\begin{table}%t1
%\centering
\par
\caption{\label{TabSatChar}\textit{Planck} satellite characteristics.}  
\begin{tabular}{l  c  c } 
\hline\hline \noalign{\smallskip}
Diameter   & 4.2~m & Defined by the solar array \\
Height    & 4.2~m &  \\
Total mass at launch   & 1912 kg & Fuel mass = 385~kg at launch; He mass = 7.7 kg \\
Electrical power demand (avg)  & 1300 W & Instrument part: 685~W (Begining of Life), 780~W (End of Life) \\
Operational lifetime    & 18 months & Plus a possible extension of one year\\
Spin rate    & 1 rpm  &  $\pm$0.6~arcmin/sec (changes due to manoeuvers)\\
&        & Stability during inertial pointing~$\sim$~$ 6.5 \times 10^{-5}$~rpm/h\\
Max angle of spin axis to Sun    & 10\degr\ & To maintain the payload in the shade. Default angle is 7$\fdg$5.\\
Max angle of spin axis to Earth    & 15\degr\ & To allow communication to Earth \\
Angle between spin axis and telescope boresight & 85\degr & Max extent of FOV~$\sim$~8\degr\ \\
On-board data storage capacity & 32~Gbit  &  Two redundant units (only one is operational at any time) \\
Data transmission rate to ground (max)  &  1.5~Mbps & Within 15\degr\ of Earth, using a 35~m ground antenna  \\
Daily contact period  &  3~h  & The effective real-time science data acquisition bandwidth is 130~kbps.  \\
\hline 
\end{tabular}
\end{table}