Behind the constant flow of "visitors" to Mars is a road to fight between electronic devices and radiation

Not long ago, in order to search for traces of ancient microbial life, the planetary probe "Perseverance" also entered the thin atmosphere of Mars. Facing challenges such as high-energy radiation in deep space and extreme cold and heat cycles, the probe has begun various core samples and experiments. The "Perseverance" scientific probe weighs less than 2,300 pounds and uses radiation-resistant technology, which will pave the way for future human exploration of the solar system.

It is worth mentioning that such cutting-edge exploration research is a comprehensive, interdisciplinary, large-scale scientific research collaboration, in which a large part of the work requires the participation of electronic engineers. Through cooperation with NASA/JPL, ADI has 63 ADI components on Perseverance, from sensors, power supplies to key signal chain devices. Because it works in a space environment, it faces various extreme situations, and the reliability and stability requirements are particularly high. It must be able to withstand the radiation of cosmic rays and the performance requirements of devices that can work reliably for a long time in common harsh environments such as industry or automobiles. This article will talk about how electronic systems can meet system design requirements for extreme application environments based on ADI's experience in the application of "Perseverance" and related aerospace projects.

The extreme environment of the universe poses severe challenges to detection equipment

What are the specific requirements for landing on Mars? First of all, the environment on Mars is very different from that on Earth. It has low gravity (Mars has a mass of about one-ninth of that of Earth and a surface gravity of about 38% of that of Earth), low air pressure (the atmosphere on the planet is thin and the air pressure is low, about 0.6% of that on Earth), large temperature difference (the temperature difference between day and night is large, the surface temperature in some areas can reach 28°C during the day and can drop to -132°C at night, with an average of -52°C), and frequent global sandstorms. In short, the environment is quite unfriendly, which naturally places high demands on the Mars rover and the electronic system equipment it carries.

All components on the vehicle must adapt to these harsh environments, especially the delicate electronic devices and sensors. The operating temperature of general industrial-grade electrical components is -25℃~70℃. Beyond this range, the device life will be greatly shortened, performance parameters will drop or even stop working. Faced with the temperature on Mars, which can reach as low as -132℃, the requirements for devices are even more stringent. In addition to temperature fluctuations, there are also different gravity environments, vibrations caused by the ground and sandstorms, which are also a big test for electronic devices. The devices that can finally work normally on the Mars rover must be carefully selected.

This crater filled with a river that once flowed across the surface of Mars is the landing site of the Perseverance rover

When it comes to the outer space environment, radiation is definitely a topic that cannot be avoided. Space radiation can produce random errors, reset processing equipment, and even damage components. Common radiation effects include: single event effects (SEE), that is, a single ion or particle hitting a specific area of ​​the device can cause various strange phenomena and errors; total ionizing dose (TID), that is, the long-term cumulative effect of ionizing radiation on components throughout their service life, which may cause offsets, such as increased power supply current on certain components; displacement damage (DD), that is, large particles such as neutrons can destroy the crystal structure of silicon chips, causing physical damage; and so on.

Now that we know why radiation testing is performed, let’s look at the different radiation effects you may encounter.

There are two types of effects that are generally observed, cumulative effects and single event effects. Cumulative effects occur when a device is repeatedly exposed to radiation over a longer period of time and the performance begins to change in some way. Due to cumulative effects, resetting the device or powering it back on will not return the device to nominal operating conditions. These cumulative effects result in semi-permanent to permanent changes in device performance. The term "semi-permanent" means that in this case the radiation-induced effects will not be eliminated by resetting the device or powering it back on, but may disappear over time or by exposure to elevated temperatures.

Radiation Effects - Cumulative and Single Event Effects

Cumulative effects are mainly divided into total ionizing dose (TID) and displacement damage. TID effects usually occur over a long period of time during the service life of the device. When testing for TID effects, the device is exposed to radiation until a certain dose is reached. The dose determines the type of TID test performed. Generally speaking, radiation doses less than or equal to 30mrad/s are considered low dose rate (LDR) and radiation doses in the range of 50 to 300 rad/s are considered high dose rate (HDR). Total ionizing radiation doses of 30 kRad to 100 kRad are quite common. The purpose is to expose the device to a large amount of radiation to measure its service life in space applications.

Cumulative Effects - TID and Displacement Damage

The device is usually tested prior to radiation exposure to establish baseline performance. It is then exposed to radiation at a specific dose rate (LDR or HDR) and for a period of time to achieve the desired total ionizing radiation dose. After exposure to radiation, the device is retested to determine any changes in its performance. During radiation exposure, the device will be adjusted to normal operating mode to simulate the operating conditions of the device in space applications.

Displacement damage occurs when radiation ions strike a device and, as a result, displace atoms in the material that makes up the device. This displacement can result in vacancies or interstitials in the crystal lattice. These atoms can subsequently recombine or form stable defects.

For more than 40 years, ADI has been using innovation to work with NASA/JPL to develop components and systems that can withstand the extremely high g-forces during launch, meet strict quality standards, and adapt to the harsh space environment. ADI's collaboration with NASA/JPL dates back to the early 1980s, and both parties have been committed to pushing the boundaries of technology and developing key components, custom procedures, and radiation-resistant technologies. No matter what its function is or what mission it is to perform, each component is subject to the harshest environmental conditions, including extreme g-forces, vibrations, temperature fluctuations, and radiation.

Unlike ground applications where faulty equipment can be replaced, equipment cannot be easily replaced once it is sent into space. Faced with strong radiation in space, it is important that electronic devices are radiation-hardened. ADI has developed related technologies in collaboration with NASA/JPL, using a variety of processes to reduce or enhance radiation tolerance. Related systems and devices will use cyclotrons and other similar facilities for radiation hardening, so that components can withstand the harsh environment of space. These facilities enable us to expose devices to radiation to measure their performance before placing them in application environments such as satellites.

Juno space probe

Prior to Perseverance, ADI worked with NASA/JPL’s Juno space probe, which launched on August 5, 2011 and traveled nearly five years through the extreme environments of deep space, arriving in orbit around Jupiter on July 4, 2016. Of all the harsh radiation environments in the solar system, Jupiter probably ranks number one. Jupiter’s magnetosphere captures a large amount of radiation in its Van Allen radiation belts, far greater than the radiation belts around our planet or other planets in the solar system. This makes Juno an extremely risky mission, requiring greatly improved radiation resistance for its electronics. By radiation testing the equipment on Earth, ADI’s components can ensure that the equipment can operate normally in the harsh radiation environment of space.