Jason-3's orbit will be identical to that of Jason-1 and Jason-2 (and of Topex/Poseidon's before september 2002). It is optimised to study large-scale ocean variability and to provide coverage of 90% of the world's oceans over a ten-day cycle.

Choice of orbit

Jason's high altitude (1 336 kilometers) reduces interactions with the Earth's atmosphere and gravity field to a minimum, thus making orbit determination easier and more precise. The orbit inclination of 66 degrees north and south enables the satellite to cover most of the globe's unfrozen oceans. The orbit's repeat cycle is just under 10 days (9.9156 days to be precise, i.e., 10 days minus two hours)-in other words, the satellite passes over the same point on the Earth's surface (to within one kilometer) every ten days. This cycle is a trade-off between spatial and temporal resolution designed for the study of large-scale ocean variability. The fact that the orbit is prograde and not sun-synchronous also avoids aliasing of different tide components at the same frequency.

Further, using the same orbit as Jason-2 will ensure better intercalibration and data continuity. The orbit is also designed to pass over two dedicated ground calibration sites : Cap Senetosa in Corsica and the Harvest oil rig platform in California, USA.

Manoeuvers

A satellite's orbit parameters tend to change over time as a result of atmospheric drag. In the long term, more or less periodic variations also occur due to instabilities in the Earth's gravity field, solar radiation pressure, and other forces of smaller magnitude.

Orbit manoeuvers are performed every 40 to 200 days. Intervals between maneuvers depend chiefly on solar flux and each manoeuver lasts 20 to 60 minutes.They are performed above solid earth, so that lost data acquisition time is reduced to a minimum.

Pass locator

Referenced orbit Jason-3

Orbit parameters