\begin{table}%t2
\small
\caption{Mass budget.}
%\centerline
$$
\begin{tabular}{l r@{~}l l}
\hline\hline
\multicolumn{1}{l}{Contribution} &\multicolumn{2}{c}{Mass} & Comment \\ 
\hline   
\noalign{\smallskip}
nuclear mass          & $1.1\times 10^{16}$ & g   & Model, $\rho$ = 0.5 \\
initial dust cover    & $3.7\times 10^{13}$ & g   & Model, $\rho$ = 1.0  \\
dust ($\sim$2~$\mu$m)   &\ \ $1\times 10^{14}$& g   & (1) \\
dust mass in halo     & $4.3\times 10^{13}$ & g   & on day 3        \\
dust production rate  & $2.0\times 10^{8}$  & g/s & for day 3         \\
burst dust mass       & $2.1\times 10^{14}$ & g   & day 3--33  \\
dust mass in halo     & $3.0\times 10^{12}$ & g   & day 35 (equil.) \\
H$_2$O production rate& $3.6\times 10^{7}$  & g/s & (2)   \\
burst H$_2$O mass     & $6.5\times 10^{13}$ & g   & day 1--23  \\
\hline
\end{tabular}$$
\medskip
\par
(1) Sekanina (\cite{sek}). \\
(2) Converted from $1.2\times10^{30}$ mols/s (Combi et~al. \cite{com}).
\label{tab2} 
\end{table}