184_projects:austin_snafu

The Artemis 13 is almost home but before they complete their final landing sequence the team needs to launch a top-secret deep space probe that will be piloted by Johnny 5 into the eye of the storm over Lakeview. However, the power supply for the whole ship is running critically low, so you are now only running the ECS to maintain oxygen in the command module. You have to somehow power up the probe to complete your mission. You no longer have communications with Austin.

You notice as you begin powering up the probe (which operates on its own reserve power system) that although the navigational controls have been primed, there are several components that are not responding to testing. It appears that the circuit switch control board got fried during the test jump, as a result, you now need to create a new circuit that will allow you to provide different amounts of energy to the propulsion system's module on the probe.

That propulsion system consists of the primary burners and the cooling system, which have a total resistance of 65 $\Omega$. The primary burners require a short burst of 200 J to power-up. The cooling system requires a short burst of 300 J to power-up.

You need to be able to deliver different amounts of power to this module; however, you are growing concerned that the power supply the probe has access to of 100 V may not be sufficient to power these probe systems. You manage to find some additional batteries onboard (three 10 V batteries from the supply room) to use if you need them.

You also have several 0.125F capacitors and resistors (1 $\Omega$, 5 $\Omega$, 10 $\Omega$, 50 $\Omega$, 100 $\Omega$) on hand. You also have access to multiple switches that can be used to open and close parts of the circuit you are designing.

There is a breaker in the circuit that is a failsafe and will trip if the current reaches 2 A. You also know that there are delicate circuit elements in the primary burners and the cooling system, so the propulsion system should not be connected to any power supplies when charging capacitors.

You should provide a circuit diagram of your design that helps you explain to your crew that the current in the circuit is safe and that you are going to be able to supply the needed power to the systems when the time comes to launch the probe. As a check for yourself, you should make sure that the voltage in the circuit adds up to the correct amount as to not suffer any voltage shortages.

Learning Goals

  • Understand how capacitors charge and discharge
  • Use the relationship between capacitance and energy
  • Understand what happens when capacitors are in parallel or in series
  • Understand how capacitors and resistors combine in a complex circuit
  • Design a circuit that can charge/discharge capacitors & meet specifications

Conceptual Questions:

  1. Where did you place switches in your circuit? What positions do they need to be in to charge & discharge the capacitors?
  2. How did you limit the current to be under 2 A?
  3. Why is it important to have a current limit in circuits? (What happens to wires if there is a very high current?)
  4. If capacitors are combined in series does that increase or decrease the total capacitance? What about parallel capacitors?
  5. Draw the I vs t, V vs t, and Q vs t graphs for charging & discharging the capacitors.
  6. What assumptions did you make in this problem?
  • 184_projects/austin_snafu.txt
  • Last modified: 2022/08/16 19:36
  • by dmcpadden