NASA scheduled its Artemis-1 mission launch at 11.47 pm, why so precise?

Source: The post is based on the article “NASA scheduled its Artemis-1 mission launch at 11.47 pm, why so precise?” published in Indian Express on 5th September 2022.

What is the News?

After an aborted attempt, NASA was to make another bid to launch its Artemis-1 mission.

There was a two-hour window to launch the mission. However, the mission was aborted for a second time due to a hydrogen leak.

Why are there launch windows for space missions?

Space missions cannot be launched anytime they are ready to go. Very precise time slots are calculated for their launch. 

Two main factors

Shortest Distance: Nothing in space is stationary. The origin (Earth) is moving, and so is the destination (Moon, or any other planetary body the mission is headed to).

– Hence, one reason for scheduling a launch window is to look for the shortest distance to the destination. 

Fuel Efficiency: The other related reason is the need for fuel efficiency. There is no refuelling opportunity in space. And, the more fuel the rocket carries, the heavier it becomes, which again means more fuel is required to propel it.

Other Factors 

Weather: A space mission cannot be launched if the temperature is too cold or too hot or if the wind is blowing at a very strong speed. Rainfall, humidity, lightning, cloud or smoke are all factors that need to be considered for a safe and successful launch.

– Favorable weather conditions are required not just at the time of the launch, but also during the fuelling of the engines.