p05-21 Question: What is the purpose of Sirius 4?
Answer: To find Pathfinder so that he can get the radio and contact Earth.
Question: The up-highers decide not to tell the crew that Mark is still alive, where are the crew now and how can it be possible they are kept from the shocking news?
They are on their way back to Earth, in the middle of a flight which requires concentration and better no devastating emotional fluctuation. The up-highers control "all communication with them", maybe control every piece of info that goes to the crew as mentioned in the book, as to how do they manage to do that, no clue. First cut down their live TV connection and network to the secular world? Or there is no such kind of thing in a spaceship in the first place? Their families must have been visited and informed the importance of their not being told of the news so that they won't get that when contact their family.
05-22 Question: Why is navigation tricky and how does he overcome it?
Answer: The Hab's nav beacon reaches only 40 kilometers but Mark is on a much longer trip, and he can't find any landmarks so the map is useless. He can't make a compass because the Mars doesn't have a magnetic field. The only indication for directions is the Phobos, which whips around Mars so fast and rises and sets twice a day, running west to east. It isn't the most accurate system but at least it helps. It is not until Sol 75 that he find a landmark on the map, a five-kilometer crater, to navigate by, and near that there will be Lighthouse of Alexandria and Hamelin crater on the map, end of the bland areas of the map.
05-24 Question: Why can't Mark use alphabet to receive messages?
Because 26 letters plus one poster around the camera will make it hard to figure out which letter is pointed to with only 13 degrees between every two letters.
Question 2: I think they will just be more than happy and relieved because Mark has emphasized that it's not the crew's fault to recon him dead and leave. They will require to take the mission to bring him back, and do anything they can to help.
05-25 Question: What do you think about Lewis?
I think she is a very responsible, determined and competent commander. She'd rather stay on Mars with Mark at first, I won't say it is right or wrong, but she is really brave and willing to risk her own life for her crew mate. It's not her fault but she blames herself because as a commander, from her own stand point, leaving a crew member on Mars alone, alive, is unacceptable under any circumstances, I can understand her deep remorse. I would feel the same if I were her.
Question: Remember the question for the last chapter?
Yes. The up-highers send message dumps to the crew members, easily controled.
05-26 What is the worst event, and what's the cause of it?
Airlock 1 was detached from the hab and caused a explosion inside the hab. It is caused by the worn hab canvas at the joint part of the hab and airlock, the canvas sheet was designed to sustain a shorter time than what Mark has stayed, and couldn't stand the stress thrown to it by Mark's get-in-and-out for everyday EVA.