WASHINGTON — Scientists are urging NASA to act quickly on concepts for repurposing a pair of NASA smallsats to visit an asteroid before it makes a very close approach to Earth in less than four years.
Recommendations recently published from the Apophis T-4 Years Workshop held last month in Tokyo called on NASA to act on responses it received from a request for information (RFI) last fall about how to use the twin Janus smallsats to visit the near Earth asteroid Apophis before it swings by Earth in April 2029.
The Janus spacecraft were built to perform flybys of other asteroids, but NASA canceled that original mission and put the spacecraft in storage when delays in the Psyche mission, on which Janus was a rideshare, kept Janus from carrying out that mission. Scientists have since then suggested that the Janus spacecraft could instead be used to study Apophis before it swings by Earth, complementing observations planned after the flyby.
The recommendations noted that, at last year’s workshop, scientists identified Janus as the best option for a NASA-led mission to Apophis before the Earth flyby, and “we follow-up by urging NASA to issue a timely response to the Apophis 2029 Innovation Using the Janus Spacecraft Request for Information.”
NASA has not discussed its plans for Janus or another Apophis mission since the deadline for RFI responses last October. At a May 15 hearing of the House Science Committee’s space subcommittee on NASA’s planetary defense work, Nicky Fox, NASA associate administrator for science, did not directly address the Janus RFI, but said a study it performed ruled out alternative approaches for missions to visit Apophis before the flyby.
“We looked at the possibility of partnering with non-traditional partners to be able to do that,” she said. “We didn’t find a viable path forward without significant budget from us that we actually didn’t have.”
NASA does have one mission going to Apophis after the flyby. The main spacecraft from the OSIRIS-REx asteroid sample return mission, rechristened OSIRIS-APEX, will arrive at Apophis shortly after the flyby. Fox said the spacecraft will be able to perform observations of Apophis starting two weeks from closest approach.
“Even though they’re going to be low-resolution, we’re going to have some really nice images of how the light and the brightness changes,” she said, which will help scientist understand how the tidal forces from the close approach reshape the asteroid’s surface.
After the hearing, Fox said NASA had not ruled out using Janus for an Apophis mission. “We’re still discussing it,” she said, noting it would depend on budgets for fiscal year 2026 and beyond.
In addition to OSIRIS-APEX, the European Space Agency has started work on its own Apophis mission, RAMSES, that would visit Apophis before the flyby. ESA provided an initial tranche of funding last year to start work on the mission, and will seek full funding of RAMSES at its next ministerial conference in November.
A Japanese spacecraft may also join them. The Japanese space agency JAXA is working on a mission called DESTINY+ that will travel to the near Earth asteroid Phaethon, the parent body of the Geminid meteor shower. A switch in launch vehicles has delayed the launch of DESTINY+ from 2025 to 2028 and created an opportunity for the spacecraft to fly by Apophis en route to Phaethon before Apophis swings by Earth.
The conference heard presentations on several other Apophis mission concepts by companies, universities and other organizations, but it is uncertain that any of them will overcome the technical and financial obstacles needed to be ready in time for the 2029 flyby.
The workshop’s recommendations included support for OSIRIS-APEX, RAMSES and DESTINY+. “These are the highest priority missions for Apophis and should be fully funded and supported to ensure successful achievement of their science objectives,” it stated.
“We collectively entreat and emphasize to our respective agencies, member states, funding sources, and all interested parties that time is of the essence for moving forward decisively in funding current science investigations proposed and underway, which are essential for achieving the Apophis science outcomes being anticipated and to be watched by the entire world,” the document added (emphasis in original.)
