All astronauts' activities and physical condition are constantly monitored by NASA
質問者様の英語はほぼ完璧です。理解できます。
「All astronauts' activity and physical condition are constantly monitored by NASA」を提案しました。「by」が抜けていたので、それを付け足したのと、行動を behavior から activity に変えました。
しかしながら、この文書は根本的なミスがあり、全ての宇宙飛行士をNASAが監視しているのではなく、NASAの宇宙飛行士のみ、宇宙船内に限定し、監視しているという意味だと思います。
なので、改めて「All NASA astronauts' activities and physical condition on board are constantly monitored by NASA」に改定いたしました。
NASA monitors every aspect their astronauts activities and physical conditioning.
This is another way in which you may hear the phrase that you are looking for. People may phrase it like this when they want to stress that it is NASA that is doing the monitoring. If you flip the phrase around you will be focusing on the the astronauts.
"All astronauts' activities and physical condition are constantly monitored by NASA"
"In order to make sure that NASA astronauts' are physically fit, they are monitored by NASA"
In order to explain that all astronauts' activities and physical condition are constantly monitored by NASA, you can simply state "In order to make sure that NASA astronauts' are physically fit, they are monitored by NASA". This sentence explains why and how NASA ensure that astronauts' are well and able to fulfil their jobs.
「宇宙飛行士の全ての行動と体調は常にNASAによって監視されている」は次のように言えます。
"In order to make sure that NASA astronauts' are physically fit, they are monitored by NASA"
（健康管理のために、宇宙飛行士はNASAによって監視している）
この文では、なぜ、そしてどのようにしてNASAが宇宙飛行士の健康を管理しているのか伝えています。
NASA astronaut's activities and physical conditions are monitored!
"NASA astronaut's activities and physical conditions are monitored!"
To ensure the safety of all their astronauts, NASA monitors their activities, actions, and physical condition. This is important for all parties concerned. The astronaut's well being is of utmost importance so that they can perform all their duties.
"NASA astronaut's activities and physical conditions are monitored!"（NASAの宇宙飛行士の行動や体調は監視されている）
宇宙飛行士の安全を確保するため、NASA は彼らの行動や体調を監視しています。これは全ての当事者にとって重要なことです。宇宙飛行士は健康でなければ職務を果たすことはできません。
All astronaut's activities and physical health are constantly monitored by NASA
NASA monitors every aspect of an astronauts activities and physical health
When talking about someone keeping on eye and checking to make sure you are healthy you can also say they are 'monitoring' it
physical health suggests your body being affected by your health rather than your mind
Astronauts' activities and physical condition are important to their job, so NASA monitors them constantly.
Physical condition and activities of astronauts are constantly monitored by NASA.
NASA monitors all astronauts' physical condition and activities.
These are three different ways to state that NASA monitors the physical activity and condition of their astronauts.
The one you choose to you is a personal preference; "Astronauts' activities and physical condition are important to their job, so NASA monitors them constantly" is perhaps the most detailed. You can also state other reasons other than 'important to their job' as you like.
Both statements - "Physical condition and activities of astronauts are constantly monitored by NASA." and "NASA monitors all astronauts' physical condition and activities." are clear and without explanation of why but have space for an explanation and you can do this simply by adding ".... because...." at the end of either of the statements.
「NASAは宇宙飛行士の行動と体調を監視している」の三通りの言い方です。
どれを使うかは、好みによります。
"Astronauts' activities and physical condition are important to their job, so NASA monitors them constantly"（行動と体調は宇宙飛行士にとって非常に重要で、NASAは常にそれらを監視しています）
は、最も具体的な言い方かもしれません。'important to their job'（宇宙飛行士にとって重要）は理由を表します、ここは好きなものに変えてもらって結構です。
"Physical condition and activities of astronauts are constantly monitored by NASA."（宇宙飛行士の体調と行動はNASAが常に監視している）
と、
"NASA monitors all astronauts' physical condition and activities."（NASAは全ての宇宙飛行士の体調と行動を監視している）
はどちらも、分かりやすい言い方です。理由は説明していませんが、説明をする余地はあります。".... because...."（なぜなら）を文末に加えるだけです、これで理由を説明できます。
All the astronauts actions and movements as well as their medical conditions are constantly observed by NASA
NASA always keeps an eye on the astronauts activities and their physical conditions.
NASA keeps a close eye on all the astronauts activities and their physical well being too.
The sentence explains that NASA are always watching and implies that they are looking for abnormalities in either their behavior (activities) or their medical (physical) condition.
There are many different ways we can explain this - see the examples above for three such ways.
Every activity carried out by the astronauts - and also their physical data is closely monitored y NASA.
You want to explain that all astronauts' activities and physical condition are constantly monitored by NASA.. The above statement is suitable forn that scenario.
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