2012rcampion
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Determining orbital position at a future point in time
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48 votes

Statement of the Problem The problem you want to solve is called the Kepler problem. In your formulation of the problem, you're starting out with the Cartesian orbital state vectors (also called ...

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What is the lowest first stage thrust for a launch reaching orbit?
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21 votes

The U.S. Vanguard rocket reached orbit three times with a first stage thrust of only 125 kN. The first stage of the three-stage Vanguard Test vehicle was powered by a GE X-405 28,000 pound (~125,000 ...

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Why aren't the ISS's nor Space Shuttle's radiators black?
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20 votes

Kirchhoff's law is only valid for objects in radiative equilibrium. The emissivity and absorptivity of a material are the same for a given wavelength, but can vary dramatically for different ...

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How powerful are reaction control wheels?
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20 votes

Background and Physics Note that there are actually two different but related types of actuators that use conservation of angular momentum1 to control a spacecraft's attitude (both of which may be ...

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Will the January 2018 government shutdown affect the Falcon Heavy launch?
14 votes

Currently unclear According to the Verge: It's possible that the [static fire] test could come early next week. But the Falcon Heavy’s launchpad is located at NASA’s Kennedy Space Center, and limited ...

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Pushing down a projectile from LEO
9 votes

This answer assumes that you start in a circular orbit of radius $r$ and speed $v_\text{circ}=\sqrt{\mu/r}$. If you push the ball along the direction of the orbit, it will go into an elliptical orbit ...

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Could a sling launcher be used on Mars?
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9 votes

We can compute the power required to maintain speed as: $$ P=\frac{C_D}2\rho A v^3 $$ Assuming the hypersonic drag coefficient is around $1$ and that the atmospheric density is $1\%$ of Earth's, we ...

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Unix Epoch in International Space Station
8 votes

Computers on the ISS do not rely on UNIX/POSIX time, they rely on GPS time. Broadcast time is the time broadcast from ISS computers that is intended to be indicative of current time. The broadcast ...

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What payloads and launch speeds could a sling launcher get using modern materials on the Moon?
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7 votes

The paper does not describe how the calculations for the tether are done, but I can make a guess. We take a small piece of the tether with mass $\delta m$ and length $\delta r$, at distance $r$ from ...

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Earth Moon Pork chop plot
6 votes

I agree with Ingolifs' answer; you can create a porkchop plot for a transfer between any two orbits. For an Earth-Moon porkchop you could pick either a point on the Earth's surface or a particular ...

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How did images taken by Perseverance's landing stage reach Earth despite its crash landing?
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4 votes

According to the press conference: ... that gold umbilical, that's what's transferring all the information between the rover and the descent stage, including this video; this picture is coming down ...

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Need help simulating solar limb darkening
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4 votes

I used the paper Wavelength dependency of the Solar limb darkening for solar limb darkening data. It uses the following model for the normalized brightness distribution across the disk of the Sun: $$...

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Single-shot Blue Marble pictures
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4 votes

First off I'll note that the linked article doesn't actually claim that Triana DSCOVR is the first spacecraft since Apollo to see the whole daylit side of Earth. The relevant quote (emphasis mine): ...

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Descending into any orbit: Which requires less delta-v, a wide one, or a narrow-elliptic one?
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3 votes

There are two different scenarios that I'll consider: Entering the circular orbit from high altitude. Entering the elliptical orbit from low altitude. Entering the circular orbit from low altitude ...

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3-axis gravity gradient stabilization?
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0 votes

Reading the paper more carefully has provided the answer. The beginning of section 4.1 states: Attitude stabilization is provided directly by gravity gradient on the pitch and roll axes, and by "...

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