Lockheed Martin has announced it will build a full-scale prototype of NASA’s proposed Deep Space Gateway (DSG), a space habitat occupying cislunar space. The facility, which if built, will be both autonomous and crew-tended, and is intended to be used as a staging point for the proposed Deep Space Transport NASA is considering for missions to Mars, as well as for robotic and crewed lunar surface missions.
DSG is part of a public-private partnership involving NASA in developing technologies for carrying humans beyond low Earth orbit called Next Space Technologies for Exploration Partnerships (NextSTEP). A Phase I study for the facility has already been completed, and the full-scale prototype will be constructed as a part of the Phase II NextSTEP habitat programme, which will examine the practical issues of living and working on a facility removed from the relative proximity of low Earth orbit, outside of the relative protection of the Earth’s magnetic field and subject to delays of up to 3 seconds in two-way communications.
“It is easy to take things for granted when you are living at home, but the recently selected astronauts will face unique challenges,” said Bill Pratt, Lockheed Martin NextSTEP program manager.
“Something as simple as calling your family is completely different when you are outside of low Earth orbit. While building this habitat, we have to operate in a different mindset that’s more akin to long trips to Mars to ensure we keep them safe, healthy and productive.”
The proposed Gateway, which if built would likely enter service in 2027/2028, will be designed to make full use of the Orion Multi-Purpose Crew Module as its command and control centre, and will also use avionics and control systems designed for the likes of NASA’s MAVEN mission in order around Mars and the Juno mission at Jupiter, which will allow the facility to operate in an uncrewed automated flight mode around the Moon for up to seven months at a time.
The core of the prototype will be the Donatello Multi-Purpose Logistics Module (MPLM), originally designed and built for flights aboard the space shuttle and capable of delivering up to nine metric tonnes of supplies to the International Space Station (ISS). Two of these units, Leonardo and Raffaello flew a total of 12 missions to the ISS between 2001 and 2011, with Leonardo becoming a permanent addition to the space station in early 2011. And if film and comic fans are wondering, yes, the modules were all named after a certain band of mutant ninja turtles – hence the MPLM mission logo (right).
Donatello was a more capable module than its two siblings, as it was designed to carry payloads that required continuous power from construction through to installation on the ISS. However, it was never actually flown in space, and some of its parts were cannibalised to convert Leonardo into a permanent extension to the space station. In its new role, Donatello will form the core habitat space for the DSG prototype, and will be used as a testbed for developing the living and working space in the station, which will also have its own power module and multi-purpose docking adapter / airlock unit.
The Phase II development of the DSG is expected to occur over 18 months. Mixed Reality (augmented reality and virtual reality) will be used throughout the prototyping process to reduced wastage, shorten the development time frame and allow for rapid prototyping of actual interior designs and systems. The results of the work and its associated studies will be provided to NASA to help further the understanding of the systems, standards and common interfaces needed to make living in deep space possible.
The DSG is one of two concepts NASA is considering in it attempts to send humans to Mars. The second is the so-called Deep Space Transport (DSH). This is intended to be a large vehicle using a combination of electric and chemical propulsion to carry a crew of six to Mars. It would be assembled at the Deep Space Gateway.
While having a facility in lunar orbit does make sense for supporting operations on the Moon’s surface, when it comes to human missions to Mars, the use of the DSG as an assembly / staging post for the DST actually makes very little practical sense. Exactly the same results could be achieved from low Earth orbit and without all the added complications of lunar orbit rendezvous. The latter simply adds an unnecessary layer of complexity to Mars missions whilst providing almost no practical (or cost) benefits, and perhaps again demonstrates NASA’s inability to separate the Moon and Mars as separate destinations – something which has hindered their plans in the past.
Musk Walks Back SpaceX Aspirations
SpaceX CEO and chief designer, Elon Musk has walked back on expectations for the initial lunch of the Falcon Heavy booster and on longer-terms aspirations for the Dragon 2 crew capsule.
Speaking at the International Space Station Research and Development Conference held in Washington DC in mid-July 2017, Musk indicated that a successful maiden flight of the Falcon Heavy rocket is extremely unlikely. He also indicated that the company is abandoning plans to develop propulsive landing techniques for the Dragon 2 when returning crews to Earth from the ISS – and to achieve a soft landing on Mars.
Falcon Heavy is slated to be the world’s most powerful rocket currently in operation when it enters service in 2018, capable of lifting a massive 54 tonnes to low Earth orbit – or boosting around 14 tonnes on its way to Mars. Designed to be reusable, the rocket uses three core stages of the veritable Falcon 9 rocket – one as the centre stage, two as “strap on boosters” either side of it.
