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77-560: The International Cometary Explorer (ICE) spacecraft, designed and launched as the International Sun-Earth Explorer-3 (ISEE-3) satellite, was launched on 12 August 1978 into a heliocentric orbit . It was one of three spacecraft, along with the mother/daughter pair of ISEE-1 and ISEE-2 , built for the International Sun-Earth Explorer (ISEE) program, a joint effort by NASA and ESRO / ESA to study

154-414: A magnetic crochet , a magnetic field detected by ground-based magnetometers induced by a perturbation of Earth's ionosphere by ionizing soft X-rays . This could not easily be understood at the time because it predated the discovery of X-rays in 1895 and the recognition of the ionosphere in 1902. About 18 hours after the flare, further geomagnetic perturbations were recorded by multiple magnetometers as

231-473: A current sheet above the PIL. Fast magnetic reconnection can be excited along the current sheet by microscopic instabilities, resulting in the rapid release of stored magnetic energy as kinetic, thermal, and nonthermal energy. The restructuring of the magnetic field cuts the strapping field's connections to the photosphere thereby decreasing the downward magnetic tension force while the upward reconnection outflow pushes

308-515: A "stretch goal" of US$ 150,000, which it also met with a final total of US$ 159,502 raised. The project members were working on deadline: if they got the spacecraft to change its orbit by late May or early June 2014, or in early July by using more fuel, it could use the Moon's gravity to get back into a useful halo orbit . Earlier in 2014, officials with the Goddard Space Flight Center said

385-419: A CME can greatly affect how it interacts with Earth's magnetic field. This interaction can result in the conservation or loss of magnetic flux, particularly its southward magnetic field component, through magnetic reconnection with the interplanetary magnetic field . In the solar wind, CMEs manifest as magnetic clouds . They have been defined as regions of enhanced magnetic field strength, smooth rotation of

462-683: A CME involves its initiation from a pre-eruption structure in the corona and the acceleration that follows. The processes involved in the early evolution of CMEs are poorly understood due to a lack of observational evidence. CME initiation occurs when a pre-eruption structure in an equilibrium state enters a nonequilibrium or metastable state where energy can be released to drive an eruption. The specific processes involved in CME initiation are debated, and various models have been proposed to explain this phenomenon based on physical speculation. Furthermore, different CMEs may be initiated by different processes. It

539-485: A CME, coincided with the first-observed solar flare on 1 September 1859. The resulting solar storm of 1859 is referred to as the Carrington Event . The flare and the associated sunspots were visible to the naked eye, and the flare was independently observed by English astronomers R. C. Carrington and R. Hodgson . At around the same time as the flare, a magnetometer at Kew Gardens recorded what would become known as

616-446: A CME, was the solar storm of 1859 . Also known as the Carrington Event , it disabled parts of the newly created United States telegraph network, starting fires and electrically shocking some telegraph operators. Near solar maxima , the Sun produces about three CMEs every day, whereas near solar minima , there is about one CME every five days. CMEs release large quantities of matter from

693-486: A camera or imaging system. Its detectors measure high-energy particles such as X- and gamma-rays, solar wind, plasma and cosmic particles. A data handling system gathers the scientific and engineering data from all systems in the spacecraft and formats them into a serial stream for transmission. The transmitter output power is five watts. Heliocentric orbit The barycenter of the Solar System, while always very near

770-513: A distance of 7,800 km (4,800 mi) of the nucleus on 11 September 1985. ICE transited between the Sun and Comet Halley in late March 1986, when other spacecraft were near the comet on their early-March comet rendezvous missions. (This " Halley Armada " included Giotto , Vega 1 and 2 , Suisei and Sakigake .) ICE flew through the tail; its minimum distance to the comet nucleus was 28 × 10 ^  km (17 × 10 ^  mi). For comparison, Earth's minimum distance to Comet Halley in 1910

847-422: A fast CME by a satellite such as ACE is a fast-mode shock wave followed by a dense (and hot) sheath of plasma (the downstream region of the shock) and a magnetic cloud. Other signatures of magnetic clouds are now used in addition to the one described above: among other, bidirectional superthermal electrons , unusual charge state or abundance of iron , helium , carbon , and/or oxygen . The typical time for

