Solar energy, long considered the main competitor among renewable energy sources, has advanced considerably in recent decades. The cost of manufacturing and installing solar panels has dropped dramatically and efficiency has increased, making them price competitive with coal, oil and fossil fuels. However, certain obstacles, such as distribution and storage, still prevent more aggressive adoption of solar energy. Plus, there’s the ever-present problem of intermittency, where berries can’t collect energy in bad weather and during evenings.
These problems led to the Space Solar Power Concept (SBSP), where satellites fitted with solar panels could collect solar power 24 hours a day, seven days a week, 365 days a year. To test this method, researchers from the California Institute of Technology (Caltech) recently launched a technology demonstrator into space. This is the Space Solar Power Demonstrator (SSPD), which will test several key components of the SBSP and assess the method’s ability to harvest clean energy and send it back to Earth.
The SSPD launched at 9:55 a.m. EST on Tuesday, Jan. 3, atop a SpaceX Falcon 9 rocket from Space Launch Complex 40 (SLC 40) in Cape Canaveral, Florida. The mission (Transporter 6) was a dedicated rideshare that carried dozens of small satellites into space and dropped them into sun-synchronous orbit (SSO). The 50-kilogram (110-pound) satellite was carried aboard a Vigoride spacecraft (provided by commercial space company Momentus) and consisted of three main experiments, each tasked with testing a different key technology.
The Space Solar Power Project (SSPP) began in 2011 when Donald Bren – philanthropist, president of the Irvine Company and life member of the Caltech board of directors – and Jean-Lou Chameau, then president of Caltech, came together to discuss the potential of a solar energy research space project. In 2013, Bren and his wife (Caltech Administrator Brigitte Bren) began funding the project through the Donald Bren Foundation, which would eventually exceed $100 million. As Bren said in a recent press release from Caltech:
“For many years I dreamed of how space solar power could solve some of humanity’s most pressing challenges. Today, I’m thrilled to support the brilliant scientists at Caltech in their race to make that dream a reality.
While the technology behind solar cells has been around since the late 19th century, generating solar power in space presents serious challenges. For one thing, solar panels are heavy and require extensive wiring to transmit power, making them expensive and difficult to launch. To overcome these challenges, the SSPP team had to create a satellite that was light enough for cost-effective launches, but strong enough to withstand the extreme environment of space. This required considering and developing new technologies, architectures, materials and structures.
On several occasions, the team enlisted the help of engineers from NASA’s Jet Propulsion Laboratory (which Caltech maintains for NASA) and other commercial space entities based in Southern California. The result was three prototype testbeds within the SSPD, which were designed and built by a team of 35 Caltech graduate students, post-docs and researchers. The Caltech team will begin testing in the coming weeks and hope to complete a full performance evaluation of the SSPD in the coming months.
The ultimate goal is to test and mature technologies that will eventually be used to create a kilometer-scale constellation of satellites that is essentially a powerhouse in space. The three core experiments include the Deployable-to-Orbit Ultralight Composite Experiment (DOLCE), ALBA, and the Low-Earth Orbit Power Transfer Microwave Array (MAPLE) Experiment. According to Caltech, these experiments will perform the following tasks:
- DOLC: A structure measuring approximately 3.5 square meters (6 x 6 feet) that demonstrates the architecture, packaging scheme and deployment mechanisms of the modular spacecraft.
- ALBA: A collection of 32 different types of photovoltaic (PV) cells to allow an evaluation of the most space efficient cell types;
- MAPLE: A range of flexible, lightweight microwave power transmitters with precise timing control that selectively focus power to two different receivers to demonstrate wireless power transmission from space.
The fourth component is a set of electronics that interfaces with the Vigoride computer and controls the three main experiments. Some elements will be tested in the next few weeks, while others will take months to be fully evaluated. The ALBA photovoltaic will require up to six months of testing before the team can determine which types of PV technology will be best suited for this application. The MAPLE experiment includes a series of tests that will evaluate system performance in different environments over time.
The DOLCE experiment has two cameras mounted on deployable poles (with additional cameras on the electronics box) that will monitor the experiment and send video back to the Caltech team on Earth. Sergio Pellegrino, Caltech’s Joyce and Kent Kresa Professor of Aerospace and Civil Engineering, is co-director of SSPP and principal investigator at JPL. As he explained:
“DOLCE introduces a new architecture for solar-powered spacecraft and phased antenna arrays. It leverages the latest generation of ultra-thin composite materials to achieve unprecedented packaging efficiency and flexibility. With the new advancements we have already started work, we anticipate applications to a variety of future space missions. We plan to order the deployment of DOLCE within days of gaining access to the Momentus SSPD. We should know right away if DOLCE is working.
The MAPLE network, meanwhile, will test the potential for power transmission via microwave networks to receiving stations on Earth. As Ali Hajimiri, Bren Professor of Electrical and Medical Engineering at Caltech (and co-director of SSPP) explained:
“The entire MAPLE flexible network, along with its wireless power transfer electronic chips and transmission elements, was designed from the ground up. It wasn’t made from items you could buy because they didn’t even exist. This fundamental system redesign from the ground up is critical to realizing scalable solutions for TPMS.
With the successful launch in their rear view mirror, the Caltech team and project managers are considering several challenges moving forward. Very little is known about the SBSP and its ability to transmit energy efficiently to Earth. But that’s the point of the experiment, and the success and failure of the benchmarks will be measured in various ways. For DOLCE, the most important test will be deployment and ensuring that the structure fully deploys from its collapsed configuration to its open configuration.
For the ALBA, a successful test will provide a clear indication of the photovoltaic cells offering maximum efficiency and performance in the extreme environment of space. For MAPLE, success will mean the demonstrable ability to transmit power to specific landside locations on demand. Regardless of the outcome, Hajimiri said, the fact that Caltech teams created a prototype capable of being sent into space represents a significant achievement:
“Whatever happens, this prototype is a major breakthrough. It works here on Earth and has passed the rigorous stages required for anything launched into space. There are still many risks, but going through the whole process has taught us valuable lessons. We believe the space experiments will provide us with a lot of additional useful information that will guide the project as we continue to move forward.
This article was originally published on Universe today through MATT WILLIAMS. Read the original article here.