Short answers, pulled from the story.
Gherman Titov became the first human to experience space sickness during a spaceflight in August 1961 while inside the Vostok 2 capsule. He suffered from nausea and disorientation while orbiting Earth, marking the beginning of recorded space adaptation syndrome cases.
Sensory conflict theory occurs when the vestibular system reports motion but the eyes see stillness, creating incongruous signals about body position relative to surroundings. Gravity plays a major role in spatial orientation, and changes in gravitational forces influence how balance systems function during space voyages.
Symptoms typically last between two and four days for most travelers without medication. Most travelers adapt naturally within one to seven days, though sleep deprivation can worsen these symptoms and extend their duration.
NASA began using an informal Garn scale to measure space sickness responses after Senator Jake Garn vomited so severely on Space Shuttle flight STS-51-D in 1985. His reaction became so severe that it prompted officials to quantify such incidents despite his experience piloting military aircraft for 17,000 hours before the mission.
Extra-vehicular activities are usually scheduled after the first few days of a mission to allow adaptation before exposure to open space. Transdermal dimenhydrinate anti-nausea patches are used whenever space suits are worn by NASA crew members to prevent vomiting from obscuring vision or blocking airflow.