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https://www.n2yo.com/satellite/?s=40059 https://www.n2yo.com/satellite/?s=40059 Looks like a pretty standard inclination for a sun synchronous roughly circular

by bagels 2y ago

https://www.n2yo.com/satellite/?s=40059 https://www.n2yo.com/satellite/?s=40059 Looks like a pretty standard inclination for a sun synchronous roughly circular orbit to me.

dylan604 2y ago
now that you say that, that does make absolute sense. why have a satellite waste time looking at the earth when it's dark? kind of one of those face palm "doh!" moments after the fact. I know polar because that's what ISS uses. I know geosync because that's what communication birds use and was directly beneficial in a former job to know. after that, I am much less familiar with the various other types of orbits. one day, i will take time to learn all of the various orbits and their benefits.
- mturmon 2y ago
  > ...why have a satellite waste time looking at the earth when it's dark? ... Exactly. Many NASA Earth-observing satellites use the same kind of sun-synchronous orbit (https://en.wikipedia.org/wiki/Sun-synchronous_orbit https://en.wikipedia.org/wiki/Sun-synchronous_orbit). (One of several exceptions are the instruments opportunistically mounted on the ISS, which has its own orbit, as you note.) One of these sequences is called the A-train (https://atrain.nasa.gov https://atrain.nasa.gov) - that's what OCO-2, discussed in OP, is part of. Having it be near noon local time (1:30pm, say) when you pass over every patch of ground has great advantages for some instruments. The sunlight passes through less atmosphere, and does so in "the same way" for most passes. So you're not seeing some places at local dawn and others at local dusk. This makes the observation less sensitive to the difficulties of atmospheric modeling. (Because you need a good atmospheric model to retrieve the solar induced flourescence [SIF] signal.) OTOH, the sun-synchronous orbit does restrict your observations to specific times. The companion instrument, OCO-3 (which is mounted on ISS), plays a special role here. OCO-3 can provide information about the daily cycles of plants that would be undersampled by a consistent 1:30pm arrival. * Separately from orbits: The discovery that you could obtain insights on plant processes at global scales from SIF using the OCO-2 measurement has been a really big deal for Earth science.
  - dylan604 2y ago
    As a side benefit, you get to see other swaths of land in other countries friend or foe which would have strategic benefits as well
- bagels 2y ago
  ISS is not in a polar orbit. It's at the inclination necessary to be serviced by Kennedy & Russian launch sites. Here's a fun one to read about: https://en.wikipedia.org/wiki/Molniya_orbit https://en.wikipedia.org/wiki/Molniya_orbit

by bagels 2y ago

https://www.n2yo.com/satellite/?s=40059 https://www.n2yo.com/satellite/?s=40059 Looks like a pretty standard inclination for a sun synchronous roughly circular orbit to me.

dylan604 2y ago

now that you say that, that does make absolute sense. why have a satellite waste time looking at the earth when it's dark? kind of one of those face palm "doh!" moments after the fact. I know polar because that's what ISS uses. I know geosync because that's what communication birds use and was directly beneficial in a former job to know. after that, I am much less familiar with the various other types of orbits. one day, i will take time to learn all of the various orbits and their benefits.

mturmon 2y ago
> ...why have a satellite waste time looking at the earth when it's dark? ... Exactly. Many NASA Earth-observing satellites use the same kind of sun-synchronous orbit (https://en.wikipedia.org/wiki/Sun-synchronous_orbit https://en.wikipedia.org/wiki/Sun-synchronous_orbit). (One of several exceptions are the instruments opportunistically mounted on the ISS, which has its own orbit, as you note.) One of these sequences is called the A-train (https://atrain.nasa.gov https://atrain.nasa.gov) - that's what OCO-2, discussed in OP, is part of. Having it be near noon local time (1:30pm, say) when you pass over every patch of ground has great advantages for some instruments. The sunlight passes through less atmosphere, and does so in "the same way" for most passes. So you're not seeing some places at local dawn and others at local dusk. This makes the observation less sensitive to the difficulties of atmospheric modeling. (Because you need a good atmospheric model to retrieve the solar induced flourescence [SIF] signal.) OTOH, the sun-synchronous orbit does restrict your observations to specific times. The companion instrument, OCO-3 (which is mounted on ISS), plays a special role here. OCO-3 can provide information about the daily cycles of plants that would be undersampled by a consistent 1:30pm arrival. * Separately from orbits: The discovery that you could obtain insights on plant processes at global scales from SIF using the OCO-2 measurement has been a really big deal for Earth science.
- dylan604 2y ago
  As a side benefit, you get to see other swaths of land in other countries friend or foe which would have strategic benefits as well
bagels 2y ago
ISS is not in a polar orbit. It's at the inclination necessary to be serviced by Kennedy & Russian launch sites. Here's a fun one to read about: https://en.wikipedia.org/wiki/Molniya_orbit https://en.wikipedia.org/wiki/Molniya_orbit