Enlarge / This artist's concept shows the possible appearance of ESA's RAMSES spacecraft, which will release two small CubeSats for additional observations at Apophis. (credit: ESA-Science Office)

For nearly 20 years, scientists have known an asteroid named Apophis will pass unusually close to Earth on Friday, April 13, 2029. But most officials at the world's space agencies stopped paying much attention when updated measurements ruled out the chance Apophis will impact Earth any time soon.

Now, Apophis is again on the agenda, but this time as a science opportunity, not as a threat. The problem is, there's not much time to design, build, and launch a spacecraft to get into position near Apophis in less than five years. The good news is there are designs, and in some cases, existing spacecraft, that governments can repurpose for missions to Apophis, a rocky asteroid about the size of three football fields.

Scientists discovered Apophis in 2004, and the first measurements of its orbit indicated there was a small chance it could strike Earth in 2029 or in 2036. Using more detailed radar observations of Apophis, scientists in 2021 ruled out any danger to Earth for at least the next 100 years.