​NASA does not give up and is trying again to launch the first rocket from the Artemis program, which will return astronauts to the surface of the moon in a few years, after a 50-year hiatus. The unmanned Orion capsule will arrive in the vicinity of the Moon in a few days, and the mission will last 26 days. Artemis is a program that could eventually be worth nearly $100 billion, and the first big step will be taken in the next few hours.

7.57: Fuel is running out. It is clear that the launch will NOT be immediately after 8, but somewhere later, in a two-hour time interval. The faulty radar switch has been replaced and is now being tested to see if it works.

7.43: There were already problems on Wednesday morning: a liquid hydrogen leak was detected, but it appears that the intervention team has fixed them. Another problem was that one of the US military’s radars, which is supposed to track the missile after launch, was malfunctioning. The switch needs to be changed, but NASA says that’s a quick fix.

The launch window starts at 1:04 am (8:04 am Romanian time) and the rocket can be launched no later than two hours later (10:04 am).

Leaks, faulty sensors, hurricanes – three months NASA wants to forget

The SLS rocket and Orion capsule were delivered to the launch pad on August 17, and this is not the first time this has happened. The SLS system was removed from the hangar and taken to the launch pad twice more: in April and June, to conduct a series of static tests and refuel the tanks, but each time there were problems.

The first launch attempt was on August 29, but the countdown was stopped when one of the engines was found to be insufficiently cooled. After checking, a malfunction of the sensor was detected.

• Why is NASA trying to launch the SLS rocket a colossal waste of money or an audacious space program with which we should be patient?

Another attempt was made five days later, on September 3, but the countdown had to be stopped again. The second launch delay was due to problems with the use of liquid hydrogen in the SLS rocket, and was mainly due to a leak in the hydrogen supply line.

A concentration of hydrogen in the air of 4% is considered a dangerous concentration, and on September 3, a concentration two to three times higher than the permissible level was reached around the hydrogen supply pipeline. An explosion was possible, and NASA didn’t want to take any chances.

The hydrogen leak discovered on September 3rd during refueling was massive, much more serious than the one that occurred on August 29th after the first failed launch attempt.

NASA kept the rocket on the launch pad in September, hoping to make another attempt, but had to take it to the VAB hangar, especially in connection with the approach of Hurricane Ian, which wreaked havoc on important areas of the US state of Florida.

It should be said here that the operation of delivering a megarocket 100 m high and weighing 2.6 million kg to the launch pad or back to the hangar is very difficult and uses a huge conveyor belt that moves at a snail’s pace (6 km in 12 hours).

The rocket returned to the launch pad on November 4, when NASA could not have known that the new Hurricane Nicole would threaten the huge SLS installation on November 10, with wind gusts reaching a maximum speed of 100 mph (165 km). ./h in the area of ​​the ramp, but fortunately this maximum speed was recorded slightly higher and the rocket suffered minor damage, the gusts were not so strong. These malfunctions, some of which are related to the sealing components of the Orion capsule, are not mission-threatening.

SLS, big delays and problems

In May 2019, the then head of NASA announced that the mission to return humans to the moon would be named after Artemis, a goddess who, according to mythology, was the twin sister of the Greek god Apollo. It has special significance: Apollo was the program that first landed humans on the moon more than 50 years ago. Artemis will return humans to the moon, with the idea that this time humans will finish building a lunar base after 2030.

It’s a long way to get there. In 2012, it was estimated that the SLS rocket could cost six billion dollars to build, but more than $23 billion has already been spent and the rocket is on its first launch. As recently as a decade ago, it was believed that the launch could cost 500 million dollars, but the latest estimates indicate more than 4 billion per launch. Ten years ago, the most optimistic believed that the rocket could be launched in 2017.

It’s an expensive program, the audit estimates, costing $93 billion between 2012 and 2025, when four Americans are expected to set foot on the moon’s south pole as part of the Artemis III mission. Already in May 2024, the Orion capsule should send several astronauts on a mission around the moon, but without landing. The schedule is likely to change as there are many technical issues and many questions are postponed.

NASA is reusing critical elements for the SLS super rocket

The launch of the SLS rocket, together with the Orion capsule, should take place on Monday, in a two-hour “window”, starting at 1.03 (8.03 in Romania), from the Kennedy Space Center, Florida.

Artemis is an expensive program that’s been delayed, but it’s great that it exists, that it’s funded, and will send humans to the moon for the first time since 1972. NASA is a changed institution, even if it still works in small steps. and very carefully.. NASA is working more efficiently than ten years ago, and it is clear that it is very important to work with private companies like SpaceX and Blue Origin, and not only with large aeronautical concerns. However, various elements were built on the SLS by major companies: Boeing, Aerojet Rocketdyne, Northrop Grumman and United Launch Alliance (a joint venture between Lockheed Martin and Boeing).

