It's the weight on Earth. Just look for a source that specifies in kg - there's no ambiguity about what the SI unit represents.

No, ambiguity was introduced when the measurement was switched from force to mass. The question remains: what is the weight/force experienced on the wheels on Mars? Knowing the mass won't tell us unless we also know the acceleration due to gravity on Mars.

Wikipedia says the dry mass is 899 kg, which is about the 2000 pounds of weight (on Earth) mentioned by GP.

https://en.wikipedia.org/wiki/Curiosity_(rover)

The pound is a unit of mass, same as the kg (it's defined as exactly 0.45359237kg). Just as 900kg is 900kg everywhere, 2000lb is 2000lb everywhere. The colloquial weight is literally a force, and its imperial unit is thus the pound-force.

This is incorrect. The pound is a unit of force, similar to a Newton. The pound-mass(notated lb-m) is similar to the kg. The conversation you gave above is based on Earth gravity for weight.

> This is incorrect. The pound is a unit of force, similar to a Newton. The pound-mass(notated lb-m) is similar to the kg.

That's the pound-force (lbf).

Pound and pound-mass are aliases. Indeed the official facts sheet defines the mass of the rover in kg and pounds.

> The conversation you gave above is based on Earth gravity for weight.

My comment is based on mass being an intrinsic property of matter, gravity does not enter the equation.

There are about a dozen different units that are all called "pounds," and you have to rely on context to know which is meant. When I took physics in high school, pounds were always force (abbreviated lbf) and we used slugs for mass ( https://en.m.wikipedia.org/wiki/Slug_(mass) )

Which would make it about 338 kilos on Mars - wikipedia lists Mars' gravity as 0.376g (vs earth's 1)

Technically that would make it 899kg on Mars, the kilogram is a unit of mass. However the Rover would weigh ~8800N on Earth and ~3300N on Mars.