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0 pointsacqq11y ago0 comments

Yes, the lander was around 100 kg, whereas RTG would weight around 40 kg alone. And it would anyway be needed only in this case of unfortunate landing in the shadow.

Once we talk about details it's clear how a lot of the complaints are based purely on a huge ignorance. It's good to ask to learn. But when somebody starts from the position that people who managed 25-year mission missed something to him "simple and obvious"...

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hrjet11y ago· 3 in thread

> It's good to ask to learn.

In that spirit, I have a question. How heavy are the solar panels? If their weight is comparable to 40kg then it makes RTG more attractive.

gtirloni11y ago

I'm not sure about the exact weight but perhaps an estimation can be derived from the specifications available in the fact sheet [1]

- Contractor: Galileo Avionica SpA

- Cells Type: Si, Hi-ETA LILT

- Cells Size: 3x3 cm2

- Power equiv. @ 3 AU: 32W

- Total Size: 2.2m2

- Lifetime: 10 years

[1] - http://www.dlr.de/rd/Portaldata/28/Resources/dokumente/rx/Ph...

acqqOP11y ago

The weight of solar cells used on the Earth comes from making them protected from the environment, the material that produces the power itself is very thin.

http://sbir.gsfc.nasa.gov/SBIR/successes/ss/3-027text.html

Note "1 kW/kg" specification but it's probably in the Earth's orbit, using the inverse square law, it should be an order of magnitude less where Philae now is. Still, it appears it can remain quite light to have 2 m^2 of cells there.

Anybody has more exact details for the weight of the cells on Philae?

throwaway_yy2Di11y ago

1.7 kg, I think:

    TABLE I
    Mass breakdown of Rosetta Lander, including sub-units on the
    Orbiter.

    Unit                          Mass (kg)
    
    Thermal Control System        3.9
    ...MLI                        ...2.7
       ("multi-layer insulation")
    
    Power System                  12.2
    ...Electronics                ...2.0
    ...Batteries                  ...8.5
    ...Solar Generator            ...1.7   *****

    Sum [Lander]                  97.9

    Sum [incl. Orbiter units]     111.0

Excerpt from table 1, page 208 of

[paywall] http://link.springer.com/article/10.1007/s11214-006-9138-2

[PDF mirror] http://www.researchgate.net/publication/257664668_The_Rosett...

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