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SOHO's Antenna Jammed
zapp writes "Space.com has a story reporting that the communications antenna on SOHO (Solar and Heliospheric Observatory) has been acting up for two weeks, and as of 3PM ET Thursday was not functioning properly. The problem appears to be with motor to position the antenna. If full use of SOHO cannot be regained, it will set space weather forcasting back 20 years."
This has nothing to do with terrestrial weather prediction.
FTA:
"SOHO monitors ejections of solar energy and in many cases provides the only warning of magnetic storms that are about to hit Earth. Though usually benign, these storms can knock out satellites and disrupt satellite and radio communications. In at least one case a solar storm disabled a power grid."
"Gold still represents the ultimate form of payment in the world." - Alan Greenspan, 1999
Fortunately for us, it is nothing like earth weather forecasting.
Magnetic storms can be very damaging to AC electric systems, and power companies go into conservative operations when storms are predicted by NOAA. The change in the earth's magnetic field (as it interacts with the solar storm) induces slight currents in the metal in the earth's crust, which can have a negative impact on high voltage transformer equipment.
SOHO has served us well. That said, it's only made of metal plastic and silicon parts and after being blasted by the solar wind for so many years, it's bound to fail eventually. SOHO's replacement is called the STEREO mission. It will actually be 2 separate spacecraft that view the sun simultaneously, in order to acquire STEREOscopic observations of the corona and coronal mass ejections. It was sometimes difficult for SOHO to tell what direction a CME was traveling in because it had only one point of view. STEREO launches in 2005. In the meantime TRACE can do a few of the things SOHO did and while at it, do some things SOHO could never do, like take these SPECTACULAR movies and images of the corona and photosphere at very high spatial and temporal resolution.
- "Hear that?! The percolations are imminent! Cease your ingress!"
There's *plenty* of reasons for it to fail!
:
;-)
Can *you* design a hinged joint that is
- rigid enough to point constantly in one direction.
- but flexible enough for a geared stepper motor to move?
- able to survive large temperature extremes (at least a difference of 250 deg C on the outside of the craft)? (Remember not to use normal lubricants that will freeze solid or boil off in the vacuum of space.)
- it costs a lot of cash to get something into orbit, so it has to be very,very light.
Now mulitply that by however many hinged joints you need to deploy and accurately point your antenna. And that's just the hinged joints.
You can also apply the same requirements to the stepper motors, drive electronics, feedback mechanisms and a whole lot of other stuff that likely makes up the antenna system.
It's not that easy, and I'll bet they didn't have an unlimited budget to design it either. And the thing's been up there , pointing its antenna about the place for 10 years now.
Sorry if this sounds like a bit of a rant, but casual comments like yours make me a little peeved
You are in a twisty maze of processor lines, all alike.
There is a lot of hype here.
I found a link to the SOHO technical description - check out figure 5 (antenna assembly)
Looks like an alt-azimuth assembly... and man, there looks like there's a lot of parts to go wrong in there!
You are in a twisty maze of processor lines, all alike.
There is a lot of hype here.
(1) SOHO has far exceeded it's 2-3 year life expectancy by about 7 years. (2) It still transmits data - just significantly slower (3) The new NOAA GOES SXI (SOLAR X-ray imager) insturment is up and running (www.sec.noaa.gov),creating images every five minutes directly at the NOAA Space Environment Center. It is the official operational X-ray imager now. (4) Space is extremely hostile to satellites (high-energy particles, spacecraft charging, meteoroid impacts, radical temperature changes, etc.) Loss of spacecraft after several years is normal. (5) The economic impact to society has been estimated to be of the order of $10 - $100 million/yr (power grids, satellite drag, disrupted radio communications, GPS inaccuracies, etc.)... and growing every year with our increasingly complex technological systems (6) Recent research had shown about 30-40% of global climate change is due to solar variability There is a lot more to Space Weather than one may guess... -Dave, SpaceWx.com