The PSA reading turned into full prostate cancer, and Kelly underwent surgery in November 2007. Just three months later he officially separated from his wife, Leslie Yandell, and started multi-lingual training. On the flight that followed, he was in space from 9 October 2010 until 16 March 2011, serving as Commander from November on. A year later, the phone rang again and the question was "Would you rather be promoted to Chief of the Astronaut Office or go back to ISS for a full year?" Kelly opted for the Astronaut Office, but was assigned the year-long mission anyway. He retired in April 2016 having clocked an aggregate 520 days in space over five missions.
Those are just a couple of highlights from Endurance—a national best-seller published last month and written by Kelly. As a space junkie, I have a full library of astronaut memoir books and I can honestly say that this is probably the best of the bunch. The book may lack the heart-stopping drama of a lunar landing, but it more than makes up for it with its intricate detail both human and technical. Kelly writes of the exhilaration of spaceflight, and the pride ISS crews take in the science they are able to accomplish, but he does not hold back (at least, doesn't seem to) on the pesky annoyances of life up there.
A case in point: Long-duration spaceflight put an end to the Apollo-era technology of lithium hydroxide canisters for removal of carbon dioxide from spacecraft atmospheres. A six-month mission would use hundreds of the bulky cartridges and the storage space just isn't available. So the ISS has a high-tech system called Seedranote 1, and it seems to be the bane of Kelly's life in space. He writes that he can check the CO2 level any time he likes on a computer readout "...but I don't need to—I can feel it. I can sense the levels with a high degree of accuracy based only on the symptoms I've come to know so well: headaches, congestion, burning eyes, irritability." He points out that the US Navy Submarine Service doesn't allow CO2 to get any worse than 2mmHg partial pressure, but the ISS considers 6mm acceptable. Add to that annoyance that the Seedra machine keeps breaking down and is a bitch to repair, and you have the recipe for a lot of pissed-off astronauts.
Scott Kelly and Terry Virts repairing one of the Seedras, from p.88 of the hardcover edition
No errors, comrades
Speaking of complaints, he reveals an interesting difference between astronauts and cosmonauts. As a NASA astronaut, Kelly's base pay was generous and his per diem minimal—actually just $5. For the cosmonauts, it's the other way around—the majority of their remuneration is in per diems, which can be reduced if they are found guilty of "errors." Kelly surmises that complaints can be viewed as errors, and that explains why, when Moscow mission control asks how things are going, the answer is always v'syoh prekrasno (everything's fine) even when it patently is not.
Kelly reports that relations between the American and Russian crews were always very cordial. During the working day they mostly stuck to their own areas of the huge space station, but they would get together for some meals, particularly on Friday evenings. Exchanges of food were commonplace, as were more important items like tools or replacement hardware. Informal exchanges, however, did not suit the bean counters on the ground, who were charged with adhering to the terms of formal international agreements. Their rules meant that every exchange, be it equipment, water, computer software, even urine—yes, urine, for urine is a resource on the ISS—has to be accounted for, placed on a balance sheet and eventually compensated in cash. Kelly tells the story of one time when the Russian crew offered him some unused space on a Progress module that was due to be detached and sent to burn up in the atmosphere. Kelly gladly got rid of several kilos of trash. The time came when the bean counters discovered the discrepancy in the trash inventory and asked Kelly to explain it. "I guess the trash fairy came in the night" was his wry reply.
Kelly with cosmonaut Mikhail Kornienko
Endurance: A Year in Space, A Lifetime of Discovery by Scott Kelly with Margaret Lazarus Dean. Knopf, October 2017. ISBN 978-1524731595 (hard cover)
 Seedra is just a pronounceable form of the acronym CDRA, Carbon Dioxide Removal Assembly