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924-448: A magnetic cloud to move past a satellite at the L1 point is 1 day corresponding to a radius of 0.15 AU with a typical speed of 450 km/s (280 mi/s) and magnetic field strength of 20 nT . The frequency of ejections depends on the phase of the solar cycle : from about 0.2 per day near the solar minimum to 3.5 per day near the solar maximum . However, the peak CME occurrence rate

1001-510: A part of a geomagnetic storm . The storm disabled parts of the recently created US telegraph network, starting fires and shocking some telegraph operators. The first optical observation of a CME was made on 14 December 1971 using the coronagraph of Orbiting Solar Observatory 7 (OSO-7). It was first described by R. Tousey of the Naval Research Laboratory in a research paper published in 1973. The discovery image (256 × 256 pixels)

1078-420: A result of the dominance of magnetic field processes in the lower corona, the majority of the energy must be stored as magnetic energy . The magnetic energy that is freely available to be released from a pre-eruption structure, referred to as the magnetic free energy or nonpotential energy of the structure, is the excess magnetic energy stored by the structure's magnetic configuration relative to that stored by

1155-501: A support station. Although NASA was not funding the project, it made advisors available and gave approval to try to establish contact. On 21 May 2014, NASA announced that it had signed a Non-Reimbursable Space Act Agreement with the ISEE-3 Reboot Project. "This is the first time NASA has worked such an agreement for use of a spacecraft the agency is no longer using or ever planned to use again", officials said. On 29 May 2014,

1232-412: A suspension between gravitational fields was possible. It rotates at 19.76 rpm about an axis perpendicular to the ecliptic , to keep it oriented for its experiments, to generate solar power and to communicate with Earth. The purposes of the mission were: After completing its original mission, ISEE-3 was re-tasked to study the interaction between the solar wind and a cometary atmosphere. On 10 June 1982,

1309-686: Is a significant ejection of plasma mass from the Sun's corona into the heliosphere . CMEs are often associated with solar flares and other forms of solar activity , but a broadly accepted theoretical understanding of these relationships has not been established. If a CME enters interplanetary space , it is referred to as an interplanetary coronal mass ejection ( ICME ). ICMEs are capable of reaching and colliding with Earth's magnetosphere , where they can cause geomagnetic storms , aurorae , and in rare cases damage to electrical power grids . The largest recorded geomagnetic perturbation, resulting presumably from

1386-467: Is often 6–12 months after sunspot number reaches its maximum. Only a very small fraction of CMEs are directed toward, and reach, the Earth. A CME arriving at Earth results in a shock wave causing a geomagnetic storm that may disrupt Earth's magnetosphere , compressing it on the day side and extending the night-side magnetic tail . When the magnetosphere reconnects on the nightside, it releases power on

1463-428: Is subject to ongoing debate. Some pre-eruption structures have been observed to support prominences , also known as filaments, composed of much cooler material than the surrounding coronal plasma. Prominences are embedded in magnetic field structures referred to as prominence cavities, or filament channels, which may constitute part of a pre-eruption structure (see § Coronal signatures ). The early evolution of

1540-611: Is unknown whether a magnetic flux rope exists prior to initiation, in which case either ideal or non-ideal magnetohydrodynamic (MHD) processes drive the expulsion of this flux rope, or whether a flux rope is created during the eruption by non-ideal process. Under ideal MHD, initiation may involve ideal instabilities or catastrophic loss of equilibrium along an existing flux rope: Under non-ideal MHD, initiations mechanisms may involve resistive instabilities or magnetic reconnection : Following initiation, CMEs are subject to different forces that either assist or inhibit their rise through

1617-549: The NASA Deep Space Network equipment necessary to transmit signals to the spacecraft had been decommissioned in 1999 and was too expensive to replace. However, project members were able to find documentation for the original equipment and were able to simulate the complex modulator/demodulator electronics using modern software-defined radio (SDR) techniques and open-source programs from the GNU Radio project. They obtained

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1694-586: The Thomson scattering of sunlight off of free electrons within the CME plasma. An observed CME may have any or all of three distinctive features: a bright core, a dark surrounding cavity, and a bright leading edge. The bright core is usually interpreted as a prominence embedded in the CME (see § Origin ) with the leading edge as an area of compressed plasma ahead of the CME flux rope. However, some CMEs exhibit more complex geometry. From white-light coronagraph observations, CMEs have been measured to reach speeds in

