What kind of energy can be used as a driving force for deep space travel?

When Kushbu Danny dreamed of crossing space and building something in the universe, she never thought about what would be her driving force.

The dream of human deep space travel (picture from the network)

Inspired by Neil Armstrong's biography and her trip to the Kennedy Space Center in Florida and the Boeing factory in Seattle, she decided to pursue a degree in aerospace engineering after earning a bachelor's degree in aerospace engineering from the University of Amrit, India. Now, as Viterbis A former member of the Master of Aviation Engineering (MS 19) and the Liquid Propulsion Laboratory (a student-led rocket construction team), she became interested in the powertrain.

This summer, Danny was an intern at the Idaho National Laboratory's Center of Space Nuclear Research (CSNR), an institution that develops advanced nuclear systems for space travel. The task of a team of four other college students is to determine the interaction of nuclear fuel with surrounding materials and how this interaction affects the efficiency of energy conversion.

Although short-range space missions can use solar panels to generate electricity, solar energy is not enough for deep-space missions and tasks that require more power. Instead, they must use nuclear energy generated by radioisotope thermoelectric generators (RTGs).

Structure diagram of radioisotope thermoelectric generators (RTGs) (picture from the network)

Basically, it works on the decay of radioactive materials, in our case 钚-238, and the heat generated is converted into electricity by thermocouples, Danny explained.

Newer RTG designs power multiple tasks, called MMRTGs. They are modular in design and generate power in smaller increments.

The first spacecraft using radioisotope power was the Transit satellite launched in 1961. Since then, RTGs have been used in many projects such as Voyager and Cassini orbiters. Recently, ' Curiosity' MMRTG is used on the Mars probe and will be used on future 2020 Mars probes.

NASA staff prepared a multi-role radioisotope thermoelectric generator (MMRTG) for the Mars Curiosity Detector.

Mars Curiosity Detector (NASA)

MMRTG typically has eight heat source modules, each containing a fuel ball made of helium-238. To protect the radioisotope, these components are wrapped in a graphite casing that is lined with a protective coating. Danny and Her team is responsible for analyzing how molecules produced during the decay of 钚-238 react and react with surrounding substances.

Danny said that 钚-238 is a strong alpha emitter that produces ruthenium. These ruthenium molecules will form ditches in the ball for a period of time, which in turn affects the speed of power generation.

This decay also releases oxygen molecules that can make the graphite shell brittle and vulnerable during potential impacts. In a year or two, these capsules are used for assembly, waiting for tasks, and having enough time to react. Blocking components.

钚-238 has a half-life of 88 years and is an ideal long-term power source. (Photo from the Internet)

The industry is currently understanding the physical principles behind it, but it is not sure what its consequences will be. So what we do is to build a model to help them analyze the internal conditions of the particles before launch, Danny said.

This is a team of students from different backgrounds, from chemical engineering, materials science to nuclear engineering, they created a framework of computer models that allow CSNR scientists to change the initial conditions of parameters such as temperature and pressure, and gas dynamics will affect materials. Interactions. Their work can help improve the future design and provide reference for MMRTGs.

Although the history of human nuclear power is full of devastating weapons, such as atomic bombs and catastrophic accidents such as Chernobyl, no energy currently produces so much energy per unit volume.

Nuclear energy can be a devastating weapon, but it is the only energy source for deep space travel. (Photo from the Internet)

'So far, in addition to nuclear energy, people have not found other practical technologies.' Danny said: 'I think that before we find better technology to power our spacecraft in deep space missions, nuclear energy is currently It may also be the only option in the future. '