How far did the Mars Polar Lander travel in its journey to the red planet?

I couldn't find the answer on Wikipedia or on the official NASA site.

I'd prefer some answer based on a good source, or rough arc-length calculation, rather than just multiplying its velocity times 11 months or something like that.

  • $\begingroup$ Interesting question! I thought I'd just download daily or hourly positions from Horizons and add up the lengths of the segments, but I can't find the spacecraft listed there. Maybe someone else can find some historical files? $\endgroup$
    – uhoh
    Commented Dec 12, 2017 at 3:29
  • $\begingroup$ In what reference frame? $\endgroup$ Commented Dec 12, 2017 at 5:27

1 Answer 1


For those not aware, Mars Polar Lander took what is known as a "Type II" transfer orbit to Mars, a lower-energy transfer that took over 11 months, whereby the spacecraft traveled more than 180° around the sun. This is illustrated in this image on the Mars Polar Lander — Cruise Phase webpage:

Mars Polar Lander Trajectoy Design

Mars Polar Lander will spend 11 months in cruise, entering Mars' atmosphere December 3, 1999. The spacecraft's flight path is called a Type 2 trajectory because it will take the lander more than 180 degrees around the Sun, enabling it to target a landing zone near Mars' south pole. By comparison, Mars Pathfinder followed a Type 1 trajectory which took it less than 180 degrees around the Sun, reaching Mars in only seven months. During the first leg of its trip, Mars Polar Lander will fly slightly inward toward the Sun before spiralling out beyond Earth's orbit to Mars. Toward the end of cruise, it will fly slightly out past the orbit of Mars before returning inward to intersect the planet's orbit.

As far as I can tell, this is the longest Earth-Mars transfer trajectory ever taken for a Mars-bound spacecraft.

Your answer, however, lies in the official Mars Polar Lander/Deep Space 2 press kit on page six: 470 million miles (757 million km).

Sadly, the last 40 metres of that journey were a bit problematic.


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