NASASpaceFlight.com Forum
Robotic Spacecraft (Astronomy, Planetary, Earth, Solar/Heliophysics) => Space Science Coverage => Topic started by: jacqmans on 05/29/2007 08:21 pm
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ESA's SOHO has helped uncover radio screams that foretell dangerous Coronal Mass Ejections, or CMEs, which produce radiation storms harming infrastructure on ground, in space as well as humans in space.
More at:
http://www.esa.int/esaSC/SEMOPF9RR1F_index_0.html
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RELEASE: 07-31
MAGNETIC FIELD USES SOUND WAVES TO IGNITE SUN'S RING OF FIRE
Sound waves escaping the Sun's interior create fountains of hot gas that shape and power the chromosphere, a thin region of the sun's atmosphere which appears as a ruby red "ring of fire" around the moon during a total solar eclipse, according to research funded by NASA and the National Science Foundation (NSF). These results were presented May 29, at the American Astronomical Society Meeting in Honolulu, Hawaii.
The chromosphere is important because it is largely responsible for the deep ultraviolet radiation that bathes the Earth, producing our atmosphere's ozone layer, and it has the strongest solar connection to climate variability. The new result also helps explain a mystery that's existed since the middle of the last century -- why the chromosphere (and the tenuous corona above) is much hotter than the visible surface of the star. "It's like getting warmer as you move away from the fire instead of cooler, certainly not what you expect," said Scott McIntosh, a researcher at Southwest Research Institute, Boulder, Colo.
“This work finds the missing piece of the puzzle that has fascinated many generations of solar astronomers. When you fit this piece in place, our vision of the chromosphere becomes clear,” said Alexei Pevtsov, Program Scientist NASA Headquarters, Washington.
Using spacecraft, ground-based telescopes, and computer simulations, these new results show that the Sun's magnetic field allows the release of wave energy from its interior, permitting the sound waves to travel through thin fountains upward into the solar chromosphere. These magnetic fountains form the mold for the chromosphere.
"Scientists have long realized that solar magnetic fields hold the key to tapping the vast energy reservoir locked in the Sun's interior," said Paul Bellaire, program director in NSF's division of atmospheric sciences. "These researchers have found the ingenious way that the Sun uses magnetic keys to pick those locks."
Over the past twenty years, helioseismologists have studied energetic sound waves as probes of the Sun's interior structure because they are largely trapped by the Sun's visible surface -- the photosphere. The new research found that some of these waves can escape the photosphere into the chromosphere and corona.
To make the new discovery, the team used observations from the SOHO and TRACE spacecrafts combined with those from the Magneto-Optical filters at Two Heights (MOTH) instrument stationed in Antarctica, and the Swedish 1 meter (3 foot) Solar Telescope on the Canary Islands. The observations gave detailed insight into how some of these trapped waves manage to leak out through magnetic "cracks" in the photosphere, sending mass and energy shooting upwards into the atmosphere above. "The Sun's interior vibrates with the peal of millions of bells, but the bells are all on the inside of the building. We have been able to show how the sound can escape the building and travel a long way using the magnetic field as a guide," continued McIntosh.
By analyzing motions of structures in the solar atmosphere in detail, the scientists observed that near strong knots of magnetic field, sound waves from the interior of the Sun can leak out and propagate upward into its atmosphere. "The constantly evolving magnetic field above the solar surface acts like a doorman opening and closing the door for the waves that are constantly passing by," said Bart De Pontieu, a researcher Lockheed Martin Solar and Astrophysics Lab, Palo Alto, Calif.
These results were confirmed by state-of-the-art computer simulations that show how the leaking waves continually propel fountains of hot gas upward into the Sun's atmosphere, which fall back to its surface a few minutes later.
The scientists were able to independently demonstrate that the magnetic field controls the release of mass and wave energy into the solar atmosphere. The combination of these results demonstrates that a lot more energy can be pumped into the chromosphere by wave motions than researchers had previously thought. This wouldn't be possible without the relentlessly changing magnetic field at the surface.
The research team includes Stuart Jefferies, University of Hawaii, Maui, Hawaii; Scott McIntosh, Southwest Research Institute, Boulder, Colo.; Bart De Pontieu, Lockheed Martin, Palo Alto, Calif.; and Viggo Hansteen, University of Oslo, Norway and Lockheed Martin.
For related images and more information, please visit on the Web:
http://www.nasa.gov/vision/universe/solarsystem/ring_of_fire_media.html
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PRESS RELEASE: 07-60
SOHO MISSION DISCOVERS RARE COMET
GREENBELT, Md. - The Solar and Heliospheric Observatory (SOHO) has discovered a rare periodic comet. During a mission where 1,350 comets have been discovered, this is the first time one has been officially designated "periodic."
Many of the comets SOHO has observed are believed to be periodic -- they follow their orbits around the sun more than twice and have orbital periods of less than 200 years. Thousands of comets have been seen by astronomers, but only around 190 are classified as periodic. Many more are believed to be. The most famous periodic comet is Halley’s comet, which comes near to the Earth every 76 years. Its most recent close pass to the sun was in 1986.
SOHO’s new find has a much smaller orbit than Halley's comet. It takes the comet approximately four years to travel once around the sun. It was first seen in September 1999 and then again in September 2003. In 2005, German PhD student Sebastian Hoenig realized that the two comets were so similar in orbit that they might actually be the same object. To test his theory, he calculated a combined orbit for the comet and consequently predicted that it would return on Sept. 11, 2007. Hoenig's prediction proved to be extremely accurate -- the comet reappeared in SOHO's Large Angle and Spectrometric Coronagraph camera right on schedule and has now been given the official designation of P/2007 R5 (SOHO). The credit for original discovery and recovery of the object goes to Terry Lovejoy (Australia, 1999), Kazimieras Cernis (Lithuania, 2003) and Bo Zhou (China, 2007).
A puzzling aspect to P/2007 R5 (SOHO) is that it does not look exactly like a comet. It has no visible tail or coma of dust and gas, as is traditionally associated with the pheonmena. Initially, this led some scientists to wonder if the object was actually an asteroid, a chunk of space-rock, rather than a chuck of space-ice. However, P/2007 R5 (SOHO) did exhibit some characteristics consistent with a comet. As scientists watched the object pass close to the sun, drawing to within 4.9 million miles, or around 5% of the distance between the Earth and the sun, they saw it brighten by a factor of around a million, which is common behavior for a comet.
“It is quite possibly an extinct comet nucleus of some kind,” says Karl Battams of the Naval Research Laboratory, Washington, who runs SOHO's comet discovery program. Extinct comets have expelled most of their volatile ices and retain little to form a tail or coma. They are theorized to be common objects among the celestial bodies orbiting close to the sun.
This comet faded as quickly as it brightened, and soon became too faint for SOHO's instruments to see. Estimates show that P/2007 R5 (SOHO) is probably only 100 to 200 yards in diameter. Given how small and faint this object is, and how close it still is to the sun, it is an extremely difficult target for observers on Earth to pick out in the sky.
Now we know for certain that P/2007 R5 (SOHO) is there, astronomers will be watching closely for it during its next return in September 2011.
SOHO is a cooperative project between the European Space Agency and NASA.
For an image, refer to:
http://www.nasa.gov/mission_pages/soho/soho_periodic_comet.html
For information about NASA and agency programs, visit:
http://www.nasa.gov/home
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It is nothing new for the ESA/NASA Solar and Heliospheric Observatory (SOHO) to discover another comet - it has already found more than 1350. But the latest is a bit different - SOHO had spotted it twice before.
Full story:
http://www.esa.int/esaCP/SEMAU2C1S6F_index_0.html
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The appearance of a very special solar spot on the sun surface a few days ago, signalled to scientists around the world that a new solar cycle had begun. This solar spot also produced two solar blasts.
Full story:
http://www.esa.int/esaCP/SEMT1J3MDAF_index_0.html
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Data from the ESA/NASA spacecraft SOHO shows clearly that powerful starquakes ripple around the Sun in the wake of mighty solar flares that explode above its surface. The observations give solar physicists new insight into a long-running solar mystery and may even provide a way of studying other stars.
Read more at:
http://www.esa.int/esaSC/SEM4SB4XQEF_index_0.html
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The ESA/NASA SOHO spacecraft has just discovered its 1500th comet, making it more successful than all other comet discoverers throughout history put together. Not bad for a spacecraft that was designed as a solar physics mission.
More at:
http://www.esa.int/esaCP/SEMB94SHKHF_index_0.html
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Space Weather News for March 12, 2010
http://spaceweather.com
Today, a newly discovered comet is plunging toward the sun for a close encounter it probably will not survive. The comet is rapidly vaporizing and appears very bright in coronagraph images from the Solar and Heliospheric Observatory (SOHO). Visit http://spaceweather.com for movies of the ongoing encounter and more information about the comet.
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SOHO sheds new light on solar flares.
After detailed analysis of data from the SOHO and GOES spacecraft, a team of European scientists has been able to shed new light on the role of solar flares in the total output of radiation from our nearest star. Their surprising conclusion is that X-rays account for only about 1 per cent of the total energy emitted by these explosive events.
Flares are sudden energy releases in the Sun's atmosphere that occur when the solar magnetic field is locally unstable. When the magnetic field lines break and reconnect, large amounts of energy are released, accelerating the surrounding particles to almost the speed of light. The temperature of the flares can soar to millions of degrees. At such sizzling temperatures, much of their radiation is emitted as X-rays.
