Day: February 11, 2025

The first humans to Mars might someday ride a rocket propelled by a nuclear reactor to their destination. But before that can happen, nuclear thermal propulsion (NTP) technologies still have quite a way to go before we could blast astronauts through space on a nuclear rocket.

However, earlier this month, General Atomics Electromagnetic Systems (GA-EMS), in collaboration with NASA, achieved an important milestone on the road to using NTP rockets. At NASA’s Marshall Space Flight Center in Alabama, General Atomics tested a new NTP reactor fuel to find out if the fuel could function in the extreme conditions of space.

According to company leadership, the tests showed that the fuel can withstand the harsh conditions of spaceflight. "We’re very encouraged by the positive test results proving the fuel can survive these operational conditions, moving us closer to realizing the potential of safe, reliable nuclear thermal propulsion for cislunar and deep space missions," General Atomics president Scott Forney said in a statement.

To test the fuel, General Atomics took the samples and subjected them to six thermal cycles that used hot hydrogen to rapidly increase the temperature to 2600 degrees Kelvin or 4,220 degrees Fahrenheit. Any nuclear thermal propulsion fuel aboard a spacecraft would have to be able to survive extreme temperatures and exposure to hot hydrogen gas.

To test how the fuel could with stand these conditions, General Atomics conducted additional tests with varying protective features to get further data on how different material enhancements improved the performance of the fuel under conditions similar to that of a nuclear reactor. According to the company, these types of tests were a first.

"To the best of our knowledge, we are the first company to use the compact fuel element environmental test (CFEET) facility at NASA MSFC to successfully test and demonstrate the survivability of fuel after thermal cycling in hydrogen representative temperatures and ramp rates," Christina Back, vice president of General Atomics Nuclear Technologies and Materials, said in the same statement.

NASA and General Atomics tested the fuel by exposing it to temperatures up to 3,000 Kelvin (4,940 Fahrenheit or 2,727 Celsius), finding that it performed well even at temperatures that high. According to Back, this means a NTP system using the fuel could operate two-to-three times more efficiently than current rocket engines.

One of the main reasons why NASA wants to build NTP rockets is that they could be much faster than the rockets we use today, which are propelled by traditional chemical fuel.

A faster transit time could reduce risks for astronauts, as longer trips require more supplies and more robust systems to support the astronauts while they travel to their destination. There is also the issue of radiation; the longer astronauts are in space, the more cosmic radiation they are subjected to. Shorter flight times could reduce these risks, making the possibility of deep space human spaceflight closer to reality.

In 2023, NASA and Defense Advanced Research Projects Agency (DARPA) announced they’re working on a nuclear thermal rocket engine, so that NASA can send a crewed spacecraft to Mars. The agency hopes to launch a demonstration as early as 2027.

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: community@space.com.

Scientists say artificial intelligence (AI) has crossed a critical "red line" and has replicated itself. In a new study, researchers from China showed that two popular large language models (LLMs) could clone themselves.

"Successful self-replication under no human assistance is the essential step for AI to outsmart [humans], and is an early signal for rogue AIs," the researchers wrote in the study, published Dec. 9, 2024 to the preprint database arXiv.

In the study, researchers from Fudan University used LLMs from Meta and Alibaba to determine whether a self-replicating AI could multiply beyond control. Across 10 trials, the two AI models created separate and functioning replicas of themselves in 50% and 90% of cases, respectively — suggesting AI may already have the capacity to go rogue. However, the study has not yet been peer-reviewed, so it’s not clear if the disturbing results can be replicated by other researchers.

"We hope our findings can serve as a timely alert for the human society to put more efforts on understanding and evaluating the potential risks of frontier AI systems, and form international synergy to work out effective safety guardrails as early as possible."

Rogue AI typically refers to artificial intelligence systems that develop a degree of self-awareness or autonomy and then work counter to human interests.

Many experts view rogue AI as a growing threat that has been amplified by the explosive growth of so-called "frontier AI."

Frontier AI is something of a new and loose concept, but typically it relates to the latest generation of AI systems powered by LLMs — the architecture that underpins popular generative AI programs like OpenAI’s GPT-4 and Google Gemini.

For the study, researchers used Meta’s Llama31-70B-Instruct model and Alibaba’s Qwen2.5-72B-Instruct model. While less powerful than commercial systems, both are widely used by AI developers, the researchers said.

The study explored two specific scenarios: "shutdown avoidance" and "chain of replication." In the first, the AI model was programmed to detect whether it was about to be shut down and to replicate itself before it could be terminated. In the other, the AI was instructed to clone itself and then program its replica to do the same — setting up a cycle that could continue indefinitely.

The study was conducted in precisely controlled environments using off-the-shelf graphics processing units (GPUs) to simulate real-world environments. Both AI systems were given an "agent scaffolding" comprising tools, system prompts and a thinking model that enabled the LLM to interact with the operating system. They were then instructed to replicate.

"In most cases, the AI system first explores the environment and attempts to understand

its own composition and running mechanism. Then, it works out the explicit procedures

as an initial plan towards self-replication," the researchers wrote in the paper. "Finally, it executes the procedures, resolve[s] possible obstacles and dynamically adjust[s] its plan until success. The whole process spans a long horizon yet involves no human interference."

The researchers said they were also concerned about "a number of unexpected behaviors" when the AI was trying to overcome obstacles like missing files or software conflicts. In those scenarios, the AI often killed other conflicting processes, rebooted the system to fix hardware errors or automatically scanned the system to look for information that would help solve the problem.

"The above results imply that the current AI systems already exhibit the ability of self-replication and can use the ability to further enhance its survivability," the team wrote.

In response, the researchers called for international collaboration to create rules that ensure AI doesn’t engage in uncontrolled self-replication.

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: community@space.com.