Diagram of IMAGE spacecraft
|Names||Imager for Magnetopause-to-Aurora Global Exploration |
|Mission type||Magnetospheric physics|
|Operator||NASA / Goddard |
Applied Physics Laboratory
|Mission duration||Planned: 2 years |
Final: 5 years, 8 months, 22 days
|Manufacturer||Lockheed Martin Missiles & Space |
Southwest Research Institute
|Launch mass||494 kg (1,089 lb)|
|Payload mass||210 kg (463 lb):17|
|Dimensions||Bus: 2.25 × 1.52 m (7.4 × 5.0 ft) |
Deployed: 504 × 22 m (1,652 × 71 ft)
|Power||286 watts (GaAs solar arrays, Super NiCd batteries)|
|Start of mission|
|Launch date||March 25, 2000, 20:34:43.929UTC|
|Rocket||Delta II 7326-9.5 #277|
|Launch site||Vandenberg SLC-2W|
|Contractor||Boeing Launch Services|
|End of mission|
|Last contact||December 18, 2005, 07:39UTC|
|Semi-major axis||29,880 km (18,567 mi)|
|Perigee altitude||1,000 km (621 mi)|
|Apogee altitude||46,004 km (28,586 mi)|
|Argument of perigee||319.86°|
|Epoch||March 25, 2000, 16:30:34 UTC|
IMAGE (Imager for Magnetopause-to-Aurora Global Exploration) is a NASA Medium Explorers mission that studied the global response of the Earth's magnetosphere to changes in the solar wind. It was believed lost but as of August 2018 might be recoverable. It was launched March 25, 2000 by a Delta II rocket from Vandenberg AFB on a two-year mission. Almost six years later, it unexpectedly ceased operations in December 2005 during its extended mission and was declared lost. The spacecraft was part of NASA's Sun-Earth Connections Program, and during its run had over 400 research articles published in peer-reviewed journals using its data. It had special cameras that provided various breakthroughs in understanding the dynamics of plasma around the Earth. The Principal Investigator was Jim Burch of the Southwest Research Institute.
In January 2018, an amateur satellite tracker found it to be transmitting some signals back to Earth. NASA made attempts to communicate with the spacecraft and determine its payload status, but has had to track down and adapt old hardware and software to the current systems. On February 25, contact with IMAGE was again lost only to be reestablished on March 4, 2018. The signal disappeared once again on August 5, 2018. Recovery efforts are underway and if successful NASA may decide to fund a restarted mission.
IMAGE was the first spacecraft dedicated to imaging the Earth's magnetosphere. IMAGE was a spacecraft developed by the Medium-Class Explorers (MIDEX) program, and it was the first spacecraft dedicated to observing the magnetosphere of the Earth, producing comprehensive global images of plasma in the inner magnetosphere. The IMAGE craft was placed in a 1,000×46,000 km orbit around the Earth, with an inclination of 90° (passing over the poles) and a 14.2 hour period.
By acquiring images every 2 minutes in wavelengths invisible to the human eye, it allowed detailed study of the interaction of the solar wind with the magnetosphere and the magnetosphere's response during a magnetic storm. From its distant orbit, the spacecraft produced a wealth of images of the previously invisible region of space in the inner magnetosphere, exceeded all its scientific goals. A senior review in 2005, just previous to its loss, described the mission as "extremely productive", having confirmed several theoretical predictions (e.g., plasmasphere plumes, pre-midnight ring-current injection, and continuous antiparallel reconnection), discovered numerous new and unanticipated phenomena (e.g., plasmasphere shoulders, subauroral proton arcs, and a secondary interstellar neutral atom stream), and answered a set of outstanding questions regarding the source region of kilometric continuum radiation, the role of solar wind pressure pulses in ionospheric outflow, and the relationship between proton and electron auroras during substorms. When the spacecraft went silent in December 2005, it had already been approved a mission extension until 2010.
Costs for IMAGE are estimated at US$132 million, including the spacecraft, instruments, launch vehicle, and ground operations.
