The purpose of this analysis is to determine an estimated orbit lifetime for the FINCH spacecraft and compare it against the new requirement to deorbit within five years following the end of the mission (1 year in our case, as per FINCH-Mission-Lifetime) as specified in FINCH-Spacecraft-DeorbitTime. Key takeaways are presented along with resulting requirements. Debris Assessment Software (DAS) is used to conduct the analysis.
All DAS project files for this analysis can be found on GitHub:
The following list of inputs are required to produce the following outputs via the tool’s Orbit Lifetime/Dwell Time module.
Years are formatted in decimal time (ex. 2005.4 = April 24, 2005). The required parameters for the analysis are derived in the following sections.
The following initial orbital parameters are used.
| Parameter | Value | Source |
|---|---|---|
| Start Year | 2026 | Estimated FINCH launch based on launch readiness date of September 1, 2025 |
| Perigee Altitude | =Altitude | Assumes circular orbit |
| Apogee Altitude | =Altitude | Assumes circular orbit |
| Altitude | 400-600km | To be varied |
| Inclination | 97.6° | FINCH-Spacecraft-OrbitalInjectionParameters |
| R. A. of Ascending Node | 103.07° | See R. A. of Ascending Node |
| Argument of Perigee | 0° | See Argument of Perigee |
Assuming a launch date of January 1, 2026, the Right Ascension of the Sun is as follows [Right Ascension of the Ascending Node]:
| Vernal Equinox | March 20, 2025 |
|---|---|
| Launch Date | January 1, 2026 |
| Days between launch & equinox | 287 |
| Right Ascension of the Sun: $RA_0 = 360° \times \frac{287}{365}$ | 283.07 |
Taking the earliest, middle, and latest LTDN specified in FINCH-Spacecraft-OrbitalInjectionParameters, the RAAN is:
| 10:00 | 12:00 | 14:00 | |
|---|---|---|---|
| LTAN | 10 - 12 = 22 | 12 - 12 = 0 | 14 - 12 = 2 |
| LTAN - 12 | 22 - 12 = 10 | 0 - 12 = 12 | 2 - 12 = 14 |
| RAAN | $\Omega = 283.07 + (15 \times 10)$ | $\Omega = 283.07 + (15 \times 12)$ | $\Omega = 283.07 + (15 \times 14)$ |
| 433.08° OR | |||
| 73.07° | 463.07° OR | ||
| 103.07° | 493.07° OR | ||
| 133.07° |
The average RAAN, 103.07°, is used in the analysis.
Since FINCH’s orbit is circular, its argument of perigee is undefined. Simply, a circular orbit has no perigee since the satellite maintains an equal distance from the Earth. Mathematically, a circular orbit has an eccentricity of 0, hence [Argument of Perigee]: