Starship Asterisk*

Ann wrote:
I think it looks as if the comet is covered in snow. Maybe it is, too. Surely it has had at least one outburst recently? Couldn't it have covered itself in its own snow?

After looking at Comet Hartley 2 it seemed to me that outgassing of carbon dioxide & water vapor mostly occurred at the spinning ends of this dipole comet (where the escape velocity is minimal).

What material doesn't escape falls/condenses mostly around the central neck (where the escape velocity is maximal).

BDanielMayfield wrote:I wonder what the mass of this thing is. Have new mass estimates been released yet?

Joules wrote:

BDanielMayfield wrote:I wonder what the mass of this thing is. Have new mass estimates been released yet?

No. last I saw was in the 0.1 to 0.4 g per cubic cm range. Too insubstantial for even CO2 or nitrogen ice. Yet the thing is obviously rigid. Now that Rosetta's in orbit, it shouldn't be too long before a proper gravity map, and mass value come out.

neufer wrote:Electostatics may play a big role here

Joules wrote:

BDanielMayfield wrote:
I wonder what the mass of this thing is. Have new mass estimates been released yet?

No. Last I saw was in the 0.1 to 0.4 g per cubic cm range. Too insubstantial for even CO2 or nitrogen ice. Yet the thing is obviously rigid. Now that Rosetta's in orbit, it shouldn't be too long before a proper gravity map and mass value come out.

http://blogs.esa.int/rosetta/2014/07/23/last-of-the-fatties/ wrote:
Last of the FATties

<<With about 4500 km separating Rosetta from comet 67P/C-G, the spacecraft will conduct the last of four FAT – ‘Far Approach Trajectory’ – orbit correction manoeuvres later today. Mass is possibly the most uncertain of all the cometary parameters (because the density is extremely uncertain) yet is the single most important parameter to be estimated from the standpoint of early navigation activities at the comet. The latest science data – including recent images indicating the comet is a complex 'contact binary' – is enabling the mission team to refine models of the comet. Based on the best estimates of the comet size & shape available before the recent images, the mass is estimated at 3.14x10¹² kg [; i.e., π billion tonnes corresponding to a mean density of 102±9 kg/m³]. This will surely change as we learn more about this enigmatic object.>>

Steve Dutch wrote:
In fifty years of space exploration, this is the very first object that has the weird spiky appearance so beloved of special effects artists!

neufer wrote:After looking at Comet Hartley 2 it seemed to me that outgassing of carbon dioxide & water vapor mostly occurred at the spinning ends of this dipole comet (where the escape velocity is minimal).

What material doesn't escape falls/condenses mostly around the central neck (where the escape velocity is maximal).

Electostatics may play a big role here.

ta152h0 wrote:
I agree , congratulations to the ROSETTA team. New Horizons was mentioned on the thread. I hope the spacecraft crashes into Pluto with the cameras rolling like the Rangers did on the moon. It would be fitting if Mr Tombaugh's ashes are on board.

• Don't expect any "postcards" from New Horizons then:

http://en.wikipedia.org/wiki/New_Horizons wrote:
<<New Horizons should perform a flyby of the Pluto system on 14 July 2015. Initial, highly-compressed images will be transmitted within days. Uncompressed images will take about nine months to transmit, depending on Deep Space Network traffic. It may turn out, however, that fewer months will be needed. The spacecraft link is proving stronger than expected, and it is possible that both downlink channels may be ganged together to nearly double the data rate.>>