Space Sunday: a Blue Moon, water worlds and moving house

Jeff Bezos, the Blue Origin founder, unveils a full-scale model of the company’s Blue Moon lunar lander. Credit: Jeff Foust

On May 9th 2019, and after a lot of speculation following an April tweet (see Space Sunday: asteroid impacts and private space flights), Blue Origin founder Jeff Bezos unveiled the next step in the company’s space aspirations: their Blue Moon lunar lander.

The vehicle has been in development for some three years, with precious few details being given until now, other than it was initially indicated it would be capable of delivering up to 4.5 tonnes of equipment and material to the Moon’s surface in support of human missions. However, the vehicle has apparently been through a number of design cycles, and the unveiling presented a massively capable machine which  – while it wasn’t openly stated at the May 9th event (but is indicated on the Blue Origin website) – could be used in support of NASA’s drive to return humans to the surface of the Moon by 2024.

Somewhat resembling the descent stage of the Apollo Lunar Excursion Module (LEM), Blue Moon has the capability to complete variable missions up to and including landing crews on the Moon’s surface and lifting them off again. In its “basic” form, the lander will be able to land 3.6 tonnes of cargo on the Moon, while a “stretch tank” version will be able to increase that deliverable payload to 6.5 tonnes.

The Blue Moon Lander with a set of four remote landers on its deck, and showing the “bonus payload” bay above the smaller of the distinctive spherical fuel tanks, which will contain liquid oxygen (LOX). Credit: Blue Origin

This payload will be carried on the flat upper deck of the lander, which will also include a robot crane (or cranes) capable of lifting it down to the Moon’s surface. In addition, the lander has an internal payload bay designed to deliver small satellites into lunar orbit as a “bonus mission”.

The most interesting element of the vehicle is perhaps its propulsion / power system. Blue Moon will be powered by the company’s new BE-7 motor, which uses liquid hydrogen and liquid oxygen propellants rather than storable hypergolic fuels. This allows the motor to generate up to 10,000 lbs of thrust, whilst also being “deeply throttlable”. The initial version of the motor will undergo its first “hot fire” test in the summer of 2019.

While the offer better performance capabilities than hypergolic fuels, liquid propellants need to be held at low temperatures, otherwise they can start to “boil off” to a gaseous state if they start to get “warm” (this is why liquid fuelled rockets appear to “steam” on the launch pad: they are venting fuel that has turned to gas that needs to be released to avoid over-pressurising and rupturing tanks).

While Blue Origin believe the exceptional low temperatures of the 2-week lunar night will help keep the lander’s fuel stocks cold and liquid, Blue Moon will still need refrigeration / insulation to prevent undue boil-off of the propellant stocks, which will add some weight to the vehicle. However, Blue Origin sees some boil-off of the liquid hydrogen ad advantageous: they plan to use boiled-off gaseous liquid hydrogen to help keep the liquid oxygen cold in its tanks and also as feedstock for the power cells that will be used to provide electrical power to the vehicle.

Bezos demonstrates Blue Moon’s ability to deliver a rover vehicle (mock-up) to the lunar surface during the May 9th event. Credit: Blue Origin

The latter are important again because of that 2-week lunar night. when there will be no sunlight to provide energy to any solar cells the vehicle might otherwise be equipped with to provide electrical power.

While initially intended to deliver science missions and payloads to the surface of the Moon in readiness for human landings. However, a future development with the vehicle could see it fitted with an upper stage crew / ascent module. Whether or not this might be used as part of NASA’s ambitions to met the goal of returning humans to the Moon by 2024 remains to be seen. However, Bezos has indicated Blur Origin is willing to help NASA to achieve this goal, and pointedly notes that that the company has a three-year headset in developing their lander when compared to others.

An artist’s impression of the Blue Moon crewed lander with the crew / ascent module on top. Credit: Blue Moon

However, even outside of NASA’s plans, Blue Origin has its own hopes to send humans to the Moon. As I noted in my last Space Sunday report, the company’s April tweet about this announcement made an indirect reference to Shackleton Crater close to the Moon’s south pole. This is one of a number of craters believed to have water ice deposits within it, making it an ideal location for establishing a lunar base – and Blue Origin and Bezos have previously indicated it is their target for establishing a lunar base.

Lunar water ice is also another reason for the company opting to use liquid propellants with Blue Moon. Should their aspirations with Shackleton come to pass, then water ice – hydrogen and oxygen  – becomes a feedstock for refuelling Blue Moon landers once they are on the Moon, making them more efficiently reusable.

Blue Moon will be 7 metres (23 ft) across its payload platform, which will stand some 4m (14 ft) above the lunar surface on the basic lander. Fully loaded and fuelled, Blue Moon will weigh 15 tonnes at launch, but having burned the majority of its fuel during its flight and landing, will weigh only 3 tonnes after landing. By comparison, the Apollo LEM weighed 16.4 tonnes fully fuelled and stood 7.07 m tall, including the crewed ascent stage. Meanwhile, Lockheed Martin’s proposed lunar lander could be as much as 62 tonnes fully fuelled and stand 14 m (46 ft) tall.