Not surprisingly, most flares are imaged and studied at X-ray or extreme ultraviolet wavelengths, since they are more difficult to observe and analyse in visible light. Although more than 20 000 flares occurred in the last solar cycle (1996-2007), only four exceptionally large ones were identified as contributors to the total solar irradiance (TSI) , i.e. the light received at all wavelengths on Earth.
In an effort to calculate how much energy is actually contributed to the TSI by flares, researchers from the Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E) in Orléans (France), collaborating with Swiss and Belgium teams, have been analysing 11 years of observations from space.
The team analysed the record of X-ray data acquired by the US GOES spacecraft during the entire solar cycle to detect the flares and record the times of their peak activity. The scientists eventually selected about 2000 flares which occurred near the centre of the solar disc. They then turned to the PMO and DIARAD radiometers of the VIRGO experiment on board the ESA/NASA SOHO spacecraft for information about the overall solar radiation heading toward Earth.
The next task was to identify any small peaks in TSI caused by the flares. This task was complicated by the random 'noise' generated by the Sun's turbulent atmosphere. In order to recognise the contribution due to flares alone, the team used a statistical method to superimpose X-ray and TSI data taken at short time intervals around the period when a flare occurred. In this way, they were able to remove the random 'noise' from the data.
"The problem was to recognise the overall output from flares, radiated simultaneously at all wavelengths and in the visible domain, despite the natural fluctuations of the solar irradiance," said Matthieu Kretzschmar, researcher at the LPC2E and first author of the study in Nature Physics. "It is like looking for 1-metre-high waves, caused by flares, within a rough sea where there are 70-metre-high waves caused by natural fluctuations."
"To solve this problem, we amplified the 'one-meter-high waves' using the 'superposed-epoch analysis' method. The idea was to temporally superpose the total irradiance light curves for several flares. Natural random fluctuations in the solar irradiance cancel each other out, but the fluctuations caused by the flares are added and amplified."
The analysis led to a surprising result: there was a significant peak in the TSI when a flare occurred. Not only was the total radiative output of the Sun sensitive to both large and small flares, but the total energy radiated by flares was found to be over 100 times greater than the energy that they radiate in X-rays. It turns out that X-rays contribute only a tiny part of the overall output of radiation during solar flares.
These results, obtained within the framework of the European Community's SOTERIA project, will help to improve current theoretical models of flares and understanding of the variability in the solar irradiance that reaches our planet. They could also help to shed light on the behaviour of more distant stars, some of which may also host planetary systems.
"Many stars are much more active than our Sun and emit extremely powerful flares," said Bernhard Fleck, ESA's SOHO Project Scientist. "This new estimate of the energy distribution of solar flares suggests that such flares may be extremely bright in visible light as well as X-rays, possibly with dramatic consequences for any nearby planets."
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=47814
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Okay, this definitely deserves a bump.
Check this out, it's fantastic:
http://ca.news.yahoo.com/blogs/daily-buzz/nasa-captures-stunning-video-comet-hitting-sun-193131383.html
I haven't see the video posted on NASA's SOHO site yet.
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The beginning of the end for comet Lovejoy
14 December 2011
The SOHO spaceborne solar observatory today captured comet Lovejoy in its field of view for the first time, indicating that the icy body is on its final destructive plunge towards the Sun.
Announced on 2 December, the newly discovered comet Lovejoy is on a near-collision course with the Sun and is expected to plunge to its fiery fate late on 15 December.
http://www.esa.int/esaCP/SEM3HD8XZVG_index_0.html
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Solar flare seen by ESA/NASA SOHO satellite 23 January, shortly after a large M8.3-class solar flare occurred at 03:59 GMT. The flare caused a Coronal Mass Ejection that reached Earth in the afternoon of 24 January 2012. Credits: ESA/NASA
http://www.esa.int/esa-mmg/mmg.pl?type=A&single=y&start=1
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Solar flare pushes plasma cloud toward Earth
5 March 2012
A large solar flare erupted from the Sun earlier today, launching a coronal mass ejection (CME) into space. This plasma 'cloud' is expected to pass Earth in 2 to 3 days, potentially causing increased nighttime auroras. No major effects on Earth are expected.
The solar flare occurred at about 05:05 CET today, and the resulting CME was detected by the Large Angle and Spectrometric Coronagraph (LASCO) instrument on board the ESA/NASA Solar & Heliospheric Observatory (SOHO) mission.
The solar flare was categorised by scientists as an 'X-class' flare; these are major events that can trigger planet-wide radio blackouts and long-lasting radiation storms.
http://www.esa.int/SPECIALS/SSA/SEML3F7YBZG_0.html
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If you go check spaceweather.com a X5 just fired off... Life is about to get interesting 8)
MAJOR SOLAR FLARE: Earth-orbiting satellites have just detected an X5-class solar flare from big sunspot AR1429. The blast peaked on March 7th at 00:28 UT. Radiation storms and radio blackouts are possible. Solar flare alerts: text, phone.
