Orbital Power Analysis Software

SWITCH TO API

Description

This flight software component computes the orbit-averaged power consumption of a spacecraft. It integrates instantaneous power draw over each orbital period and calculates the running average, storing the final average power for each completed orbit. The results can be used for power budget analysis, battery sizing validation, and mission planning.

The software accepts power data from either a Power Monitor message or a Power Node message, prioritizing the Power Monitor when both are available. It also requires an Orbital Message to determine the orbital period for averaging calculations.

---

Example Use Cases

• Power Budget Analysis: Validate spacecraft power budgets by analyzing orbit-averaged power consumption across different mission phases.
• Battery Sizing Validation: Verify that battery capacity is sufficient by monitoring average power draw over complete orbital periods.
• Mission Planning: Support mission planning activities by providing power consumption metrics that account for varying operational modes throughout an orbit.
• Single Device Analysis: Monitor power consumption of individual devices by connecting to a specific Power Node instead of the full spacecraft Power Monitor.

---

Module Implementation

Power Data Sources

The software prioritizes power data sources in the following order:

1. Power Monitor Message: The ideal source for spacecraft-level analysis, as it accounts for all power nodes on the spacecraft. The net power is read directly from the message.
2. Power Node Message: Used as an alternative for single-device analysis. The net power is calculated as:

$$P_{net}=I_{in}\cdot V_{node}$$

where $I_{in}$ is the current into the node and $V_{node}$ is the node voltage.

Orbit-Averaged Power Calculation

The software integrates instantaneous power over time within each orbital period. For a given time $t$ within an orbit that started at time $t_0$:

$$P_{total}(t)={\int }_{t_0}^t{P}_{net}(\tau )d\tau$$

In the discrete simulation, this is computed as:

$$P_{total}(t+\Delta t)=P_{total}(t)+P_{net}\cdot \Delta t$$

where $\Delta t$ is the simulation step size.

The running average power for the current orbit is then:

$$P_{avg}=\frac{P_{total}}{t-t_0}$$

Orbit Completion

When the elapsed time since the start of the current orbit exceeds the orbital period $T$:

$$t-t_0\ge T$$

The software resets for the next orbit by:

1. Recording the last orbit time as the current simulation time
2. Resetting the total accumulated power to zero
3. Incrementing the orbit counter
4. Fetching the new orbital period from the Orbital Message

---

Assumptions/Limitations

• The orbital period is obtained from the input Orbital Message and is assumed to be valid. If the period is zero, no calculations are performed.
• The software requires at least one power input message (Power Monitor or Power Node) to function.
• Power averaging resets at the start of each new orbit, so partial orbit data is not retained across orbit boundaries.