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### What were the most inaccurate or accurate things in “The Martian”?

I am curious what the most accurate, versus most inaccurate things that were depicted in the space movie, "The Martian"? I thought the part where he punctures his suit and jets over to the rescue ...
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### Why are obsolete geostationary satellites re-orbited above the geostationary belt?

That seems a bit counter-intuitive, because in an orbit above the belt, the satellite would eventually lose gain velocity, so its orbit would intersect the orbital plane of the geostationary ...
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### Optimal trajectory for solar electric propulsion?

Consider using solar electric propulsion for, e.g. Earth-Mars trip, or for asteroid retrieval mission. Is there a benefit to first entering an eccentric orbit so that part of the time is spent ...
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### Could a cubesat propel itself to Mars?

I wrote the answer below to the question Could a cubesat be propelled to the moon? before realizing that it said Moon and I'd written it for Mars, so I've cloned that question and moved the answer ...
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### What delta-v is required to move between Phobos and Deimos?

I wonder how practical it would be for a spacecraft to visit both moons of Mars on the same mission. Areostationary orbit lies between the two moons, and GEO is demanding to reach from LEO.
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### What is the gravitational acceleration of the Sun?

What is the gravitational acceleration of the Sun? I've seen numbers such as 274 m/s2, but that doesn't make sense to me seeing that relatively weak sources of spacecraft thrust such as Electric ...
566 views

### Ratio of low-thrust slow spiral to Hohmann transfer $\Delta V$?

Going from one circular orbit to another, there are tables out there and equations that give the total $\Delta V$ needed for a two or three impulse maneuver scenario. For a very low thrust propulsion ...
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### Why would a slow spiral from a C3 of zero take about 2.4 times as much ΔV as an impulsive maneuver?

I just read a fascinating comment that I don't understand. In part it says ...the Oberth effect does not depend on the mass of the object. A slow spiral in to a low orbit from a C3 of zero will ...
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### CubeSat Orbit Determination

I'm thinking about the feasibility of making a CubeSat to test the EM drive thruster. Assuming the microwave electronics and resonant cavity could be scaled down to CubeSat size (5 watts, let's say), ...
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### Delta-V of Starlink Satellites

The recently launched Starlink satellites are designed to use their HAL Ion thrusters to seek their own independent orbits, evade collisions, and de-orbit at the end of their lives. That's a lot of ...
644 views

### Spiraling out from circular orbit to escape via low thrust, what is γ (gamma)?

@MarkAdler's comment led me to ask Why would a slow spiral from a C3 of zero take about 2.4 times as much ΔV as an impulsive maneuver? which resulted in this tidy and efficient @MarkAdler answer which ...
341 views

### What are the travel times associated with different low-thrust accelerations going to Mars?

It doesn't have to be an exact answer, but something close to reality would be nice. Specifically I want to know what the travel time to Mars would be using constant firing low-thrust engines. What ...
436 views

### Quick and dirty way to estimate flight times for constant acceleration rockets

Thought experiment: Suppose we build a spacecraft with a low thrust electric propulsion and have a flight plan that involves constant acceleration on the first half of the journey, breaking on the ...