But computer modelling has revealed that firing all 27 motors on the stages (nine engines apiece) at launch has dramatically increased vibrations throughout the vehicle stack, making it impossible to gauge by simulation whether or not the rocket will shake itself apart without actually flying it. Hence Musk’s statement that the maiden flight of the Falcon Heavy – slated for later in 2017 – is unlikely to achieve a successful orbit. However, telemetry gathered during the flight – should the worse happen – will help the company more readily identify stresses and issues created by any excessive vibration, allowing them to be properly countered in future launches.
Once Falcon Heavy is fully operational, all three of the core stages are intended to return to Earth and achieve a soft landing just as they do when used as the first stage of a Falcon 9 launch vehicle, and SpaceX is also working to make the upper stage of the Falcon 9 / Falcon Heavy recoverable as well.
Also at the conference, Musk announced SpaceX will no longer be using propulsive landings for the crewed version of their Dragon 2 space capsule, due to enter operations in 2019 ferrying crews two and from the ISS, operating alongside Boeing’s CST-100 Starliner capsule. Initial flights of the Dragon 2 were intended to see the vehicle make a “traditional” parachute descent through Earth’s atmosphere followed by an ocean splashdown – the technique currently used by the uncrewed Dragon I ISS resupply vehicle.
However, SpaceX had planned to shift Dragon 2 landings from the sea to land – using parachutes for the majority of the descent back through the atmosphere, before cutting the vehicle free and using the built-in Super Draco engines (otherwise used as the crew escape system to blast the capsule free of a Falcon launch vehicle if the latter suffers any form of pre- or post-launch failure). The engines would fire during the last few metres of decent, placing the capsule into a hover before setting it down on four landing legs.
Extensively tested in tethered “hover” flights, propulsive landings would in theory made the recovery and refurbishment of Dragon capsules for future launches a lot easier, lowering the overall operating costs for the capsule. In announcing the decision to scrap the propulsive landing approach, Musk indicated it would have unnecessarily further drawn out the vehicle’s development as SpaceX sought to satisfy NASA’s requirements for crewed vehicle operations.
The decision also affects Musk’s hope of placing a robotic mission on the surface of Mars in 2020. Under that mission, a special cargo version of Dragon 2 – called Red Dragon- would fly a NASA science payload to Mars and use supersonic propulsive landing to slow itself through the tenuous Martian atmosphere and achieve a successful soft landing. This approach was seen as ideal, because using parachutes on Mars is extremely difficult with heavy payloads – NASAs studies suggest parachute on Mars have an upper limit of payloads around 1.5-2 tonnes. A Red Dragon capsule is liable to mass around 8-10 tonnes.
However, Musk no longer believes the use of a propulsive landing mechanism is “optimal” for Red Dragon, and the company has a better way of realising their goal – although he declined to indicate what this might be. Instead, propulsive landing systems would seem to be something the company will return to in the future – particularly given their hopes of placing vehicles massing as much as 100 tonnes on the surface of Mars.
No, ET Isn’t Calling Us
The Internet was agog recently after it was announced some very “peculiar signals” had been noticed coming from Ross 128, a red dwarf star just 11 light-years away. While not known to have any planets in orbit around it, and despite the best attempts of astronomers – including the team picking up the signals at the Arecibo radio telescope, Puerto Rico – news of the signals led to widespread speculation that “alien signals” had been picked up.
The usual signals – officially dubbed the “Weird!” signal, due to the comment made in highlighting the signals in an image – were first picked up on May 12th/13th, 2017. However, it was not until two weeks later that the signals were identified and analysed, the PHL team concluding that they were not “local” radio frequency interference, but were in fact odd signals coming from the direction of Ross 128 – sparking the claims of alien signals, even though the director at PHL and the survey team leader -Abel Mendez – was one of the first to pour water on the heat of the speculation. “In case you are wondering, he stated in response to the rumours, “the recurrent aliens hypothesis is at the bottom of many other better explanations.”
Without drawing any conclusions on what might be behind the signals, PHL liaised with astronomers from the Search for Extra-Terrestrial Intelligence (SETI) Institute to conduct a follow-up study of the star. This was performed on Sunday, July 16th, using SETI’s Allen Telescope Array and the National Radio Astronomy Observatory‘s (NRAO) Green Bank Telescope. The fact that SETI was involved probably also helped fan the flames of “alien signal” theories. However, initial analysis of the signal and the portion of the sky where it was observed have suggested a far more mundane explanation: geostationary satellites.
“The best explanation is that the signals are transmissions from one or more geostationary satellites,” Mendez stated in an announcement issued on July 21st. “This explains why the signals were within the satellite’s frequencies and only appeared and persisted in Ross 128; the star is close to the celestial equator, where many geostationary satellites are placed.”
While certain this explanation is correct, Mendez does note it doesn’t account for the strong dispersion-like features of the signals (diagonal lines in the figure). His theory for this is that it is possible multiple reflections caused the distortions, but the astronomers will need more time to evaluate this idea and other possibilities.
So sorry, no ETs calling out into the night – yet.