Bezos declined to answer specifics on the vehicle such as when test flights are likely to commence, what will be the launch vehicle (although Blue Origin’s New Glenn would appear to be the most obvious choice), or how much overall development of the lander and its variants will cost. Doubtless, some of these details will become public in time.

Water Worlds Might Be More Common Than Rocky Worlds

Over the past 20+ years, astronomers have confirmed the existence of thousands of exoplanets, many of them discovered as a result of NASA’s now-defunct Kepler orbital telescope spacecraft, which is responsible for 2,702 (to date) confirmed exoplanets, with several thousand more “candidates” still awaiting confirmation.

As I’ve noted in these pages, exoplanets come in all manner of sizes and classes, from worlds smaller than Earth through to many roughly of Earth’s size or larger, to so-called super-Earths with diameters of around twice that of Earth, all the way up “super Jupiters”, bigger than the largest planet in the solar system.

An artist’s impression of the K2-138 system. The distances of the planets from their parent star would appear to be exaggerated, and the Earth-like clouds-on-blue a product of wishful thinking. Credit: NASA

One of the most common classes of exoplanet is the sub-Neptune” class – planets with a diameter more than twice that of Earth but smaller than Neptune (roughly four times the diameter of Earth). These worlds have been of particular interest to astronomers because so little is known about them in terms of their formation and composition.

Now a new study, made using Kepler’s data, and led by Li Zeng, a planetary scientist at Harvard University, Massachusetts, suggests sub-Neptune class planets are more likely to be water worlds than gaseous in nature, as with Neptune. Specifically, the study suggests that the majority of sub-Neptune planets are at least 25% liquid or frozen water by mass – and possibly more than 50%. By contrast, Earth is only 0.02% water, liquid or frozen, by mass.

Our study suggests that there are on the order of 1,000 water worlds in just the Kepler confirmed and candidate planets. Statistically speaking, these water worlds may be more abundant than Earth-like rocky planets. Perhaps every typical sun-like star — a star of about one solar mass — has one or more of these water worlds.

– Li Zeng, study lead, Growth model interpretation of planet size distribution

As well as raising the potential that water worlds might be more common than solid, rocky worlds like Earth, the study reinforces a number of intriguing questions. Why, for example, is it that our solar system has a much wider spread of planets orbiting the Sun than the majority of planetary systems found by Kepler – where the orbital periods of planets can often be measured in terms of terrestrial days, rather than years, the planets packed tightly into orbits smaller than that of Mercury or Venus around the Sun. There’s also the question as to why our solar system lacks any planets in the mini-Neptune range when they appear to be so common around so many other stars, including those of the same or similar spectral class and size to the Sun.

Virgin Galactic to Move House

On May 10th, Virgin Galactic announced it will be moving its development and testing activities from Mojave, California, to its commercial-operations headquarters, Spaceport America, New Mexico, a 7,300 hectare, US $200 million launch complex some 72 km from the town of Las Cruces.

Virgin Galactic already has dedicated passenger and operations centre, called Gateway to Space, at the facility, and is updating its hangar facilities there ready for the commencement vehicle operations. This work including the building of a fuelling facility, and will see the company development of a dedicated warehouse in support of their planned operations.

More than 100 employees will relocate, starting immediately. Virgin’s suborbital system, the space plane VSS Unity and its WhiteKnightTwo carrier ‘plane, VMS Eve, will make the move this summer, after technicians complete Unity’s cabin interior ready for carrying passengers and some other finishing touches, company representatives said.

WhiteKnightTwo carrier aircraft, VMS Eve on the tarmac in front of Virgin Galactic’s Gateway to Space building at Spaceport America, which will house vehicles, flight operations and astronaut preparation. Credit: Virgin Galactic

New Mexico delivered on its promise to build a world-first and world-class spaceport. Today, I could not be more excited to announce, that in return, we are now ready to bring New Mexico a world-first, world-class spaceline. Virgin Galactic is coming home to New Mexico where together we will open space to change the world for good.

– Sir Richard Branson, founder of Virgin Galactic, May 10th, 2019

Construction of new aircraft to add to the Virgin Galactic fleet will remain based in California and undertaken by the company’s sister enterprise, The Spaceship Company.

The company has yet to comment on when flights with fare-paying passengers will commence, but Branson has previously indicated he’d like to fly on one of the SpaceShipTwo vehicles to celebrate the 50th anniversary of Apollo 11’s landing on the Moon, which occurred in July 1969. When asked about when passenger flights might commence, Virgin Galactic’s CEO George Whitesides responded:

We still need to finish out our flight test program, though we do feel we are in our final stretch. We will do that in New Mexico using the unique and valuable airspace above the Spaceport. Before commercial operations begin, we will need to finish evaluation of the new outfitted cabin, the experience and the training program for our astronaut customers.