
This white paper provides an overview of LIGO Laboratory's vision for operating the two LIGO Observatories at least to the period when the next generation (U.\ S.) observatories begin taking data, and presents near and longer term LIGO Laboratory detector research and development programs that will provide pathfinder concepts and implementations in support of a full scale Cosmic Explorer detector\cite{CEHorizonStudy}. It is based upon our current planning for completing the A+ detector upgrade program and carrying out the O5 observing campaign, increasing LIGO Hanford and Livingston observatory sensitivities through detector upgrades, collectively known as \Asharp{}, and through the expansion of the current global ground-based gravitational-wave network with the addition of LIGO-India in the early 2030s. 

\Cref{schedule} presents the Laboratory's current plan for the next 5-year period starting in CY2024.  Following the completion of the O4 observing run at the end of 2024, the LIGO interferometers will undergo a series of upgrades completing the A+ upgrade program with the goal of improving their sensitivities up to double those of the O4 run.  Upon completion of the upgrades and detector commissioning toward the end of 2026, the O5 observing run will be carried out over a three-year period, ending in late 2029.

\begin{figure}[h!]
\centering
% \includegraphics[width=1.0\textwidth]{figures/MO-Schedule-2024-2028.jpg}
\includegraphics[width=1.0\textwidth]{figures/FY24-36_timeline-vD.jpg}
\caption{\footnotesize{\fontfamily{phv}\selectfont \emph{The top-level plan for LIGO Operations and R\&D during the next five years. LIGO maintenance \& operations (M\&O) are funded by the NSF under cooperative agreements (CAs) of five-year duration between Caltech and NSF. Operations will be primarily dedicated to executing the observing run, O4, and preparing for (through A+ and Detector Improvement (DI) installation/commissioning) and executing the observing run, O5. In parallel, the Laboratory will carry out preparatory R\&D to conceptualize, propose, construct, and prepare for installation of the \Asharp{} upgrade discussed in this white paper. Shown in gray are projects outside the scope of the next cooperative agreement, showing the progress toward \Asharp{} installation and commissioning, and then a subsequent period of running interspersed with further enhancements up to the 3$^{rd}$ generation era.}\vspace{-5mm}}}
\label{schedule}
\end{figure}
  
% \dhr{The following is true, but I think it's better incorporated as a footnote. As part of the main text, it has the implicit effect of telling the reader not to take this WP too seriously.} It should be noted, however, that the LIGO observatories are part of the NSF's Major Research Infrastructure and as such the operation of the observatories by Caltech and MIT is limited to 5-year periods under cooperative agreements (CA) with the NSF. The time horizon under consideration in this white paper will span three or four NSF CA cycles; thus who the future operator(s) of LIGO Laboratory for the NSF is(are) not, in principle, known today.