Launch delays decoded: Weather woes and technical troubles in space missions

The morning of June 11 saw a further delay in Indian astronaut, Group Captain Shubhanshu Shukla’s journey to the International Space Station (ISS) on board the American rocket Falcon-9 along with three other crew members as part of the Axion-4 scientific mission.

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“Standing down from tomorrow’s Falcon 9 launch of Ax-4 to the @Space_Station to allow additional time for SpaceX teams to repair the LOx leak identified during post static fire booster inspections. Once complete – and pending Range availability – we will share a new launch date,” read a statement posted on X by SpaceX, the American space technology company executing the mission along with Axiom Space and the National Aeronautics and Space Administration (NASA).

https://www.tribuneindia.com/news/india/axiom-4-mission-put-off-as-spacex-detects-leak-in-falcon-9-rocket/

In fact, on June 10 a day after Axiom-4 was postponed due to weather, SpaceX had launched 23 Starlink satellites, meant to provide internet services, from the same Falcon-9 series rocket from the US Air Force’s Cape Canaveral Space Force Station in Florida, which adjoins the NASA center.

Space mission vulnerabilities

Postponing rocket launches is not uncommon and results from various factors such as weather, technical glitches or other miscellaneous factors. In the past NASA and SpaceX have temporarily put off some high-profile launches. Even ISRO has rescheduled some of its launches.

There are specified launch windows and launch periods during which a rocket is permitted to take-off. These vary due to the requirement of the mission and depend upon several factors such as weather, intended trajectory, size and capability of the rocket, the payload and its intended positioning, Earth’s position vis-à-vis other planetary bodies and rendezvous point in space.

A launch window can vary from about half an hour to a few hours in a day, while a launch period can extend up to several days. If the widow or period is missed, the launch has to wait till the next suitable time is available.

Weather conditions 

Weather is the most common reason for deferring rocket launches. Strong winds can make the rocket structurally unstable while on the launch pad or during flight can affect the control parameters and make it veer off course. Wind shear can affect its trajectory and flight stability.

Lightning and thunderstorms also pose a major hazard to rockets, especially during the launch phase when they are vulnerable to electric discharges. Launch will be postponed if there is a forecast of a thunderstorm within a certain distance of the launch site. Cloud cover and precipitation are other critical factors. Dense cloud cover leading to poor visibility can reduce the ability to monitor the launch and identify any problems that may arise and also make it difficult to visually assess and track the rocket’s trajectory.

If a cloud layer in the launch center’s vicinity is more than 4,500 feet thick or stretches into sub-freezing temperatures, the launch will be put off. Further, a rocket cannot launch if there is any form of precipitation. Hot weather suits rocket launches. Air temperature can impact engine performance while low atmospheric temperatures can result in dangerous ice development. General weather conditions, both around the launch center as well as in upper atmosphere in the launch corridor are forecast well in advance by a team of meteorology specialists and are closely monitored as the launch date approaches.

Tech glitches

A rocket is a hugely complex machine comprising thousands of systems, sub-systems, circuits and components, covering metallurgy, electronics, mechanical, electrical, radio-signal, software and chemical domains. A fault or damage to even one component can jeopardize the entire mission.

For this reason, hundreds of sensors collect data up until the last few seconds of a launch to ferret out any possible defect or damage. Visual inspections by scientists and engineers are also part of the countdown and each activity from inspecting and testing components, integrating them and assembling the rocket is carefully calibrated and monitored according to established protocols, with checks and counter-checks in place.

Then there are miscellaneous factors like the flow of high energy particles in space within or near the trajectory, possibly due to cosmic activity, that could impact on board electronics, navigation systems or signal links with ground control. Even the breach of the sanitized airspace or sea swath by an aircraft or boat can put off the launch at the last minute.