1771-401: The solar dynamo . These magnetic fields rise to the Sun's surface—the photosphere —where they may form localized areas of highly concentrated magnetic flux and expand into the lower solar atmosphere forming active regions . At the photosphere, active region magnetic flux is often distributed in a dipole configuration , that is, with two adjacent areas of opposite magnetic polarity across which

1848-408: The 1999 contact. A status check revealed that 12 of its 13 experiments were still functioning, and it still had enough propellant for 150 m/s (490 ft/s) of Δv . It was determined to be possible to reactivate the spacecraft in 2014, when it again made a close approach to Earth, and scientists discussed reusing the probe to observe more comets in 2017 or 2018. Sometime after NASA's interest in

1925-401: The CME as eruptive prominences. Eruptive prominences are associated with at least 70% of all CMEs and are often embedded within the bases of CME flux ropes. When observed in white-light coronagraphs, the eruptive prominence material, if present, corresponds to the observed bright core of dense material. When magnetic reconnection is excited along a current sheet of a rising CME core structure,

2002-504: The CME structure upwards. A positive feedback loop results as the core is pushed upwards and the sides of the strapping field are brought in closer and closer contact to produce additional magnetic reconnection and rise. While upward reconnection outflow accelerates the core, simultaneous downward outflow is sometimes responsible for other phenomena associated with CMEs (see § Coronal signatures ). In cases where significant magnetic reconnection does not occur, ideal MHD instabilities or

2079-501: The Earth resulting in gradual solar particle events . Interactions between these energetic particles and the Earth can cause an increase in the number of free electrons in the ionosphere , especially in the high-latitude polar regions, enhancing radio wave absorption, especially within the D-region of the ionosphere, leading to polar cap absorption events. The interaction of CMEs with the Earth's magnetosphere leads to dramatic changes in

2156-695: The ICE waned others realized that the spacecraft might be steered to pass close to another comet. A team of engineers, programmers, and scientists began to study the feasibility and challenges involved. In April 2014, its members formally announced their intentions to "recapture" the spacecraft for use, calling the effort the ISEE-3 Reboot Project. A team webpage said, "We intend to contact the ISEE-3 (International Sun-Earth Explorer) spacecraft, command it to fire its engine and enter an orbit near Earth, and then resume its original mission... If we are successful we intend to facilitate

2233-559: The ISEE-3 Reboot Team announced that all attempts to change orbit using the ISEE-3 propulsion system had failed. Instead, the team said, the ISEE-3 Interplanetary Citizen Science Mission would gather data as the spacecraft flies by the Moon on 10 August 2014 and enters a heliocentric orbit similar to Earth's. The team began shutting down propulsion components to maximize the electrical power available for

2310-527: The International Solar Terrestrial Physics (ISTP) program. The spacecraft is a spin axis-stabilized satellite that carries eight instruments measuring solar wind particles from thermal to greater than MeV energies, electromagnetic radiation from DC to 13 MHz radio waves, and gamma-rays. On 25 October 2006, NASA launched STEREO , two near-identical spacecraft which, from widely separated points in their orbits, are able to produce

2387-478: The Moon, on 22 December 1983, was only 119.4 km (74.2 mi) above the lunar surface; following this pass, the spacecraft was re-designated as the International Cometary Explorer (ICE). Its new orbit put it ahead of the Earth on a trajectory to intercept comet Giacobini-Zinner . On 11 September 1985, the craft passed through the comet's plasma tail. ICE did a flyby of the comet nucleus at

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2464-601: The Sun in Greek mythology . The first spacecraft to be put in a heliocentric orbit was Luna 1 in 1959. An incorrectly timed upper-stage burn caused it to miss its planned impact on the Moon . A trans-Mars injection (TMI) is a heliocentric orbit in which a propulsive maneuver is used to set a spacecraft on a trajectory , also known as Mars transfer orbit , which will place it as far as Mars orbit. Every two years, low-energy transfer windows open up, which allow movement between

2541-598: The Sun's atmosphere into the solar wind and interplanetary space . The ejected matter is a plasma consisting primarily of electrons and protons embedded within its magnetic field. This magnetic field is commonly in the form of a flux rope, a helical magnetic field with changing pitch angles . The average mass ejected is 1.6 × 10  kg (3.5 × 10  lb). However, the estimated mass values for CMEs are only lower limits, because coronagraph measurements provide only two-dimensional data. CMEs erupt from strongly twisted or sheared, large-scale magnetic field structures in

