IPB

Welcome Guest ( Log In | Register )

2 Pages V   1 2 >  
Reply to this topicStart new topic
2 Pallas
Paolo
post Oct 11 2009, 08:49 AM
Post #1


Senior Member
****

Group: Members
Posts: 1729
Joined: 3-August 06
From: 43° 35' 53" N 1° 26' 35" E
Member No.: 1004



no one seems to have noticed this
http://www.sciencemag.org/cgi/content/abstract/326/5950/275
Go to the top of the page
 
+Quote Post
nprev
post Oct 11 2009, 08:57 AM
Post #2


Merciless Robot
****

Group: Admin
Posts: 8783
Joined: 8-December 05
From: Los Angeles
Member No.: 602



Well, well, well! Guess it's extremely premature to start lobbying for an XM for Dawn, but hopefully some wheels are turning in that regard already.


--------------------
A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
Go to the top of the page
 
+Quote Post
Paolo
post Oct 11 2009, 10:55 AM
Post #3


Senior Member
****

Group: Members
Posts: 1729
Joined: 3-August 06
From: 43° 35' 53" N 1° 26' 35" E
Member No.: 1004



I discussed about this with Mark Rayman a few weeks ago and he told me that

QUOTE
There has never been an investigation into a flyby of Pallas
Go to the top of the page
 
+Quote Post
vjkane
post Oct 12 2009, 05:03 AM
Post #4


Member
***

Group: Members
Posts: 704
Joined: 22-April 05
Member No.: 351



QUOTE (nprev @ Oct 11 2009, 09:57 AM) *
Well, well, well! Guess it's extremely premature to start lobbying for an XM for Dawn, but hopefully some wheels are turning in that regard already.

Ancient memory suggest that 2 Pallas orbits in an inclined orbit. If the memory chips are still functioning, this would make it hard...


--------------------
Go to the top of the page
 
+Quote Post
nprev
post Oct 12 2009, 05:11 AM
Post #5


Merciless Robot
****

Group: Admin
Posts: 8783
Joined: 8-December 05
From: Los Angeles
Member No.: 602



I was thinking that it was maybe a few degrees off the ecliptic, but it's actually 35(!) freakin' degrees! Good trace memory, VJ.

Guess a flyby by Dawn might still be technically possible if Pallas is doing a plane crossing at the right time & place with respect to the spacecraft, but the whole thing sounds unlikely to the point of ain't-gonna-happen. Oh, well.


--------------------
A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
Go to the top of the page
 
+Quote Post
Paolo
post Oct 12 2009, 05:38 AM
Post #6


Senior Member
****

Group: Members
Posts: 1729
Joined: 3-August 06
From: 43° 35' 53" N 1° 26' 35" E
Member No.: 1004



From Wikipedia

QUOTE
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.
Go to the top of the page
 
+Quote Post
tedstryk
post Oct 12 2009, 02:54 PM
Post #7


Interplanetary Dumpster Diver
****

Group: Admin
Posts: 4404
Joined: 17-February 04
From: Powell, TN
Member No.: 33



There was a blurb about a Pallas encounter that briefly appeared on Astronomy Now's website back before DAWN launched, but it was pulled within a few hours of being posted.


--------------------
Go to the top of the page
 
+Quote Post
vjkane
post Oct 12 2009, 04:19 PM
Post #8


Member
***

Group: Members
Posts: 704
Joined: 22-April 05
Member No.: 351



QUOTE (tedstryk @ Oct 12 2009, 03:54 PM) *
There was a blurb about a Pallas encounter that briefly appeared on Astronomy Now's website back before DAWN launched, but it was pulled within a few hours of being posted.

There has been talk from time to time about Dawn extended missions. The official blurb put out awhile ago is that any planning now is premature. The team will want to see how long they spend at Ceres, how much fuel is left, and what the efficiency of the engines will be at that distance from the sun. Very different than normal ballistic missions.


--------------------
Go to the top of the page
 
+Quote Post
PaulM
post Oct 12 2009, 07:34 PM
Post #9


Member
***

Group: Members
Posts: 206
Joined: 15-August 07
From: Shrewsbury, Shropshire
Member No.: 3233



I wonder if the Indians or Chinese have considered a flyby of 2 Pallas? Indian and Chinese missions to the Moon and Mars will never generate the public interest that would result from sending a spacecraft past a new Solar System body.

2 Pallas is one of the biggest objects in the Asteroid belt and so I am sure would have interesting and varied landscapes. For me the mission that really put the Japanese Space Agency on the map was Hayabusa because Itokawa was unlike any Solar System body visited before.
Go to the top of the page
 
+Quote Post
Paolo
post Oct 14 2009, 06:17 PM
Post #10


Senior Member
****

Group: Members
Posts: 1729
Joined: 3-August 06
From: 43° 35' 53" N 1° 26' 35" E
Member No.: 1004



Note also this LPSC paper http://www.lpi.usra.edu/meetings/lpsc2009/pdf/2421.pdf
and its thanks to "STSCI and the Dawn mission for supporting this work."
Go to the top of the page
 
+Quote Post
djellison
post Oct 15 2009, 07:01 AM
Post #11


Founder
****

Group: Chairman
Posts: 14431
Joined: 8-February 04
Member No.: 1



A series of barely funny but fairly inappropriate posts have been culled.
Go to the top of the page
 
+Quote Post
Paolo
post Dec 21 2009, 06:43 AM
Post #12


Senior Member
****

Group: Members
Posts: 1729
Joined: 3-August 06
From: 43° 35' 53" N 1° 26' 35" E
Member No.: 1004



On ArXiv today: Physical Properties of (2) Pallas
Go to the top of the page
 
+Quote Post
nprev
post Dec 21 2009, 06:55 AM
Post #13


Merciless Robot
****

Group: Admin
Posts: 8783
Joined: 8-December 05
From: Los Angeles
Member No.: 602



Huh. Almost the same average density as Mars.

Hate to say it, but it's probably dry as a bone....metal-rich, though.


--------------------
A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
Go to the top of the page
 
+Quote Post
elakdawalla
post Dec 22 2009, 06:05 PM
Post #14


Administrator
****

Group: Admin
Posts: 5172
Joined: 4-August 05
From: Pasadena, CA, USA, Earth
Member No.: 454



Thanks very much for the pointer to that article, Paolo.

Of interest to some of the 3D modeling types here might be this website mentioned in the article, which has a database that currently includes 179 shape models for 112 asteroids.

http://astro.troja.mff.cuni.cz/projects/asteroids3D/web.php

--Emily


--------------------
My website - My Patreon - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
Go to the top of the page
 
+Quote Post
HSchirmer
post Apr 24 2016, 12:06 AM
Post #15


Member
***

Group: Members
Posts: 684
Joined: 24-July 15
Member No.: 7619



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.
Go to the top of the page
 
+Quote Post

2 Pages V   1 2 >
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 19th March 2024 - 10:18 AM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member.