[magicalhippo]

Cassini[1] was quite massive too at launch, at 5712 kg. Though to be fair, 320 kg was due to the Huygens[2] probe it carried with it.

[1]: https://en.wikipedia.org/wiki/Cassini%E2%80%93Huygens

[2]: https://en.wikipedia.org/wiki/Huygens_(spacecraft)