Dawn Cruise Options

[machi]

Dawn is about 5 million kilometers away now. How close will it have to be before its highest magnification cameras will be able to get the best ever images (so far) of Vesta? I don't know much about the imaging systems on this craft.

I don't know exact resolution of HST or 8-10m class telescopes. My guess is about 50 km/pix. Framing Cameras onboard Dawn have resolution 1 km from distance 10 750 km. So Dawn must be more closely than ~500 000 km to Vesta.

[Holder of the Tw...]

As was discussed earlier on this thread, DAWN will begin to match the resolution of the best Hubble images around early June. The best from Hubble was from May of 1996, when approximately 35 km/pixel resolution on the .04 arcsec per pixel camera was achieved. You will have to get closer (as machi said) than about half a million km from Vesta to match this. The two identical framing cameras on DAWN only have about three times the resolution of normal human eyes.

[antoniseb]

... The two identical framing cameras on DAWN only have about three times the resolution of normal human eyes.

Alas, I've been spoiled by MRO's HiRES. I start now trying to regain realistic hopes for what Dawn will show.

[qraal]

Hurry up! (said like Blackboard from Mr. Squiggle... a uniquely Australian children's show)

Vesta will, no doubt, be a fascinating little world, but I'm hanging out for amazing scenes from Ceres. Both are rather odd, even so. Basalt! On an asteroid, no less.

[Holder of the Tw...]

A little bit of trivia to pass the time while we're waiting.

In the first week of December 2012, about five months after DAWN leaves Vesta, and around twenty-six months before it arrives at Ceres, while it is enroute from one to the other, Ceres and Vesta will be having their own close encounter with each other. At that time they will be 0.390 a.u. (58,300,000 km or 36,200,000 miles) apart. Ceres as seen from Vesta will be a 3.9 magnitude object in the constellation Ursa Major, and Vesta as seen from Ceres will be magnitude 4.2 (41 percent phase) in Piscis Austrinus.

Ceres, however, will not be in opposition to Vesta at that time. That will occur fully fifteen months later in March 2014, when they will be 0.401 a.u.apart.

The 2012 close approach will be the closest the two have been since November 1892, when they were separated by 0.373 a.u. They will not be this close again until November 2081, when they will pull within 0.284 a.u.

All this according to "Starry Night", anyway.

[Stefan]

MPS press release.

[MarkG]

At its current distance from Dawn, Vesta is only maybe about 3 pixels wide in the framing cameras, not much fun yet. At some point, there will be navigational benefit from the cameras, but I'm unsure when that starts.

It is indeed encouraging to see that the cameras are operational again after all this time in the cold irradiated vacuum of space. Congrats to the Dawn teams!

[Greg Hullender]

New Dawn Journal: http://www.dawn-mission.org/mission/journal_03_31_11.asp


Apparently their big task for March was to calibrate the thusters. Since the thust is so gentle, they cannot measure it directly, so there's a trick to it.

--Greg

[stevesliva]

This is cute:



Clickable for info.

[Decepticon]

All I can find in terms of arrival is July 2011.

Is there a projected date plus or minus?

[elakdawalla]

The date of "arrival" is still kind of up in the air, though I think it's unlikely to be more than a few days before or after July 16. It depends on a lot of factors -- thrusting time trades off with other useful activities on the spacecraft. They may know internally by now but haven't specified a date publicly. Anyway, Dawn doesn't so much arrive as it wanders into Vesta's neighborhood; pictures from orbit won't really look much different from pictures from approach until they start spiraling down.

[Greg Hullender]

Not final for a week or two, but the current plan looks something like this:

First optical images: May 3 (5 pixels wide, but up to 12 by end of month)

Arrival: July 17

Survey Orbit: August 8

--Greg

[bagelverse]

Yeah, just in time for my birthday.

Full inline quote removed - ADMIN

[elakdawalla]

New topic for the Vesta Approach phase of Dawn's mission here...

[belleraphon1]

Dawn Operating Normally After Safe Mode Triggered 09/11/2014
http://www.nasa.gov/jpl/dawn/operating-nor...mode-triggered/

Engineers immediately began working to restore the spacecraft to its normal operational state. The team determined the source of the problems, corrected them, and then resumed normal ion thrusting on Monday night, Sept. 15.

As a result of the change in the thrust plan, Dawn will enter into orbit around dwarf planet Ceres in April 2015, about a month later than previously planned. The plans for exploring Ceres once the spacecraft is in orbit, however, are not affected.