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If you go check spaceweather.com a X5 just fired off... Life is about to get interesting 8)
MAJOR SOLAR FLARE: Earth-orbiting satellites have just detected an X5-class solar flare from big sunspot AR1429. The blast peaked on March 7th at 00:28 UT. Radiation storms and radio blackouts are possible. Solar flare alerts: text, phone.
8) (Mr Burns moment: ...excellent...)
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Venus approaches the Sun
Venus appeared in the field of view of ESA/NASA’s SOHO satellite on 1 June, and has been fast approaching ahead of transit on 5-6 June. SOHO’s LASCO instrument won’t be able to see the transit because its coronagraph blocks out the bright solar disc so that it can study the fine detail of the Sun’s atmosphere. Here it provides a unique view of the soon-t0-be transiting planet, which is currently difficult to observe from Earth while it is bathed in the Sun’s glare.
http://blogs.esa.int/venustransit/2012/06/05/venus-approaches-the-sun/
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NASA | Magnificent Eruption in Full HD
Published on Sep 5, 2012 by NASAexplorer
On August 31, 2012 a long filament of solar material that had been hovering in the sun's atmosphere, the corona, erupted out into space at 4:36 p.m. EDT. The coronal mass ejection, or CME, traveled away from the sun at over 900 miles per second. This movie shows the ejection from a variety of viewpoints as captured by NASA's Solar Dynamics Observatory (SDO), NASA's Solar Terrestrial Relations Observatory (STEREO), and the joint ESA/NASA Solar Heliospheric Observatory (SOHO).
http://www.youtube.com/watch?v=GrnGi-q6iWc
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SOHO’s 3000th comet
The ESA/NASA Solar and Heliospheric Observatory, SOHO, detected its 3000th comet on 14 September 2015, seen as the dot in the crosshairs in the inset heading towards the Sun (left). It was spotted by Worachate Boonplod of Samut Songkhram, Thailand.
SOHO was launched in 1995 to observe the Sun and its stormy atmosphere, and the flow of the solar wind out into interplanetary space. The telescope’s prowess as a comet-hunter, however, was unplanned, but turned out to be an unexpected success. With its clear view of the Sun’s surroundings, SOHO can easily spot a special kind of comet called a sungrazer – so-called because of their close approach to the Sun.
Around 95% of SOHO comets have been found by ‘citizen scientists’ thanks to the SOHO data being publicly available online in near-real time.
Related article: ESA/NASA Solar Observatory Discovers Its 3,000th Comet
http://www.nasa.gov/feature/goddard/esa-nasa-solar-observatory-discovers-its-3000th-comet
Image credit: ESA/NASA/SOHO
https://youtu.be/7l16fVKKURs
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http://www.esa.int/About_Us/ESA_Publications/ESA_Publications_Brochures/ESA_BR-328_SOHO
ESA BR-328 SOHO (Brochure)
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20 years in space and still running well. Must be ESA own Voyager - longuest mission so far.
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SOHO launch: December 2, 1995, and still operating today! (And with no operating gyroscopes!)
The last page of the brochure mentioned that the current, 7th mission extension finishes at the end of 2018.
What foreseeable limits are there to operating SOHO? (consumables, solar panel health, instrument electronics, etc.?)
Hearty congratulations to the SOHO team!
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Come to think of it, given SOHO's age and the fact that there are system failures that must slowly degrade the probe's performance, have either ESA or NASA SMD talked seriously about a replacement spacecraft? After all, SOHO has long since gone beyond a scientific instrument; it is a key part in the day-to-day assessment of deep space environmental conditions and assists in tracking of new comets as they pass perihelion.
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I'm working with images from LASCO C3 coronagraph
I'm able to download pictures from LASCO C3 using this form https://sohodata.nascom.nasa.gov/cgi-bin/data_query
Then, i want to do some analysis of CMEs on this pictures and determine some of their parameters, such as direction and speed (i know that is better to use STEREO A\B for that purposes), but also i need exact coordinates of SOHO station to determine the direction of the ejection in space
How can I get the coordinates of the station for these pictures?
I will be happy with any comment and help
PS:I started studying CMEs, but I'm just starting - so I apologize for the stupid questions ::)
PSS: Maybe I created a topic in the wrong section
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I'm working with images from LASCO C3 coronagraph
I'm able to download pictures from LASCO C3 using this form https://sohodata.nascom.nasa.gov/cgi-bin/data_query
Then, i want to do some analysis of CMEs on this pictures and determine some of their parameters, such as direction and speed (i know that is better to use STEREO A\B for that purposes), but also i need exact coordinates of SOHO station to determine the direction of the ejection in space
How can I get the coordinates of the station for these pictures?
I will be happy with any comment and help
PS:I started studying CMEs, but I'm just starting - so I apologize for the stupid questions ::)
PSS: Maybe I created a topic in the wrong section
You might want to check the Orbit and Attitude files in https://sohowww.nascom.nasa.gov/data/ancillary/
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22 YEARS OF SOHO
The activity cycle of the Sun – where the number of sunspots increase and decrease – has been monitored regularly for around 250 years, but the use of space-based telescopes has given us a whole new perspective of our nearest star.
On 22 December 2017 the Solar and Heliospheric Observatory (SOHO) reached 22 years in space. That duration is significant because it is the average length of the complete solar magnetic cycle. Sunspot cycles are known to occur over about 11 years, but the full cycle is double this length owing to the behaviour of the magnetic fields. The Sun’s polarity gradually changes through its cycle, so that after 11 years the orientation of the field will have flipped between the northern and southern hemispheres. At the end of a 22-year cycle, the orientation of the magnetic field is the same as it was at the start.
Each image shown here is a snapshot of the Sun taken every spring with the Extreme ultraviolet Imaging Telescope on SOHO. Observing in the ultraviolet reveals the Sun’s corona – the extremely hot atmosphere, up to some 2 million degrees, that extends millions of kilometres into space.
When the Sun is at its most active, strong magnetic fields show up as bright spots in the ultraviolet images of the corona. Activity also becomes obvious on the photosphere, which is the surface we see in visible light.
When the Sun is active, sunspots appear on the surface. Concentrations of magnetic fields can reduce the surface temperature in some areas and this reduced temperature makes these areas appear black in visible light images. The last 11-year cycle began in 1996, and the current one started in 2008, with solar maximum occurring in 2014.
By monitoring the Sun for almost a complete 22-year cycle, SOHO has provided a wealth of data on solar variability. This has been vital for monitoring the interaction of the Sun’s activity with Earth, and improving capabilities in space weather forecasting.
SOHO has made many important discoveries with its suite of instruments, such as revealing the existence of sunquakes, detecting waves travelling through the corona and identifying the source of the ‘fast’ solar wind.
http://m.esa.int/spaceinimages/Images/2018/02/22_years_of_SOHO
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It's not as showy as a planetary probe, but SOHO has been a tremendous success. Having an entire 22-year, full solar magnetic cycle's worth of data from a single, well-characterized spacecraft is incredibly useful to the solar physics folks. There's been some drama with the mission--comms were lost for a month or so in 1998, but the spacecraft was recovered a few months later. All the gyros have even died, but she's still working.
Here's a link to an interesting article about the 1998 event.
https://sohowww.nascom.nasa.gov/operations/Recovery/vandenbu.pdf
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It's not as showy as a planetary probe, but SOHO has been a tremendous success. Having an entire 22-year, full solar magnetic cycle's worth of data from a single, well-characterized spacecraft is incredibly useful to the solar physics folks. There's been some drama with the mission--comms were lost for a month or so in 1998, but the spacecraft was recovered a few months later. All the gyros have even died, but she's still working.
Here's a link to an interesting article about the 1998 event.
https://sohowww.nascom.nasa.gov/operations/Recovery/vandenbu.pdf
Does it not need its gyros for station keeping, surely without them it will slowly drift away from its position?
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They're not missing any capabilities without the gyros. The sun sensors, reaction wheels and thrusters keep it pointed right. I think they can use the reaction wheels as sort of gyros for the three axis stabilization.
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They're not missing any capabilities without the gyros. The sun sensors, reaction wheels and thrusters keep it pointed right. I think they can use the reaction wheels as sort of gyros for the three axis stabilization.
Yes, SOHO has been operating gyroless since February 1, 1999. There's a brief explanation of the gyroless mode here:
On December 21 1998, the third and last gyro was lost, which put SOHO into ESR mode. With new solutions to:
- reduce the orbit perturbation of the ESR mode (by manual yaw braking from the ground),
- accurately measure the roll rate (wheels spun-up so that there is a net momentum on pitch, which combined with the roll rate creates a yaw disturbance torque),
- patch the Attitude Control Software to fly SOHO without gyro control,
- implement new or updated procedures, including the one to recover from ESR (now done without gyroscope control),
SOHO spacecraft was put back into normal mode on February 1, 1999. Since then it is the first three-axis-stabilized ESA spacecraft to be operated without a gyro.
ftp://zeus.nascom.nasa.gov/pub/oldwww/operations/Recovery_nocss/olive.pdf
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They're not missing any capabilities without the gyros. The sun sensors, reaction wheels and thrusters keep it pointed right. I think they can use the reaction wheels as sort of gyros for the three axis stabilization.
They still have fuel for the thrusters after all this time.