2618-455: The Sun, CMEs are sometimes referred to as interplanetary CMEs , or ICMEs . As CMEs propagate through the heliosphere, they may interact with the surrounding solar wind, the interplanetary magnetic field, and other CMEs and celestial bodies. CMEs can experience aerodynamic drag forces that act to bring them to kinematic equilibrium with the solar wind. As a consequence, CMEs faster than the solar wind tend to slow down whereas CMEs slower than

2695-399: The Sun, moves through space as time passes, depending on where other large bodies in the Solar System, such as Jupiter and other large gas planets , are located at that time. A similar phenomenon allows the detection of exoplanets by way of the radial-velocity method . The helio- prefix is derived from the Greek word "ἥλιος", meaning "Sun", and also Helios , the personification of

2772-547: The Ulysses project. On 5 May 1997, NASA ended the ICE mission, leaving only a carrier signal operating. The ISEE-3/ICE downlink bit rate was nominally 2048 bits per second during the early part of the mission, and 1024 bit/s during the 21P/Giacobini–Zinner comet encounter. The bit rate then successively dropped to 512 bit/s (on 9 December 1985), 256 bit/s (on 5 January 1987), 128 bit/s (on 24 January 1989) and finally to 64 bit/s (on 27 December 1991). Though still in space, NASA donated

2849-479: The chance of Earth being hit by a Carrington-class storm in the next decade to be between 0.46% and 1.88%. CMEs have been observed indirectly for thousands of years via aurora. Other indirect observations that predated the discovery of CMEs were through measurements of geomagnetic perturbations, radioheliograph measurements of solar radio bursts, and in-situ measurements of interplanetary shocks. The largest recorded geomagnetic perturbation, resulting presumably from

2926-405: The corona that are kept in equilibrium by overlying magnetic fields. CMEs erupt from the lower corona, where processes associated with the local magnetic field dominate over other processes. As a result, the coronal magnetic field plays an important role in the formation and eruption of CMEs. Pre-eruption structures originate from magnetic fields that are initially generated in the Sun's interior by

3003-478: The craft to the Smithsonian Museum . By January 1990, ICE was in a 355-day heliocentric orbit with an aphelion of 1.03 AU, a perihelion of 0.93 AU and an inclination of 0.1°. In 1999, NASA made brief contact with ICE to verify its carrier signal. On 18 September 2008, NASA, with the help of KinetX , located ICE using the NASA Deep Space Network after discovering that it had not been powered off after

3080-514: The downward reconnection outflows can collide with loops below to form a cusp-shaped, two-ribbon solar flare. CME eruptions can also produce EUV waves, also known as EIT waves after the Extreme ultraviolet Imaging Telescope or as Moreton waves when observed in the chromosphere, which are fast-mode MHD wave fronts that emanate from the site of the CME. A coronal dimming is a localized decrease in extreme ultraviolet and soft X-ray emissions in

3157-540: The dragging force from the solar wind can theoretically accelerate a CME. However, if sufficient acceleration is not provided, the CME structure may fall back in what is referred to as a failed or confined eruption . The early evolution of CMEs is frequently associated with other solar phenomena observed in the low corona, such as eruptive prominences and solar flares. CMEs that have no observed signatures are sometimes referred to as stealth CMEs . Prominences embedded in some CME pre-eruption structures may erupt with

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3234-422: The erupting flux rope; secondary dimmings are interpreted as the result of the expansion of the overall CME structure and are generally more diffuse and shallow. Coronal dimming was first reported in 1974, and, due to their appearance resembling that of coronal holes , they were sometimes referred to as transient coronal holes . Observations of CMEs are typically through white-light coronagraphs which measure

3311-481: The evolution of some ICMEs, but not all of them. CMEs typically reach Earth one to five days after leaving the Sun. The strongest deceleration or acceleration occurs close to the Sun, but it can continue even beyond Earth orbit (1 AU ), which was observed using measurements at Mars and by the Ulysses spacecraft . ICMEs faster than about 500 km/s (310 mi/s) eventually drive a shock wave . This happens when

3388-453: The famous Carrington event in 1859 had several eruptions and caused auroras to be visible at low latitudes for four nights. Similarly, the solar storm of September 1770 lasted for nearly nine days, and caused repeated low-latitude auroras. The interaction between two moderate CMEs between the Sun and Earth can create extreme conditions on Earth. Recent studies have shown that the magnetic structure in particular its chirality /handedness, of

