Soaring through space on solar sails
S. Himmelstein | May 25, 2020The history of solar sailing. Source: The Planetary Society
Space exploration missions have been limited by the performance margins of state of-the-art chemical rocket engines and by the amount of fuel a spacecraft must carry, which can add up to 25% of the launch weight of typical planetary-exploration spacecraft. Researchers at NASA and the European Space Agency are developing a key in-space propulsion technology that could replace conventional chemical fuels with an inexhaustible natural resource: Energy from the sun.
Solar sail propulsion is envisioned as a way to give spacecraft more mobility and versatility during flight, and to open new regions of the solar system for exploration. The technology uses solar photons, which are reflected off giant, mirror-like sails made of lightweight, reflective material 40 to 100 times thinner than a piece of writing paper. Continuous photonic pressure provides enough thrust to perform maneuvers, such as hovering at a fixed point in space and rotating the space vehicle’s plane of orbit, which would require too much propellant for conventional rocket systems. The sun supplies the necessary propulsive energy, eliminating the need for onboard propellant and reducing payload mass.
In 2019, The Planetary Society launched LightSail 2 with an aluminized Mylar sail. The vessel is the first spacecraft to use solar sailing for propulsion in Earth orbit, the first small spacecraft to demonstrate solar sailing and the second solar sail spacecraft to successfully fly, following Japan's IKAROS, which launched with The ACS3 solar sail system fits within a 12U CubeSat at launch. Source: NASAa polyimide-based sail in 2010.
NASA engineers are currently planning a mission to advance the next generation of solar sail technology for small interplanetary spacecraft. As part of this development effort, the Advanced Composite Solar Sail System (ACS3) will demonstrate deployment of a 74 m2 composite boom (mast) solar sail system in low-Earth orbit, marking the first use of composite booms and sail packing and deployment systems for a solar sail in orbit. An innovative tape-spool boom extraction system has been designed to minimize blossoming, or jamming, of the coiled booms during deployment. The mission will serve as a technology pathfinder for a future 500 m2 composites-based small spacecraft solar sail system suitable for low cost heliophysics research and small body planetary science.
The ACS3 solar sail system is sized to fit within a 12-unit (12U) CubeSat. The solar sail consists of four, 20 m2 triangular aluminum-coated plastic membrane sails supported by four 6.5 m thin-ply collapsible composite booms. The thin-ply composite booms, which are 75% lighter and experience 100 times less in-space thermal distortion than the current state-of-the-art metal booms, are flattened and rolled onto spools for compact stowage within the spacecraft. NASA Ames Research Center has tapped NanoAvionics to design and build the 12U nanosatellite bus.
Experiments with a 3 mm wide piece of graphene convinced ESA researchers that a solar sail composed of the one atom-thick material would be effective. A series of 1 W lasers was directed at the graphene sample as it was dropped from a 100 m tall tower, which served to accelerate it by as much as 1 m/s². Under operating conditions in space, the graphene sails are expected to continue accelerating under solar exposure and increase the speed of its host craft. The researchers envision scaling up the material to assemble kilometer-wide sails.
In addition to benefitting space exploration missions, solar sail technology might be used in an advanced space-weather warning system to more quickly and accurately alert satellite operators and utilities on Earth of geomagnetic storms caused by coronal mass ejections from the sun. NASA researchers theorize that the technology also could help remove some of the thousands of pieces of orbital debris ringing the planet, conduct space station-keeping tasks or hover at high latitudes for communications and observation.
"...state of-the-art chemical rocket engines and by the amount of fuel a spacecraft must carry, which can add up to 25% of the launch weight of typical planetary-exploratio n spacecraft. ..."
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25% ?!? Ha!
Would that it were! Propellant alone without the mass of the engines is typically not too far off 85% of launch mass even for just low Earth orbit.
Surely the 25% figure is a typo, right?
Re 25% weight savings
As I read the article I understood perhaps incorrectly the 25% weight figure was related to amount of fuel and engines required for maneuverability of craft after deployment and not the weight associated with lift off. % figures depend on what your base value is. Saving 25% on weight after deployment could result in more or better instrumentation on board.
Gshaiffer
In reply to #2
"... Space exploration missions have been limited by the performance margins of state of-the-art chemical rocket engines and by the amount of fuel a spacecraft must carry, which can add up to 25% of the launch weight of typical planetary-exploratio n spacecraft. ...."
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To me, 'launch weight' rather unambiguously describes weight at lift off.
Perhaps I am reading that completely wrong somehow. If anyone can confirm I am in error, especially with some reference I would be appreciative.
In reply to #3
add up to 25% of the launch weight of typical planetary-exploratio n spacecraft. ...."
Not trying to be a smart alec,and my english scores were not that great but the above phrase is what I am seeing. the terms 25% of the launch weight of typical planetary space craft does not seem to me to be describing the launch weight of the entire vehicle stack but only the launch weight of the craft going to orbit.If the basic craft weighed 2000 lbs 500 lbs of that would be engine and orbiting propellant mass, this says nothing about the weight of the total launch assembly as I read this.
GShaiffer
In reply to #4
That would certainly make more sense. It may be a bit convoluted, and certainly leas than clear from my vantage, but given that what I read is so far off base realistically, you probably are on point with what was intended.