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http://www.esa.int/Our_Activities/Space_Science/Earth_s_atmosphere_stretches_out_to_the_Moon_and_beyond
“The Moon flies through Earth’s atmosphere,” says Igor Baliukin of Russia’s Space Research Institute, lead author of the paper presenting the results.
Images of the plasmasphere/geocorona also seen by the Apollo telescopes and, more recently, Chang'e-3's: http://www.ecns.cn/visual/hd/2014/01-11/31086.shtml
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Comet SWAN in all-sky map from SOHO
One of the images that was used by Australian amateur Michael Mattiazzo to discover Comet C/2020 F8 (SWAN). The image was taken by the Solar Wind ANisotropies (SWAN) instrument aboard the ESA/NASA Solar and Heliospheric Observatory (SOHO).
It is a full-sky map showing differences in ultraviolet brightness between 10 and 11 April 2020. Most spots are just residuals of star signals that have not been completely eliminated in the subtraction process. They are easily discarded, however, because they stay fixed in the sky, while the comet (indicated by the labelled white arrow) changes position from day to day.
On all SWAN maps, there are two large black areas. These are regions that are too bright to be observed. One is centred on the Sun (indicated here with a yellow star), the other on parts of the SOHO spacecraft that reflect sunlight. These areas are often surrounded by bright areas, because the stray light generated by the sun shade and SOHO is variable and so cannot be fully eliminated by the difference process.
Related article: The discovery of Comet SWAN by solar-watcher SOHO (https://www.esa.int/Science_Exploration/Space_Science/The_discovery_of_Comet_SWAN_by_solar-watcher_SOHO)
https://www.esa.int/Science_Exploration/Space_Science/The_discovery_of_Comet_SWAN_by_solar-watcher_SOHO
Image credit: ESA/NASA/SOHO
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Citizen scientist discovers Sun-watcher SOHO’s 4000th comet
17-06-2020
Using data from the ESA/NASA Solar and Heliospheric Observatory, or SOHO, a European citizen scientist spotted a never-before-seen comet in the satellite data — the 4,000th comet discovery in the spacecraft’s 25-year history.
Currently nicknamed SOHO-4000 and pending its official designation from the Minor Planet Center, the comet has a rather small nucleus, estimated around five to ten metres in size, and it was extremely faint and close to the Sun when discovered. This means SOHO is the only observatory that has spotted the comet, as it is impossible to see from Earth – with or without a telescope.
The comet is seen here in a series of images from SOHO, along with the spacecraft’s 3999th comet discovery. The two comets are relatively close, approximately 1.5 million km apart, suggesting that they could have been connected together as recently as a few years ago.
Author of the discovery is Trygve Prestgard, who recently completed a Master’s degree in geophysics from Université Grenoble Alpes in France.
Like most other SOHO-discovered comets, SOHO-4000 is part of the Kreutz family of sungrazers. The Kreutz family of comets all follow the same general trajectory, one that carries them skimming through the outer atmosphere of the Sun.
“I feel very fortunate to have found SOHO’s 4,000th comet. Although I knew that SOHO was nearing its 4,000th comet discovery, I did not initially think that this sungrazer would be it,” said Trygve, who first spotted the comet in SOHO’s data. “It was only after discussing with other SOHO comet hunters, and counting through the most recent sungrazer discoveries, that the idea sunk in. I am honored to be part of such an amazing collaborative effort.”
Like most who have discovered comets in SOHO’s data, Trygve is a citizen scientist, searching for comets in his free time with the Sungrazer Project – a NASA-funded citizen science project, managed by Karl Battams from the US Naval Research Lab, which grew out of comet discoveries by citizen scientists early into SOHO’s mission.
“I have been actively involved in the Sungrazer Project for about eight years. My work with sungrazers is what solidified my long-term interest in planetary science,” said Trygve, who has discovered around 120 previously-unknown comets using data from SOHO and NASA’s STEREO mission. “I enjoy the feeling of discovering something previously unknown, whether this is a nice “real time” comet or a “long-gone” overlooked one in the archives.”
Launched in 1995, SOHO studies the Sun from its interior to its outer atmosphere, with an uninterrupted view from its vantage point between the Sun and Earth, about a million miles from our planet. But over the past two and half decades, SOHO has also become the greatest comet finder in human history.
SOHO is a cooperative effort between ESA and NASA. Mission control is based at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. SOHO’s Large Angle and Spectrometric Coronagraph Experiment, or LASCO, which is the instrument that provides most of the comet imagery, was built by an international consortium, led by the US Naval Research Lab.
https://youtu.be/X4f5VSNn68E
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Using data from the ESA/NASA Solar and Heliospheric Observatory, or SOHO, a European citizen scientist spotted a never-before-seen comet in the satellite data — the 4,000th comet discovery in the spacecraft’s 25-year history.
