How NASA is preparing the spacecraft for intense radiation from space


How NASA is preparing the spacecraft for intense radiation from space

Long-term radiation dose tests at the radiation treatment processing facility take place in a small room walled by four feet of concrete. Each part of NASA's space flight instrument undergoes radiation tests to ensure its survival in space. Credit: Goddard Space Flight Center NASA / Genna Duberstein

In a small square room walled by four feet of concrete, the air feels as if a storm had just crossed – bright and pungent, like cleaning equipment. Outside, it is the smell of lightning that destroys oxygen in the air, which mixes easily with ozone. But in one of NASA's radiation treatment processing facility parts, the odor of ozone persists after high-energy radiation tests. The radiation used by engineers to test the electronic components of spaceflight is so powerful that it destroys the oxygen in the room.

Each part of NASA's space flight instrument undergoes radiation tests to ensure its survival in space. It is not easy to be a spaceship; Invisible energetic particles spread all over the place. Although there is so little that space is considered a void, nothing is missing. Tiny particles can cause damage with the electronic components we send in space.

As NASA explores the solar system, radiation tests are becoming more and more crucial. The Radiation Facility, housed at NASA's Goddard Space Flight Center in Greenbelt, Maryland, facilitates the inspection of equipment allowing NASA to explore the Moon, the Sun and our solar system – since the missions to understand the beginnings of the universe until the program Artemis. trip to the moon much closer to home.

"We will be able to guarantee the survival of human beings, electronics, spacecraft and instruments – everything we send in space – in the environment in which we place it. said Megan Casey, an aerospace engineer in the Radiation Analyzes and Effects Group. to Goddard.

The exact conditions encountered by a spacecraft depend on its orientation. The engineers therefore carefully tested and selected the parts adapted to the destination of each machine. The Earth's magnetic field, for example, traps swarms of particles in two donut-shaped bands called radiation belts. Other planets also have radiation belts, like Jupiter, whose belt is 10,000 times more powerful than the Earth's. Generally, the closer the sun is, the more difficult it is to wash the solar particles, called the solar wind. And galactic cosmic rays – fragments of star particles exploded away from the solar system – can be encountered anywhere.

Timing is also a factor. The sun undergoes natural cycles of eleven years, from a period of high activity to a low activity. In the relative calm of the solar minimum, cosmic rays easily infiltrate the solar magnetic field and enter the solar system. On the other hand, at the maximum of solar energy, frequent solar flares flood the space with high energy particles.

"Depending on their destination, we explain to the mission designers their spatial environment.They come back to us with their instrument plans and ask," Will these pieces survive there? Casey said, "The answer is always yes, no, or I do not know. If we do not know, we perform additional tests. That's the vast majority of our work. "

The Goddard Radiation Center, along with partner facilities located throughout the country, is equipped to mimic the range of space radiation, from the constant irritation of the solar wind to flaming belts of radiation and the brutal blows of solar flares. and cosmic rays.

How NASA is preparing the spacecraft for intense radiation from space

The Earth's radiation belts are filled with energy particles trapped by the earth's magnetic field that can cause considerable damage to the electronic components we send into space. Credit: NASA / Tom Bridgman Science Visualization Studio

The effects of spatial radiation

Engineers use computer models to determine the destination of a spacecraft – the amount of radiation that it will encounter there – and the type of tests they need to reflect that lab environment.

Radiation is energy in the form of waves or tiny subatomic particles. For spacecraft, the main concern is particle radiation. This radiation, which includes protons and electrons, can affect their electronics in two ways.

The first type, known as single-event effects, are immediate threats – rapid energy explosions when a solar particle or cosmic ray breaks a circuit. "High energy particles waste energy in your electronics," said Clive Dyer, electrical engineer at Space Center of the University of Surrey, England. "Single-event effects will mess up your computers and scramble your data, in binary code, from 1 to 0."

