⏳ Orbit Lifetime & Drag Decay Calculator

Drag decay integration · lifetime estimate · drag make-up Δv · 25-year rule check

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Spacecraft & Orbit

Results

Ballistic coefficient
– kg/m²
Density @ altitude
– kg/m³
Initial decay rate
– km/yr
Estimated lifetime
–
Drag make-up Δv
– m/s/yr
25-year rule
–
–

Altitude vs Time

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📖 How to use

  1. Enter the altitude, mass, average projected drag area and C_d (2.2 if unknown).输入高度、质量、平均迎风阻力面积与 C_d（不确定时取 2.2）。
  2. Pick a solar activity level — LEO density varies by an order of magnitude over the 11-year cycle, so check both moderate and high.选择太阳活动水平——LEO 大气密度随 11 年周期变化可达一个量级，建议中、高两档都算。
  3. Read the lifetime and the 25-year rule verdict; the chart shows altitude vs time to re-entry (integration stops at 150 km).读取寿命与 25 年规则结论；曲线为高度-时间衰减过程（积分至 150 km 终止）。
  4. The drag make-up Δv is what propulsion must supply per year to hold the altitude — feed it into your Δv budget.“阻力补偿 Δv”为每年维持轨道高度所需速度增量——请计入 Δv 预算。

Drag decay model

For a circular orbit the semi-major axis decays at da/dt = −ρ·√(μa)·(C_d·A/m). The tool integrates this from the initial altitude down to 150 km, interpolating log-density in a reference table (CIRA/SMAD-class values) for the selected solar activity.

Drag make-up: continuous compensation of the drag deceleration a_D = ½·ρ·v²·C_d·A/m gives Δv/year = a_D · 31.6×10⁶ s.

Accuracy: real lifetimes vary with the actual solar cycle phase, attitude history and density model — treat results as order-of-magnitude (±50% is typical even for professional tools). For compliance filings use a full propagator (e.g. NASA DAS/ORSAT-class analysis).

All computation runs locally in your browser.

阻力衰减模型

圆轨道半长轴衰减率为 da/dt = −ρ·√(μa)·(C_d·A/m)。工具从初始高度积分至 150 km，密度按所选太阳活动水平在参考密度表（CIRA/SMAD 量级）中做对数插值。

阻力补偿：连续抵消阻力减速度 a_D = ½·ρ·v²·C_d·A/m，得 Δv/年 = a_D · 31.6×10⁶ s。

精度说明：实际寿命取决于太阳周期相位、姿态历史与密度模型——结果应视为量级估计（专业工具也常有 ±50% 偏差）。正式的空间碎片合规分析请使用完整轨道递推工具（如 NASA DAS/ORSAT 级）。

全部计算在你的浏览器本地完成。