SYSTEMS DATA BOOK.
Flown on Apollo 13, a sheet from the LM Systems Data Book, pp 34-35, 10½ by 8 inches, with a tab reading "LM Ascent amp-hrs" and "LM Descent O2" on recto and verso.
Accompanied by a Typed Letter Signed by Fred W. Haise, which reads in part: "Accompanying this letter is a sheet ... from the Apollo 13 LM Systems Data Book carried on the flight of Apollo 13 during April 11 to 17, 1970.
Page 34 is a graph of the LM-7 ascent stage amp hours available. It plots the ascent battery charge status in amp hours versus the Ground Elapsed Time (GET) or time in the mission since launch. The key points are LM lift-off from the lunar surface, rendezvous, and docking with the CSM. We expected to have almost 600 amp hours at the start of the initial LM checkout with the power dwindling down to around 200 amp hours once the LM was jettisoned. The data plots on both of these graphs could be checked during the flight via our LM RCS and AMP gages located on the control panel. The reserve power and propellant carried were life saving consumables because our emergency situation required more than was planned for a nominal mission.
Page 35 is a graph of the LM Descent Oxygen profile that plots the total usable breathable oxygen from our Descent Stage in both pounds and percent remaining in versus the GET. The key points are lunar touchdown, our lunar EVAs, and lunar lift-off. We expected to have almost 100 pounds of oxygen at the beginning with that amount reduced to barely 10 pounds at LM liftoff. Of course the Service Module oxygen tank explosion caused the lunar landing to be canceled, but this oxygen was vital for our survival during the four days that were needed to return to the earth.
I have inscribed and signed page 34 with: 'Flown around the Moon on Apollo 13, Fred Haise, Apollo 13 LMP.'"