Dawn Drops To 1470km Orbit, Snaps Sharper Pictures of Ceres

An anonymous reader writes: NASA's Dawn spacecraft, after an extensive series of high orbits around Ceres, has now dropped to just 1,470 kilometers over the dwarf planet's surface. It has begun an 11-day process to map the entirety of Ceres, which it will repeat several times over the next couple months. Its lower orbit now allows photo resolution of ~140 meters per pixel, and it has sent back some great images. "Engineers and scientists will also refine their measurements of Ceres' gravity field, which will help mission planners in designing Dawn's next orbit — its lowest — as well as the journey to get there. In late October, Dawn will begin spiraling toward this final orbit, which will be at an altitude of 230 miles (375 kilometers)."

Comments

The shiny thing is a mountain?

[GoodNewsJimDotCom]

That's pretty cool. Maybe it was made with an impact of another object from somewhere else. Does anyone know what the official scientists think it is?

Re:The shiny thing is a mountain?

[Tablizer]

What's an "official scientist"? You mean NASA staff scientists?

Re:The shiny thing is a mountain?

[Bathroom Humor]

I think it's something taking pictures of our probe. Or maybe it's muzzle flash from a shotgun.

We are violating their privacy first, so by all means I think they have the right retaliate.

Re:The shiny thing is a mountain?

[The Grim Reefer]

What's an "official scientist"?

Anyone wearing a white lab coat standing in front of panels with lots of blinking lights, in this case.

Re:The shiny thing is a mountain?

[Greyfox]

Did you see that 4 mile high glowing pyramid? That's precursor technology right there! We need to mount an expedition to it so we can be the bait in a real-life "Alien vs Predator" scenario! Because that's ALWAYS what happens when you mount an expedition to a 4 mile high glowing pyramid on Ceres!

Re:The shiny thing is a mountain?

[Maritz]

Richard Hoagland..!? :)

Re:The shiny thing is a mountain?

[mcswell]

with tape drives

Is this a joker?

[Anonymous Coward]

Why so Ceres?

Re: Is this a joker?

[Anonymous Coward]

You can't be Sirius.

Mis-parsed the headline

[Anonymous Coward]

I thought it said "Dow drops 1470" and had a minor arrhythmia.

Me, too

[smittyoneeach]

First day, new eyes.

Alternate Link?

[advocate_one]

Anyone got an alternate link to the photo? Cos you beggars have killed NASA's servers yet again...

how low can it go?

[dominux]

Clearly it is at a good height now for imaging the whole surface, but as there is no atmosphere could it get down to a mountain scraping orbit? Just high enough to get round the lumps and bumps and variability in the roundness of the object? Would that enable it to image things at a really small pixel size?

Re:how low can it go?

[cobbaut]

Clearly it is at a good height now for imaging the whole surface, but as there is no atmosphere could it get down to a mountain scraping orbit? Just high enough to get round the lumps and bumps and variability in the roundness of the object? Would that enable it to image things at a really small pixel size?

Not really. The lower your orbit, the faster your spacecraft has to fly to maintain that orbit.

Re:how low can it go?

[stevelinton]

as there is no atmosphere could it get down to a mountain scraping orbit? Just high enough to get round the lumps and bumps and variability in the roundness of the object? Would that enable it to image things at a really small pixel size?

Apart from the question of what range the instruments were designed tooperaqte best at, the other problem is the unevenness of Ceres gravity. They are mapping that now, but it's unlikely the mass of Ceres is perfectly symmetrically arranged, so the gravity will be uneven. Those unevennesses distort the orbit and cause it to change over time. If you're 300 km away that's not a big problem, except that you occasionally have to use up some reaction mass to get back where you want to be. At 10km it would probabl;y be disasterous.

For the same reason it's very hard to keep a probe in a stable orbit less than 100km or so above Earth's moon.

Re:how low can it go?

[stevelinton]

Clearly it is at a good height now for imaging the whole surface, but as there is no atmosphere could it get down to a mountain scraping orbit? Just high enough to get round the lumps and bumps and variability in the roundness of the object? Would that enable it to image things at a really small pixel size?

