Kamo'oalewa (2016 HO3)

Asteroid Kamo'oalewa (JPL Horizons ID469219; name Kamoʻoalewa / 2016 HO3)

Plot of Kamo'oalewa's orbit (static) (File: 4.4 MB)

Plot of Kamo'oalewa's orbit (animated over 10 months) (File: 1.8 MB)

NASA Website

JPL Horizons Ephemeris:

JPL/HORIZONS            469219 Kamo`oalewa (2016 HO3)      2025-Jul-05 08:35:28

Rec #:  469219 (+COV) Soln.date: 2025-Feb-20_05:52:49    # obs: 330 (2004-2025)

 IAU76/J2000 helio. ecliptic osc. elements (au, days, deg., period=Julian yrs):

   EPOCH=  2457854.5 ! 2017-Apr-11.00 (TDB)         Residual RMS= .081651

   EC= .1040534310625292   QR= .8968644455386475   TP= 2458029.6369096744

   OM= 66.43991583004482   W=  307.0951007739783   IN= 7.773894173631178

   A= 1.00102447694204     MA= 187.6486415815915   ADIST= 1.105184508345433

   PER= 1.00156            N= .984095007           ANGMOM= .017117482

   DAN= .93171             DDN= 1.05649            L= 13.7898314

   B= -6.1937829           MOID= .0345833          TP= 2017-Oct-03.1369096744

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The name Kamo'oalewa has a beautiful and meaningful origin in the Hawaiian language.

It was named in 2019 by A Hua He Inoa at the 'Imiloa Astronomy Center of Hawai'i, as part of a program that integrates Hawaiian language and cultural practices into the process of officially naming astronomical discoveries.

The name is derived from the Hawaiian words:

• Ka - meaning "the"

• moʻo - meaning "fragment" or "offspring" (referring to the idea that it might be a piece broken off a larger object, like the Moon)

• a - meaning "of"

• lewa - meaning "to oscillate" or "to wobble" (referring to its peculiar, oscillating motion in the sky as viewed from Earth)

So, essentially, Kamo'oalewa translates to "the oscillating fragment" or "the offspring that oscillates." This name perfectly captures both the hypothesized lunar origin and the asteroid's unique orbital behavior as Earth's quasi-satellite.

Classification and Orbit: 

Kamo'oalewa is a very small, elongated asteroid belonging to the Apollo group of near-Earth objects. What makes it particularly unique is its status as Earth's best and most stable "quasi-satellite." This means it orbits the Sun with parameters very similar to Earth's, appearing to "dance" around our planet in a looping, oscillating path. While it's too distant to be gravitationally bound like a true moon, it remains relatively close to Earth, between 38 and 100 times the distance of the Moon. Its orbit is relatively stable and is expected to remain in this configuration for hundreds of thousands of years.

Physical Characteristics: 

Kamo'oalewa is estimated to be between 40-100 meters (130-330 feet) in diameter, making it one of the smallest asteroids ever targeted for a mission. It's also a fast rotator, completing a rotation in approximately 28 minutes.

Mysterious Origin: 

One of the most intriguing aspects of Kamo'oalewa is its potential origin. Research suggests that its reflected light spectrum matches lunar rocks from NASA's Apollo missions. This has led to the hypothesis that Kamo'oalewa might be a fragment of our own Moon, ejected by an ancient impact. Confirmation of this theory through sample analysis would be groundbreaking, as no other known asteroid has been definitively linked to lunar origins.

Tianwen-2 Mission

Tianwen-2 is China's ambitious deep space mission designed to explore asteroid Kamo'oalewa and a main-belt comet. It's a multi-objective mission with significant scientific goals.

• Launch and Objectives: 

The Tianwen-2 mission launched on May 28, 2025, aboard a Long March 3B carrier rocket from the Xichang Satellite Launch Center. Its primary objectives are:

• • Asteroid Sample Return: The mission's initial target is Kamo'oalewa. Tianwen-2 will rendezvous with the asteroid in mid-2026 and spend about nine months in its vicinity. It aims to collect approximately 100 grams of regolith (surface material) using both "touch-and-go" and "anchor-and-attach" methods. The "anchor-and-attach" method would be a first for asteroid sampling. The collected samples are planned to be returned to Earth in November 2027. Analyzing these samples will be crucial in determining Kamo'oalewa's true origin (e.g., lunar fragment or main-belt asteroid) and providing insights into the early solar system.

  • Comet Exploration: After delivering the samples to Earth, the main spacecraft will perform a gravity assist maneuver using Earth's gravity to propel itself toward its second target: main-belt comet 311P/PANSTARRS.

Apollo Group Asteroids:

• Definition: 

Apollo asteroids are a group of Near-Earth Asteroids (NEAs). Their key characteristic is that their orbits cross Earth's orbit. Specifically, they have a semi-major axis greater than Earth's (meaning their average distance from the Sun is greater than Earth's) but a perihelion distance (closest approach to the Sun) less than Earth's aphelion distance (farthest point from the Sun). This allows them to cross our planet's path.

• Location: 

They can be found in various parts of the inner solar system as their eccentric orbits bring them sometimes closer, sometimes farther from the Sun than Earth.

• Significance: 

Their Earth-crossing nature makes them a focus of planetary defense efforts, as they represent a potential impact hazard. Kamo'oalewa, as mentioned, is an Apollo asteroid.