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Look at that:

enter image description here enter image description here enter image description here enter image description here

...and now tell me how comes Opportunity weighs 530kg and Curiosity 900kg.

It looks, like by volume, Curiosity is good 4x larger, if not more. Plus it contains heavyweight RTGs, its chassis/frame is much thicker, in short it looks like way more than twice the weight. Meanwhile, it's only 70% heavier.

What properties, construction solutions, mass savings allowed such weight savings in a construction so much bigger?

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    $\begingroup$ What's your source for the 530kg figure? Wikipedia says the Opportunity rover is 180kg. Maybe the EDL package is 530kg? $\endgroup$
    – Russell Borogove
    Commented May 13, 2016 at 0:19
  • $\begingroup$ @RussellBorogove: space.stackexchange.com/a/15254/103 $\endgroup$
    – SF.
    Commented May 13, 2016 at 0:47
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    $\begingroup$ The premise of the question is incorrect. The Opportunity rover mass was about 175 kg. $\endgroup$
    – Mark Adler
    Commented May 13, 2016 at 1:35

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The number is slightly misleading. NASA provides a complete breakdown on the mass.

  • Rover 185 kg
  • Lander 348 kg

Almost 2/3rds of the mass that soft landed was in the stand and airbags, only about 1/3rd of the mass of the rover.

The bottom line is, Curiosity was more effective in terms of the mass of the rover to the mass of the EDL package. The skycrane deployment allowed it to make use of such a high useful mass.

See this video for why so much mass of MER was in the non-roving lander portion, or see this picture of the landing platform for Spirit.

Spirit's landing platform

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  • $\begingroup$ What's the mass of the MSL aeroshell and sky crane? $\endgroup$
    – Russell Borogove
    Commented May 13, 2016 at 1:39
  • $\begingroup$ EDL package is 2,401 kg including 390 kg of landing propellant, and a 899 kg rover is the best I can find. $\endgroup$
    – PearsonArtPhoto ♦
    Commented May 13, 2016 at 1:47
  • $\begingroup$ Thanks. Apples to apples, 2,400 vs 530 and 900 vs 185, now the comparison doesn't violate the square-cube law. $\endgroup$
    – SF.
    Commented May 13, 2016 at 2:08
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    $\begingroup$ That's still not quite right. 820 kg vs 3300 kg is the closest comparison I believe, and the 185 vs 900 for the landed rovers. $\endgroup$
    – PearsonArtPhoto ♦
    Commented May 13, 2016 at 2:10

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