Education Post #2: Power, Power Everywhere

Hello everyone,

It’s time for another Educational Post, and since our last newspost focused on the great work being done by our Power Team, we thought it’d be great to give you some info about satellite power systems! It’s the most critical system on a satellite: there are very few ways to try to work around power failure, and many satellites have failed in space due to power system problems. There is a ton of information available on these kinds of systems, but we’ll try to provide solid overview without getting too bogged down in details. Here we go!

Satellite Power Systems:

Essentially the goal of a power system on a satellite is to ensure  that every electronic component onboard receives enough current at the correct voltage to do its job. This includes the processors, antennas, heaters and more, so it’s a big job!  This is accomplished by four major components working together:

1) Primary Power Source: This component converts some form of fuel into electrical energy for the satellite. This fuel could be solar energy from the sun, nuclear, chemical energy like a hydrogen fuel cell, and many others. Sometimes there is no primary source and the satellite relies entirely on a battery it brings with it to space, but this limits the satellite’s lifespan and performance as the battery runs down.

2) Secondary Power Source: This component is generally a battery. Its purpose is to store energy so that it can provide energy to the satellite when the primary source isn’t enough. An example of when you’d need this are when the short-term power you require is greater than the maximum the Primary Source can provide. As mentioned above, sometimes there will be no primary source and all of the satellite’s power will come from a battery, but it is very rarely the reverse. There are a lot of choices for battery type, and the choice is made by a combination of weight, cost, reliability, and capacity.

3) Battery Management System: This component controls and protects the battery. Its most important responsibility is to ensure that the battery doesn’t overcharge. Overcharging is when you try to deliver more energy to a battery that is at its maximum charge already. This can damage a battery, and in space you can’t replace a satellite’s battery, so it’s very important to avoid this! It also includes thermal systems to keep the battery at its correct operating temperature for proper performance.

4) Regulation & Distribution Harness: This component is responsible for distributing power to the other subsystems at regulated (consistent) voltages. Each subsystem has a different requirement for what voltage they run at. These voltages are usually 3.3V, 5V, and 12V. However, the battery itself can only provide one voltage, which depends on its charge level. To provide the different voltages needed,  this system takes the battery voltages and boosts(increases) or bucks (decreases) it to the required voltages. The distribution system then delivers the power at the regulated voltages to the subsystems.

Still with us? Great! As always, we hope you had fun and maybe learned a little something, too. Check back in with us soon for our next Educational Post: Attitude Determination and Control, or ‘Where Are We Pointing and How Do We Point Where We Want’?

Keep on circlin’ the sun,

The Orbit Team

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