SPACEFLIGHT Return to the Moon 50 years on

Walking on the Moon again?

From his vantage point of working on the Apollo Program in the 1960s in Houston, PAT NORRIS FRAeS looks at current attempts to return humans to the surface of the Moon.

In May of this year, Jeff Bezos, founder of Blue Origin, unveiled this concept for a Lunar lander the company has been working on. NASA

It is hard to get to the Moon, especially if you want to come back! The first humans stepped onto the Moon’s surface 50 years ago this month but no one has been back there since the last Apollo mission in 1972. The details of that first mission, Apollo 11, highlight the technical challenges involved.

The Apollo 11 Lunar Module that Neil Armstrong and Buzz Aldrin piloted down to the Sea of Tranquillity on 20 July 1969 weighed just over seven tons. It had weighed 15 tons when it left Michael Collins in the Command & Service Module (CSM) two and a half hours earlier, then burned up 97% of its eight tons of propellant in landing. Of the seven tons that landed, about two and a half tons were left on the surface – the descent engine, used equipment, science instruments, the spindly landing legs, etc. Half of the estimated five tons that took off from the Moon was fuel to get them back to the CSM – you have to reach a speed of about 3,800mph to go into orbit around the Moon, made easier by virtue of the Moon’s gravity being only one-sixth of that of the Earth.

The CSM weighed 17 tons as the three astronauts cast the Lunar Module adrift and fired up its engines to get out of lunar orbit and head for the Earth, in two and a half minutes the engine consumed four and a half tons of propellant. As they approached the Earth they jettisoned the Service Module part of the CSM so that the vehicle that landed on Earth weighed slightly less than five tons.

Pat Norris speaking at RAeS HQ.

The 15-ton Lunar Module and 17-ton CSM that were in lunar orbit started out together as a 46 ton vehicle hurled away from Earth at 23,300mph by the massive Saturn V rocket. That velocity was a lot more than the 17,000mph needed to get the Apollo capsules into a low Earth orbit and required the Saturn V third stage rocket to burn an additional 71 extra tons of propellant. More than 11 of the 46 tons were propellant consumed in getting into orbit around the Moon.

The hard fact is that you have to bring a rocket plus its fuel down to the Moon’s surface with you. If you want five tons to take off from the Moon’s surface (as Apollo did), then you have to get about 25 times that into low Earth orbit and send about ten times it outbound from Earth at 23,000mph.

The Soviet Union also planned to put cosmonauts on the Moon in the 1960s. In their version the lunar lander was about a third the weight of the Apollo Lunar Module, sized for a single person. Their N1 rocket had about two thirds the capability of the Saturn V, which dictated the smaller Moon landing vehicle. The N1 never made it into space – its first stage blew up on each of the four test flights it made before being cancelled.

Pat Norris’ latest book: Returning People to the Moon After Apollo – Will It Be Another Fifty Years? (Springer, 2019) is now available

The reason this is ‘hard’ is because no other space mission needs more than about 15% of the power of a Saturn V, and most get by with less than 10%. Other users of space share the cost of developing the rockets that can place them in orbit around the Earth or outbound to Mars, Jupiter and beyond. However, a human Moon landing mission has to bear the full cost of developing a superheavy-lift rocket. That is why the left-over Saturn V rockets were sent to museums and why no one has developed a rocket with a similar capability.

Now that is set to change, as groups in the US, China and Russia are at various stages of developing a rocket powerful enough for a human mission to the Moon’s surface.

The US contenders

First up is SpaceX, the American company that has shaken up the world’s space business by creating rockets that are half the price of the competition and which are reusable. The bread and butter SpaceX rocket is the Falcon 9 that can loft as much as 23 tons into Earth orbit. Strapping three of these together results in the Falcon Heavy which can place about 63 tons in orbit and is currently the world’s most powerful rocket by more than a factor of two.

The first launch of the SpaceX Falcon Heavy from Kennedy Space Center on 6 February, 2018. SpaceX

Three Falcon Heavy launchers, costing about $120m each plus two Falcon 9s at about $60m each, could underpin a Moon landing mission according to independent experts such as Robert Zubrin. The Falcon 9s would carry astronauts while the Falcon Heavy would bring the materials for staying on the Moon and the Moon lander to which the astronauts would transfer in space. His suggestion would result in the creation of a Moon base capable of supporting astronauts for two or three months plus a lunar rover.

The larger-than-life founder of SpaceX, Elon Musk, has embarked on an even more ambitious scheme. He is developing the Super Heavy booster plus its Starship crewed upper stage that will be able to place 150 tons in orbit and be completely reusable (or you could choose not to reuse it and instead fly 300 tons to orbit). This fantastic combination could undertake a human Moon landing mission involving a single Super Heavy and Starship launch plus a second launch of a Super Heavy with a more modest payload. Musk has said that he hopes to have this futuristic spaceship ready by 2023, although he admits that this is an optimistic schedule.

Blue Origin

Meanwhile, NASA is in the Moon landing business again, this time with the Space Launch System (SLS) in place of the Saturn V. $12bn and ten years into its development, SLS will initially be able to place 70-90 tons in orbit – a bit more than Falcon Heavy but well short of the Saturn V. The first test flight of this version of SLS is due in 2021 – mind you that date has been slipping – and a version qualified to carry humans is due about two years later. The cost will be a lot more than Falcon Heavy, at least ten times as much at over $1bn per flight! Various enhancements to SLS have been identified by NASA but are not currently funded. In fact, even the initial version of SLS is only viable for four flights because each SLS uses four of the 16 left-over Space Shuttle engines, after which later SLS launches will need new and more expensive engines.

