Please help explain differences in the Rosetta and Pioneer TRP models

[leonAzul]

The paper I wish to cite can be found here:
High precision thermal modeling of complex systems with application to the flyby and Pioneer anomaly

Briefly, it explores thermal radiation pressure (TRP) as a possible explanation for the unanticipated velocities observed for the Rosetta and Pioneer space probes—the so-called anomalies. It then proposes a general method for estimating such pressures and applying them to the calculation of actual positions and velocities for similar objects.

What I am curious about is that: internal heat sources and surface optical properties were explicitly accounted for in the case of Pioneer, yet they were not for Rosetta.

Why?

Is it assumed that, at the distances from the Sun involved, solar inputs are significantly greater for Rosetta, or is there something else about Rosetta that makes internal sources less significant?

The paper never discusses why the finite element (FE) models of the two are different—unless of course I just missed it, in which case I would be grateful to anyone who could point it out to me.

 

[BowlOfRed]

Rosetta doesn't have any RTGs, does it? I would think that would make internal heat sources much less important.

 

[leonAzul]

Rosetta doesn't have any RTGs, does it? I would think that would make internal heat sources much less important.

Thanks, that is one question I am trying to find an answer for.

The ESA web site does not go into much detail concerning power supplies for either the Rosetta orbiter or the lander.

Is there a better place to search for such information?

 

[BowlOfRed]

This passage suggests to me that the craft is solar powered:
http://www.esa.int/Our_Activities/Space_Science/Rosetta_correctly_lined_up_for_critical_Mars_swingby

Later today, the Flight Control Team is scheduled to begin charging Rosetta's batteries for the planned 25-minute eclipse during the swingby. During the eclipse, Rosetta's solar panels will be shadowed from sunlight by Mars, and all but essential systems will be turned off or placed into low-power modes.

That wouldn't have been necessary if RTGs were used.

ETA:
No mention of RTGs in any of the system descriptions I've read, and a note about Rosetta in here (http://www.esa.int/esapub/br/br202/br202.pdf) about how large the arrays have to be convince me that it is (only) solar powered.

 

[leonAzul]

This passage suggests to me that the craft is solar powered:
http://www.esa.int/Our_Activities/Space_Science/Rosetta_correctly_lined_up_for_critical_Mars_swingby



That wouldn't have been necessary if RTGs were used.

I did, indeed, miss that.

Thanks for your help.

Yet would the operation of the batteries have any thermal significance?

 

[BowlOfRed]

Yet would the operation of the batteries have any thermal significance?

It's certainly possible. I read through the paper, but I can't begin to follow the math. I have no idea if the lack of an RTG means that the modeling the interior temperature can be ignored.

My guess is yes it can be ignored. Any thermal emissions from inside the craft must necessarily be only a fraction of that impinging on it from the sun. But I'm not studying this stuff.

 

[WhatRoughBeast]

It's pure solar.

http://www.esa.int/Our_Activities/Operations/Rosetta_to_sleep_through_loneliest_leg_of_comet_mission

"Rosetta is getting farther from the Sun, and soon there simply isn't going to be enough sunlight to power its systems," says Paolo Ferri, Head of ESOC's Solar and Planetary Mission Operations Division.

And batteries produce far less waste heat than any RTG, so it's not likely a factor.

 

[leonAzul]

It's certainly possible. I read through the paper, but I can't begin to follow the math. I have no idea if the lack of an RTG means that the modeling the interior temperature can be ignored.

My guess is yes it can be ignored. Any thermal emissions from inside the craft must necessarily be only a fraction of that impinging on it from the sun. But I'm not studying this stuff.

Thanks.

Another possibility is that the batteries are effectively insulated from the outer surface and therefore do not contribute significantly to TRP.

Thanks again for your quick and thoughtful replies.

 

[leonAzul]

It's pure solar.

http://www.esa.int/Our_Activities/Operations/Rosetta_to_sleep_through_loneliest_leg_of_comet_mission



And batteries produce far less waste heat than any RTG, so it's not likely a factor.

Well, that answers that.

Thank you for pointing me there.