LAMO, aka Low Altitude Mapping Orbit Options

[dilo]

I think is time to start this new topic, now that Dawn is more than half-way in the transition from HAMO to LAMO (as showed in the plot below).

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[Phil Stooke]

The latest four images were posted on the same day... I check every day, believe me. We had a minibreak. But these are spectacular!

Phil

[dilo]

Updated situation, all plots:

Engines are now silent and average height is around 270 km...

[dilo]

Now that we have an improved simulator (better Vesta digital model and, especially, more frequent screen updates) I am frequently monitoring the simulated height of the probe; in the last 24 hours, engines were off but orbit isn't completely stable:

The interpolated sinusoidal curve correspond to a 5.1 hours average period between 235 and 285 km height. The reason of slight phase/amplitude variations sould be the irregular gravity field of Vesta. In fact, as explained in the last Mission Status, the purpose of these thrust stops is a natural or passive orbit adjustment (especially the orientation).

Edit: slightly modified previous text and updated plot (no orbit decay)

[dilo]

New update after two long simulator black-outs:

Based on today's status report, "The spacecraft thrusts occasionally with its ion propulsion system, but most of the time it coasts, letting Vesta's gravity reorient its orbit."
Note also that last two published images were taken 15 days ago from an intermediate distance of 480km:
http://dawn.jpl.nasa.gov/multimedia/imageo...p?date=20111123 http://dawn.jpl.nasa.gov/multimedia/imageo...p?date=20111122

[dilo]

Further update:

Dawn is almost there!

[dilo]

Now short engine burns are frequent: