NASA Goddard's Coordinated Data Analysis Web. CINDI data are available through the William B. Hanson Center for Space Science at the

University of Texas at Dallas The University of Texas at Dallas (UTD or UT Dallas) is a public research university in Richardson, Texas. It is one of the largest public universities in the Dallas area and the northernmost institution of the University of Texas system. It w ...

Current status

On 28 May 2008, the USAF

Space Development and Test Wing The Space Development and Test Wing (SDTW) was a unit of Air Force Space Command's Space and Missile Systems Center of the United States Air Force. The wing is located at Kirtland Air Force Base in Albuquerque, New Mexico. The unit was combined w ...

announced its launch and early orbit portion of the spacecraft's operations had been completed successfully. On 9 June 2008, the manufacturer of the separation systems used to deploy the C/NOFS solar panels, payload antennas and magnetometer boom indicated they had all functioned correctly. On 9 September 2011, SMC announced that it had extended the C/NOFS satellite maintenance contract from 1 October 2011 to 31 March 2012 to Orbital Sciences Corporation for the continued On-Orbit Support of the C/NOFS mission. On 3 June 2013, the C/NOFS satellite has been placed in safe mode, with all scientific instruments turned off, due to budgetary restrictions. On 21 October 2013, the C/NOFS satellite is out of safe mode and operating nominally. On 28 November 2015, C/NOFS burned in the

atmosphere of Earth The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing fo ...

during a planned reentry.

C/NOFS related publications

* "A new satellite-borne neutral wind instrument for thermospheric diagnostics", Earle ''et al.'', ''Review of Scientific Instruments'' 78, 114051 (2007) * "C/NOFS: a mission to forecast scintillations", O. de La Beaujardiere, ''Journal of Atmospheric and Solar-Terrestrial Physics'', 66 (2004) 1573–1591 * "Behavior of the O+/H+ transition height during the extreme solar minimum of 2008", Heelis ''et al.'', ''Geophysical Research Letters'', (2009) * "Broad Plasma Decreases in the Equatorial Ionosphere", Huang ''et al.'', ''Geophysical Research Letters'', (2009) * "Comparing F region ionospheric irregularity observations from C/NOFS and Jicamarca", Hysell ''et al.'', ''Geophysical Research Letters'', (2009) * "C/NOFS observations of intermediate and transitional scale-size equatorial spread F irregularities", Rodrigues ''et al.'', ''Geophysical Research Letters'', (2009) * "Assimilative modeling of equatorial plasma depletions observed by C/NOFS", Su ''et al.'', ''Geophysical Research Letters'', (2009) * "Longitudinal and seasonal dependence of nighttime equatorial plasma density irregularities during solar minimum detected on the C/NOFS satellite", Dao ''et al.'', ''Geophysical Research Letters'', (2011) * "Assimilative modeling of observed post-midnight equatorial plasma depletions in June 2008", Su ''et al.'', ''Journal of Geophysical Research'', (2011) * "Multiple phase screen modeling of ionospheric scintillation along radio occultation raypaths", Carrano ''et al.'', ''Radio Science'', (2011)

References

External links

NSSRM – C/NOFS

CINDI home page

{{Orbital launches in 2008 Earth observation satellites of the United States Satellites of the United States Air Force Spacecraft launched in 2008 Spacecraft which reentered in 2015 Spacecraft launched by Pegasus rockets