3465-559: The first stereoscopic images of CMEs and other solar activity measurements. The spacecraft orbit the Sun at distances similar to that of Earth, with one slightly ahead of Earth and the other trailing. Their separation gradually increased so that after four years they were almost diametrically opposite each other in orbit. On 9 March 1989, a CME occurred, which struck Earth four days later on 13 March. It caused power failures in Quebec, Canada and short-wave radio interference. On 23 July 2012,

3542-476: The globe to improve diurnal coverage, in order to upload additional commands while the spacecraft is close to Earth and later to receive data. On 10 August 2014 at 18:16 UTC, the spacecraft passed about 15,600 km (9,700 mi) from the surface of the Moon. It will continue in its heliocentric orbit and will return to the vicinity of Earth in 2031. On 25 September 2014, the Reboot team announced that contact with

3619-543: The image onto Polaroid print. David Roberts, an electronics technician working for NRL who had been responsible for the testing of the SEC-vidicon camera, was in charge of day-to-day operations. He thought that his camera had failed because certain areas of the image were much brighter than normal. But on the next image the bright area had moved away from the Sun and he immediately recognized this as being unusual and took it to his supervisor, Dr. Guenter Brueckner , and then to

3696-577: The interaction between the Earth's magnetic field and the solar wind . ISEE-3 was the first spacecraft to be placed in a halo orbit at the L 1 Earth-Sun Lagrange point . Renamed ICE, it became the first spacecraft to visit a comet , passing through the plasma tail of comet Giacobini-Zinner within about 7,800 km (4,800 mi) of the nucleus on 11 September 1985. NASA suspended routine contact with ISEE-3 in 1997 and made brief status checks in 1999 and 2008. On 29 May 2014, two-way communication with

3773-413: The interplanetary medium, they may collide with other ICMEs in what is referred to as CME–CME interaction or CME cannibalism . During such CME-CME interactions, the first CME may clear the way for the second one and/or when two CMEs collide it can lead to more severe impacts on Earth. Historical records show that the most extreme space weather events involved multiple successive CMEs. For example,

3850-400: The lower corona. Downward magnetic tension force exerted by the strapping magnetic field as it is stretched and, to a lesser extent, the gravitational pull of the Sun oppose movement of the core CME structure. In order for sufficient acceleration to be provided, past models have involved magnetic reconnection below the core field or an ideal MHD process, such as instability or acceleration from

3927-415: The lower corona. When associated with a CME, coronal dimmings are thought to occur predominantly due to a decrease in plasma density caused by mass outflows during the expansion of the associated CME. They often occur either in pairs located within regions of opposite magnetic polarity, a core dimming, or in a more widespread area, a secondary dimming. Core dimmings are interpreted as the footpoint locations of

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4004-578: The lowest-energy magnetic configuration the underlying photospheric magnetic flux distribution could theoretically take, a potential field state. Emerging magnetic flux and photospheric motions continuously shifting the footpoints of a structure can result in magnetic free energy building up in the coronal magnetic field as twist or shear. Some pre-eruption structures, referred to as sigmoids , take on an S or reverse- S shape as shear accumulates. This has been observed in active region coronal loops and filaments with forward- S sigmoids more common in

4081-404: The magnetic field arches. Over time, the concentrated magnetic flux cancels and disperses across the Sun's surface, merging with the remnants of past active regions to become a part of the quiet Sun . Pre-eruption CME structures can be present at different stages of the growth and decay of these regions, but they always lie above polarity inversion lines (PIL), or boundaries across which the sign of

4158-413: The magnetic field vector, and low proton temperature. The association between CMEs and magnetic clouds was made by Burlaga et al. in 1982 when a magnetic cloud was observed by Helios-1 two days after being observed by SMM . However, because observations near Earth are usually done by a single spacecraft, many CMEs are not seen as being associated with magnetic clouds. The typical structure observed for

4235-525: The needed hardware, an off-the-shelf SDR transceiver, and power amplifier, and installed it on the 305 m (1,001 ft) Arecibo dish antenna on 19 May 2014. Once they gained control of the spacecraft, the capture team planned to shift the primary ground station to the 21 m (69 ft) dish located at Morehead State University Space Science Center of Kentucky . The 20 m (66 ft) dish antenna in Bochum Observatory , Germany , would be

4312-688: The occulting disk of the coronagraph. Halo CMEs are interpreted as CMEs directed toward or away from the observing coronagraph. When the expanding ring does not completely surround the occulting disk, but has an angular width of more than 120 degrees around the disk, the CME is referred to as a partial halo coronal mass ejection . Partial and full halo CMEs have been found to make up about 10% of all CMEs with about 4% of all CMEs being full halo CMEs. Frontside, or Earth-direct, halo CMEs are often associated with Earth-impacting CMEs; however, not all frontside halo CMEs impact Earth. In 2019, researchers used an alternative method ( Weibull distribution ) and estimated

4389-418: The orbital maneuver in early July. On 2 July 2014, the reboot project fired the thrusters for the first time since 1987. They spun up the spacecraft to its nominal roll rate, in preparation for the upcoming trajectory correction maneuver in mid-July. On 8 July 2014, a longer sequence of thruster firings failed, apparently due to loss of the nitrogen gas needed to pressurize the fuel tanks. On 24 July 2014,

4466-508: The order of terawatts directed back toward Earth's upper atmosphere . This can result in events such as the March 1989 geomagnetic storm . CMEs, along with solar flares , can disrupt radio transmissions and cause damage to satellites and electrical transmission line facilities, resulting in potentially massive and long-lasting power outages . Shocks in the upper corona driven by CMEs can also accelerate solar energetic particles toward

4543-452: The outer radiation belt , with either a decrease or an increase of relativistic particle fluxes by orders of magnitude. The changes in radiation belt particle fluxes are caused by acceleration, scattering and radial diffusion of relativistic electrons, due to the interactions with various plasma waves . A halo coronal mass ejection is a CME which appears in white-light coronagraph observations as an expanding ring completely surrounding

4620-412: The plane-of-sky ranging from 20 to 3,200 km/s (12 to 2,000 mi/s) with an average speed of 489 km/s (304 mi/s). Observations of CME speeds indicate that CMEs tend to accelerate or decelerate until they reach the speed of the solar wind ( § Interactions in the heliosphere ). When observed in interplanetary space at distances greater than about 50 solar radii (0.23 AU) away from

4697-549: The precise orbital location information needed to point transmissions at the craft. The ICE spacecraft is a barrel-like cylindrical shape covered by solar panels. Four long antennas protrude equidistant around the circumference of the spacecraft, spanning 91 m (299 ft). It has a dry mass of 390 kg (860 lb) and can generate nominal power of 173 watts. ICE carries 13 scientific instruments to measure plasmas, energetic particles, waves, and fields. As of July 2014, five were known to be functional. It does not carry

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4774-422: The probe was lost on 16 September 2014. It is unknown whether contact can be reestablished because the probe's exact orbit is uncertain. The spacecraft's post-lunar flyby orbit takes it further from the Sun, causing electrical power available from its solar arrays to drop, and its battery failed in 1981. Reduced power could have caused the craft to enter a safe mode , from which it may be impossible to awaken without

4851-440: The probe was lost. ISEE-3 carries no cameras; instead, its instruments measure energetic particles, waves, plasmas , and fields. ISEE-3 originally operated in a halo orbit about the L 1 Sun-Earth Lagrange point , 235 Earth radii above the surface (about 1,500,000 km (930,000 mi). It was the first artificial object placed at a so-called "libration point", entering orbit there on 20 November 1978, proving that such

4928-562: The reboot team successfully commanded the probe to switch into Engineering Mode to begin to broadcast telemetry. On 26 June 2014, project members using the Goldstone Deep Space Communications Complex DSS-24 antenna achieved synchronous communication and obtained the four ranging points needed to refine the spacecraft's orbital parameters. The project team received approval from NASA to continue operations through at least 16 July 2014, and made plans to attempt

5005-487: The science experiments. On 30 July 2014, the team announced that it still planned to acquire data from as much of ISEE-3's 300-day orbit as possible. With five of the 13 instruments on the spacecraft still working, the science possibilities included listening for gamma-ray bursts , where observations from additional locations in the Solar System can be valuable. The team was also recruiting additional receiving sites around

