Dawn at Ceres Thread

[lajoswinkler]

Even less exposed photo of the spots.

[KerikBalm]

Is that a new photo, or did you just digitally manipulate it like I did?

Seems to be even brighter relative to the background that the image I posted (in which I said it may be even brighter relative to the background because the source was overexposed)

Whatever it is... its albedo must be pretty high...

I dare say its white or shiny, and not just less dull than everything else

Edited June 29, 2015 by KerikBalm

[lajoswinkler]

Nah, it's the real deal.

http://photojournal.jpl.nasa.gov/catalog/PIA19584

I'd say it's albedo is similar to these rocks'.

[KerikBalm]

The contrast shown in that ceres image... to me... seems more than the contrast you'd get between coal and those rocks (granite, I assume).

Are you assuming the rest of ceres has an albedo lower than coal? or do you think I over estimate the albedo difference?

[lajoswinkler]

I think you're underestimating the albedo of these rocks.

[smjjames]

I wonder if theres any plans for a Ceres lander or rover because that's what I would send next.

Probably a lander or two at first to get a better idea of the surface before sending a rover.

[Red Iron Crown]

I wonder if theres any plans for a Ceres lander or rover because that's what I would send next.

Probably a lander or two at first to get a better idea of the surface before sending a rover.

A rover would be tricky, Ceres' surface gravity is only 3% of Earth's which would make traction difficult. Landers might have to grab the surface somehow, much like Philae.

[StrandedonEarth]

Apod has a great pic of Ceres today.

Edited July 1, 2015 by StrandedonEarth

[lajoswinkler]

I'd send a spiderlike robot there. Something that does not care much about flipping.

[KerikBalm]

A cubli like robot could work well too, I think... just little hops around, and reaction wheels that can always flip it into the right orientation

[Kryten]

I wonder if theres any plans for a Ceres lander or rover because that's what I would send next.

Probably a lander or two at first to get a better idea of the surface before sending a rover.

Not possible to add to New Frontiers potential missions list before the next decadal survey (2023). Could be proposed for discovery, but it would be difficult to produce one with that cost cap, and harder to produce one that could outcompete missions to easier targets.

[Frida Space]

Another photo of the mysterious mountain

[smjjames]

I wonder what a shield volcano would look like with Ceres gravity.

[Frida Space]

Today Dawn left its Survey Orbit at 4400 km from Ceres.

Some stats on its next orbit, the High Altitude Mapping Orbit (HAMO):

- Dawn will reach it on August 4, 2015...

- ...and stay there until October 15, 2015

- Altitude: 1450 km

- Resolution: 140 m/pixel (compared to 410 in Survey Orbit), that's 72x Hubble's

- Orbital Period: 19h (compared to 3.1 day in Survey Orbit)

Some stats from the Survey Orbit campaign, June 5-30:

- Mapped: bright spots and bright areas; sharp and fresh, soft and aged craters with and without central peaks and terraced walls, 5-km tall mountains, crust-cooling and impact canyons etc.

- 1600+ pictures

- 5+ million visible and infrared spectra

- 100s of hours of gravity measurements

- 3 glitches (two of VIR, one of the camera)

Sources: 1 and 2

[KerikBalm]

So, according to wikipedia, the albedo of the bright spots is 0.4 ... citing an astronomy lecture...

"Snow albedo is highly variable, ranging from as high as 0.9 for freshly fallen snow, to about 0.4 for melting snow, and as low as 0.2 for dirty snow.[21] Over Antarctica they average a little more than 0.8"

So... well... maybe its not so white... not like enceledus...

But the spot albedo is greater than any planet's average except venus...

[Mighty1]

Does Dawn have any cameras that could point at the Earth and not have it blurry.

http://static.tweakers.net/ext/f/8E0fim1f5ODNRqf5g7LWz8Xy/full.png

Earth, Venus and Jupiter are quite close in the Ceres sky riht now

[Kryten]

They aren't all that close. That image assumes circular orbits and equal distances between planets, it's not a good model for basically anything.

[Frida Space]

Earth, Venus and Jupiter are quite close in the Ceres sky riht now

From Marc Rayman:

On July 22, Earth and Dawn will be at their closest since June 2014. As Earth laps Ceres, they will be 1.94 AU (180 million miles, or 290 million kilometers) apart. Earth will race ahead on its tight orbit around the sun, and they will be more than twice as far apart early next year.

[Camacha]

They aren't all that close.

It seems you left out the bit where you tell us how you reached this conclusion

On July 22, Earth and Dawn will be at their closest since June 2014. As Earth laps Ceres, they will be 1.94 AU (180 million miles, or 290 million kilometers) apart. Earth will race ahead on its tight orbit around the sun, and they will be more than twice as far apart early next year.

This is about apparent positions as seen from Ceres (i.e. conjunction), not about physical distance.

Edited July 2, 2015 by Camacha

[Kryten]

It seems you left out the bit where you tell us how you reached this conclusion

The fact that planetary orbits aren't circular or remotely equally spaced? Slot in the real distances and it'll look nothing like that.

[Frida Space]

Sorry, the term "blurry" used in this context confused me. However, let's just say this: no, engineers definitely won't want to point the Framing Camera anywhere near Earth, 'cause the Sun's nearby too.

In fact, here you go:

[Camacha]

The fact that planetary orbits aren't circular or remotely equally spaced? Slot in the real distances and it'll look nothing like that.

Instead of speculating, I looked into it and it seems you actually can group Venus, Jupiter and Earth together in a somewhat decent fashion. However, it appears you have to choose a close conjunction between two, or a looser constellation of three, though I suspect it might be close enough for Dawn to make a nice group shot. At one point in May even Mercury could be included, though that admittedly made it a bit of a broad spread.

It does seem the best moment has already passed, though. This is June 8 (not the closest point):

Sorry, the term "blurry" used in this context confused me. However, let's just say this: no, engineers definitely won't want to point the Framing Camera anywhere near Earth, 'cause the Sun's nearby too.

Fair point, though I am unsure how much damage the sun does that far out, and whether that is an issue when not directly pointing at it.

Edited July 2, 2015 by Camacha

[LordFerret]

http://photojournal.jpl.nasa.gov/jpeg/PIA19586.jpg

Another photo of the mysterious mountain

Using Gimp to enlarge the image and take a look, it kind of reminds me of a frost heave.

[Frida Space]

So yea, safe modes FTW!

www.jpl.nasa.gov/news/news.php?feature=4649

NASA's Dawn spacecraft is healthy and stable, after experiencing an anomaly in the system that controls its orientation. It is still in its second mapping orbit 2,700 miles (4,400 kilometers) above dwarf planet Ceres.

On June 30, shortly after turning on its ion engine to begin the gradual spiral down to the next mapping orbit, its protective software detected the anomaly. Dawn responded as designed by stopping all activities (including thrusting), reconfiguring its systems to safe mode and transmitting a radio signal to request further instructions. On July 1 and 2, engineers made configuration changes needed to return the spacecraft to its normal operating mode. The spacecraft is out of safe mode, using the main antenna to communicate with Earth.

Dawn will remain at its current orbital altitude until the operations team has completed an analysis of what occurred and has updated the flight plan.

Because of the versatility of Dawn's ion propulsion system and the flexibility of the mission's plan for exploring Ceres, there is no special "window" for starting or completing the spiral to the third mapping orbit. The plans for the third and fourth mapping orbits can be shifted to new dates without significant changes in objectives or productivity.

Edited July 7, 2015 by Frida Space

[LordFerret]

Interesting. Now define the anomaly. I'm wondering if by chance it's the same that hit New Horizons.