On December 18, 2005, the satellite failed to make an expected contact at 16:20 UTC. An earlier contact had ended successfully at 07:39 the same day with no sign of trouble.:14 Over the following days and weeks, commands were sent "blind" to reset the transmitter, change antennas, and otherwise attempt to re-establish contact with the spacecraft, but no signal (not even an unmodulated carrier wave) was received. Recovery efforts included using different DSN antennas, using non-NASA ground stations in case there was some systematic DSN error, transmitting no commands for several days to trigger a 72-hour watchdog timer, increasing transmit power in case the antenna was badly misaligned, and optical and radar observations of the satellite to check for debris, change in spin rate or change in orbit indicative of a collision or other damage.:16–17
The spacecraft was also commanded to slightly increase its spin rate and asymmetrically turn on its heaters. If observed, these would indicate that it could receive commands but not transmit. Neither change was seen and analysis later indicated that the temperature change would have been undetectable.:9–10 An attempt to observe the craft's temperature to determine if it was completely dead or consuming the power expected in safe mode was inconclusive.:10–11
A careful failure analysis revealed that, among plausible causes for an abrupt bidirectional loss of communication, the Solid State Power Converter (SSPC) for the transponder had, among its features, an "instant trip" shutdown in response to a high-current (100 A) short circuit. Critically, such a shutdown was not reported in the power supply's telemetry output and this lack was not documented.  Because it was undocumented the spacecraft's hardware and software had no provision for attempting to reset the SSPC if it reported good status.:13 This would result in the observed symptoms: no radio communication with an apparently undamaged spacecraft.:1,12–13,22,29–31
Although such a short circuit would be almost impossible without fatal damage to the spacecraft, the shutdown could be falsely triggered by a radiation-induced single event upset.:1,30–31 It could be simply fixed by power-cycling the supply, but the spacecraft design left no way to send such a command, nor was one built in.
In January 2006, NASA declared the mission over, declaring that "Preliminary analysis indicated the craft's power supply subsystems failed, rendering it lifeless." Despite this, they continued to try and establish contact. In early 2006, NASA convened a board of experts to figure out what went wrong. After several months they created a report in which they theorized that IMAGE had tripped a power breaker and might fix itself.
It was hoped that an eclipse when the spacecraft passed through the Earth's shadow in October 2007 would result in a sufficiently deep supply voltage sag that it would trigger a total bus reset, which would cause a power cycle of the suspect supply.:14–18 However, attempts to contact the craft after this eclipse were not successful.
On January 20, 2018 IMAGE was found by Canadian radio amateur and satellite tracker Scott Tilley to be broadcasting, and he reported it to NASA. He had been scanning the S-band (microwaves) in the hopes of finding the Zuma satellite.
On January 24, 2018 Richard Burley of NASA reported that they were trying to establish communication with the satellite using the NASA Deep Space Network. Two days later, Burley reported that engineers at Goddard Space Flight Center successfully acquired the signal, and confirmed on January 30, 2018 that IMAGE is the source. It is not known when the satellite started broadcasting, but re-examination of old data recorded by Tilley and fellow satellite tracker Cees Bassa showed transmissions from the same satellite in October 2016 and May 2017. Bassa hypothesized that while the 2007 eclipse did not manage to reset the satellite, another one did the trick, probably sometime between 2014 and 2016.
On February 8, 2018 NASA published a detailed account of the IMAGE satellite's recovery. The satellite was transmitting data beyond simple telemetry, indicating that some of its six onboard instruments were still active. NASA engineers are attempting to determine the satellite's status, but since the software and hardware type used in the IMAGE Mission Operations Center have been discarded and no longer exist, they are in the process of adapting old software and databases to their modern systems and track down replacement hardware.
On February 25, 2018 NASA again lost contact with the satellite, but not in the same manner it did in 2005. Richard Burley, former IMAGE mission director, stated that he believes there is an issue with IMAGE's spin axis in relation to its medium-gain antenna placement. If NASA can regain control of the spacecraft, and the status of data and ground systems can be assessed, it will decide if it can fund a mission restart.
On March 4, 2018 the Applied Physics Laboratory at Johns Hopkins University reported detecting the signal from the satellite, but it was too faint to lock onto.
On May 9, 2018 Scott Tilley again detected a strong signal from IMAGE. Hours later NASA and APL engineers had locked onto the signal and were receiving telemetry. Commands were transmitted to IMAGE, but for unknown reasons the spacecraft only acknowledged receipt of a fraction of those commands.
On January 20, 2019 a full year passed since the spacecraft's rediscovery date and it has remained out of contact since August 5, 2018.
False-colour image montage of ultraviolet aurora australis
Picture of the ultraviolet glow from relatively cold plasma surrounding Earth
False-colour image of ultraviolet auroral lights from particles excited by collisions with protons, so called proton aurorae
IMAGE in preparation
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