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Orts

軌道寿命解析

ArkEdge Space の 6U CubeSat AE1b (YODAKA, NORAD 62295) の軌道減衰を再現し、大気モデル・太陽活動データ・弾道係数の違いが寿命予測に与える影響を比較する example。

Altitude Decay Comparison

Target satellite

Section titled “Target satellite”
NameYODAKA (AE1b)
NORAD ID62295
COSPAR1998-067XB
BusArkEdge Space 6U (10 kg class)
Deployment2024-12-09 08:15 UTC (J-SSOD from ISS)
Decay2025-02-25 (CelesTrak SATCAT)
Observed lifetime78 days
Initial orbit~415 km circular, 51.6° incl (ISS orbit)

Scenarios

Section titled “Scenarios”

3 グループ × 複数の大気モデル / 弾道係数で比較:

Group 1: Predictive (打上げ前情報のみ)

Section titled “Group 1: Predictive (打上げ前情報のみ)”
#AtmosphereSpace WeatherB [m²/kg]
AExponential—0.015
BHarris-Priester—0.015
CNRLMSISE-00ConstantWeather(F10.7=170, Ap=15)0.015

Group 2: Launch-day (打上げ時データでカットオフ)

Section titled “Group 2: Launch-day (打上げ時データでカットオフ)”

CSSI 実測データを打上げ日で truncate_after() し、それ以降は最終日の値で外挿。

#AtmosphereSpace WeatherB [m²/kg]
DNRLMSISE-00CSSI@launch0.015
ENRLMSISE-00CSSI@launch0.012
FNRLMSISE-00CSSI@launch0.018

Group 3: Retrospective (後出し実測データ)

Section titled “Group 3: Retrospective (後出し実測データ)”

decay 後に取得した CSSI 実測データをフルに使用。

#AtmosphereSpace WeatherB [m²/kg]
GNRLMSISE-00CSSI(full)0.015
HNRLMSISE-00CSSI(full)0.018

Ballistic coefficient

Section titled “Ballistic coefficient”

弾道係数 B = Cd·A/(2m) の推定:

  • Cd = 2.2 — LEO 標準値 (Vallado, 4th ed. §8.6.2)
  • A = 0.132 m² — bus body (0.061 m²) + deployed SAP 2 wings (0.071 m²), tumbling average
  • m = 10 kg — ArkEdge Space “10 kg class” 6U bus

→ B = 0.015 m²/kg (nominal), ±20% mass uncertainty で 0.012–0.018

Results

Section titled “Results”
  Group | # |  Atmosphere |    Weather | B [m2/kg] | Lifetime | vs Observed
  ------+---+-------------+------------+-----------+----------+------------
   Pred | A | Exponential |          - |     0.015 |   234 days |   +156 days
   Pred | B |         H-P |          - |     0.015 |   124 days |    +46 days
   Pred | C | NRLMSISE-00 | Const(170) |     0.015 |   105 days |    +27 days
  Launch | D | NRLMSISE-00 | CSSI@launch |     0.015 |    87 days |     +9 days
  Launch | E | NRLMSISE-00 | CSSI@launch |     0.012 |   106 days |    +28 days
  Launch | F | NRLMSISE-00 | CSSI@launch |     0.018 |    73 days |     -5 days
  Retro | G | NRLMSISE-00 | CSSI(full) |     0.015 |    92 days |    +14 days
  Retro | H | NRLMSISE-00 | CSSI(full) |     0.018 |    76 days |     -2 days
  ------+---+-------------+------------+-----------+----------+------------
                 Observed                               78 days

Nominal B=0.015 + 打上げ時 CSSI データで +9 days (+12%) の精度。

Usage

Section titled “Usage”
Terminal window
# Group 1 (predictive) only
cargo run --example orbital_lifetime -p orts


# All groups (requires network for CSSI fetch)
cargo run --example orbital_lifetime -p orts --features fetch-weather


# Generate plot
cargo run --bin orts -- convert --format csv \
    orts/examples/orbital_lifetime/orbital_lifetime.rrd \
    --output orts/examples/orbital_lifetime/orbital_lifetime.csv
uv run orts/examples/orbital_lifetime/plot_altitude.py

References

Section titled “References”