2 Pallas Options

[Paolo]

no one seems to have noticed this
http://www.sciencemag.org/cgi/content/abstract/326/5950/275

[Paolo]

From Wikipedia

Pallas has not been visited by spacecraft, but if the Dawn probe is successful in studying 4 Vesta and 1 Ceres, it is possible its mission may be extended to include a flyby of Pallas as Pallas crosses the ecliptic. However, due to the high orbital inclination of Pallas, it will not be possible for Dawn to enter orbit.

[HSchirmer]

Since there is already a 2 Pallas thread, so I'm putting thoughts about a Dawn extended mission to Pallas here.

If Dawn leaves Ceres, could it rendezvous with Pallas? Could it orbit it?
I'm beginning to suspect it could; if Dawn can catch Pallas as Pallas crosses Ceres' orbit then it would
appear that Dawn could use a gravity assist from Pallas to match the inclination of Pallas' orbit to the ecliptic.
Once Dawn is heading in the same general direction as Pallas, it could chase down Pallas the same way
it chased down Ceres.

I think this might work because I noticed a few very interesting things about the orbits of Ceres and Pallas-
They have an almost exact 1:1 orbit resonance. Not locked exactly, but the same orbital period
Ceres = 1680 days. Pallas = 1686 days They also have essentially identical mean motion (speed).
And, yes, Pallas is at 35 degrees inclination to the ecliptic, however, Ceres is at 10 degrees.
We were able to achieve a 10 degree inclination to rendezvous with Ceres without breaking the spacecraft,
so conceptually we can do 10 degrees again, and again, and then 5 degrees.

url="http://nssdc.gsfc.nasa.gov/planetary/factsheet/asteroidfact.html"]http://nssdc.gsfc.nasa.gov/planetary/facts...teroidfact.html[/url]
Asteroid Diameter ~Mass Rotation Orbital Spectral Semimajor Orbital Orbital Number
Name (km) 1015 kg Period Period Class Axis Eccentricity Inclination and Name
1 Ceres 965 x 961 x 891 939,300 9.074 hrs 4.60 yrs C 2.768 AU 0.0758 10.59 deg
2 Pallas 582 x 556 x 500 205,000 7.813 hrs 4.61 yrs U 2.772 AU 0.2310 34.84 deg

That makes this VERY interesting- Ceres and Pallas have essentially identical orbital period and semimajor axis.
The eccentricity and inclination are different, but if I recall my physics and mechanics correctly (not guaranteed)
then the energy of the two orbits is essentially the same, it is the direction and the shape of the orbits that is different.
Essentially, the total energy of the two orbits is the same, but the eccentric orbit exchanges
gravitational potential energy for kinetic energy as Pallas goes from perihelion to aphelion and back again.

So, remember Ulysses? No it's not Bloomsday...
Ulysses the spacecraft was redirected into an out-of-the-ecliptic orbit by using a gravitational slingshot around Jupiter.
That was able to redirect the spacecraft's orbit out of the ecliptic, not much of a change in delta-V IIRC, but change in direction.

Seems that when Pallas crosses [edit the ecliptic] the plane of ceres' orbit, Dawn could do a slingshot manoeuvre to
redirect it from a Ceres-like 1686 day 10 degree orbit into an inclined Pallas-like 1680 day 35 degree orbit.