Kleopatra.space

Is Kleopatra made of metal?

Radar, density and spectra give mixed answers about one of the best-known M-type asteroids.

Published 2026-10-23

M-type asteroids have spectra that fit metal, and some are thought to be cores of shattered protoplanets.[4] Kleopatra has long been a leading example — but the evidence is mixed.[2]

The radar clue

Metal reflects radar strongly. Kleopatra’s radar albedo suggests high metal content in its southern hemisphere, but along the equator it looks more like common S- and C-type asteroids.[2]

The density clue

Solid iron-nickel is dense. Kleopatra’s bulk density is 3.38 ± 0.50 g/cm³ — closer to rock.[2] The latest mass estimate is also lower than earlier ones.[2]

Putting it together

One way to reconcile these: Kleopatra is a rubble pile with significant porosity, perhaps metal-rich pieces loosely packed with lots of empty space.[2][6]

Compare 16 Psyche

JPL lists the largest M-type asteroid, 16 Psyche, with a density of about 4.2 g/cm³ — higher than Kleopatra’s.[9] NASA’s Psyche mission aims to settle what such objects are made of.

Numbered citations link to the sources list on the Kleopatra overview page.

Meteorite buying guide

Metal-rich asteroids like Kleopatra are related to the iron meteorites you can actually hold. Answer five quick questions and we’ll suggest specimen types that match your budget and interests — with links to browse current listings.

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