Dealing with Potentially Hazardous Asteroids

A trio of asteroid stories: OSIRIS-REx’s sample of Bennu on schedule to return; researchers develop method to map asteroid density distribution; and 3200 Phaethon’s rotation speeds up.

Beth Johnson
3 min readOct 27, 2022


Science can be a long game, especially when dealing with space science. Distances are astronomical; scales are measured in millions and billions. And while our asteroid belt isn’t far away, astronomically speaking, researchers have had to do a lot of waiting — waiting for missions to be designed, approved, launched, arrive, and sometimes even take samples.

Today, we look at three stories about asteroid science that require patience, new methods, and even new spacecraft.

IMAGE: This image from NASA’s OSIRIS-REx spacecraft show material leaking out of its sampling collector after a successful gathering of rock and soil from the asteroid Bennu. CREDIT: NASA

First up, and probably most relevant to our community, NASA announced that the OSIRIS-REx sample of Bennu is on course to arrive at Earth on September 23, 2023. The delivery is not a foregone event, however, as the approach must be at a precise speed and direction. Deputy project manager Mike Moreau explains: If the capsule is angled too high, it will skip off the atmosphere. Angled too low, it will burn up in Earth’s atmosphere.

The spacecraft has already performed one course correction to stay on track for safe delivery, and design lead Daniel Wibben notes: Over the next year, we will gradually adjust the OSIRIS-REx trajectory to target the spacecraft closer to Earth.

At least this wait is down to under a year, right?

IMAGE: Illustration of the DART spacecraft heading for impact with the asteroid Dimorphos. CREDIT: NASA/Johns Hopkins APL

One of the things we learned from sampling Ryugu and Bennu is that rubble pile asteroids may be a lot less dense than more solid asteroids. And now that the DART mission has shown that we can nudge an asteroid, any future planetary defense plans will have to take into account the density of the body we need to move. We won’t know just how much damage Dimorphos took from DART until the Hera mission arrives in 2026, and researchers aren’t waiting until then to improve their tools.



Beth Johnson

Planetary scientist, podcast host. Communication specialist for SETI Institute and Planetary Science Institute. Buy me a coffee: