{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"4cd18fee13e2a8fe874d5fd3c1d499742924dab31eb944f91b556d7d3ae58e31","created":"2026-10-03T07:18:03Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"508e5dd8a05107bb6679187dfaf9af884b457e8ccc25ce02fd908a42097c85e0","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"earth.solar-system-dynamics.small-mars","kind":"phenomenon","literature_status":"contested","n":"1","parents":[],"plain":"Standard models of planet formation build a Mars almost as big as Earth, yet the real Mars is about ten times lighter. Something must have removed or never supplied material near Mars's orbit.","posed_since":"","precise":"Explain the mass of Mars (about 0.11 Earth masses) and its rapid formation (within about 10 Myr from Hf-W chronometry) in terms of the initial solid distribution or dynamical depletion: Jupiter's inward-outward migration, an early giant-planet instability, a narrow annulus of planetesimals, or pebble accretion. An answer is a scenario reproducing the masses, orbits and isotopic compositions of all terrestrial planets and the asteroid belt.","problem_ref":null,"references":"","settled_by":"A formation model that reproduces terrestrial planet masses and orbits and the nucleosynthetic isotope differences between Earth and Mars, and fails in its competitors.","status_note":"","title":"Why is Mars only about one tenth of Earth's mass?","topic_ref":"b929a620dac9f17771effc8b71b936420a6fad08ab629dcf3f51f65829dd7067"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"60ce837baf8dcd5f341b6158bc76e5cf02d976a3cc028d278140af29414c4a29","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"713ce7ae9f459dcbc2b29a55f528c3ccdfd838d20f78fd21e34fdf66e630347f","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"XCcC6Efh5xLE2XJmi3LrMU0qfDQcLwgs9cgmpBgasvm2aCeRglgusE9JmQBUOvrAMFsVLeKZrz5pVqEyIydUDw"},"schema":"pubphys.envelope/1"},"record_hash":"60ce837baf8dcd5f341b6158bc76e5cf02d976a3cc028d278140af29414c4a29","leaf_index":1368}