A little less than four years from now, a killer asteroid will narrowly fly past planet Earth. This will be a celestial event visible around the world—for a few weeks, Apophis will shine among the brightest objects in the night sky.

The near miss by the large Apophis asteroid in April 2029 offers NASA a golden—and exceedingly rare—opportunity to observe such an object like this up close. Critically, the interaction between Apophis and Earth's gravitational pull will offer scientists an unprecedented chance to study the interior of an asteroid.

This is fascinating for planetary science, but it also has serious implications for planetary defense. In the future, were such an asteroid on course to strike Earth, an effective plan to deflect it would depend on knowing what the interior looks like.

"This is a remarkable opportunity," said Bobby Braun, who leads space exploration for the Johns Hopkins Applied Physics Laboratory, in an interview. "From a probability standpoint, there’s not going to be another chance to study a killer asteroid like this for thousands of years. Sooner or later, we’re going to need this knowledge."

But we may not get it.

NASA has some options for tracking Apophis during its flyby. However, the most promising of these, a mission named OSIRIS-Apex that breathes new life into an old spacecraft that otherwise would drift into oblivion, is slated for cancellation by the Trump White House's budget for fiscal year 2026.

Other choices, including dragging dual space probes out of storage, the Janus spacecraft, and other concepts that were submitted to NASA a year ago as part of a call for ideas, have already been rejected or simply left on the table. As a result, NASA currently has no plans to study what will be the most important asteroid encounter since the formation of the space agency.

"The world is watching," said Richard Binzel, an asteroid expert at the Massachusetts Institute of Technology. "NASA needs to step up and do their job."

Two Chinese satellites have rendezvoused with one another more than 20,000 miles above the Earth in what analysts believe is the first high-altitude attempt at orbital refueling.