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### What artificial satellite has the farthest orbit around the Earth?

What is the furthest Earth orbiting satellite? What is its speed and purpose?
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### What is a near rectilinear halo orbit?

A proposed option for the lunar orbit of a Lunar Orbital Platform-Gateway (formerly known as Deep Space Gateway) is a near rectilinear halo orbit, or NRHO. This excellent answer discusses the ...
213 views

### What is the current state of commercial space stations?

Many years ago, in the 2005 - 2010 area, it seemed like there were a lot of proposals to create commercial space habitats. These included inflatable modules, usage of spent fuel tanks, and ...
158 views

### How does a butterfly orbit move in 3D? Way to generate or visualize?

The paper Earth-Moon Near Rectilinear Halo and Butterfly Orbits for Lunar Surface Exploration (AAS 18-406) says Periodic Orbits in the Earth-Moon System The current investigation focuses on three ...
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### Aspects of “true deep space environment” on Gateway not thoroughly explored by decades of habitation of nine space stations already?

The ABC News article President Trump prompts state of confusion over space policy with tweet covers POTUS' tweet and NASA director Bridenstine's clarification tweet a few hours later, as well as cites ...
267 views

### Do Lagrangian points apply to eccentric orbits or binary systems?

The assumptions about the Lagrangian points being stable (...in the traditional meaning of the word: not moving around; they are unstable in the mathematical sense, except for arguably L4, L5) that I'...
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### LOPG/Deep Space Gateway - What is a cislunar orbit?

Formerly the Deep Space Gateway and now the Lunar Orbital Gateway or LOPG station, is planned for Expedition 1 aka the maiden launch of the SLS. After reading several specifications, to avoid the "...
602 views

### How will the Lunar Gateway go to L2 and L1; how much delta-v is needed?

In a talk to the press which can be heard in the YouTube video NASA Administrator Jim Bridenstine Explains the Lunar Gateway, NASA director Jim Bridenstine says after about ...
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### Is the Gateway's halo orbit bound to Earth? Would the Gateway remain in Earth orbit of the Moon disappeared?

Discussion below this answer involves my feeling that calling halo orbits in very asymmetric systems (e.g. Sun-Earth or Earth-Moon) as orbits around the primary, in 1:1 resonance with the secondary. ...
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### How do I calculate the Characteristic Energy for a rocket to Near Rectilinear Halo Orbit where the Deep Space Gateway is gonna orbit moon?

How do I calculate the Characteristic Energy for a rocket to Near Rectilinear Halo Orbit (NRHO) where the LOP-G or the Deep Space Gateway is going to be orbiting the moon? Or if someone already has a ...
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### How much delta-v does it take to get from a Lunar Transfer Orbit to a Near Rectilinear Halo Orbit around the moon

There has been a lot of talk of NASA putting a Lunar Gateway in a Near Rectilinear Halo orbit around the moon, but I don't actually know how much delta-v it takes to get there. Most delta-v maps I can ...
257 views

### Rendezvouses in halo or lissajous orbits

If a spacecraft was in an EM-L2 halo/lissajous orbit, and another craft would was going to approach EM-L2 a few days later, could they rendezvous immediately or is there a limitation when the second ...
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### Station-keeping delta-v per year for an Earth-Moon vanilla halo orbit?

This answer reminds us that an Earth-Moon L1 or L2 vanilla1 halo orbit remaining always visible to some patch on the Moon's surface requires station-keeping. Queqiao uses such an orbit having ...