This is a guest post by John Banks, a first year law student at the University of Manchester, with edits from Kali. John was so excited by the concept of solar sails that he wouldn't shut up until we let him write this post.
We call this the power of science.
Science!
In February, I, an aspiring law student, attended an event hosted by ReThinkX at CityLabs in Manchester. This was focused on the advances required in medicine to address problems associated with extended periods of space travel on the human body. I already know what you are thinking; ‘How did a plucky law student like myself end up at an event like this?’
It’s a compelling tale; with an infinitely witty main character, a dialogue tormented by puns, and a nostalgic soundtrack. A story for another time.
My curiosity was captured by Colin McInnes, MBE, Professor of Engineering Science at the University of Glasgow. From his speech stems my inspiration for this post, for Professor Colin McInnes was not present to talk of medicine.
Professor McInnes was there to talk about space.
There came a moment in our brief history when mankind ceased to worship celestial bodies like the pharaohs of old and began to look to the stars with greater promise. Jules Verne aimed for the moon, Katherine Johnson calculated how to land there, and a young boy named Anakin dreamt of visiting all the stars; he would later play a pivotal role in eradicating the Jedi but that was a long time ago in a galaxy far, far away. One fateful day, these efforts culminated into a giant leap for mankind.
Since then, all those stars have seemed a little closer.
This brings me to the topic addressed by Professor Colin McInnes; how to voyage this distance with greater effectiveness and efficiency.
Imagine if a member of an alien race landed on earth tomorrow…
Let’s call this alien 'Buzz'. Buzz successfully makes peaceful contact with the natives (us).
While describing his vastly superior technology, Buzz asks us how we can navigate through space without any of the technological advances that have allowed him to traverse the journey.
We would explain and Buzz would summarise that, essentially, we sit in a cockpit attached to a colossal tank filled with combustible material and let the explosion blow us into orbit.
Though not to worry, we have since developed a nuclear alternative.
‘Like a nuclear reactor to power your spacecraft?’ Asks a curious Buzz.
‘Oh no, nothing like that,' we reply. 'We use nuclear explosions instead.’
After an awkward silence, Buzz attempts to leave before we can show him the developments of Project Orion.
Yet, these nuclear alternatives are currently the most promising methods for escaping the gravity of Earth. However, once in space there is very little resistance acting on a ship and Newton’s laws of motion may be enjoyed to great benefit,possibly saving face with our galactic neighbours.
We are concerned with Newton’s first and third laws of motion. Namely;
To learn more about this, Crash Course has an excellent video. Which we've embedded. Enjoy!
We should also consider James Clerk Maxwell’s theory of electromagnetic fields and radiation. This theory proves that light has momentum and as such may exert a force upon a body. In other words...light can push something. Jules Verne somewhat predicted this, writing ‘there will someday appear velocities far greater...of which light or electricity will probably be the mechanical agent’.
Enter Konstatin Tsiolkovsky, who suggested, in 1925, that we could use ‘tremendous mirrors of very thin sheets to utilize the pressure of sunlight to attain cosmic velocities’. In other words, if we got our hands on a very thin, very big, mirror-sheet, the light might be able to push it enough to be useful.
Here, we need to understand a little about polyimide, particularly aluminized Kapton polyimide. Kapton polyimide is a material capable of withstanding temperatures between -269 and +400 °C, with good chemical resistance, and incredible flexural and tensile strengths, weighing 12 grams a metre squared with a depth of 2 micrometres. Almunizing it provides a reflective layer - in other words, it's strong, heat-resistant, thin, light, and shiny! Almost, one might say, like a very thin, very big, mirror-sheet.
Secondly, we must also regard our sun, insofar that it is an enormous nuclear fusion reactor constantly emitting photons, particles that carry light.
I present the solar sail.
A sail 800 metres or 2 kilometres square made from Kapton polyimide acts as the second body described in Newton’s third law to which photons emitted from the sun act as the first, thrusting the sail through the momentum they were theorised to have by Maxwell. The sheet stays in motion as it is not acted on by another force whilst in space.