Many spaceships are equipped to recover from these skirmishes with particles. But some strikes can disrupt the operation of programs, which can impact communication or navigation systems and cause computer crashes. At worst, the result can be catastrophic. Years ago, astronauts' laptops on the Space Shuttle crashed as they traversed particularly hairy areas of radiation belts. NASA's Hubble Space Telescope preemptively extinguishes its scientific instruments as it travels through the region.

And then, there are effects that worsen with time. The charged particles can accumulate on the surface of a spacecraft and accumulate a charge in a few hours. Just like walking in a carpeted room and spinning a metal door knob, charging triggers static electricity that can damage electronic components, sensors and solar panels. In April 2010, the charge deactivated the communication systems of the Galaxy 15 satellite, leaving it adrift for eight months.

Space ships must withstand radiation throughout their lives. Long-term radiation – called total doses – depletes materials and progressively reduces instrument performance over time. Even relatively weak radiation can degrade solar panels and circuits.

Nested in a room adjacent to a safe distance from the radiation, the test facility engineers cover the components of the instrumentation instrument with a mixture of energetic particles, looking for signs of weakness.

In general, the effects of their tests are not visible. A jump in temperature or electrical current could indicate that a single particle has struck a circuit. On the other hand, during total dose tests, engineers monitor the slow and gradual degradation, a side effect of the trip into the space with which most missions can live, given that they have enough time to reach their scientific goals.

How NASA is preparing the spacecraft for intense radiation from space

A particle accelerator in the radiant power plant projects high energy particles onto the instruments, mimicking the solar wind or galactic cosmic rays. Credit: Goddard Space Flight Center NASA / Genna Duberstein

"The worst case is a single destructive event effect, when you see a catastrophic failure because an instrument is short-circuited," Casey said. "It's bad news for the mission, but it's the most fun to test in. Sometimes there's so much energy that you see something happen – some light or a burn mark in some case."

Resist the radiation storm

So how do engineers protect spacecraft against the constant dangers of space radiation? One tactic is to build pieces that are hardened against radiation from their very foundations. Engineers can select certain materials that are less sensitive to particle impacts or load.

Spacecraft designers rely on armor to defend their instruments against long-term effects. Aluminum or titanium layers slow down energetic particles, preventing them from reaching sensitive electronic components. "At the present time, we assume that all missions will have a shielding thickness of about 10 cm," Casey said.

After their tests, the engineers make specific recommendations for the shielding if the environment requires it. Shielding increases volume and weight, which increases fuel requirements or costs, so engineers always prefer to use as little as possible. "If we can improve our models and refine the appearance of the radiation environment more accurately, we may be able to clear up these walls," she said.

The collection of observations from various spatial environments is a key step in the improvement of models. "The refinement of our space radiation models is finally helping us to make a better selection of devices," said Michael Xapsos, a member of the project's science team for NASA's Space Environment Testbeds mission, dedicated to study the effects of radiation on the material. "With more data, engineers can improve the exchanges between the risks, costs, and performance of the electronic devices they select."

The most energetic particles are impossible to avoid, even with intensive shielding. After testing the effects of single events, engineers calculate how often such a shock could occur. For example, a spacecraft may have a chance to hit particles every 1,000 days. These are isolated events that are as likely to occur on the first day of a satellite in space as its 1,000th day – and it is up to the mission designers to decide on the level of risk that will occur. they can bear.

A common strategy against the effects of single events is to equip an instrument with multiples of the same coin that operate simultaneously. If a chip is temporarily disabled by a particle hit, its counterparts can take over.

Engineers can plan and develop such mitigation strategies, but the best thing to do is to fully understand the spatial environment in which a satellite is evolving. Missions such as Space Environment Testbeds, or SET, which is scheduled for release in late June, and radiation treatment processing facility modeling efforts ensure that they get this information. .

Small particles can have big consequences for electronics in space missions

Provided by
NASA Goddard Space Flight Center

How NASA is preparing the spacecraft for intense radiation from space (11 June 2011)
recovered on June 11, 2019

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