On 26 March, Vice President Pence instructed NASA to have Americans back on the Moon’s surface by 2024. NASA has yet to seek the necessary extra funding from Congress but seems intent on sticking with the SLS as the rocket of choice. Given that two or more SLS launches costing more than $1bn each will be needed for a human Moon landing, NASA may come under pressure to use the much cheaper Falcon Heavy instead.

Before looking at China and Russia, let us not forget a third American contender for the New-Apollo crown: Blue Origin. The founder of this relatively secretive US company is the world’s richest man, Jeff Bezos. Although his day job is CEO of the world’s leading online retailer, Amazon, he has always admitted to being a space enthusiast. He founded Blue Origin to build rockets in order to eventually enable largescale manufacturing on the Moon and other Solar System bodies.

An illustration of NASA’s Space Launch System (SLS) in the Block 1 cargo configuration. NASA

Blue Origin’s first rocket is the relatively modest New Shepard which will give paying passengers a trip 100km high, floating in weightlessness for several minutes and then returning, Sir Richard Branson’s Virgin Galactic is offering a similar experience. New Shepard is a fully reusable rocket, a feature Bezos considers essential for its long-term viability, he and Elon Musk agree on this, if on little else. Blue Origin is developing a much larger rocket, called New Glenn, based on a much more powerful engine that will compete head-to-head with the Falcon Heavy. Test flights are due to begin in about 2021, three years after the equivalent stage of the Falcon Heavy.

The names of these Blue Origin rockets recall the names of the first American to make a suborbital spaceflight, Alan Shepard, and the first to orbit the Earth, John Glenn. Bezos has announced that the next Blue Origin rocket will be the New Armstrong, presumably named after the first American to walk on the Moon. No details of the New Armstrong have been released, so it calls for a leap of faith to speculate on Blue Origin as supplier of rockets for human Moon landing missions. Nevertheless, Bezos’ vision for space manufacturing, underpinned by his financial muscle makes him a wild card in the after-Apollo race.

China

China has been undertaking steadily more sophisticated robotic Moon missions for the past decade and has announced plans to develop the Long March 9 super-heavy lift rocket compatible with a human Moon landing mission in the 2030 timeframe. The latest manifestation of this Moon programme is the Chang’e 4 robotic vehicle (named after the Chinese Moon goddess) and its Yutu-2 rover (her Jade Rabbit companion) that landed inside the Von Karman crater on the Moon’s farside that is always hidden from us here on Earth – a feat not previously achieved by any other nation.

The mid-latitude crater (45.5°S) was chosen because the crater floor is lava-covered and hence flat, and perhaps also because Von Karman was the PhD adviser of QianXuesen founder of China’s space programme. Communication with the probes is achieved through the Queqiao (Magpie Bridge) communications satellite that is orbiting around a stable Lagrange point about 50,000km beyond the Moon and can be seen simultaneously from Earth and from the lunar farside.

Next up is a robotic mission, Chang’e 5, that will return samples of the Moon’s surface to Earth, a feat previously only achieved by the Soviet Union in the 1970s.

The Chinese government has not yet approved the full development of the massive Long March 9 and will presumably await the results of the current engine prototype work and of the ongoing ambitious robotic missions to the Moon before doing so. Nevertheless, the roadmap leading to a Saturn V class launcher has been publicised, raising expectations at home and abroad.

CNSA​Russia

In February, Russia’s space agency, Roscosmos, announced plans for robotic missions to the Moon alongside development of a heavy lift rocket and eventual manned Moon landings. In 2021, 2023 and 2024 robotic probes are to be sent to the Moon’s south pole region to seek permanent deposits of ice on or close to the surface. A sample return mission will follow in about 2025 and a mission equipped with a rover a year or so later.

The new Yenisei rocket (named after Russia’s longest river) will be able to place a payload greater than the Falcon Heavy in low Earth orbit. Payload values of 70 to 100 tons have been quoted in the press. The schedule for its development has not been publicised, except that the first unmanned flight to the region of the Moon (but not to the surface) could be as soon as 2025. The concept calls for Russia to create a base in orbit around the Moon and to mount expeditions from there to the surface – similar to NASA’s much criticised Lunar Gateway concept – the 2030s appears to be the likely timeframe. Approval for the funding to develop the Yenisei rocket is contingent on a number of earlier rocket and spacecraft developments being completed successfully and, given Russia’s relatively poor recent record of such developments, there must be some doubt about the whole scheme.

The Chang’e-4 lander imaged by the Yutu-2 rover on the lunar far side. Above right: Model of proposed lunar exploration base from Russia’s Roscosmos at the 2019 Paris Air Show

Conclusions​

This illustration depicts a high-power 50-kilowatt solar electric propulsion spacecraft that will constitute the foundation of NASA’s Gateway, lunar orbiting staging point to send astronauts to the Moon’s surface in five years. NASA

For the first time since the last Apollo mission, there are serious plans underway to send humans back to the Moon’s surface. The USA seems likely to get there first, involving NASA and/or SpaceX, probably in the mid-2020s. The financial strength of Blue Origin makes it a realistic candidate to be involved in human Moon landings by the end of the 2020s.

The first Chinese citizens seem likely to arrive on the surface of the Moon in about 2030, a date made credible by China having achieved its various robotic Moon exploration milestones over the past 15 years. Russian plans to do likewise lack credibility but could morph into collaboration with a partner. Vladimir Putin has met more than 25 times with Xi Jinping, far more frequently than either has with any other head of state, so perhaps this close relationship will extend to the Moon.