W(h)ither Artemis?

It is a while since I wrote something and, in the intervening time, important changes have happened. One of NASA’s biggest nightmares over the decades has been lack of continuity: one President, or party starts a programme, and the next cancels it. Again, we are going through a regime change in the United States. At the same time, an audit of the Artemis programme has suggested that it will struggle to reach its target of a Moon landing in 2024. Just as Richard Nixon killed the Apollo programme championed by John F. Kennedy and Lyndon Johnson once it had suited his purposes, Barak Obama killed the launcher to return to the Moon proposed by George Bush. An Artemis programme that was already surviving, at least in part, because Donald Trump was promised that chance to see astronauts on the Moon before he left the White House, now depends on a new President who has already indicated that it may not be one of his spending priorities.

The Artemis I Core Stage arriving at the barge that will transport it to the integration facility for mating to the Solid Rocket Boosters.

It is one of those ironies that, as NASA mounts the Artemis I rocket that will test America’s capability to take astronauts back to the Moon on Artemis III, already mating the two Solid Rocket Boosters to the Artemis I Core Stage, that the Artemis III Moon landing is the last flight guaranteed under the current launcher contract and, even it is not fully funded yet. As I write, construction of the core stage of Artemis II is well advanced (this is the circumlunar mission that will return astronauts to lunar space in 2022), with work started on installing all the wiring that this massive craft requires. Meanwhile, the structure of the Artemis III core stage is taking shape at Michoud Assembly Facility in New Orleans.

Finishing the panelling inside the giant Artemis I hydrogen tank.

Starting to stack the SRB sections that will form the Solid Rocket Booster for the crewed Artemis II moonflight. The Artemis III Moon-landing craft is being prepared simultaneously.

NASA has big plans for Artemis, including a permanent presence on the Moon in the second half of the decade and long-duration flights (3 months) into deep space by the end of it. The aim is that these will be followed by a crewed Mars landing in the 2030s.  Some people though feel that Artemis is a dead end that is about to be cancelled anyway. For some, the only way back to the Moon is to wait for the promised giant rockets from private companies that will operate for profit. What no one wants to see is another programme that is scrapped after years of development, an enormous amount of investment and a small number of flights.

That said, early indications are not promising. Although the new administration has promised to make science a priority rather than a target, it has already indicated that possibly Artemis and a return to the Moon will not be the first in line for spending those tax dollars. In any programme of this kind, momentum is everything. In the 1960s the Moon programme had such unstoppable momentum that even the Apollo 1 disaster could not kill it. In the 2020s, momentum is a precious commodity that Artemis simply does not possess.

Originally, Artemis was intended to land on the Moon in 2028. The acceleration to 2024 was a calculated one. Without putting too fine a point on it, offering the President the chance of setting American astronauts on the Moon before his second term ended was very much an appeal to his vanity and desire to go down in history. It was also a calculated attempt to build up some desperately needed momentum for crewed spaceflight outside Earth orbit of the kind that is happening with the Crew Dragon flights to the ISS.

One of the issues that NASA has had is lack of continuity. After Apollo, the giant Saturn rockets were scrapped in favour of a reusable booster. As planned, the Space Shuttle or, to give it its grander name, the Space Transportation System, was an attempt to make space flight simpler and cheaper by using a launcher that could, in part, be re-used. In practice, delays and budget cuts meant that it was a compromise that satisfied no one. Too small to launch the large satellites that the military wanted it to carry, yet too large to be cheap to fly. The recovery of the Solid Rocket Boosters looked thrifty but, in reality, it would have cost NASA very little more to build new ones for each flight and, as Challenger showed, their re-use had its dangers. And, as history recalls, the original aim for each Shuttle, to make one hundred flights was never realistic: no Shuttle even reached thirty flights. By the end of the Shuttle programme, it was becoming increasingly difficult to keep them flying because they were using totally out of date technology and finding spare parts was becoming harder with every launch.

