31
votes
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 ...
- 1,950
20
votes
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. ...
- 14.9k
15
votes
Accepted
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 ...
- 6,667
15
votes
Accepted
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 ...
- 8,001
13
votes
Accepted
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 ...
- 19.3k
12
votes
Accepted
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 ...
11
votes
Accepted
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 ...
- 18.2k
10
votes
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 ...
- 73.2k
9
votes
Accepted
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 ...
- 741
8
votes
Accepted
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 ...
- 149k
8
votes
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 ...
- 6,667
8
votes
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 ...
- 3,844
7
votes
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 ...
- 54.9k
7
votes
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 ...
7
votes
Accepted
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 ...
- 73.2k
6
votes
Accepted
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 ...
- 3,844
5
votes
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 ...
- 15.6k
5
votes
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....
- 167k
5
votes
Accepted
How would Solar Flares affect Solar Sail navigation?
This response addresses the last part of the question: "what is the proportion between "propulsive power" between the two accelerating factors of solar sail?"
Solar Wind is between 1-6x10-9 N/m2
"...
- 9,414
5
votes
Accepted
A more accurate way of solar sail calculation?
In his text Solar sailing: Technology, Dynamics and Mission Applications (see here for some of his open access titles), Colin R. McInnes derives the pressure on a perfect sail face on to Sol as
$$P(r)...
- 181
5
votes
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 ...
- 465
5
votes
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 ...
- 4,297
5
votes
Why put chromium on the back side of this JPL-designed solar sail?
1) Is simple to answer - to get rid of heat. Aluminium has a reflectivity of about 90% in the range below 1000nm wavelength. At a perihelion of 0.2 AU the total power of the Sun is about 30 kW/m² of ...
- 14.9k
5
votes
Why isn't "cylindrical alien derelict spacecraft" more common in theories of Oumuamua as an alien probe?
tl;dr: In order to maintain plausibility they chose something plausible.
The abstract includes the following:
The observed trajectory is best explained by an excess radial acceleration $\Delta a ∝ r^-...
- 149k
5
votes
Accepted
Solar Turbines on the moon
This is an interesting question (to me at least) so I'll try an answer. I'll address the following aspects
...would a turbine of some form be plausible as a power generation option.
...whether it's ...
- 149k
4
votes
Accepted
Can a solar sail reduce the speed from 1-10% light speed to achieve a solar orbit?
No
1-10% of the speed of light is really, really fast. A solar sail would not receive a noticeable amount of light before it is about 5 AU away from the star (even then much less light than at 1 AU ...
4
votes
Can solar sail prevent orbital decay?
There is also the issue of eccentricity- accelerating only on one side of a planet would, as far as I know, gradually increase your eccentricity, until it eventually would escape the orbit it was in ...
- 41
4
votes
Can you use a light sail to achieve a survivable landing anyplace in our solar system?
A light sail in orbit around the sun can reflect light in a way to increase or decrease the orbit.
A light sail in orbit around another body is much more constrained. I haven't seen that you could ...
- 6,667
4
votes
Is there software that allows me to experiment with solar sail parameters?
Martin Schweiger's "Orbiter" (a freely downloadable simulation/game) has basic radiation pressure simulation and apparently a solar sail scenario which would be the first thing to try. (I haven't ...
- 5,178
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