r2s2

r2s2 is a cislunar space-time coordinate transformation library supporting conversions between various coordinate systems.

Main Features

  • Space-Time Coordinate Conversion: Supports conversion between common cislunar coordinate systems
  • Time System Conversion: TT, TAI, UTC, UT1 and other time systems
  • Epoch Conversion: Julian Date, Modified Julian Date, time tags
  • Coordinate System Definitions: J2000, EME2000, ICRF, etc.

Installation

pip install r2s2

Supported Coordinate Systems

Coordinate SystemDescription
J2000J2000.0 Mean Equator Coordinate System
EME2000Earth Mean Equator 2000
ICRFInternational Celestial Reference Frame
LVLHLocal Vertical Local Horizontal
RTNRadial-Tangential-Normal

Supported Time Systems

Time SystemDescription
TTTerrestrial Time
TAIInternational Atomic Time
UTCCoordinated Universal Time
UT1Universal Time
JDJulian Date
MJDModified Julian Date

Example Usage

import r2s2
from r2s2 import TimeSystem, CoordinateSystem

# Time conversion
jd = r2s2.tt_to_jd(tt_time)
utc_time = r2s2.jd_to_utc(jd)

# Coordinate conversion
state_eci = [7000, 0, 0, 0, 7.5, 0]  # km, km/s
state_lvlh = r2s2.eci_to_lvlh(state_eci, position, velocity)

# Batch conversion
times = [jd, jd + 0.5, jd + 1.0]
states_eci = [...]  # ECI coordinate states
states_rtln = r2s2.batch_transform(times, states_eci, 
                                   CoordinateSystem.ECI, 
                                   CoordinateSystem.RTN)

Resources