24/7 Space News
Small solar sails could be the next 'giant leap' for interplanetary space exploration
Schematic of components for the proposed femtoscale solar sail. The pressure of solar radiation against the sail will provide propulsion for the spacecraft, while cell phone-based and MEMS technologies will enable navigation, communication and image capture. (Image courtesy of Alexander Alvara)
Small solar sails could be the next 'giant leap' for interplanetary space exploration
by Marni Ellery for Berkeley News
Berkeley CA (SPX) Jan 23, 2024

Nearly 70 years after the launch of the first satellite, we still have more questions than answers about space. But a team of Berkeley researchers is on a mission to change this with a proposal to build a fleet of low-cost, autonomous spacecraft, each weighing only 10 grams and propelled by nothing more than the pressure of solar radiation. These miniaturized solar sails could potentially visit thousands of near-Earth asteroids and comets, capturing high-resolution images and collecting samples.

Led by Kristofer Pister, professor of electrical engineering and computer sciences, the researchers seek to leverage advancements in micro-scale technology to make interplanetary space exploration more cost-effective and accessible - and to accelerate new discoveries about our inner solar system. They describe their work, the Berkeley Low-cost Interplanetary Solar Sail (BLISS) project, in a study published in the journal Acta Astronautica.

The BLISS project brings together researchers from the Department of Electrical Engineering and Computer Sciences and the Department of Mechanical Engineering, as well as the Berkeley Sensor and Actuator Center and the Space Sciences Laboratory. Their work builds on other small spacecraft projects, including CubeSats, ChipSats and the Breakthrough Starshot Initiative, while seeking to improve solar sail maneuverability and further reduce fabrication costs by using low-mass consumer electronics.

In addition to Pister, the team includes lead author and mechanical engineering doctoral student Alexander Alvara and co-authors Lydia Lee, Emmanuel Sin, Nathan Lambert and Andrew Westphal.

In a recent conversation, Pister and Alvara shared their group's vision for this project with Berkeley Engineering.

Your latest paper focuses on fleets of small solar sails. What advantages do solar sails have over other types of spacecraft?

Alexander: Solar sails use a non-consumable propulsion force. They are propelled by sunlight, similar to how a sailboat is propelled by wind. So, unlike other spacecraft, solar sails can travel around the galaxy, or, more specifically, our solar system, without having to carry any fuel or worry about refueling.

Kris: The magic is that light, even though it doesn't have mass, has momentum. When light bounces off a mirror, you get a force due to that change in momentum. And on a square meter sail, that force is tiny. It's about the weight of a grain of sand, but you get it for free. And you get it for as long as you want, as long as you're sitting in space with the sunlight striking you.

Could you tell us about the Berkeley Low-cost Interplanetary Solar Sail, or BLISS, project? What was the genesis of this project and what are its goals?

Kris: It started several years ago, when friends of mine were exchanging emails about an object, called Oumuamua, that was moving through our solar system. Some people were saying that maybe it's an alien solar sail, and then [physicist] Dick Garwin sent around a paper that he had written in 1959 about solar sails. It said that you can use this light pressure to move out, away from the sun, which makes sense - the light pushes in that direction. But you can also use it to move in. It's kind of like tacking against the wind in sailing. Light is much more like wind, and you can tack using solar radiation pressure.

So this lightbulb went off in my brain. All the work we do in my group is focused on miniaturizing things, and I thought we could miniaturize a solar sail spacecraft. Seeing that you can tack against light pressure made me realize that we could make spacecraft [weighing] 10 grams with almost all off-the-shelf technology. And our latest study provides evidence that this is feasible.

Our initial goal for the BLISS project was simple: capture images of all the near-Earth asteroids, starting with the biggest ones. Roughly a thousand near-Earth asteroids are bigger than a kilometer in diameter. And we have pictures, usually fuzzy pictures, of maybe 10 of them. We were excited by the idea that you could potentially take an iPhone camera, orbit around one of these things, take a thousand high-resolution color photographs from a very close distance and then beam that information down.

Speaking of miniaturizing things, why make the solar sails small in the first place?

Alexander: A smaller size allows the spacecraft to be more agile. We don't have to worry about buckling of the sail, which is just one square meter. This is a huge issue with larger solar sails. Imagine taking a solar sail that is 50 square meters into space, then having unfolding components spreading out like origami. It's still relatively small compared to other spacecraft, but the unfolding components add weight. And, as Kris mentioned, you're getting the force of a grain of sand continuously on your sail, the light pressure, so you want to have a solar sail close to that mass. You don't want something that's huge, or it will take forever to move, and it's going to be less easy to maneuver.

Kris: Cost is another advantage to going small. We're proposing to start at about 10 grams for an interplanetary spacecraft. If we do everything right, the cost of the solar sails will be a thousand dollars or less. We could then put thousands of these tiny spacecraft in a little package, the size of a small satellite, and launch them into space.

Alexander: So, for the cost of a single launch, we could send out thousands of these solar sails and accomplish multiple missions.

These spacecraft will need to be highly functional yet also light. How will they not be weighed down by all of their components?

Kris: We're leveraging all the technology, all the miniaturization and low power consumption that goes into the design of cell phones. But there are also many other instruments that MEMS [microelectromechanical systems] has managed to miniaturize.

Schematic of components for the proposed femtoscale solar sail. The pressure of solar radiation against the sail will provide propulsion for the spacecraft, while cell phone-based and MEMS technologies will enable navigation, communication and image capture. (Image courtesy of Alexander Alvara)

The BLISS spacecraft uses a MEMS device called an inchworm motor. What is an inchworm motor and why is it important?

Alexander: You can think of an inchworm motor as something that takes electricity and turns into a moveable force. Almost like a piston. We use the inchworm motor to grab onto things, in this case, things that are much larger than itself, and move it back and forth.

Kris: Our little spacecraft has roughly a 1/2 meter diameter, super-lightweight mirror - maybe the size of a card table - that is connected to the body of the spacecraft by a few carbon fiber filaments. The inchworms inch their way along those filaments, pulling on the filaments and moving the sail relative to the center of mass of the spacecraft. It turns out that's what you need to navigate - just like on a sailboat. You pull on the lines and change the attitude of the sail through the wind, and that affects direction.

How will these spacecraft navigate the inner solar system?

Alexander: The majority of the analysis is done using something called the Lost in Space [Identification] Algorithm. The idea is that you map the stars that you can see, then compare them to the pixels of the images that you can get from your on-board cell phone camera. So we can basically use smartphones to help navigate.

There are many hazards in space, including ionizing radiation and large floating particles. How do you design the tiny solar sails to withstand these potential dangers?

Alexander: A lot of work has already been done analyzing off-the-shelf parts that have endured space-like radiation. To mitigate such hazards, we can either build in redundancy and add multiple components that have the greatest likelihood of failure, or pair these BLISS spacecraft in what we call partner constellations, which basically adds redundancy for us.

Could you tell us about the concept missions that you've proposed for BLISS spacecraft? How long would it take to complete these missions?

Alexander: Kris had mentioned earlier sending the solar sails to explore near-Earth asteroids. One of the other main concept missions is cometary sample retrieval, so getting microdust from comet plumes. To date, there's been only one real successful return of cometary material, and that was the Stardust mission in the early 2000s. It did a flyby of a comet called Wild 2 and collected material and brought it back to Earth. But unfortunately, the spacecraft was less maneuverable than they expected, and it caught the comet dust particles at high velocity, vaporizing any organic-rich components in the sample. Though the sample they retrieved was still vastly important, we currently have only about 300 micrograms of comet material on Earth. And by designing our tiny solar sails to be agile and highly maneuverable, we hope to capture cometary samples at low relative speeds to avoid damaging any organics.

