Smallsats + solar sails = Photos of exoplanets at 1970s digital camera resolution
(2023/04/19)
- Reference: 1681889834
- News link: https://www.theregister.co.uk/2023/04/19/smallsats_solar_sails_sundiver/
- Source link:
It's time to stop hemming and hawing about the monetary and temporal costs of exploring the outer solar system and beyond, say an international group of boffins. We've all the materials we need to do it faster and cheaper by combining modern smallsats with solar sails, and the end result could be actual photographs of exoplanets.
[1]Authored by a group led by NASA Jet Propulsion Laboratory physicist Slava Turyshev, the team of 27 researchers say that current solar sail technology, combined with the increasingly popular smallsat form factor (classified by NASA as being [2]under 180 kg ) would be enough to build a craft able to reach speeds of up to 33 kilometers per second, or around seven astronomical units (the rough distance between the Sun and Earth, around 150m kilometers) per year.
At that speed, a solar-sailing smallsat could reach Jupiter in a year, and Saturn's moons in less than three. Seven AU/yr is fast - around [3]double the speed of the Voyager probes.
[4]
"Velocities larger than seven AU/yr will require novel sail materials and technologies," the team wrote, but that doesn't mean we'll be waiting forever to get considerably faster. "With [5]sail materials already being developed, smallsat velocities up to 20-25 AU/yr will be achievable in 5-7 years," the researchers added.
[6]
[7]
All of this, mind you, is without any propellant, greatly reducing weight and volume of potential spacecraft. Solar sails are highly reflective, and accelerate by reflecting photonic energy from the Sun. It's a small force but it adds up over time, although the further you are from the Sun the more acceleration drops off.
Solar sailing spacecraft may seem like science fiction, but a pair of experiments over the past few years have proved their efficacy. [8]LightSail 2 , a cubesat deployed in 2019, used a 32 square meter sail to increase its speed and gain altitude over the course of a [9]couple of years in orbit, while the Japan Space Agency's IKAROS used a 14x14 meter sail to power its flight past Venus in 2010.
[10]
With those projects as reference, the researcher say they've developed potential craft that could be built for between $30-$75 million (£24-£60m), as opposed to the $2-$5 billion (£1.6-£4b) cost "of a typical flagship-type deep space mission."
[11]I've seen things you people wouldn't believe. Spacecraft with graphene sails powered by starlight and lasers
[12]LightSail 2 successfully unfurls its silvery solar sails, prepares to become a truly solar-powered satellite
[13]US Air Force reveals what's inside its top-secret space plane, this time
[14]The years fly by on first exoplanet confirmed by James Webb Space Telescope
Because the craft themselves are quite small - NASA describes smallsats as being, at their largest, around the size of a refrigerator - they can piggyback on crafts like SpaceX's Falcon Heavy, as was the case with LightSail 2, further reducing costs.
In order to achieve their record-breaking speeds, solar-sailing smallsats would need to get as close to the sun as their materials allow in order to get on a high-energy hyperbolic trajectory that would allow them to capture as much energy as possible.
All in the name of exoplanet photography
The team behind the paper proposes a new class of solar sail craft it calls "Sundiver" that's designed with the ultimate goal of fulfilling NASA's [15]desire for a spacecraft that can reach a location in the deep recesses of the solar system known as the solar gravitational lens (SGL) focal region. Doing this in less than 25 years, would require speeds greater than 20 AU/year.
[16]
The SGL focal region begins at a whopping 547 AUs from the Sun (dwarf planet Pluto, for comparison, is around 30-49 AUs from Sol), and is the point in space where Albert Einstein once predicted an observer could use our star's gravitational field to magnify distant objects.
Exoplanets, which we've been able to [17]confirm the existence of but not directly observe, could theoretically be photographed in relative detail, as the SGL offers intense brightness amplification and angular resolution.
Even in the presence of the solar corona, NASA said that six months of integration time at the strong interference region of the SGL (beyond 547.6 AUs) would allow researchers to "reconstruct the exoplanet image with ~25 km-scale surface resolution, enough to see surface features and signs of habitability."
By contrast, a traditional optical instrument would need an aperture some 90.5 kilometers wide "to capture even a single-pixel image of an Earth-like exoplanet," according to the boffins.
Another frequently used space photography tool, the interferometer (which merges multiple light sources to create a single image), would also be unsuitable for the task: thousands of 30m telescopes would require around 10 5 years to get a signal-to-noise ratio greater than 1 when trying to snap an image of a planet orbiting another star, they predict.
The proposed solar sail smallsat craft sitting at the SGL focal point, however, "can yield a 250 x 250-pixel image … in just 12 months," the researchers said.
[18]
Concept art of the potential resolution of an exoplanet photographed at the SGL focal point - Click to enlarge. Credits: Slava Turyshev.
"Missions could also target the outer solar system quickly, including flights to potentially life-supporting bodies, such as Enceladus, and beyond, to the neglected ice giants, Uranus and Neptune," the team said.
"None of these very small and special purpose missions would replace the desire and planning for the larger, more expensive flagship class missions for solar system science. But they would provide us with initial reconnaissance data while we wait for the orbiters and landers."
Of course, that's for local science - no one is going to land a craft on an exoplanet in our lifetimes. Photographing one, on the other hand, might actually be possible. ®
Get our [19]Tech Resources
[1] https://dx.doi.org/10.48550/arxiv.2303.14917
[2] https://www.nasa.gov/content/what-are-smallsats-and-cubesats
[3] https://voyager.jpl.nasa.gov/frequently-asked-questions/fast-facts/
[4] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2ZD@7xaFeXhCobLZubbtp0QAAAI8&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0
[5] https://www.theregister.com/2020/05/09/lightsails_graphene/
[6] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44ZD@7xaFeXhCobLZubbtp0QAAAI8&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[7] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33ZD@7xaFeXhCobLZubbtp0QAAAI8&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[8] https://www.theregister.com/2019/07/24/lightsail_2_unfurls_sails/
[9] https://www.planetary.org/sci-tech/lightsail
[10] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44ZD@7xaFeXhCobLZubbtp0QAAAI8&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[11] https://www.theregister.com/2020/05/09/lightsails_graphene/
[12] https://www.theregister.com/2019/07/24/lightsail_2_unfurls_sails/
[13] https://www.theregister.com/2015/05/19/us_air_force_x37b_space_plane/
[14] https://www.theregister.com/2023/01/12/jwst_confirms_its_first_exoplanet/
[15] https://www.nasa.gov/directorates/spacetech/niac/2020_Phase_I_Phase_II/Direct_Multipixel_Imaging_and_Spectroscopy_of_an_Exoplanet/
[16] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33ZD@7xaFeXhCobLZubbtp0QAAAI8&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[17] https://www.theregister.com/2023/01/12/jwst_confirms_its_first_exoplanet/
[18] https://regmedia.co.uk/2023/04/18/sgl-exoplanet-concept.jpg
[19] https://whitepapers.theregister.com/
[1]Authored by a group led by NASA Jet Propulsion Laboratory physicist Slava Turyshev, the team of 27 researchers say that current solar sail technology, combined with the increasingly popular smallsat form factor (classified by NASA as being [2]under 180 kg ) would be enough to build a craft able to reach speeds of up to 33 kilometers per second, or around seven astronomical units (the rough distance between the Sun and Earth, around 150m kilometers) per year.
At that speed, a solar-sailing smallsat could reach Jupiter in a year, and Saturn's moons in less than three. Seven AU/yr is fast - around [3]double the speed of the Voyager probes.
[4]
"Velocities larger than seven AU/yr will require novel sail materials and technologies," the team wrote, but that doesn't mean we'll be waiting forever to get considerably faster. "With [5]sail materials already being developed, smallsat velocities up to 20-25 AU/yr will be achievable in 5-7 years," the researchers added.
[6]
[7]
All of this, mind you, is without any propellant, greatly reducing weight and volume of potential spacecraft. Solar sails are highly reflective, and accelerate by reflecting photonic energy from the Sun. It's a small force but it adds up over time, although the further you are from the Sun the more acceleration drops off.