Then it should be said that the engines on the SLS rocket, which launches on Monday, are part of the NASA inventory and have been used by the space shuttles in the past. These are the engines that have been used on past space shuttle flights (over 20 flights in total), but unfortunately, the Artemis mission will not have the engines recovered, but will fall into the Pacific Ocean after the first stage fuel is exhausted. was used completed

The SLS rocket has four RS-25 engines and two auxiliary boosters. The main stage tanks will contain a total of 3.3 million liters of liquid hydrogen and liquid oxygen.

The Orion capsule isn’t new either: it was built almost 20 years ago, but the cancellation of the Constellation program in 2010 meant that Orion had no chance of going into space. After a series of modifications, Orion will reach space and be essential to the Artemis program, provided it can be successfully recovered and thus safely reach ocean waters.

In the capsule will not be people, but three mannequins: Helga, Zoar and Commander Munikin Campos, two mannequins equipped with plastic models of human organs, the purpose of which is to measure the effects of cosmic radiation on future astronauts.

Orion should lift off when the SLS rocket reaches 3,700 km from Earth and the engines will carry it on a mission around the Moon, after which Orion will have a 26-28 day mission and reach 100 km from the lunar surface. The return is scheduled for December 12, in the waters of the Pacific Ocean.

Orion and what happens immediately after launch

On September 3, Orion will reach the closest point to the surface of the Moon (altitude 100 km), and on September 8, it will reach the farthest point reached by a space shuttle designed to carry people (more than 450,000 km from Earth, surpassing the record set by Apollo 13 in April 1970 The Moon is 384,000 km from Earth, and Orion will reach its maximum point 64,000 km from the Moon.

Orion will also launch 10 small satellites, called “cubsats,” to study the moon and its surroundings.

Orion cannot land, but it will also be used in the Artemis III mission, which will return humans to the lunar surface in 2025 or later. Orion will take astronauts into lunar orbit, near the south pole, and they will arrive on the surface of the moon after landing in a capsule that will be built by SpaceX.

A big advantage is that Orion is designed to also handle re-entry into the Earth’s atmosphere from interplanetary orbit (where speeds are higher than re-entry from lunar orbit), meaning NASA will be able to use the capsule for future missions to Mars and from it.

On August 29, two minutes and 12 seconds after launch, the boosters disengaged and fell into the ocean. Eight minutes after launch, the rocket’s orange main stage will disengage. After that, Orion will be in Earth orbit with the rocket’s upper stage still attached to it.

Orion’s solar arrays will open, followed by an Earth orbit, and the upper stage will set Orion on the correct trajectory toward the Moon and detach from the capsule two hours after launch. About half an hour before that time, Orion will reach a speed of more than 35,000 km/h.

The journey back to Earth will begin on October 3, but the point of maximum distance from Earth will be reached on September 24. When re-entering the atmosphere, Orion will reach a maximum speed of more than 39,000 km at an altitude of more than 130 km. It will also be possible to see if the heat shield perfectly withstands temperatures of several thousand degrees, after re-entry into the atmosphere, and then three special parachutes will have to open.

Why is it so difficult to work with liquid hydrogen?

NASA has been using hydrogen in its rockets for a long time, and the advantages of this fuel, and especially its disadvantages, have been talked about for a long time.

Hydrogen, being light, burns at high temperatures and is a very efficient fuel for use in various rocket stages.

The problem is that hydrogen has the smallest molecule and is very difficult to contain in a sealed chamber. This is not a problem at normal ambient temperatures and pressures, but becomes a problem at extremely low temperatures and high pressures because it escapes through any small opening.

NASA has had problems with hydrogen leaks before and more than three decades ago. For example, the summer of 1990 was referred to by some as the “summer of hydrogen” after the space shuttle had several problems at the Kennedy Space Center due to this type of fuel. The difference is that the Space Shuttle was operational then, while the SLS, in the fall of 2022, is a test rocket that will now make its first major flight.

SLS engines cannot run without liquid hydrogen and liquid oxygen since they were developed more than three decades ago. When the SLS project was conceived in 2010 under the direction of Congress, it was clear that it would also use liquid hydrogen, rather than kerosene or methane.

The SpaceX Starship rocket will use methane, a gas that is more efficient than kerosene, which means that for the same volume we have more energy available for the rocket. If kerosene is used in a reusable engine, there can be problems with kerosene soot settling on the engines and making cleaning difficult. Combustion is cleaner with methane. Methane has attracted the attention of several companies because it works well and is cheaper.