Kris: As for the mission durations, they vary a lot. It will take us some number of months to get out of Earth's orbit, it will take us months or years to get to the asteroid or comet that we're interested in, and then the reverse of that coming back in. So, certainly months at the short end, and maybe a decade or so at the long end.

How far off are we from the first launch?

Alexander: We could feasibly do it in a few years. For example, CubeSat projects usually come out of high schools or community college or four-year institutions, from undergrads. And those go from zero to launch in about two years. So with grad students, post-docs or research scientists on the job, who've been doing this sort of thing for many years, we should be able to launch within that same timeline once we complete development.

Kris: So far, Alexander's worked on some of the theories and some of the motors. But there are six other systems and all kinds of software still needed, so it would be an undertaking. But I'm hopeful that we can obtain funding for further research.

Related Links
Space Sciences Laboratory
Berkeley Sensor and Actuator Center
The latest information about the Commercial Satellite Industry

Subscribe Free To Our Daily Newsletters

The following news reports may link to other Space Media Network websites.
NASA Tests Solar Sail for CubeSat that Will Study Near-Earth Asteroids
Huntsville AL (SPX) Jul 03, 2018
NASA's Near-Earth Asteroid Scout, a small satellite designed to study asteroids close to Earth, performed a successful deployment test June 28 of the solar sail that will launch on Exploration Mission-1 (EM-1). The test was performed in an indoor clean room at the NeXolve facility in Huntsville, Alabama. NEA Scout is a six-unit CubeSat that relies on an innovative solar sail for propulsion. It is one of 13 secondary science payloads NASA selected to fly on EM-1. The first in a series of increasing ... read more

Sierra Space unveils full-scale prototype of expandable space station structure

Salad in space? New study says it's not a healthy choice

Ax-3 Crew Joins Expedition 70 in Space Station for Dual Operations and Research

ISS set to receive enhanced HPE Supercomputer

CAS Space achieves new milestone with Kinetica 1 Y3 launch deploying 5 satellites

Spain's PLD Space Selected for European Institutional Space Launch Contracts

Equatorial Launch Australia unveils advanced horizontal integration facility

China's LandSpace achieves new feat with Zhuque-3's Vertical Recovery Test

NASA helicopter's mission ends after three years on Mars

New Year, New images from Perseverance on Mars

Polka Dots and Sunbeams: Sol 4078

Buried water ice at the Martian equator

Shenzhou 18 and 19 crews undertake intensive training for next missions

Tianzhou 6 burns up safely reentering Earth

Yan Hongsen's future dreams as 'Rocket Boy'

China's Tianzhou 7 docks with Tiangong Space Station

Into the Starfield

Booz Allen Ventures Invests in Albedo's groundbreaking VLEO satellite technology

Sidus ships LizzieSat to Vandenberg for upcoming SpaceX launch

Small solar sails could be the next 'giant leap' for interplanetary space exploration

Novel color holographic 3D display offers enhanced viewing angle

Redwire joins forces with Blue Origin on Blue Ring Space Mobility Platform

Scientists trap krypton atoms to form one-dimensional gas

GMV and Astroscale UK spearhead new ESA initiative for improved satellite collision avoidance

New Insights into Earth's Earliest Life Forms Discovered in Palaeoarchaean Rock Samples

Revolutionizing Chemistry: Over 4 Billion Early-Life Reactions Simulated via Blockchain

NASA's Hubble Finds Water Vapor in Small Exoplanet's Atmosphere

Shallow soda lakes show promise as cradles of life on Earth

New images reveal what Neptune and Uranus really look like

Researchers reveal true colors of Neptune, Uranus

The PI's Perspective: The Long Game

Webb rings in the holidays with the ringed planet Uranus

Subscribe Free To Our Daily Newsletters


The content herein, unless otherwise known to be public domain, are Copyright 1995-2023 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.