Here is some renditions of 216 Kleopatra.

enter image description here

Kleopatra is a relatively large asteroid, measuring 217 × 94 × 81 km.Calculations from its radar albedo and the orbits of its moons show it to be a rubble pile, a loose amalgam of metal, rock, and 30–50% empty space by volume, likely due to a disruptive impact prior to the impact that created its moons. [from wikipedia]

It is a fairly large asteroid with moons. Could a person or vehicle with treads circumnavigate it the long way round? If traveling along the narrow bit which way would be down?

  • 1
    $\begingroup$ It would be like falling in love. You'd be dazzled by its curves and motions and tumbled around without any fixed point or direction. And then you will crash and die as a crater in the shadow. $\endgroup$
    – LocalFluff
    Jan 29, 2016 at 14:45

1 Answer 1


Really weird

In the neck region between the lobes, the gravity is almost cancelling out. On the other parts of the asteroid, the surface gravity is going to be about $30 \space mm/s^2$. But 216 Kleopatra is spinning really fast, providing up to $20\space mm/s^2$ of radial acceleration due to inertia. $10 \space mm/s^2$ is barely enough to walk. If you are not careful with your steps, you are going to fly for a while before returning to the ground. (Seven minutes airtime for a normal Earth step). You are however not able to throw rocks into orbit, like on Phobos or Deimos, except around the neck where an unstable orbit is just requiring $14 \space m/s$. Just manageable.

As for circumnavigating the asteroid, it is simply going to take too much time. Being patient with the low gravity, moving at say $0.1 \space m/s$, the whole $500km$ trip is going to take about 60 days. Orbiting it is much simpler, only taking a few hours and a minuscule amount of $\Delta v$.

"Down" is going to shift a great deal depending on your location, but your acceleration vector is never going over the local horizon. Otherwise pieces of this rubble pile would have flown into space.

  • $\begingroup$ The way towards the middle is going to resemble sliding a very steep slope, practically a cliff. Probably crossing over from one end to the other by a single jump would be more practical. $\endgroup$
    – SF.
    Jan 29, 2016 at 14:12
  • $\begingroup$ @SF travelling in low gravity is never practical, therefore I suggested to do the whole trip in a "jump" :) $\endgroup$ Jan 29, 2016 at 14:14
  • $\begingroup$ OTOH with this spin rate probably a space elevator would be quite easy to build to facilitate launches or lobbing raw materials towards distant destinations. $\endgroup$
    – SF.
    Jan 29, 2016 at 14:36
  • $\begingroup$ @SF But anchoring it is going to be difficult, as the asteroid is basically a pile of gravel. Wikipedia says 30-40% empty space inside it. $\endgroup$ Jan 29, 2016 at 14:41
  • 1
    $\begingroup$ @PearsonArtPhoto Orbital velocity is even within catapult range :D $\endgroup$ Jan 29, 2016 at 14:47

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.