Solar sailing spacecraft may seem like science fiction, but a pair of experiments over the past few years have proved their efficacy. [8]LightSail 2 , a cubesat deployed in 2019, used a 32 square meter sail to increase its speed and gain altitude over the course of a [9]couple of years in orbit, while the Japan Space Agency's IKAROS used a 14x14 meter sail to power its flight past Venus in 2010.
[10]
With those projects as reference, the researcher say they've developed potential craft that could be built for between $30-$75 million (£24-£60m), as opposed to the $2-$5 billion (£1.6-£4b) cost "of a typical flagship-type deep space mission."
[11]I've seen things you people wouldn't believe. Spacecraft with graphene sails powered by starlight and lasers
[12]LightSail 2 successfully unfurls its silvery solar sails, prepares to become a truly solar-powered satellite
[13]US Air Force reveals what's inside its top-secret space plane, this time
[14]The years fly by on first exoplanet confirmed by James Webb Space Telescope
Because the craft themselves are quite small - NASA describes smallsats as being, at their largest, around the size of a refrigerator - they can piggyback on crafts like SpaceX's Falcon Heavy, as was the case with LightSail 2, further reducing costs.
In order to achieve their record-breaking speeds, solar-sailing smallsats would need to get as close to the sun as their materials allow in order to get on a high-energy hyperbolic trajectory that would allow them to capture as much energy as possible.
All in the name of exoplanet photography
The team behind the paper proposes a new class of solar sail craft it calls "Sundiver" that's designed with the ultimate goal of fulfilling NASA's [15]desire for a spacecraft that can reach a location in the deep recesses of the solar system known as the solar gravitational lens (SGL) focal region. Doing this in less than 25 years, would require speeds greater than 20 AU/year.
[16]
The SGL focal region begins at a whopping 547 AUs from the Sun (dwarf planet Pluto, for comparison, is around 30-49 AUs from Sol), and is the point in space where Albert Einstein once predicted an observer could use our star's gravitational field to magnify distant objects.
Exoplanets, which we've been able to [17]confirm the existence of but not directly observe, could theoretically be photographed in relative detail, as the SGL offers intense brightness amplification and angular resolution.
Even in the presence of the solar corona, NASA said that six months of integration time at the strong interference region of the SGL (beyond 547.6 AUs) would allow researchers to "reconstruct the exoplanet image with ~25 km-scale surface resolution, enough to see surface features and signs of habitability."
By contrast, a traditional optical instrument would need an aperture some 90.5 kilometers wide "to capture even a single-pixel image of an Earth-like exoplanet," according to the boffins.
Another frequently used space photography tool, the interferometer (which merges multiple light sources to create a single image), would also be unsuitable for the task: thousands of 30m telescopes would require around 10 5 years to get a signal-to-noise ratio greater than 1 when trying to snap an image of a planet orbiting another star, they predict.
The proposed solar sail smallsat craft sitting at the SGL focal point, however, "can yield a 250 x 250-pixel image … in just 12 months," the researchers said.
[18]
Concept art of the potential resolution of an exoplanet photographed at the SGL focal point - Click to enlarge. Credits: Slava Turyshev.
"Missions could also target the outer solar system quickly, including flights to potentially life-supporting bodies, such as Enceladus, and beyond, to the neglected ice giants, Uranus and Neptune," the team said.
"None of these very small and special purpose missions would replace the desire and planning for the larger, more expensive flagship class missions for solar system science. But they would provide us with initial reconnaissance data while we wait for the orbiters and landers."
