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Why might it be desirable to have an observation craft so far away from the earth? I'm having a hard time imagining the advantage compared to being a bit close
by metadat 2y ago
Why might it be desirable to have an observation craft so far away from the earth?
I'm having a hard time imagining the advantage compared to being a bit closer, unless it's a more energy-efficient parking situation while the vehicle isn't in active use.
- deleted 2y ago[deleted]
- QuarterReptile 2y agoI assume better survivability against anti-satellite weapons.
- prpl 2y agomaybe observing satellites, in real time, in multiple orbits, and yeah, maybe just free parking (and testing orbital transitions).
- aaron695 2y ago[dead]
- SkyPuncher 2y agoMy understanding is it’s on an offset elliptical orbit. This is essentially the farthest point away from earth with the other end of orbit being very close to Earth. From a tactical perspective, that means this can interact with basically any other satellite.
- samplatt 2y agoWith a far point so far away from Earth it also means that it requires only tiny amounts of fuel for major orbit changes.
- justahuman74 2y agoMy orbital mechanics is (like most people) weak, is this intended as a generalized physical threat to other satellites?
- samplatt 2y agoIntended? I don't know, you'd have to ask NASA. Does it have that capability? Sure, if it can deploy arbitrary payloads on destination.
- kjkjadksj 2y agoIt has carried payloads before but little is known about its missions.
- everfrustrated 2y agoNot necessarily. These types of orbits also have the property that the perceived loiter time is different for the perigee and apogee. At perigee (closest to Earth) it will be moving very fast and so any changes to velocity will have a large impact (easily change orbit). While at apogee it will appear to sit in space and move quite slowly. As an example this is used for the Russian GPS system so their satellites can sit in high earth latitudes for longer needing fewer satellites to cover Russia.
- xattt 2y agoIsn’t GLONASS in geostationary orbit like NAVSTAR/GPS? This would be a fixed orbital distance from Earth. You may be thinking of highly-elliptical molniya/lightning orbits (1), which enabled state TV broadcasts for high-lat places in Siberia. (1) https://en.m.wikipedia.org/wiki/Molniya_orbit https://en.m.wikipedia.org/wiki/Molniya_orbit
- rcxdude 2y agoGps isn't in geostationary orbit. They're in medium earth orbit and complete an orbit about twice a day
- dredmorbius 2y agoAs well as change orbital characteristics (apogee, perigee, inclination) at reasonably low cost, enabling closer observation of specific portions of Earth, or of objects in space. Burns at closest approach (perigee) have the largest influence on total orbital characteristics. Burns at furthest approach (apogee) can raise the entire orbit if desired. (Or so I understand.)
- exDM69 2y agoBurns at perigee have best efficiency to make in-plane changes (raise or lower orbit) due to the Oberth effect. Burns at apogee have best efficiency for out-of-plane maneuvers (change orbital inclination plane) due to lowest velocity of the spacecraft. Highly elliptical orbits can do both at a few hours' notice.
- dredmorbius 2y agoThanks, I've got only a vague grasp of this.
- roelschroeven 2y agoBurns at perigee can only raise or lower part of the orbit though, right? A burn at perigee lowers or raises the apogee. To lower or raise the perigee, you need to burn at apogee.
- exDM69 2y agoCorrect. Burns don't have to happen only at perigee/apogee so there's more flexibility in practice. And counter intuitive stuff like bi-elliptic transfers.
- monkeyfun 2y agoAhhhh, bi-elliptic transfers! It's funny, I remember first learning to use such arcane maneuvers in a game called Children of a Dead Earth, in order to get into a terribly low orbit of Neptune to strike a methane refinery... My poor brain was always used to simple Hohmann transfers in games like KSP!
- DoingIsLearning 2y agoInteract as in fly-by repair? Or interact as in interfere/tamper/destroy?
- jl6 2y agoLooks like it would be able to deploy high speed instant-action repair kits.
- tliltocatl 2y agoUnlikely, velocity difference would be too large for anything constructive. One thing about orbits is that velocity difference is sort of a distance dimension in itself.
- NikkiA 2y agoYes, also steal ala Glomar Explorer
- kjkjadksj 2y agoPast flights have been years long and are classified what might have even been achieved. I wonder how much of the space war doesn’t ever get published?
- bagels 2y agoOne use for highly elliptical orbits is being able to linger over some part of the earth for longer periods. https://en.wikipedia.org/wiki/Molniya_orbit https://en.wikipedia.org/wiki/Molniya_orbit I haven't seen the orbital parameters of the X-37, so it may be in an elliptical orbit for some other reason, such as spying on or interfering with geostationary satellites or who knows what else.
- dylan604 2y agoThis thing is definitely out of SAM range, so that's an advantage.
- rich_sasha 2y agoI was going to say, not out of range of anti-satellite missiles, at least at a low perigee... But maybe it's zipping too fast there to be easily shot down? Whereas at apogee, when it's slow, it's also very far away.
- credit_guy 2y ago> But maybe it's zipping too fast there to be easily shot down? A satellite in LEO already has a speed of about 8 km/s. The highest speed of a satellite in a highly elliptical orbit is 11 km/s. It you can shoot a satellite at 8 km/s, you probably can also shoot it at 11 km/s. The problem is, of course, that the perigee of a satellite in a highly elliptical orbit can be over a different part of the planet than your SAM battery.
- jjk166 2y ago> It you can shoot a satellite at 8 km/s, you probably can also shoot it at 11 km/s. Assuming all else is equal (same altitude, same targeting capability, same flight characteristics), an interceptor for an 11 km/s target needs about 89% more kinetic energy than an interceptor for an 8 km/s target. Realistically, between the rocket equation and atmospheric effects, the faster interceptor would likely need to be far larger still. You're probably talking about a 2.5 to 3 times bigger missile. While a country that could develop one could likely develop the other if they so chose, it doesn't seem like a safe assumption that a country with one has the other.
- s1artibartfast 2y agoI dont think that it is correct to assume your interceptor needs to match velocity. Any speed will do if you can intercept it on approach instead of chase it down.
- tonyhart7 2y ago"Why might it be desirable to have an observation craft so far away from the earth?" more range the merrier in case there is alien invasion. you would need aircraft that allow travel interplanetary system
- newsclues 2y agoLess predictable orbit.
- tehbeard 2y agoPossibly easier for optics? Lower orbit = faster velocity. So your screaming by over Emutopia's enrichment plant, and trying to take photos. Telephotography might be an easier solve than faster image capture for the same resolution and clarity. A higher orbit means you have to do less drastic tracking corrections to observe the same area while over it. Alternative: it's a space plane and has been mentioned it uses aero braking for orbital adjustments. A highly elliptical orbit imparts a significant chunk of potential energy that can be expended for orbital changes using aero braking instead of needing to expend limited propellent. Source: personal experience with several hundred hours of KSP.
- 6510 2y agoHow can you tell that is the earth?