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SOHO’s pioneering 25 years in orbit
02/12/2020
The ESA-NASA Solar and Heliospheric Observatory (SOHO) is celebrating its twenty-fifth launch anniversary.
Two and a half decades of scientific discovery is a major milestone for any space mission. But when the spacecraft at the heart of the celebration was only designed to last for two years, and operates from an area outside the Earth’s protective magnetosphere, it’s an unalloyed triumph in the history of space exploration.
SOHO launched on 2 December 1995. It is stationed 1.5 million kilometres closer to the Sun than the Earth, from where it enjoys uninterrupted views of our star.
The mission was launched with three scientific objectives in mind. The first was to study the dynamics and structure of the solar interior. The second was to study why the Sun’s outer atmosphere, known as the corona, is so much hotter than its surface, and the third was to study where and how the solar wind of particles is accelerated.
Almost 6000 papers have now appeared in refereed journals based on SOHO data, many of them representing significant progress in our understanding of the original objectives.
In addition to investigating how the Sun works, SOHO is the most prolific discoverer of comets in astronomical history, having spotted more than 4000 of these icy mini-worlds during the sunward leg of their journeys.
https://www.esa.int/Science_Exploration/Space_Science/SOHO_s_pioneering_25_years_in_orbit
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29 November 2020 coronal mass ejection
02/12/2020
The Sun started SOHO’s 25th anniversary celebrations early, unleashing a coronal mass ejection – a large release of plasma and magnetic fields – on 29 November.
The eruption was associated with a powerful medium-class flare on the scale used to measure solar storms.
SOHO, the Solar and Heliospheric Observatory, launched 2 December 1995. The mission is an international collaboration between ESA and NASA.
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Re: SOHO
As Jupiter and Saturn enter the solar glare after their historic embrace in December, this is a good time to check out the SOHO photos at https://sohowww.nascom.nasa.gov/data/realtime-images.html
The GIF movies play on my firefox browser at https://sohowww.nascom.nasa.gov/data/realtime/gif/, not the MPEG movies.
To plan ahead for transits across the SOHO's C3 and C2 fields, see the charts at the U.S. Navy Research Laboratory's web site at https://sungrazer.nrl.navy.mil/index.php?p=transits/transits
(Graphic of paths of the planets for 2021 enclosed. Today's C3 photo with Jupiter and Saturn on the left.)
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Comet dives into sun as SOHO spacecraft watches
https://youtu.be/kpXR4ibIyCc
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The planet Mercury enters the field of view of SOHO's outer LASCO C3 imager today, and transits from viewer right-to-left until November 22nd:
https://twitter.com/Astroguyz/status/1585621095012569092
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SOHO chases asteroid's tail
25/04/2023
The ESA/NASA SOHO observatory has overturned 14 years of thinking about the strange Sun-skirting ‘rock comet’ known as Phaethon that could reopen the mystery of how the Geminid meteor shower was born.
Every December, the Geminid meteor shower lights up Earth's skies as our planet plunges through a vast cloud of dust in space. For years, the parent body of this meteor shower was unknown. Most of the annual meteor showers are associated with comets, which leave clouds of dust trailing behind them in the form of their tails. But the Geminids were different: no parent body was obvious.
When Phaethon was discovered in 1983 by the joint US/UK/Netherlands IRAS satellite, astronomers thought the mystery was solved. This small 5.8 km-wide object circled the Sun in an orbit very similar to that of the Geminid dust cloud, providing near-certain proof that Phaethon was the meteor shower's parent body even though Phaethon was an asteroid not a comet.
Each orbit of Phaethon, lasting 524 days, consists of an unusually close approach to the Sun. At a closest approach (perihelion) distance of 21 million km, Phaethon is hidden from observatories on Earth by the blinding glare of the Sun. Therefore, solar observatories provide the only way to capture vital images to study the extreme activity of the asteroid at perihelion.
Since 2009, the NASA Solar Terrestrial Relations Observatory (STEREO) has observed a sudden brightening of the asteroid a few hours after perihelion. At this close approach, Phaethon also sports a tail, hundreds of kilometres in length, facing away from the Sun. This activity was originally thought to be caused by the release of small dust grains from the cracking of the asteroid’s surface as it passes the Sun. This led to Phaethon being dubbed a ‘rock comet’.
Now, new observations from SOHO recorded in May 2022 have shown for the first time that, contrary to 14 years of previous thought, the emission of sodium atoms is likely responsible for this activity.
As part of a special observing plan devised by Qicheng Zhang and Karl Battams, long-exposure, filtered images were taken by SOHO’s Large Angle and Spectrometric Coronagraph (LASCO) telescope. Phaethon and its tail are absent from images taken with LASCO’s blue filter, which can detect dust. But, it is bright in the sodium-sensitive orange filter, offering compelling evidence that sodium emission is occurring. The emission is caused by fluorescence, when sodium atoms get excited by the Sun and glow orange, similar to a street lamp.
