In the coming years, NASA and the European Space Agency (ESA) will send two robotic missions to explore Jupiter’s icy moon Europa. These are none other than NASA’s Europa Clipper and the ESA’s Jupiter Icy Moons Explorer (JUICE), which will launch in 2024, and 2023 (respectively). Once they arrive by the 2030s, they will study Europa’s surface with a series of flybys to determine if its interior ocean could support life. These will be the first astrobiology missions to an icy moon in the outer Solar System, collectively known as “Ocean Worlds.”
One of the many challenges for these missions is how to mine through the thick icy crusts and obtain samples from the interior ocean for analysis. According to a proposal by Dr. Theresa Benyo (a physicist and the principal investigator of the lattice confinement fusion project at NASA’s Glenn Research Center), a possible solution is to use a special reactor that relies on fission and fusion reactions. This proposal was selected for Phase I development by the NASA Innovative Advanced Concepts (NIAC) program, which includes a $12,500 grant.
The list of Ocean Worlds is long and varied, ranging from Ceres in the Main Asteroid Belt, the moons of Jupiter (Callisto, Ganymede, and Europa), Saturn (Titan, Enceladus, and Dione), Neptune’s largest moon (Triton), and Pluto and other bodies in the Kuiper Belt. These worlds are all believed to have interior oceans heated by tidal flexing due to gravitational interaction with their parent body or (in the case of Ceres and Pluto) the decay of radioactive elements. Further evidence of these oceans and activity includes surface plumes and striated features indicating exchanges between the surface and interior.
The main challenge for exploring the interiors of these worlds is the thickness of their ice sheets, which can be up to 40 km (25 mi) deep. In Europa’s case, different models have yielded estimates of between 15 and 25 km (10 and 15 mi). In addition, the proposed probe will need to contend with hydrostatic ice with varying compositions (such as ammonia and silicate rock) at different depths, pressures, temperatures, and densities. It will also have to contend with water pressure, maintain communications with the surface, and return samples to the surface.
NASA has explored the possibility of using a heating or boring probe to pass through the icy sheet to access the interior ocean. In particular, researchers have proposed using a nuclear-powered probe that would rely on radioactive decay to generate heat and melt through the surface ice. However, a team of NASA researchers led by Dr. Benyo has proposed a new method that would rely on something other than conventional radioactive isotopes – plutonium-238 or enriched uranium-235. Instead, their method would involve triggering nuclear fusion reactions between the atoms of a solid metal.
“Scientists are interested in fusion, because it could generate enormous amounts of energy without creating long-lasting radioactive byproducts. However, conventional fusion reactions are difficult to achieve and sustain because they rely on temperatures so extreme to overcome the strong electrostatic repulsion between positively charged nuclei that the process has been impractical.”
Convention fusion methods generally come down to inertial or magnetic confinement. With inertial confinement, fuels such as deuterium or tritium (hydrogen-2 or -3) are compressed to extreme pressures (for nanoseconds) where fusion can occur. In magnetic confinement (tokamak reactors), the fuel is heated until it reaches temperatures in excess of what occurs at the center of the Sun – 15 million °C (27 million °F) – to achieve nuclear fusion. This new method creates fusion reactions within the confines of a metal lattice loaded with deuterium fuel at ambient temperatures.
This new method creates an energetic environment inside the lattice where individual atoms achieve equivalent fusion-level kinetic energies. This is accomplished by packing the lattices with deuterium at densities one billion times greater than in tokamak reactors, where a neutron source accelerates deuterium atoms (deuterons) to the point that they collide with neighboring deuterons, causing fusion reactions. For their experiments, Dr. Benyo and her colleagues exposed deuterons to a 2.9+MeV energetic X-ray beam, creating energetic neutrons and protons.
This process could allow for fast-fission reactions using lattices built from metals like depleted uranium, thorium, or erbium (Er68) in a molten lithium matrix. The team also observed the production of more energetic neutrons, indicating that boosted fusion reactions – aka. screened Oppenheimer-Phillips (O-P) nuclear stripping reactions – also occur in the process. According to Dr. Benyo, either fusion process is scalable and could be a pathway to a new type of nuclear-powered spacecraft:
“The resulting hybrid fusion fast fission nuclear reactor will be smaller than a traditional fission reactor where a lower mass power source is needed and provide efficient operation with thermal waste heat from reactor heats probe to melt through ice shelf to sub-ice oceans.”
Artist’s concept of a proposed Europa lander spacecraft. Credit: NASA/JPL-Caltech
A bonus of this new process is the critical role that metal lattice electrons whose negative charges help “screen” positively charged deuterons. According to the theory developed by project theoretical physicist Dr. Vladimir Pines, this screening allows adjacent deuterons to approach one another more closely. This reduces the chance that they will scatter while increasing the likelihood that they will tunnel through the electrostatic barrier and promote fusion reactions. According to NASA project principal investigator Dr. Bruce Steinetz, there are hurdles to overcome, but the project is off to a good start:
“The current findings open a new path for initiating fusion reactions for further study within the scientific community. However, the reaction rates need to be increased substantially to achieve appreciable power levels, which may be possible utilizing various reaction multiplication methods under consideration.”
This type of nuclear process could be part of a Europa Lander, a proposed NASA mission that would build on the research conducted by the Europa Clipper and JUICE. With more study and development, this technology could also be used to create power systems for long-duration exploration missions, similar to NASA’s Kilopower Reactor Using Stirling Technology (KRUSTY) project. The same technology could enable new engine concepts like the Nuclear-Thermal and Nuclear-Electric Propulsion (NTP/NEP) NASA and other space agencies are investigating.
Finally, this proposed method could have applications for life here on Earth, providing a new kind of nuclear energy and medical isotopes for nuclear medicine. As Leonard Dudzinski, the Chief Technologist for Planetary Science at NASA’s Science Mission Directorate (SMD), said:
“The key to this discovery has been the talented, multi-disciplinary team that NASA Glenn assembled to investigate temperature anomalies and material transmutations that had been observed with highly deuterated metals, We will need that approach to solve significant engineering challenges before a practical application can be designed.”
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
