Ground
A book for the wait, and for the leaving.
Launch windows, Earth time, and the road to Mars.
Hohmann transfer
Next Earth–Mars window
Optimal ballistic departure Sep 15 2026. Arrival about May 31 2027 after a 259-day cruise. Practical windows span roughly three weeks around the peak.
20711
Days
0
Hrs
0
Min
0
Sec
Opposition Aug 10 1971 · 586 days out
Ephemeris
Earth–Mars range
Separation
1.576 AU
235.8 million km
One-way light
13m 07s
26m 13s round-trip
Earth 0.983 AU from Sun
Mars 1.416 AU from Sun
Chronometers
Two worlds, one instant
Earth · UTC
00:00:00
Thu Jan 1 1970
Mars · MTC
07:04:53
MSD 34127.295
Curiosity sol 0 · Perseverance sol 0 · Ls 315.0°
Sky
Now
Lunar
Last Quarter
45%
illuminated
383 thousand km · 22.6 days since new
Gateway, not destination. Transit to lunar orbit is always open; about three days.
Navigator
Today's brief
A short reading of this epoch from your station. Uses the live almanac numbers — it will not invent a weather report.
Stationed on Earth.
Leaves of the book
Almanac notes
- A Martian sol is 39 minutes 35 seconds longer than an Earth day.
- Surface gravity is 38% of Earth's — 38%.
- Solar constant at Mars is about 43% of Earth's, varying with the eccentric orbit.
- Synodic Earth–Mars period is 780 days, so launch seasons repeat every 26 months.
- Regional storms are common in southern spring and summer.