greatest engineering challenges of the 21st century

What are they?

* Make solar energy affordable.
* Provide energy from fusion.
* Develop carbon sequestration methods.
* Manage the nitrogen cycle.
* Provide access to clean water.
* Restore and improve urban infrastructure.
* Advance health informatics.
* Engineer better medicines.
* Reverse-engineer the brain.
* Prevent nuclear terror.
* Secure cyberspace.
* Enhance virtual reality.
* Advance personalized learning.
* Engineer the tools for scientific discovery.