Not really. The lower your orbit, the faster your spacecraft has to fly to maintain that orbit.

True, but in zero gee and with no atmosphere that isn't really a problem. It would take some time and reaction mass to get into such a low orbit. The problem is the uneven gravity field -- see my other post,

Re:how low can it go?

[userw014]

The NASA/JPL page says that the planned closest orbit will be at an altitude of 375km (235 miles). (I'm not sure how that'll be measured from a somewhat irregular object like Ceres.) The orbit at 1470km will take 14 orbits to make 11 passes.

Does anyone have any idea of how many small objects might orbit Ceres and pose a threat to Dawn?

Angel Delight (UK centric)

[whimdot]

After peering at these pictures for a while, trying to interpret the mounds and hollows I finally realised that the surface of Ceres is made of Angel Delight. To you non-UK folk out there, Wikipedia has a nice picture of butterscotch Angel Delight that may give you a flavour of what I'm trying to convey. It even has a few of those lumps that used to surface after it had been mixed unevenly, with the slight crunch.

Re:Angel Delight (UK centric)

[JonnyCalcutta]

I dunno. Its a good theory but how would you account for the 4km high pyramid? Standard angel delight is too gloopy.

NASA can't get to the moon, let alone "outside"

[Thing 1]

The Earth is provably flat; level water proves it. Moonlight makes things colder (it's warmer in moonlight's shadow), unlike sunlight, so it's not reflected sunlight. A lunar eclipse has been witnessed with the sun also in the sky; this is impossible if the Earth is a ball.

NASA has been proven to lie. Why trust liars? They employ graphic artists to "wow" us.

Look through the strongest telescope you can; the planets are a bright light. It's only through NASA's "you have no access" devices that we can see higher resolution paintings. (Did you know the Vatican's telescope is named Lucifer?)

The ISS "space walk" footage is performed in a pool in Texas; look carefully at the footage and you can see bubbles arising. There aren't bubbles in space. This woman "on the ISS" permed her hair so we can't see it move around from the turbulence in the "vomit comet" airplane, in which the footage is being filmed; you can hear the airplane engines during said footage.

See http://ifers.boards.net/ as well as Samuel Rowbotham's "Zetetic Astronomy": http://www.sacred-texts.com/ea...

Re:NASA can't get to the moon, let alone "outside"

[RogerWilco]

Hah. You even believe that NASA exists.

NASA doesn't exist, as the "American continents" are a lie by the government.
Those few "Americans" we see here are government spies, don't believe anything they say.

Re:NASA can't get to the moon, let alone "outside"

[Peristaltic]

You poor, naive, fool.

NASA exists, it's run by Masons.

The pics of the "bright light" craters were photoshopped to remove evidence of a replica of the Lodge of the Holy Saints John of Jerusalem.

We're everywhere, my friend...everywhere.

Re:NASA can't get to the moon, let alone "outside"

[mcswell]

All of humanity is contained in a processing unit on a dwarf planet in the asteroid belt

This was leaked (albeit in a slightly different version) in 1943, by Antoine de Saint-Exupéry.

Re:Typical Federal employee

[Tablizer]

to take five months to get within...

It has an ion engine. While quite efficient, current ion engines are slow. One advantage of ion engines is that they can use electricity from solar panels for power, and thus the probe doesn't have to carry large amounts of chemical fuel. This makes the launch cheaper, saving tax-payers money. See, the government cares!

Re:Here's an idea

[Peristaltic]

Yes because Donald Trump is going to need all of our spare taxpayer money to build a huge wall, purge non white people from amerikkka, and also to bomb Iran, and start WW3 with the North Koreans. .

My goodness, you say all that like it's a bad thing... I mean, come on- we wouldn't want to build a small wall, "purge the non white people" from Iran, bomb North Korea, or start WW3 with "amerikkka", would we?

Seriously- Thanks for your input, but we already know Trump's an ass-hat. When you're finished handing out fliers for the second coming of Jesus and Bigfoot, be sure and get your meds refilled.

Re:Here's an idea

[Lodlaiden]

That's a party line I can hang my hat on. That's a weird way to spell AMURICA though.