Dawn Cruise Options

[SkyeLab]

Pushing out of Earth orbit now...........

[peter59]

I nearly forgot about these cancelled missions.

Pre-Dawn: The French-Soviet VESTA mission

Very interesting three proposed trajectory for two spacecrafts.

Trajectory 1:
-launch from Earth
-Mars gravity assist
-flyby of 2335 James (a 10 km X-type asteroid) (an Amor-asteroid)
-Mars gravity assist
-109 Felicitas (C-type, 76 km)
-739 Mandeville (EMP(?) type, 110 km)
-4 Vesta (V-type, or Vestoid. Has a diameter of 570 km) flyby with 3.5 km/s. A penetrator is released.
Total delta-v: 450 m/s

Trajectory 2:
-launch from Earth
-Mars gravity assist
-flyby of the P/Tritton short period comet
-Mars gravity assist
-2087 Kochera (30 km?)
-1 Ceres (flyby & releasing a penetrator)
Total delta-v: 1150 m/s

Trajectory 3:
-launch from Earth
-Mars gravity assist
-1204 Renzia (10 km?) (an Amor-asteroid)
-Mars gravity assist
-435 Ella (U type, 30 km)
-46 Hestia (F type, 165 km)
-135 Hertha (M type, 80 km)
Total delta-v: 350 m/s

[dmuller]

Pre-Dawn: The French-Soviet VESTA mission

I noticed the following paragraph in the above article:

I've heard it's not ruled out that Dawn will be directed to rendezvous with 2 Pallas (for a slow flyby) in 2018, after the main mission at Vesta and Ceres is completed and enough fuel is left.

Is that possibly still on the cards?

[3488]

I'm just pleased that we get regular updates on the mission.
The possible post-main mission rendezvous with Pallas hasn't been mentioned for a while, but IIRC the mechanics of setting it up are difficult due to Pallas' orbit being appreciably out of ecliptic.
Maybe the mission planners are going to present the relevant trajectories as a fait accompli when they're lobbying for that mission extension...

I hope so. In December 2018, 2 Palles is on the descending node. In fact DAWN would not even have to leave the plane of 1 Cere's orbit to do this, as 2 Pallas will intersect that plane. The biggest issues will be the supply of Xenon, & the state of the solar arrays, will they still be producing enough power?

I really, really hope that the 2 Pallas option stays open. To bag all three of the Asteroid Belt's largest members would be a real accomplishment. However 2 Pallas would not be orbited, but could be a slow encounter, enabling much of the giant asteroid to be seen at a fairly high resolution.

Whilst 4 Vesta & 1 Ceres are primary mission aims, I think to not lose sight of 2 Pallas as an encore right at the very end, would be worthwhile.

No decent Hubble Space Telescope images exist of 2 Pallas do they, or have I not been able to find them?

Andrew Brown.

[Del Palmer]

No decent Hubble Space Telescope images exist of 2 Pallas do they, or have I not been able to find them?

Depends what you mean by "decent." I don't recall seeing any press release images of Pallas from STScI, but there is a set of WFPC2 images in the MAST archive. Looks like they were taken using gyro-guiding, and so the targeting was a little off...

[3488]

from http://www.lpi.usra.edu/meetings/lpsc2008/pdf/2502.pdf

"Figure 1: Pallas imaged by HST in 336nm UV filter."

Thank you very much Dan,

I tried, high & low to find HST imagery of 2 Pallas. I had heard before that the triaxial shape had been determined from rotational light curves. That is a very good image & quite clearly shows a rounded triangular profile, the best I've ever seen of this gigantic asteroid.

I've downloaded the image.

Depends what you mean by "decent." I don't recall seeing any press release images of Pallas from STScI, but there is a set of WFPC2 images in the MAST archive. Looks like they were taken using gyro-guiding, and so the targeting was a little off...

Thank you very much Del also for your help.

The scientific case for DAWN to go onto 2 Pallas after the end of the primary mission is compelling.

It's great to be back here, hopefully I can contribute something of interest at some point.

Andrew Brown.

[tedstryk]

This is another Hubble view. During the 2001 observations, the Hubble missed Pallas with its Planetary Camera chip, getting the image with its lower-resolution wide field portion of WFPC2.