"We are not only talking of launches, we are talking of human exploration," he said, adding that future missions would seek to send astronauts to the moon "and beyond."
In the meantime, the agency will continue to develop its robotic capability, including a spacecraft capable of carrying large loads to the Moon that would support joint missions with partners such as NASA.
ESA is also in the early stages of working on a probe that would fly to an ice moon, such as Saturn's Enceladus, to recover a sample and bring it back to Earth.
"It could be that there's very simple, primitive life in the water underneath the ice cover," said Aschbacher.
One challenge is that with current technology, the round-trip could take decades to complete.
Time is also a factor in the replacement of one of ESA's science satellites, Sentinel 1-B, which stopped functioning properly in late December.
Simonetta Cheli, the agency's director of Earth observation, said the root cause of the malfunction was still being investigated and it was too soon to say whether the successor model, Sentinel 1-C, will need to be modified to avoid suffering a similar fate.
Any delay in replacing Sentinel 1-B could cause problems for scientists who rely on the satellite's data for their research, including into climate change.
"Of course, we would need to try and look for options to launch the satellite as soon as possible if 1-B terminates its own lifetime," said Cheli.