How Satellites Will 3D Print Their Own Antennas in Space

On-orbit tech to yield radio dishes larger than what can be launched from Earth

4 min read
A circular object lit in bluish purple UV light.

Via Mitsubishi Electric’s satellite-antenna printing process, a resin is cast into a parabolic dish shape and then hardened by the sun’s ultraviolet light.

Mitsubishi Electric

A crucial part of any satellite launched into orbit is its antenna. The challenge, however, is that its (typically) dish-shaped antenna is big, heavy, and difficult to fit comfortably into any reasonably-sized rocket fairing. So researchers at Mitsubishi Electric Research Laboratories (MERL) in Cambridge, Mass., wondered, What if satellites simply skip over the whole problem? That is, don’t bring an entire, oversize antenna assembly up into space with the satellite but instead 3D print it once the satellite reaches orbit.

MERL has in fact developed an on-orbit, antenna 3D-printing technology that uses photosensitive resin, hardened by solar ultraviolet light. The new technique, the researchers say, potentially allows the dish to achieve high gain and wide bandwidth (which requires a large antenna), while still keeping the satellite that’s launched from Earth lightweight and small.

Printing the antenna on orbit solves another big problem, too: Satellites launched from the ground undergo enormous vibrational pressure during takeoff. So every part of the satellite—including the antenna dish and mount—has to be overbuilt to withstand the intense stress. This adds to the antenna’s weight and cost, and therefore the cost of the launch.

Of course, if the antenna is manufactured in space, none of these difficulties ever need bother the engineers designing the satellite.

As a case study, MERL researchers considered NASA and the European Space Agency’s Cassini-Huygens spacecraft—whose exceptionally large antenna measured 4 meters across and weighed 105 kilograms. If Cassini-Huygens (launched in 1997) could have substituted its oversize dish with an antenna that could have been fabricated in space, the spacecraft would have saved 80 precious kilograms of launch weight, translating to a launch-cost savings of 80 percent on the antenna and antenna-mount weight.

“It’s about as viscous as honey, sticks like glue, and hardens like a rock in a few seconds in the sun.”
—William Yerazunis, Mitsubishi Electric Research Laboratories

“Yet even with smaller satellites, we estimate the reduced weight will [still] make a significant difference,” says William Yerazunis, senior principal researcher at MERL. “Right now, United Launch Alliance is charging US $73 million to put 15 metric tons into low earth orbit. If we can reduce the overall payload by even 5 percent, that would be a savings of $3.5 million with multiple launches.”

A key element of the cost-saving technology involves developing the right resin, the researchers note. “If you put standard resins in a vacuum chamber, they boil away and contaminate everything nearby,” says Avishai Weiss, principal research scientist at MERL.

Instead, the researchers developed a photosensitive resin that can be extruded and cured into a rigid solid in a vacuum—a world’s first, according to the company. As well as being heat-resistant to at least 400 °C, “it’s about as viscous as honey, sticks like glue, and hardens like a rock in a few seconds in the sun,” says Yerazunis. And, he says, it’s no more expensive to create than any of the already existing resins on the market.

“In general, on-orbit fabrication of antennas and other structures in space is a promising technology,” says Professor Saburo Matunaga, who researches in-space systems engineering and small satellite systems development at the Tokyo Institute of Technology. “Mitsubishi Electric‘s prototype 3D printing looks to be a good first step because the UV curable resin appears to have the characteristics of stable extrusion and rigidization in the environment of a vacuum, and it is heat resistant to a high degree.”

A four part conceptual illustration starting with a 100 x 300mm object in space and ending with the object with a large circular satellite antenna.Mitsubishi Electric’s planned satellite antenna can be manufactured in outer space using on-orbit 3D printing and the sun’s UV rays.Mitsubishi Electric

The MERL researchers say their new antenna fabrication process involves first creating the antenna structure and then coating it with the metallic layer that enables it to reflect. A motor turns the hub of the antenna-to-be, while the resin valve opens—allowing a trail of resin to spiral out from the hub, ultimately into the dish’s parabolic shape. The sun’s UV light, they say, hardens the resin within a few seconds upon extrusion.

The process continues, until a dish of concentric layers of hardened resin is completed. Finally, a layer of conductive metallization is applied through vacuum metallization via a second nozzle that boils aluminum and sends the vapor out in a stream that coats the entire dish—the same process that coats potato chip bags with a superthin layer of aluminum to keep the chips fresh.

On-orbit 3D Printing Technology for Fabrication of Satellite Antennaswww.youtube.com

In their (terrestrial) lab, the MERL team has already printed small parabolic dishes in a vacuum, while a 165 millimeter-diameter dish they printed in air yielded a working antenna with a gain of 23.5 decibels at 13.5 gigahertz in the Ku communication band.

They expect next to test the technology at full scale using a larger dish in a thermal vacuum chamber at a low-earth-orbit-level of vacuum—and then ultimately to test it out on a cubesat platform in orbit. The team says to expect this technology to become commercially available within five years.

An advanced version of the technology, Matunaga says, will eventually be used “to fabricate and assemble other fundamental parts of a satellite’s structure, such as the antenna support structure and truss elements, which would further reduce weight and the cost of launch.”

The Conversation (3)
John Boyd07 Jun, 2022

Maybe, but one small step...

FB TS03 Jun, 2022
INDV

Size problem is far bigger than satellite antennas, though!

Constructing bases on Moon, for example, would be a lot easier/faster, if we could send bulldozer size objects there!

I think the solution is creating large dome space vehicles which are carried to space by attaching 3/4/5/6 rockets underneath (like Falcon 9 etc)!

1 Reply

Metamaterials Could Solve One of 6G’s Big Problems

There’s plenty of bandwidth available if we use reconfigurable intelligent surfaces

12 min read
An illustration depicting cellphone users at street level in a city, with wireless signals reaching them via reflecting surfaces.

Ground level in a typical urban canyon, shielded by tall buildings, will be inaccessible to some 6G frequencies. Deft placement of reconfigurable intelligent surfaces [yellow] will enable the signals to pervade these areas.

Chris Philpot

For all the tumultuous revolution in wireless technology over the past several decades, there have been a couple of constants. One is the overcrowding of radio bands, and the other is the move to escape that congestion by exploiting higher and higher frequencies. And today, as engineers roll out 5G and plan for 6G wireless, they find themselves at a crossroads: After years of designing superefficient transmitters and receivers, and of compensating for the signal losses at the end points of a radio channel, they’re beginning to realize that they are approaching the practical limits of transmitter and receiver efficiency. From now on, to get high performance as we go to higher frequencies, we will need to engineer the wireless channel itself. But how can we possibly engineer and control a wireless environment, which is determined by a host of factors, many of them random and therefore unpredictable?

Perhaps the most promising solution, right now, is to use reconfigurable intelligent surfaces. These are planar structures typically ranging in size from about 100 square centimeters to about 5 square meters or more, depending on the frequency and other factors. These surfaces use advanced substances called metamaterials to reflect and refract electromagnetic waves. Thin two-dimensional metamaterials, known as metasurfaces, can be designed to sense the local electromagnetic environment and tune the wave’s key properties, such as its amplitude, phase, and polarization, as the wave is reflected or refracted by the surface. So as the waves fall on such a surface, it can alter the incident waves’ direction so as to strengthen the channel. In fact, these metasurfaces can be programmed to make these changes dynamically, reconfiguring the signal in real time in response to changes in the wireless channel. Think of reconfigurable intelligent surfaces as the next evolution of the repeater concept.

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