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).

Attached thumbnail(s)

 

[Phil Stooke]

I'm looking forward to seeing some whole-frame images during the departure, a different view than we had during the approach.

Phil

[dilo]

Based on simulated viewer and yesterday's Marc report, engines were ON for more than 24 hours and, as showed in the following plots, Dawn orbit is rapidly changing:

Last apoapsis was 776.5 km above Vesta surface, about 63 km above HAMO2 in last days... Total energy is clearly increasing too, however departure phase will last more than a month.
Meanwhile, starting from Phil idea, I made these compositions of last 3 posted images in the "revealing shadows" series:

(first one is in Oppia quadrangle and latter two inside Marcia quadrangle). Consider that, for shadowed region, besides the different hue I used negative image in order to have an illumination roughly coherent with illuminated part.

[dilo]

Further update on escape maneuver:

Dawn is rapidly receding from HAMO orbit thanks to uninterrupted engine thrust; based on simulator figures, during last orbit there was an increase of apoapsis/periapsis heights of 57.9/59.3 km (a rising rate greather than 80 km/day); total energy/mass increased by 2.1 kJ/Kg in 4 days.

Added: same processing for the 5th image of "revealing shadows" series, in the Floronia quadrangle:

[dilo]

Further update:

The first engine stop, on July 31, lasted less than 15 hours and, after this, energy increase was very regular.

[dilo]

The second engine stop, on Aug 2-4, was longer (between 30 and 45 hours) and, probably, was used to map the northern emisphere; in fact Dawn flied twice above North Pole at an estimated height of 1450 km (considering Vesta shape).
Herebelow last two "revealing shadow" processed images, from Caparronia and Floronia quadrangles, respectively: