HOW TO TURN COTS HARDWARE INTO SPACE-GRADE, RAD-HARD IN ONE STEP

Space is hard, unforgiving, it does not cooperate; it will kill your hardware if you disrespect it, that is a fact many have come to learn the hard way.

In the early times of astronautics they used to talk about the ‘space gods’ a reference to the five main factors in the space environment: Vacuum, Plasma, Radiation, AOA (Atomic Oxygen Attack) and MMOD (Micro Meteorites and Orbital Debris), they said they are the ones who will decide if your mission succeeds or not, provided that everything else works fine.

So, this is the kind of situation where you can do everything right and still lose, the only thing you can do is prepare for everything as much as you can, explore all possible failure modes, test and test and test again, all kind of tests, have the best engineering, acquire TRL9 components and implement TRL9 techniques, strategies and procedures and still, you can find a random MMOD or a solar flare sends a plasma tsunami your way and then, mission fails. One of the most insidious factors is the radiation: Space is full of it, not only electrons, protons, alphas, gammas, x-rays and hard UV, but also the unstoppable cosmic radiation coming from the galactic center, you will need to shield your spacecraft with several meters of lead in order to stop it, which, of course, is never going to happen.

Then what do we do? How come there are so many satellites working in orbit so many years? Maybe we better ask how many derelicts are in orbit and they are many more than working satellites. One of the most successful techniques is to use radiation hardened (rad-hard) components, these are chips and components that are radiation resistant, practically immune (as much as possible) to space radiation and these components are not cheap, for example take the humble and ubiquitous 555 timer, the terrestrial version costs a few cents and the rad-hard version costs US$250+ and this is only one chip, other components can reach thousands of dollars, This is why space is not only hard but also expensive when done the right way.

Many satellites, especially cubesats use what is called COTS components Common Off-The-Shelf components, terrestrial ones, like the cheap 555 of a few cents and of course they will not last long, even when there are cases when the cubesats lasts years, but it is rare. So you if you really want to push a mission for many months and even years you should use as many rad-hard components as you budget allows?

Fortunately, there is other way,

What if, instead of using expensive components and breaking the budget, you do something smarter, what if you shield all your spacecraft the way EVA space suits are, with a MLI that can not only attenuate and in most cases defeat many types of radiation before it gets into your electronics, a shield that can also regulate the internal temperature of your spacecraft eliminating the thermal cycles and maintain a reasonable average temperature inside, eliminating the need for coolers or heaters and the power budget burden of it. That MLI exists, it has been tested successfully in space in many cubesats, it is called SEAM NEMEA developed by EXA in 2010 and tested in 2013 on their own satellites.

The Space Environment Attenuation MLI NEMEA (Yes, the name of the lion in the legend of Hercules that had a skin so though that cannot be pierced by arrows of spears) is a multi-layered polymer insulation of 27 layers that attenuates and in most cases stops VUV, alpha, beta gamma, x-rays and neutrons it also fends off most of infrared maintaining a high thermal inertia inside the spacecraft, regulating the temperature between 5 and 10 degrees inside and eliminating the thermal cycle.

NEMEA has allowed many missions of humble 1U cubesats to beat the 5 year mission duration mark and in some cases even 10 years, the cost is humble, the gains are huge. At this time, SEAM NEMEA is standard equipment in all the EXA KRATOS cubesat platforms; there are versions that can withstand even the lunar environment. Know more about it by reading the (very) technical paper at: https://www.researchgate.net/publication/317265155_SEAMNEMEA_A_SPACE_ENVIRONMENT_ATTENUATION_MANIFOLD_MLI_SHIELD

Ronnie NaderChief Designer – EXA – rnader@exa.ec - ORCID: 0000-0002-1399-6973 - Scopus ID: 36125329900 Academician – Engineering Sciences – International Academy of AstronauticsNuclear Propulsion Technical Committee – American Institute of Aeronautics and Astronautics