https://www.iana.org/dnssec/ce...
Here is a link. The ceremonies are performed to do any cryptographic operations which require a Root Signing Key. When you need to use such a key, you usually have to get a number of people called "key custodians" who each have independent physical access to one part of the cryptographic key, usually stored on a smart card or other secure token device. You will usually have an overall number of custodians and a certain quorum of them will need to be there for a given operation. Like, six of ten, three of seven, etc.
They all have to get their fragment of the key (their assigned device) which is usually stored in a safe which only they have access to. Then they all need to be in the same room, usually a SCIF (think a bank vault with a data center inside it). Whatever process they run will ask for their components individually, and then once the required number of components have been entered, the system will reassemble the master crypto keys and do whatever it needs to do.
The process is designed to make sure that fraud is very difficult and cannot happen without being detected. All the systems and physical access along the way will typically be monitored, controlled with biometrics and other secure mechanisms, and easily auditable. Any activity requires an intentional quorum of people to agree to do it, so you can't just get one guy to go do something bad.
It is kind of like nuclear missile launching, the root of a certificate authority, the root of a financial processing crypto scheme, etc.
In this case, sounds like something broke down and they can't get into a safe or some other secure location to retrieve key components. Usually these systems are designed to fail secure except in the case of life safety (i.e. you can get out if there's a fire, it just creates a huge audit nightmare).