TOPICS2001 CC21 naming campaign
We're on the look out for a name for asteroid 2001 CC21!

We are looking for a name for asteroid 2001 CC21, which is scheduled for flyby exploration in July 2026 during Hayabusa2 Extended Mission. Please submit your suggestions!

Submit a name here:

Application notes:

• The period for suggesting a name is from December 6, 2023 to May 9, 2024.
• One name suggestion per person. If multiple applications are submitted, the last application will be the valid submission.
• There are guidelines for naming asteroids set by the International Astronomical Union. Please refer to the rules listed below.
• What we currently know about asteroid 2001 CC21, and the flyby exploration of the asteroid, is also listed below. Please use this when considering a suitable name.
• The information submitted will only be used in this campaign.

How the campaign will be conducted

We first ask everyone to think of a name for asteroid 2001 CC21, and submit their choice. Once the application deadline for submitting names has passed, we will gather the entries and select a name. Priority will be given to names that have a high number of suggestions.

However, the name with the most suggestions will not necessarily be selected as the final choice. We will also elementary and junior high school students to help choose the name.

Elementary and junior high school students who will help with the name selection will be nominated by the YAC (Japan Space Youth Association) and KU-MA (Children, Space, Future Association, an NPO). We plan to choose a name by the summer of 2024, and submit the proposal to the International Astronomical Union is collaboration with the US LINEAR (LIncoln Near-Earth Asteroid Research) team, who discovered 2001 CC21.

Those who select the final name choice will receive a commemorative gift from the Hayabusa2 Extended Mission team.

About Asteroid 2001 CC21
Asteroid 2001 CC21 (see note) was discovered by the US LINEAR team on February 3, 2001. After discovery, the orbit of the asteroid was accurately determined through repeated observations, and the asteroid was assigned the designation number 98943. Once an asteroid has a designated number, it can be given a name. The team that discovers the asteroid and that are the first to estimate the asteroid orbit can propose a name to the International Astronomical Union. Therefore, the LINEAR team are able to propose a name for 2001 CC21, but accepted a request from the Hayabusa2 Extended Mission team for a name to be proposed by Japan. Incidentally, the LINEAR team also discovered asteroid Itokawa and Ryugu! This will therefore be the third time that Japan has proposed a name for an asteroid for the LINEAR team. (Note: notation such as 2001 CC21 is a temporary designation for an astroid and is assigned when the orbit is estimated.) Telescope observations have taught us a lot about 2001 CC21. First of all, for the current location and orbit of 2001 CC21, please take a look at the top page of the Hayabusa2 Extended Mission website! The asteroid orbit is about the same length as the Earth, but it moves around the Sun at a slightly different angle from our own orbit. The rotation period for the asteroid is approximately 5 hours. The asteroid was reported to have a L-type spectral class in early observations, but more recent observations (from 2022) have indicated it may be more likely to be an S-type asteroid. If 2001 CC21 proves to be S-type, then the spectral type will be the same as asteroid Itokawa. The size of 2001 CC21 is not well known, with estimates varying between about 440m to 700m. Not much is also known about the asteroid shape. It seems to be elongated, similar to Itokawa, rather than a more spherical shape like Ryugu.The table below shows what is currently known about 2001 CC21.

Table: What we know about asteroid 2001 CC21

About the flyby exploration of asteroid 2001 CC21

The flyby exploration of 2001 CC21 is scheduled for July 2026, when the asteroid and spacecraft will pass each other at an ultra-high speed of 5 km/s (18,000 km/h!). Hayabusa2 was originally built as a spacecraft for asteroid rendezvous, and is not designed for flyby missions, which involve observing asteroids passing by at high relative speeds from a distance.
Because of this, the Hayabusa2 flyby mission will approach as close to the asteroid as orbital guidance precision allows, and observe the asteroid until just before the closest approach, while keeping the attitude of the spacecraft as unchanged as possible.
As shown in the figure, a collision trajectory allows the spacecraft attitude to remain unchanged until the very end, and the asteroid can be tracked and captured with the onboard cameras. Very similar characteristics are true for a trajectory that passes by the asteroid's edge. At the time of closest approach during a close flyby, the angular velocity needed to keep the asteroid in view will be extremely high, but just prior to this point, the onboard cameras can be directed at the asteroid without significantly changing the spacecraft attitude, as in the collisional case.
During this time, the spacecraft will get as close as possible to the asteroid, allowing observations at high resolution from close proximity. We are currently considered how close we can approach, but we would like to achieve an orbital guidance precision that is high enough to be capable of hitting the asteroid, and then instead, just pass by the asteroid edge.
This kind of technology is equivalent to that needed to collide a spacecraft into an asteroid in order to adjust its orbit, which makes the flyby mission one that can also contribute to planetary defense.

Figure: Hayabusa2 ultra-close flyby trajectory study

Rules for naming asteroids

The International Astronomical Union has the following rules for naming asteroids. Please suggest a name that does not violate any of the following points:

• 16 alphabetical characters or less in length
• Preferably one word
• Pronounceable (in some language)
• Non-offensive
• Not too similar to an existing name of a Minor Planet or natural Planetary satellite.
• The names of individuals or events principally known for political or military activities are unsuitable until 100 years after the death of the individual or the occurrence of the event.
• Names of pet animals are discouraged
• Names of a purely or principally commercial nature are not allowed.
• Objects that approach or cross Earth's orbit (so-called Near Earth Asteroids or Near Earth Objects: NEOs) are generally given mythological names.

2001 CC21 is a NEO, so the last rule about relevant in this case! If possible, therefore consider a name for 2001 CC21 that is related to mythology. That said, there are exceptions to this rule, such as asteroid Itokawa. Itokawa is a NEO, but has a non-mythological name. So you are also welcome to suggest a name outside mythology.


We would like to thank the LINEAR team in the USA for allowing Japan to choose the name of the asteroid, following Itokawa and Ryugu.

Hayabusa2# Project