# Tag Info

### How realistic is the 1 kg/km² solar sail in "Death's End"?

A solar sail with an areal density of $1~\mathrm{kg}/\mathrm{km}^2 = 1~\mathrm{mg}/\mathrm{m}^2 =0.001~\mathrm{g}/\mathrm{m}^2$ is impossible by known materials science because graphene has an areal ...
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### How realistic is the 1 kg/km² solar sail in "Death's End"?

There is a extensive summary report on possible improvements of solar sail materials: "Ultra-Thin Solar Sails for Interstellar Travel - Phase I Final Report" December 1999, Dean Spieth, Dr. ...
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### Is it possible to reach the Sun without expending any fuel/reaction mass?

If you're already in a solar orbit, then yes. You can use a sail at an angle and send the reflections prograde. The result is to reduce your orbital energy and you spiral in. I recall it was a ...
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### Influence of solar wind and radiation pressure on a sail

According to wikipedia, solar wind pressure at 1AU is about 1-6 nN/m2. Solar light pressure on the other hand is apparently 4.54-9.08 μN/m2. It therefore seems unlikely that solar wind pressure will ...
• 8,188
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### Could the International Space Station be fitted with solar sails?

Ignoring the ISS, the question is simply whether light pressure on the sail can counteract the drag on the sail from atmosphere. Light pressure near Earth is about $10 \mu Pa$ (with optimum geometry ...
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### Can dust be in orbit around a spacecraft which orbits the Earth or Moon?

A starting point for checking orbital stability is the Sphere of Influence for short term stability (or rather, to select a suitable frame a reference in the patched conic approximation), and the Hill ...
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### At what size does a bigger solar sail stop increasing your acceleration?

As long as other variables are held constant (such as the orientation with respect to the direction to the sun, reflectivity of the sail surface, etc.) the force produced by a solar sail is always ...
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### To what extent could JWST continue to be useful after the propellant runs out?

Could JWST be moved to an Earth-trailing orbit (or other useful orbit) without sacrificing too much precious remaining propellent? The JWST will be moved to an Earth-trailing heliocentric orbit as an ...
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### Can a solar sail be added to an ion engine and work better?

Intro This is a tricky question, primarily because solar sails benefit from a low mass spacecraft and with the addition of an electric propulsion system, you are increasing the mass decreasing the ...
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### Maximum velocity achieved by solar sail

tl;dr: Can we get close to the speed of light with that? No, at least not very easily. The terminal velocity $v_{\infty}$ is only about 0.2% the speed of light if you start at 1 AU using a 10 ...
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### Is it possible to launch a satellite into orbit with a solar sail and a weather balloon using the magnetic poles?

The problem is that you have to go from low-speed regime in the atmosphere (the balloon), to a high-speed regime out of the atmosphere (~7000m/s). The low forces available from a solar sail don't ...
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### Why do "Relativistic Light Sails Need to Billow"?

The Hoop stress is proportional to the radiation pressure but inversely proportional to the curvature of the sail. Allowing the sail to billow increases the curvature and reduces the tension in the ...
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### Is it possible to launch a satellite into orbit with a solar sail and a weather balloon using the magnetic poles?

You need 1000km of altitude to break even between air drag and light pressure of sunlight. Below that the solar sail acts as a parachute, dragging against the remains of the atmosphere. You must reach ...
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### How will NEA Scout control its attitude during deep space flight & keep its camera steady without vibrations or damage to its 85 m² solar sail?

The NEA Scout contains multiple items aimed at controlling attitude: An inertial measurement unit that contains rate gyros that sense the vehicle's rotation rate with respect to inertial, A star ...
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### Why did my vis-viva math solution get so close despite being wrong? Under what conditions would it have been a good approximation?

First, you appear to have the following misunderstanding of the solar sail force vectors: Tilt it at 45 degrees to make the thrust tangential Thrust is not tangential at 45 degrees. In fact, a ...
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### Are solar sail spirals logarithmic? Can this be shown analytically or by dimensional analysis alone?

The answer has to be 'not necessarily', because, in general, as you go along, you're free to adjust the solar sail angle and thus the trajectory. In addition, the trajectory need not lie in a single ...
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### Solar Reflective Plasma Drive

Sounds a bit like a solar thermal rocket. Here's a diagram of one from page 49 of Solar Rocket System Concept Analysis. It would use a pair of parabolic reflectors to use sunlight to heat propellant. ...
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### Can a solar sail be added to an ion engine and work better?

Ikaros had solar panels embedded in the solar sail The sail, shaped somewhat like a kite, also has solar cells embedded to generate electricity. It was not expected to make much power during this ...
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### How effective are solar sails to deflect an asteroid?

Simply white-painting an asteroid probably isn't enough to avoid a predicted collision in typical cases according to my back-of-the-envelope math. A 10km diameter asteroid has a mass of around 1e15kg....
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### How will JWST manage solar pressure effects to maintain attitude and station keep it's unstable orbit?

Brilliant question. I'm surprised nobody referred to the amazing JSWT User Documentation available at STScl-JWST. (This question was active again, somehow, so adding an answer.) Antzi's answer was ...
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### Tacking a solar sail to increase duration of acceleration

A solar sail can meet the sunlight at any angle, and that's essentially the only way to operate it because the light pressure is too small to blow you arbitrarily far away. And by choosing your ...
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