🔁 Repeat Ground Track Orbit Designer

Ground-track shift · exact R revs / D days repeat altitude · J2 included

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Current Orbit

Ground-Track Analysis

Inclination used
– deg
Nodal period
– min
Revs per nodal day
– rev
Ground-track shift / rev
– deg W
Equator spacing / rev
– km

Repeat Solver

Solves the circular altitude whose ground track repeats exactly after R revolutions in D nodal days, with the inclination mode chosen above.

按上方选定的倾角模式，求解地面轨迹恰好在 D 天内 R 圈后重复的圆轨道高度。

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📖 How to use

  1. Enter the altitude and choose the inclination mode — sun-synchronous (i follows altitude) or fixed.输入高度并选择倾角模式——太阳同步（倾角随高度）或固定倾角。
  2. Read the revs per nodal day and the westward shift per rev; the table lists the nearest exact repeat cycles and the altitude that achieves each.读取每交点日圈数与每圈西移量；表格列出最近的精确回归周期及其对应高度。
  3. Or ask directly: enter R revs / D days in the solver — e.g. Landsat uses 233/16 at ≈ 705 km.也可直接反解：在求解器中输入 R 圈 / D 天——如 Landsat 为 233/16，高度约 705 km。
  4. Check the resulting equator spacing against your payload swath in Coverage & Swath to confirm full coverage within one cycle.把回归周期内的赤道条带间距与覆盖与幅宽工具算出的载荷幅宽对比，确认一个周期内能无缝覆盖。

Repeat ground track condition

Per nodal revolution the ground track shifts westward by ΔL = (ω_E − Ω̇)·T_node, where Tnode = 2π/(Ṁ + ω̇) is the draconitic period and Ω̇, ω̇, Ṁ include J2 secular rates. The track repeats exactly when

R · ΔL = D · 2π — R revolutions span D nodal days.

Writing R/D = k + q as integer-plus-fraction (e.g. 233/16 = 14 + 9/16) shows the daily pattern: the track advances by the sub-cycle fraction each day and closes after D days. The solver bisects on altitude, re-evaluating the SSO inclination at each step when coupled.

All computation runs locally in your browser.

回归轨道条件

每交点圈地面轨迹西移 ΔL = (ω_E − Ω̇)·T_node，其中交点周期 Tnode = 2π/(Ṁ + ω̇)，且 Ω̇、ω̇、Ṁ 含 J2 长期项。当满足

R · ΔL = D · 2π（R 圈恰好跨 D 个交点日）时轨迹精确重复。

把 R/D 写成整数加分数（如 233/16 = 14 + 9/16）即可看出逐日推进规律：轨迹每天推进一个子周期分数，D 天后闭合。求解器对高度做二分迭代，太阳同步模式下每步重算倾角。

全部计算在你的浏览器本地完成。