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SOHO Is Back
c4tp's friend writes "Space.com reports that SOHO (Solar and Heliospheric Observatory) is back and almost fully operational. The satellite should be able to transmit 98% of the data it was able to transport before an electric motor stuck disabling its high gain attenae in June (covered by Slashdot). The fix includes a 180 degree rotation of SOHO and use of another satellite dish transmitting the information via the Deep Space Network. SOHO will be out of order for about nine to sixteen days every three months."
The Solar and Heliospheric Observatory
This device is operational for alreay seven years, whereas it has been designed for two operational years, with a possible extension to five.
The Sun-watching SOHO spacecraft is back in full operational mode after a partial blackout period that raised serious concerns among space weather forecasters. The probe could survive until 2008, when a replacement probe could be launched SPACE.com has learned.
Though limping a bit, SOHO is now able to resume meeting most of its original mission objectives thanks to creative engineering solutions, an elated mission official said.
SOHO (Solar and Heliospheric Observatory) began having problems in early June. A stuck motor drive would not permit its high-gain antenna to move. The antenna is used for transmitting important pictures and data back to Earth, and it must be pointed toward the planet.
No other set of satellites can produce the data provided by SOHO, scientists say.
This week the spacecraft's orbit brought it into a favorable position and, as planned, engineers flipped the craft 180 degrees so its antenna could point toward Earth. SOHO orbits a gravitationally stable point in space, partway between Earth and the Sun, every six months.
"Things are back in full operation," said Joe Gurman of the Solar Data Analysis Center at NASA's Goddard Space Flight Center.
Gurman said in a telephone interview that despite continuing gaps in SOHO's ability to transmit, about 98 percent of the data required by space weather forecasters will be returned during the rest of the spacecraft's lifetime.
That life has lasted more than seven years, even though SOHO was designed for a two-year mission with a possible three-year extension.
"The actual scientific impact is pretty limited," Gurman said. "And we're really happy about that."
When SPACE.com first reported the problem on June 19, officials said the result might be total blackout periods for several weeks each year. Space weather forecasters who rely on the data said it would gut their forecasts, which in turn are used by satellite operators and power companies to minimize risk of failure during strong solar storms. Even commercial television broadcasts and pager services would have been at greater risk for downtime if storms struck without warning.
The SOHO team has proven resourceful, however.
The probe entered an expected blackout period on June 27. Since then, officials have employed a slower backup antenna to transmit data. A creative solution was devised. Some data was recorded on board and then downloaded using high-speed transmissions -- through the backup antenna -- when time could be spared on large 70-meter dishes of NASA's Deep Space Network (DSN).
SOHO does not normally use the high-capability DSN.
SOHO officials will meet later today with the DSN team to discuss how much time they can get on the network. Gurman said beginning early next year the spacecraft's needs will find tough competition from a plethora of Mars missions that will also rely on the DSN.
Meanwhile, a similar approach allows some data to be returned to a 34-meter dish when the DSN is not available.
Full and normal operation resumed on July 14. Partial blackouts lasting between nine and 16 days will continue to occur every three months.
"It is good to welcome SOHO back to normal operations, as it proves that we have a good understanding of the situation and can confidently work around it," said Stein Haugan, acting SOHO project scientist with the European Space Agency.
Engineers expect the craft to endure. Barring catastrophe, SOHO could last until a similar probe, the Solar Dynamics Observatory (SDO), is launched, possibly in 2008.
Gurman said SDO, if it goes up as planned, would be a 100-percent replacement for SOHO.
Meanwhile, solar activity is lessening. An 11-year cycle peaked over the past two years and is ramping down to a low point that will come between 2005 and 2007.
"I see no reason to believe we can't continue to operate in this fashion through the end of the solar cycle," Gurman said.
SOHO is a joint project between NASA and the European Space Agency.ht
When you get right down to it, space is not the problem. It is getting there, or getting back that is the problem (especially atmospheres). Once you get out into the void, things seem to work pretty well (at least until you leave space and try to enter another atmosphere, such as Mars)
Getting through the atmosphere is indeed dangerous. But I think you underestimate how harsh an environment space really is. It's full of micrometeorites that will tear through your craft if you're travelling fast, and the radiation is killer, because you aren't shielded by the atmosphere. Solar flares could easily put you out of commission too - that's why satellites include technology originally developed during the Cold War to shield against EMP from nuclear blasts. And the temperature gradient is killer too - hundreds of degrees on the side of the craft facing the Sun, and near absolute zero on the other side. If you don't have good heat dissipation systems you're fried (quite literally).
Again, this is not near as harsh on NASA's equipment as our own atmosphere is. Once the stuff gets into space safe and clear, it seems to run pretty well precisely because space is pretty safe when it comes to danger to the craft.
99% of the things in the Earth's atmosphere do a lot better in the atmosphere than in space. I don't think you appreciate what amount of engineering goes into even the simplest of satellites that are put into space. And once you put things up there, maintenances is, for the most part, out of the question. You better make sure you get it right, because you can't just send out a maintenance team to fix things up every year like you could with something installed on the ground.
Let me sum up with a final comment: I'm glad the parent was only modded up interesting, not informative, because it's quite wrong.
Cyde Weys Musings - Scrutinizing the inscrutable
I don't know where you got that disinformation! It is currently near the center position.
The antenna CAN be moved (it is NOT stuck, as we found out during testing), but with a high risk that it could get stuck permanently. However, the antenna beam pattern needed to be tested, *in flight*, so that we could optimize its final position.
It is safer to "leave well enough alone", and that was the case here. But first we moved it to the optimum spot. There are no plans to move the antenna again.
Disclaimer: I work for the SOHO Flight Ops team, but I don't speak for NASA or my employer, yada yada yada
I hold it, that a little rebellion, now and then, is a good thing. -- Thomas Jefferson
This is incorrect. SOHO exclusively uses the DSN, but normally needs only 26-meter antennas. However, when downlinking using the "backup" low-gain antenna (which is omnidirectional), the 26-meter dish does not have enough gain to lock on telemetry. When using larger dishes, downlink is possible -- but the bit rate might be limited. For a 34-meter dish, SOHO can downlink at 56 kbps. For a 70-meter dish, SOHO can downlink at its normal rate, 256 kbps.
The problem is, time on the larger dishes is hard to come by. When SOHO can't get time on a larger dish during the "blackout" period, it can't downlink. There are only 3 70-meter dishes in the DSN; most of the time another mission further out in space is using them.
I hold it, that a little rebellion, now and then, is a good thing. -- Thomas Jefferson
SOHO originally had 3 gyroscopes, but they all broke after the deep-freeze in 1998. With new software, we can use the reaction wheels as gyroscopes (albeit much less sensitive ones).
I hold it, that a little rebellion, now and then, is a good thing. -- Thomas Jefferson
SOHO was launched at the end of 1995 and arrived in its orbit in mid-1996. The mission was originally scheduled to end in 1998. So we are now 5 years past its originally planned mission.
But to answer your question -- there is currently no other spacecraft that could do SOHO's job. However, there are plans for a "Solar Dynamics Observatory (SDO)", part of the "Living with a Star" program. After it launches (maybe in 2006), then SOHO will no longer be a single point of failure. Hopefully, SOHO will last that long.
#standard disclaimer: I work for SOHO, but don't speak for NASA or my employer
I hold it, that a little rebellion, now and then, is a good thing. -- Thomas Jefferson
This success doesn't reflect anyting about consumer HW/SW because it's at an entirely different place in the good/fast/cheap space. As ever, consumer software isn't going to be NASA grade because people aren't willing to pay NASA prices for it.