Of course, that's for local science - no one is going to land a craft on an exoplanet in our lifetimes. Photographing one, on the other hand, might actually be possible. ®
Get our [19]Tech Resources
[1] https://dx.doi.org/10.48550/arxiv.2303.14917
[2] https://www.nasa.gov/content/what-are-smallsats-and-cubesats
[3] https://voyager.jpl.nasa.gov/frequently-asked-questions/fast-facts/
[4] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2ZD@7xaFeXhCobLZubbtp0QAAAI8&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0
[5] https://www.theregister.com/2020/05/09/lightsails_graphene/
[6] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44ZD@7xaFeXhCobLZubbtp0QAAAI8&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[7] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33ZD@7xaFeXhCobLZubbtp0QAAAI8&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[8] https://www.theregister.com/2019/07/24/lightsail_2_unfurls_sails/
[9] https://www.planetary.org/sci-tech/lightsail
[10] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44ZD@7xaFeXhCobLZubbtp0QAAAI8&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[11] https://www.theregister.com/2020/05/09/lightsails_graphene/
[12] https://www.theregister.com/2019/07/24/lightsail_2_unfurls_sails/
[13] https://www.theregister.com/2015/05/19/us_air_force_x37b_space_plane/
[14] https://www.theregister.com/2023/01/12/jwst_confirms_its_first_exoplanet/
[15] https://www.nasa.gov/directorates/spacetech/niac/2020_Phase_I_Phase_II/Direct_Multipixel_Imaging_and_Spectroscopy_of_an_Exoplanet/
[16] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33ZD@7xaFeXhCobLZubbtp0QAAAI8&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[17] https://www.theregister.com/2023/01/12/jwst_confirms_its_first_exoplanet/
[18] https://regmedia.co.uk/2023/04/18/sgl-exoplanet-concept.jpg
[19] https://whitepapers.theregister.com/
Re: Proper sailing spaceship????
KittenHuffer
"I wonder if it would also be possible to tack 'downwind' so to speak i.e. diagonally towards the sun." - Technically that would be upwind rather than downwind, as you would be heading towards the source of the wind.
Yes, I believe that it is possible. What you would be doing is to angle your sail such that you would be reducing your orbital velocity. This would then cause your orbit to shrink, and you'd find yourself closer to the sun. It is actually the case that from the Earth more delta-v (change of velocity) is required to get something to hit the Sun than for it to leave the Solar System.
I believe that the proposed sails would be set to work the other way. They would be increasing their orbital velocity, which would raise their orbits, and eventually lead to solar escape velocity.
Re: Proper sailing spaceship????
Peter Mount
You might want to look up the Light Sail 2 mission by the Planetary Society. It showed it was possible to perform orbital maneuvers using just the sail.
Re: Proper sailing spaceship????
Anonymous Coward
With the sail at an angle you will get an angular force. As it will begin in a solar orbit, to raise the orbit and move away from the sun at all, the sail will be angled to increase the speed. It's possible it could be launched into Earth orbit and use the sail to leave earth orbit and get into solar orbit, but I'd expect a chemical rocket would do that easier.
Space is BIG
en.es
Incredible that even the SGL point mentioned is only 1/460 of the way to the nearest star or alternative planet.... We need warp drives or TARDISes or something (icon because burning stuff will not get us there!)! :)
Re: Space is BIG
KittenHuffer
If we had either of those devices then why would we stop at reaching the SGL point just to take photos of exo-planets? Why not just visit the exo-planets instead?
BackInFiveMinutes
After a (very quick) rough calculation, it seems travelling at 33Km/s a craft could get tol Proxima Centauri in around 125 years. To me that seems doable considering Voyager has been going for, IIRC, 40 years.
Any real reason for not shooting one off to 2nd nearest star?
Can we crowdfund it?
Anonymous Coward
This seems such an obvious 'Duh' just-do-it project. At a cost of $20M, can we just crowdfund it? Or get Elon or Jeff or whoever to reach into their back pockets?
Proper sailing spaceship????
The traditional images I've seen of solar sails are basically like giant parachutes, and as I understand it, they can accelerate only in the direction of the solar wind, directly away from the sun. However it should be possible to use a mast and spars, just like in a sailing ship, to hold the sail at an angle and therefore be able to accelerate in a diagonal (away from the sun but not directly away, having a bit of sideways component). Given the lack of gravity and the minuscule forces involved, it should be able to work with extremely large 'masts' and 'spars' without reaching forces large enough to break them - the limit would be more how much you can fold / unfold them.
I wonder if it would also be possible to tack 'downwind' so to speak i.e. diagonally towards the sun. In real sailing this works because the full sail acts like a wing, using the Bernoulli principle of lower pressure where airflow velocity is higher. Since the solar 'wind' is essentially a stream of particles, however tiny they are, would the Bernoulli principle still work??