Basically, what we have here is a huge mirror in space. Light particles from the sun push it. It's only a little push, but it's continuous, and that's enough to create a continual increase in acceleration, pushing the big shiny sheet faster and faster.
Now who looks silly, Buzz?
The elegant nature of solar sails can be observed in their many functions. Here comes the maths!
It is theorised that a solar sail that starts 0.05 AU, 7.4 million kilometres, from the sun would begin with a starting acceleration of 36.4 metres a second and could reach up to 950 kilometres a second, 0.00234% of the speed of light. In other words, the continual acceleration will make the solar sail go very, very fast,
In short, this could reach the Oort cloud, a shell of icy objects on the edge of the solar system, in less than 30 years.
We could set up a solar sail as a satellite around another planet or even the sun itself, allowing for more consistent observations to be made. The solar sail would remain static as the sails momentum counterbalances gravitational attraction; in other words, the solar sail would stay in the same place and let us take pictures of the same bit of a planet over time.
The theory of a solar sail may also be used to make navigational corrections to spacecraft trajectory, this has been used to make corrections to the MESSENGER probe orbiting Mercury, whilst a concentrated manufactured source of light beams has also been theorised to obtain speeds closer to the speed of light.
Lastly, solar sails could be used to voyage between planets. Travelling outward from the sun a solar sail could reach Jupiter in two years and Neptune in 8.5. Whilst travelling inward a solar sail could reach Mars in 400 days with a payload of 2 tons with a sail 80 metres square. It could reach Mars in 3 days carrying 100 kilograms. Traversing these distances in such short amount of time is only possible by taking full advantage of the solar sail being in a constant state of acceleration, much like traditional aircraft are required on Earth to counter the planets intense gravity.
These solar sails can't carry a huge payload, but could, for example, carry medicine to an astronaut in a much shorter timespan than we could otherwise manage. Receiving medicine in 3 days as opposed to six to eight months is, quite literally, a matter of life and death to an astronaut on Mars.
How does the solar sail stop? Aerobraking. The solar sail enters the atmosphere of the destination planet to gain drag and slow to a speed where it is possible to retrieve the payload.
This technology may represent a small step in space travel, but it is undoubtedly a leap for mankind’s dreams of sailing the stars.
Where next?
We call this the power of science.
Science!
Lawyers and Engineers
In February, I, an aspiring law student, attended an event hosted by ReThinkX at CityLabs in Manchester. This was focused on the advances required in medicine to address problems associated with extended periods of space travel on the human body. I already know what you are thinking; ‘How did a plucky law student like myself end up at an event like this?’
It’s a compelling tale; with an infinitely witty main character, a dialogue tormented by puns, and a nostalgic soundtrack. A story for another time.
My curiosity was captured by Colin McInnes, MBE, Professor of Engineering Science at the University of Glasgow. From his speech stems my inspiration for this post, for Professor Colin McInnes was not present to talk of medicine.
Professor McInnes was there to talk about space.
There came a moment in our brief history when mankind ceased to worship celestial bodies like the pharaohs of old and began to look to the stars with greater promise. Jules Verne aimed for the moon, Katherine Johnson calculated how to land there, and a young boy named Anakin dreamt of visiting all the stars; he would later play a pivotal role in eradicating the Jedi but that was a long time ago in a galaxy far, far away. One fateful day, these efforts culminated into a giant leap for mankind.
Since then, all those stars have seemed a little closer.
This brings me to the topic addressed by Professor Colin McInnes; how to voyage this distance with greater effectiveness and efficiency.
Imagine if a member of an alien race landed on earth tomorrow…
Let’s call this alien 'Buzz'. Buzz successfully makes peaceful contact with the natives (us).
While describing his vastly superior technology, Buzz asks us how we can navigate through space without any of the technological advances that have allowed him to traverse the journey.
We would explain and Buzz would summarise that, essentially, we sit in a cockpit attached to a colossal tank filled with combustible material and let the explosion blow us into orbit.
Though not to worry, we have since developed a nuclear alternative.
‘Like a nuclear reactor to power your spacecraft?’ Asks a curious Buzz.
‘Oh no, nothing like that,' we reply. 'We use nuclear explosions instead.’