5082-473: The sharing and interpretation of all of the new data ISEE-3 sends back via crowd-sourcing". On 15 May 2014, the project reached its crowdfunding goal of US$ 125,000 on RocketHub , which was expected to cover the costs of writing the software to communicate with the probe, searching through the NASA archives for the information needed to control the spacecraft, and buying time on the dish antennas. The project then set

5159-520: The solar physics branch head, Dr. Tousey. Earlier observations of coronal transients or even phenomena observed visually during solar eclipses are now understood as essentially the same thing. On 1 November 1994, NASA launched the Wind spacecraft as a solar wind monitor to orbit Earth's L 1 Lagrange point as the interplanetary component of the Global Geospace Science (GGS) Program within

5236-423: The solar wind tend to speed up until their speed matches that of the solar wind. How CMEs evolve as they propagate through the heliosphere is poorly understood. Models of their evolution have been proposed that are accurate to some CMEs but not others. Aerodynamic drag and snowplow models assume that ICME evolution is governed by its interactions with the solar wind. Aerodynamic drag alone may be able to account for

5313-416: The solar wind. In the majority of CME events, acceleration is provided by magnetic reconnection cutting the strapping field's connections to the photosphere from below the core and outflow from this reconnection pushing the core upward. When the initial rise occurs, the opposite sides of the strapping field below the rising core are oriented nearly antiparallel to one another and are brought together to form

5390-454: The southern hemisphere and reverse- S sigmoids more common in the northern hemisphere. Magnetic flux ropes—twisted and sheared magnetic flux tubes that can carry electric current and magnetic free energy—are an integral part of the post-eruption CME structure; however, whether flux ropes are always present in the pre-eruption structure or whether they are created during the eruption from a strongly sheared core field (see § Initiation )

5467-557: The spacecraft performed a maneuver which removed it from its halo orbit around the L 1 point and placed it in a transfer orbit . This involved a series of passages between Earth and the Sun-Earth L 2 Lagrange point, through the Earth's magnetotail . Fifteen propulsive maneuvers and five lunar gravity assists resulted in the spacecraft being ejected from the Earth-Moon system and into a heliocentric orbit . Its last and closest pass over

5544-611: The spacecraft was reestablished by the ISEE-3 Reboot Project , an unofficial group, with support from the Skycorp company and SpaceRef Interactive. On 2 July 2014, they fired the thrusters for the first time since 1987. However, later firings of the thrusters failed, apparently due to a lack of nitrogen pressure in the fuel tanks. The project team initiated an alternative plan to use the spacecraft to "collect scientific data and send it back to Earth", but on 16 September 2014, contact with

5621-488: The speed of the ICME in the frame of reference moving with the solar wind is faster than the local fast magnetosonic speed. Such shocks have been observed directly by coronagraphs in the corona, and are related to type II radio bursts. They are thought to form sometimes as low as 2  R ☉ ( solar radii ). They are also closely linked with the acceleration of solar energetic particles . As ICMEs propagate through

5698-578: The two planets with the lowest possible energy requirements. Transfer injections can place spacecraft into either a Hohmann transfer orbit or bi-elliptic transfer orbit. Trans-Mars injections can be either a single maneuver burn, such as that used by the NASA MAVEN orbiter in 2013, or a series of perigee kicks, such as that used by the ISRO Mars Orbiter Mission in 2013. Coronal mass ejection A coronal mass ejection ( CME )

5775-415: The vertical component of the magnetic field reverses. PILs may exist in, around, and between active regions or form in the quiet Sun between active region remnants. More complex magnetic flux configurations, such as quadrupolar fields, can also host pre-eruption structures. In order for pre-eruption CME structures to develop, large amounts of energy must be stored and be readily available to be released. As

5852-469: Was 20.8 × 10 ^  km (12.9 × 10 ^  mi). An update to the ICE mission was approved by NASA in 1991. It defines a heliospheric mission for ICE consisting of investigations of coronal mass ejections in coordination with ground-based observations, continued cosmic ray studies, and the Ulysses probe. By May 1995, ICE was being operated under a low-duty cycle, with some data-analysis support from

5929-402: Was collected on a Secondary Electron Conduction (SEC) vidicon tube, transferred to the instrument computer after being digitized to 7 bits . Then it was compressed using a simple run-length encoding scheme and sent down to the ground at 200 bit/s. A full, uncompressed image would take 44 minutes to send down to the ground. The telemetry was sent to ground support equipment (GSE) which built up

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