A criticism of Artemis is that it uses old and left over engines from the Space Shuttle. With the F-1 engine that launched the Saturn V towards the Moon now just a distant memory, Artemis uses a development of the much smaller J-2 engine that powered the Saturn V second and third stages. For the Space Shuttle, the J-2 was developed into the RS-25, which will now be used for Artemis. Apart from the fact that the RS-25 generates nearly twice the thrust of the J-2, the major difference between them is that the J-2 could not be used to launch – in other words, it cannot be used in a first stage – because the stresses of launch would tear it apart, while the RS-25 was designed to work both on the ground and in space. A further big difference is that the RS-25 can be throttled-back a great deal to reduce the stresses on the launcher, while the J-2 had much more limited capabilities.

For those who lived through the Apollo launches, one of the big calls was always “Max Q”: maximum dynamic pressure. This is the point at which the speed of the rocket had built up so much in the still thick, lower atmosphere, that the pressure from the atmosphere resisting passage of the rocket reached a maximum. Before Max Q, the atmosphere is thicker, but the rocket is travelling more slowly, so the pressure on the rocket’s structure is less. After Max Q, the rocket is travelling much faster, but the atmosphere is so much thinner that its resistance is much slighter. Max Q is the moment when the rocket’s airframe is being most stressed. The Space Shuttle used to throttle back its engines so as reduce the stress on it as Max Q approached and would then throttle up after this point was safely passed to hurry the Shuttle up towards orbit. A huge advantage of the RS-25 over the J-2 is that it can be set between 65% and 109% of nominal thrust according to the moment in the flight although, after Challenger, the thrust was capped at 100% for safety reasons. In contrast, the J-2’s thrust could only be varied by changing the amount of propellant flowing into the engine: in other words, the thrust could be varied by making the mix of fuel and oxidiser richer or thinner so that, as the fuel tanks emptied, the g-forces on the crew were kept to a reasonable limit.     

A Saturn V at Max Q. The typical cape of vapour forms around the top of the 1st Stage and, to the lesser extent, the shroud around the Command Module. This is the point at which the airframe of the rocket suffers most stress from pressure as it slices through the dense, lower atmosphere at increasing speed.

However, the fact that Artemis uses old technology – solid rocket boosters and left-over Shuttle engines – is one of the arguments that have been used against it. The RS-25 is extremely trustworthy – it has never had an in-flight failure – but the only fundamentally new aspect of Artemis is the Orion capsule that will carry the astronauts and even that looks astonishingly like an updated Apollo capsule, although much more modern and luxurious. Another familiar item from the past is that, like most NASA projects since Apollo, Artemis is running over budget and well behind schedule. To land on the Moon in 2024 will take massive support from Congress, which, although both parties are generally highly supportive, it is far from clear that the necessary commitment to spend the money necessary to make it happen actually exists. With the President facing a Senate with a likely narrow Republican majority and a House with almost certainly a waver-thin Democrat majority, steering a budget through Congress that requires massive extra funding for Artemis would not be easy at the best of times and a post-COVID world is certainly not the best of times.

The longer that Artemis takes to fly, the later it gets, the greater the chances that it will be an easy target for cancellation. With Elon Musk making the provocative comment that he expects to see astronauts on Mars by 2026, something that NASA knows that it cannot do, the prospect arises that private enterprise could even put boots on the planet Mars before NASA can put them on the Moon. If that were to happen, would it make sense to persist with the Artemis programme? Many people would argue that it would not.

Maybe the answer lies in an analogy with air travel. Many private airlines exist – the terrestrial equivalent of Space-X and the like – but state carriers have the prestige, if not always the passenger numbers. A healthy airline industry requires both. A healthy space programme will need a State and a Private sector too. ESA abandoned decades ago its efforts to have an independent crewed launcher capability, but continues to launch astronauts, to launch satellites and to carry out cutting-edge science, developing technology that has flown out as far as Saturn and that will, hopefully, in the next few decades, reach Uranus and Neptune too. Maybe ESA might even one day become the model for “state spacelines”?

Hopefully, the future will see a suite of State-owned and privately owned giant boosters such as Artemis, Long March 9 and Starship all flying humans deeper and deeper into space, making the human race truly a space-faring culture that is not tied to a single and increasingly fragile planet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s