“Our unique observing plan found the mysterious asteroid Phaethon for the first time in SOHO data,” says PhD student Qicheng Zhang, who led the study. “The distinctive filters of the 27-year-old LASCO camera were used in a special interruption to the regular observing schedule to uncover these hidden secrets. By digging in the treasure chest of SOHO, we showed that Phaethon is visible in LASCO images from 18 different orbits back to 1997.”
Phaethon is not the only object near the Sun to be releasing sodium. The planet Mercury also exhibits a bright sodium tail that peaks around two weeks after perihelion – something that the joint ESA/JAXA BepiColombo mission will investigate once in orbit around Mercury. Observations of Mercury’s sodium tail from the STEREO H1-1 heliospheric imager were used as a calibration standard, like a standard lamp, to study this emission from Phaethon to support Zhang’s theory.
SOHO has observed hundreds of tiny Sun-skirting objects that are classified as comets – icy bodies which appear to brighten when very close to the Sun. These can be hard to distinguish from asteroids like Phaethon which shine temporarily. However, the sodium identified in this study has opened the possibility that perhaps the so-called comets discovered by SOHO are more like rocky asteroids similar to Phaethon.
This study shines more light on the events which could have formed the Geminid meteoroids, which range in size from sand-grains to pea-sized. Sodium activity on the surface is not enough to lift these particles and contribute to the stream. Instead, an unobserved and unknown disruption of Phaethon, perhaps over two thousand years ago, is assumed to have created the shower.
The fresh layers of volatile sodium which contribute to the brightening observed today suggest that another mass-loss event may have resurfaced Phaethon more recently, perhaps less than 1000 years ago. Therefore, the exact origin of the Geminids meteoroids may be better understood by studying Phaethon.
There is great interest in Phaethon due to its distinctive activity and mysterious history, which make it an essential and intriguing source of up-close future study. Hence, JAXA is preparing to send a flyby mission called DESTINY+ to image the surface of Phaethon in 2028 and uncover more about its history.
In addition to future missions, citizen scientists can play their part in revealing new discoveries using SOHO. Over 4500 Sun-skirting objects have been identified in SOHO images, the majority with the help of the Sungrazer Project. Citizen scientist ‘comet hunters’ can sift through SOHO and STEREO data to identify new objects.
Karl Battams, principal investigator of both LASCO and the Sungrazer project, explains, “SOHO is the most prominent comet hunter in history, with a huge catalogue of discoveries still awaiting detailed analysis. Both SOHO and STEREO are uniquely placed to be able to routinely observe objects extremely close to the Sun. The future of asteroid and comet studies is bright thanks to these and future encounter missions that will help us uncover more about these dynamic objects.”
“Since its launch in 1995, SOHO and its instruments continue to deliver exciting science, using the mission in different ways to study asteroids and comets in addition to its primary target, the Sun,” adds Bernhard Fleck, ESA’s SOHO project scientist.
https://www.esa.int/Science_Exploration/Space_Science/SOHO_chases_asteroid_s_tail
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Rare sighting of ‘doomed’ SOHO comet during solar eclipse
19/04/2024
Early on 8 April 2024, a citizen scientist found a comet in images from the ESA/NASA Solar and Heliospheric Observatory (SOHO). It follows the recent discovery of SOHO’s 5000th comet. But this one – named Comet SOHO-5008 – was special for a different reason.
Karl Battams (US Naval Research Lab), manager of the SOHO Sungrazer Project, predicted that comet SOHO-5008 would be visible during the total solar eclipse, which was due to plunge parts of the United States and Mexico into darkness later that very same day.
Petr Horálek, from the Institute of Physics in Opava (Czechia), was in Mexico for the eclipse. The clouds cleared and Petr could take this beautiful shot of the Sun’s awe-inspiring corona. To the lower left of the Sun, Comet SOHO-5008 is revealed.
Soon after Petr captured the comet on camera, it met its demise, coming so close to the Sun that it disintegrated.
Observations of these ‘sungrazing’ comets from the ground are extremely rare, and this sighting was only possible thanks to the total solar eclipse.
The image is a composite of 100 frames, with the wide corona imaged at a focal length of 200 mm (exposure time from 1/4000 to 2 seconds) and the inner corona imaged at a focal length of 1100 mm (exposure time from 1/500 to 4 seconds).
SOHO’s prowess as a comet-hunter was unplanned, but turned out to be an unexpected success. With its clear view of the Sun’s surroundings, SOHO can easily spot sungrazing comets. This has made it the most prolific discoverer of comets in astronomical history.
https://www.esa.int/ESA_Multimedia/Images/2024/04/Rare_sighting_of_doomed_SOHO_comet_during_solar_eclipse