Limb and Disk? NASA doesn't give any explanation about their acronym! I went to their site, and while they went on about it, "limb" puzzles me.
NASA’s Global-scale Observations of the Limb and Disk (GOLD) instrument is successfully heading into orbit – after the Ariane 5 rocket lifting it into space worryingly lost its radio link with Earth. The GOLD probe will investigate how space weather and Earth’s magnetic field affects terrestrial weather conditions. It’s the …
"GOLD scans the entirety of the Earth’s disk every half hour."
Limb, as in looks at the edge of Earth's atmosphere?
I'm imagining that some data resolves more sharply seen edge-on but other data is from tracking changes across wide areas.
And, of course, projects get funded and championed much more if they have sexy names. I mean, the Arecibo dish would get lots more money if it was called 'Marilyn'.
"I'm imagining that some data resolves more sharply seen edge-on but other data is from tracking changes across wide areas."
Disk view, you're looking straight down and get a plan view of all the layers at once.
Limb, you see a cross section.
At least, that's how I'd expect it to be working
"Powerful events in the lower atmosphere, such as hurricanes or tsunamis, disrupt these charged particles."
Good article overall, but I must take issue with this statement.
Charged particles from the sun that get trapped in Earth's magnetosphere generally stay far above even the stratosphere. Those that don't, interact with very high altitude air molecules and produce those eerie polar light shows we've all heard about or witnessed.
Hurricanes and tsunamis are quite low (tsunamis particularly so) and therefore the two regimes are separated by a considerable distance. Further, those low events are not magnetic.
How do those low altitude events affect space particles? Does the generated electric potential of a hurricane have the reach to disturb the paths of those high flying particles, so far above?
Note this is not a "secondary payload" bolted to the launcher. It's a secondary payload to the satellite.
IIRC some sats carry transponders for the SAT/SAR (satellite Search & Rescue) service that are distress beacons for anywhere on the planet.
I hope NASA does more more of these. Obviously it has to be something that is small enough for the commercial operators not to mind carrying and provide useful data from the orbit they want to operate in (which sounds a lot like GEO comm sats mostly). Logically they need about 3 of them to get full Earth coverage, and the sats have to be at latitudes far enough apart to get each one at least 120 degrees FoV.
BTW Some years ago JPL looked at doing probes to other planets launched as secondary payloads on Comm sat launches. The payoff was not waiting a decade to get the funding for their own LV. The downside was the very limited (by JPL standards) mass. So a couple of instruments, rather than the half a dozen or a dozen of their typical launch. So 1-2 instruments per launch, but maybe 3-4 launches a year.
This seems to use a similar approach. One really good (and quite heavy) instrument to get a lot of data.
@ Martin Gregorie
Help me out, it's midnight and I am a bit confused.
I used to be quite good at celestial navigation long ago. But as Field of View is a circle, is it not, then does it really matter if you "define" it as latitude or longitude.
PS. for Scandinavian readers who find it difficult to remember which is "lat" and which is "long" just remember "lat är den som ligger". To my surprise Google translate does quite well here but is slightly missing the point still.
PPS is that "s" at the end in latitude and longitude actually proper English, it doesn't sit with me.
Icon for time in the problem of the longitude. (did I spot the solution here, even if the glass is empty)
The inclination of the orbit is way off, which is why they probably lost comms.
"TLEs are out - the Ariane objects are in 230 x 43160 km x 20 degree geotransfer instead of the intended 250 x 45000 x 3 deg, so inclination totally off but height pretty much fine"
I once worked with someone who'd worked as a software developer at the European Space Agency. They all had to be very sanguine about the fact that the code they'd spent months / years writing for a satellite could go up in a ball of flames if lady luck failed to smile on them.
I found it rather baffling at first as to why he'd left to work on the far, far less interesting projects available at this particular company we both now worked for, but he basically said that every tiny aspect of coding was so tightly controlled, and everything was triple checked before each one of these checks was again triple checked, that he decided to move on to something where he'd at least be able to display a bit of personal creativity. And as everybody in that company could basically do things any way they wanted he certainly achieved that goal, if for far less impressive end uses. I guess you have to really be 100% into space stuff to be prepared to work within such limitations.
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