Nestled on the foot of a steep, forested hill, 16 kilometers outdoors Wellington, New Zealand, is a fairly unassuming constructing; one amongst many on a analysis campus that was first established within the Forties. From outdoors, there’s little to recommend that that is the birthplace of a outstanding piece of know-how sure for the International Space Station (ISS) within the coming months.
The constructing is house to the Paihau-Robinson Research Institute, a part of Victoria College of Wellington. And the know-how being developed there might at some point cut back the house trade’s reliance on chemical rockets.
“Our focus right here is applied-field magnetoplasmadynamic [AF-MPD] thrusters. It’s a category of electric propulsion that makes use of an utilized magnetic area to speed up ions to extraordinarily excessive speeds,” says Randy Pollock, the chief engineer for house at Paihau-Robinson, throughout a go to to its labs.
This group isn’t the primary to work on AF-MPD thrusters—the know-how has been tinkered with for the reason that Seventies—however Pollock and his workforce have overcome a significant hurdle to their software in spacecraft. Slightly than use typical copper electromagnets to create the magnetic area, their magnet is made with high‐temperature superconductors (HTS); a category of supplies which have close-to-zero electrical resistance, permitting them to generate sturdy magnetic fields whereas consuming minimal energy.
How Electrical Propulsion Works
In 2023, Paihau-Robinson put in the primary model of its superconducting electromagnet onto an existing ion thruster at Nagoya College in Japan. The magnet operates on the “excessive temperature” (so far as superconductors are involved) of -198.15 °C (75 kelvins). To achieve that temperature, the researchers used a cryocooler—successfully a miniaturized mechanical fridge—that had beforehand been certified for spaceflight. This did away with the necessity for a steady circulate of pricy liquid helium.
They efficiently fired the thruster over 100 instances, and generated magnetic fields of 1 tesla with lower than 1 watt of magnet energy. That was a 99 p.c discount in enter energy in comparison with a copper electromagnet, whereas producing a area thrice as sturdy.
Again on the lab in Wellington, the workforce are actually creating their very own thruster, which they check inside a car-size vacuum chamber. Atop the chamber is a gentle toy kōkako—the mascot for his or her mission, and its namesake. The kōkako is a species of fowl native to New Zealand, immediately recognizable due to a wealthy blue wattle beneath its beak. “To call these missions, we labored with Professor Rawinia Higgins, who’s the deputy vice-chancellor (Māori) at Victoria,” says Betina Pavri, a senior principal engineer at Paihau-Robinson. “Kōkako comes from the truth that the plasma glows a particular blue-purple colour when the thruster is in operation.”
The HTS magnet, barely seen contained in the vacuum chamber, includes four “double-pancake” coils of superconducting tape. It’s concerning the measurement of a dinner plate, and the ion propellant line runs via the opening within the heart of it. The cryocooler is simply out of view, but it surely’s the identical space-qualified mannequin the workforce trialed in Japan. The following stage of the undertaking will contain shifting to a smaller magnet, roughly the dimensions of a bagel, with the aim of creating the system extra suited to spaceflight.
Hēki Will Take a look at Kōkako’s Tech
Kōkako is one half of the analysis effort—the ground-based growth of a sensible AF-MPD thruster. The opposite half has been on constructing a know-how demonstrator that may quickly be mounted onto the outside of the ISS by way of a business experiment portal referred to as the NanoRacks External Platform. Pavri describes the demonstrator as “a critically necessary precursor to the Kōkako thruster,” which is why it’s named Hēki, the phrase for “egg” within the Māori language.
“As I prefer to say, we took a place on the chicken-egg query,” says Pollock.
On 7 November, Hēki was packed up and shipped to Houston, the place it’ll bear remaining exams at Voyager Space’s services. (Voyager Area can be the corporate behind the NanoRacks platform.)
The Hēki demo resulting from arrive on the ISS later this 12 months carries an outline of the story of how the Kōkako fowl received its blue wattle.Laurie Winkless
Hēki is, in impact, all the things wanted for Kōkako, excluding the ion line. Within the heart of the baseplate is a metal bagel—light-weight exterior shielding for the smaller superconducting magnet. When in operation, this magnet will generate a area of as much as 0.5 T, “comparable in degree to what you’ll see inside an MRI machine however in a really small house,” explains Pavri.
“To our information, that is essentially the most highly effective electromagnet that may have ever flown,” Pollock says. “So, it took quite a lot of design work to fulfill the very stringent stray magnetic area necessities of the ISS.”
Sitting simply above the protect is a flux pump—one other new element constructed at Paihau-Robinson. It acts as an inductive power supply that steadily builds present within the magnet over a number of hours. As a result of it additionally makes use of superconductors, the flux pump doesn’t warmth up, which helps keep the magnet’s temperature. It too is new to the house atmosphere. The soda-can-size cryocooler and all the assist electronics for the system sit on the underside of the baseplate—a choice motivated by thermal management wants.
Testing the Magnets in Area
When put in on the ISS—which on the time of publication, will almost definitely be June—the magnet will probably be operated remotely, biking via numerous area strengths, and testing shutdown situations. Pavri describes the general aim as “an illustration that these new applied sciences—the excessive temperature superconducting magnet and flux pump energy provide—can survive and function reliably within the house atmosphere.”
Zenno, an area startup based mostly in Auckland, New Zealand, says it has been testing a superconducting magnet in orbit since 2023. Zenno has not but revealed any information on its experiment.
The Paihau-Robinson workforce additionally has a secondary goal for the mission; “an experiment of alternative,” says Pollock, made doable by its high-field magnet. “Folks have talked for the reason that sixties about utilizing sturdy magnetic fields for shielding in house. Whereas Hēki will not be the best setup for measuring it, I used to be eager to include sensors to see what impact our magnet may need on the radiation atmosphere.” He sourced two sensors from the Czech Technical University in Prague, putting in one straight above the magnet, and the opposite a brief distance away throughout the enclosure. “As we ramp the sector up and down, I consider we’ll see an impact.”
The ultimate view of Hēki earlier than it’s packed away is its protecting cowl. The coated sheet of metallic features a checklist of the workforce members who labored on the undertaking, and those that funded its growth. But it surely’s the entrance that’s most eye-catching. Adorned with the work of latest Māori artist Reweti Arapere, the imagery tells the story of how the Kōkako fowl received its blue wattle.
“When the astronauts pull this out, we wish to not go away any doubt about the place this instrument has come from,” says Pollock.
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