After an awkward silence, Buzz attempts to leave before we can show him the developments of Project Orion.
Yet, these nuclear alternatives are currently the most promising methods for escaping the gravity of Earth. However, once in space there is very little resistance acting on a ship and Newton’s laws of motion may be enjoyed to great benefit,possibly saving face with our galactic neighbours.
The Science
We are concerned with Newton’s first and third laws of motion. Namely;
1) A body in motion stays in motion, unless acted upon by another force, and;
3) When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction of the first body.
To learn more about this, Crash Course has an excellent video. Which we've embedded. Enjoy!
Enter Konstatin Tsiolkovsky, who suggested, in 1925, that we could use ‘tremendous mirrors of very thin sheets to utilize the pressure of sunlight to attain cosmic velocities’. In other words, if we got our hands on a very thin, very big, mirror-sheet, the light might be able to push it enough to be useful.
Here, we need to understand a little about polyimide, particularly aluminized Kapton polyimide. Kapton polyimide is a material capable of withstanding temperatures between -269 and +400 °C, with good chemical resistance, and incredible flexural and tensile strengths, weighing 12 grams a metre squared with a depth of 2 micrometres. Almunizing it provides a reflective layer - in other words, it's strong, heat-resistant, thin, light, and shiny! Almost, one might say, like a very thin, very big, mirror-sheet.
Secondly, we must also regard our sun, insofar that it is an enormous nuclear fusion reactor constantly emitting photons, particles that carry light.
I present the solar sail.
A sail 800 metres or 2 kilometres square made from Kapton polyimide acts as the second body described in Newton’s third law to which photons emitted from the sun act as the first, thrusting the sail through the momentum they were theorised to have by Maxwell. The sheet stays in motion as it is not acted on by another force whilst in space.
Basically, what we have here is a huge mirror in space. Light particles from the sun push it. It's only a little push, but it's continuous, and that's enough to create a continual increase in acceleration, pushing the big shiny sheet faster and faster.
Now who looks silly, Buzz?
How We Use Solar Sails
The elegant nature of solar sails can be observed in their many functions. Here comes the maths!
It is theorised that a solar sail that starts 0.05 AU, 7.4 million kilometres, from the sun would begin with a starting acceleration of 36.4 metres a second and could reach up to 950 kilometres a second, 0.00234% of the speed of light. In other words, the continual acceleration will make the solar sail go very, very fast,
In short, this could reach the Oort cloud, a shell of icy objects on the edge of the solar system, in less than 30 years.
 |
| From Universe Today. |
We could set up a solar sail as a satellite around another planet or even the sun itself, allowing for more consistent observations to be made. The solar sail would remain static as the sails momentum counterbalances gravitational attraction; in other words, the solar sail would stay in the same place and let us take pictures of the same bit of a planet over time.
The theory of a solar sail may also be used to make navigational corrections to spacecraft trajectory, this has been used to make corrections to the MESSENGER probe orbiting Mercury, whilst a concentrated manufactured source of light beams has also been theorised to obtain speeds closer to the speed of light.
Lastly, solar sails could be used to voyage between planets. Travelling outward from the sun a solar sail could reach Jupiter in two years and Neptune in 8.5. Whilst travelling inward a solar sail could reach Mars in 400 days with a payload of 2 tons with a sail 80 metres square. It could reach Mars in 3 days carrying 100 kilograms. Traversing these distances in such short amount of time is only possible by taking full advantage of the solar sail being in a constant state of acceleration, much like traditional aircraft are required on Earth to counter the planets intense gravity.
These solar sails can't carry a huge payload, but could, for example, carry medicine to an astronaut in a much shorter timespan than we could otherwise manage. Receiving medicine in 3 days as opposed to six to eight months is, quite literally, a matter of life and death to an astronaut on Mars.
How does the solar sail stop? Aerobraking. The solar sail enters the atmosphere of the destination planet to gain drag and slow to a speed where it is possible to retrieve the payload.
This technology may represent a small step in space travel, but it is undoubtedly a leap for mankind’s dreams of sailing the stars.
Where next?
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