So i am doing a group project, and this seemed like a good place to ask. We’re designing a satellite that has to monitor a particular location 24/7, which would have been easy with a geostationary orbit. But our location is not near the equator, so if we use geostationary, we will have to make do with low resolution. So what could be a solution to this? We tried using Molniya orbits, but due to its precession, it did not stay above the location for too long. Can this precssion be countered, or are there other orbits we could try? Some sources would be really helpful. Thank you.
EDIT:
This is the orbit simulation in GMAT, running over a month. I have marked the area which we are planning on observing.
The satellite is using hyperspectral imaging with the objective of detecting explosives. Will a geostationary orbit suffice?
5 Comments
> Can this precssion be countered
Presumably it can, there’s no mention of precession issues on [the wikipedia page](https://en.wikipedia.org/wiki/Molniya_orbit)
Also, orbital precession usually takes place over timescales *vastly* longer than the normal service life of a satellite – were you running your sim for like 100k years and didn’t like the outcome, not realising that your satellite wouldn’t last that long anyway?
Using a Molniya orbit or inclined geosynchronous orbit would give you a better monitoring angle when overhead, at the cost of less time there, as you might have figured out. It all depends on which is more important– better resolution or more up-time. Without knowing details about what the satellite is supposed to do it’s hard to answer.
To monitor a high-latitude location 24/7 with a Molinya orbit, you’ll need 3 satellites (maybe you can get away with 2).
I’d like to question your premise that you would be forced to take lower-resolution photos at latitudes other than the equator using a geostationary orbit.
Geostationary orbit is 22,236 miles altitude. The Earth’s radius is 3958 miles. Now I’m napkin-mathing this, but that means the north pole is about 5,000 miles further from the geostationary orbit than the equator is, a difference of only around 25%. Is something 275 feet away really that much harder to photograph than something 220 feet away? Sure, 275 ft will be lower resolution than 220 ft, but only 25% worse.
Granted, there are other considerations. Latitudes above 85 degrees aren’t visible at all from geostationary orbit. Also, higher latitudes mean a more oblique photographic angle and more atmosphere to shoot through, but these are probably not much of an issue until you’re approaching 60+ degrees.
Also, we’re using geostationary orbit over the equator as the benchmark. If you need spy-satellite-like resolution, geostationary over the equator is already way too far away. Spy sattellites orbit 10x to 20x closer than geostationary. If you need that type of resolution, you can already throw out geostationary and molniya orbits. Your only choice left is more satellites.
Do you need to design “a” satellite or just a system that solves a problem?