Mars Colonisation Transportation: Project Revelation Before Rumours

In our analysis of end 2015 (available on our website, and its summary in the English section) we tried to discern what might look like the project SpaceX Mars Colonization Transportation (MCT), Elon Musk has finally unveiled Sept. 27 at the next International Astronautical Congress. This year included the meagre clues gleaned from the various statements of the contractor, some alter the previous information (eg abandonment of multi-body launcher formula type Falcon Heavy) or, coercion, seemed to confirm the fundamental options such as refuelling earth parking orbit by a second launcher, the total reuse and descent of March of the entire interplanetary shuttle ( “landing the whole thing”) . Since then, other indications of various origins have appeared on fans forums. Examine their possible significance.

A pitcher of 15 m in diameter

The choice single-body launcher recoverable and we had driven to approach the performance target (100 T Payload deposited on Mars) to increase the diameter of the drive bay 15 m, although it seemed sufficient to limit that of upstairs itself to 12.5m (pm the first two stages of the Saturn 5 moon had a diameter of 10 m). This configuration allowed to stay a maximum of 31 engines of 300 T thrust and achieve take-off weight (GLOW) 7750 T. Unfortunately, the shape flared rear of the first floor, certainly favourable to the stability phase of ascent , is very unfavourable for the return (flight in opposite direction), especially since it has less then effective ways to stabilise the trajectory. Since it is difficult to imagine that we can reduce the GLOW and therefore the take-off thrust, the solution is to increase the diameter of the whole floor to 15 m. Now it is one of the rumours on forums “MCT-geeks”; SpaceX had solicited tooling suppliers for this diameter.

A take-off weight (GLOW) of nearly 10,000 T

At the time, it evoked a Raptor 250 Tf thrust (optimal size for mass according SpaceX). Wishing nevertheless not to increase the number of engines (compared to what is allowed with the Falcon Heavy), we considered it necessary to increase the engine thrust to 300 Tf, that remained liveable in the 15 m the Bay. The problem is that even with this power, the desired performance is not achieved (unless we assume our assumptions about the structure of the masses too pessimistic shuttle); Indeed there were 90 T CU (referred to 100) and more in the most favourable conditions: Mars at perihelion and transfer long (Hohmann). But a noise is that SpaceX would work on a Raptor 700 Tf ! This level of unit thrust would exceed the planned takeoff thrust, reached with 13 of these engines easily Lodgeable. Given the performance deficit, we can imagine that SpaceX, once the diameter of 15 m admitted, will seek to accommodate the maximum engine. Here the pace compared two versions that originally planned (Bay of 15 m, 12.5 m floor, pushing 31 × 300 = 9300 Tf Tf, 7750 GLOW T) and an even more powerful version (bay floor 15 m pushing 17 × 700 = 11900 Tf Tf, 9917 GLOW T).

Bay diameter 15 m, with the top 31 × 300 Tf and down, 17 × Tf 700 (mass increased takeoff 2166 T).

The arrangement allows presented the tangential movement of the median 4 engines (arranged in a square) to assume control. The rolling efficiency was improved with the use of peripheral motor, but they are too tight to allow a significant deflection.

Ambitious Performance Targets

The launcher configuration of our study did not achieve the desired performance. But in a recent interview about the difficulty of passengers for the long trip transfer classically considered (6 months or more), Elon Musk tightened requirements, indicating that a 3-month period should be.

From the parking lot in LEO 300 km (note: other parking places are envisaged: elliptical orbit, lunar Lagrange point …), to provide the DV (excluding losses gravity) are:

• When Mars is near its perihelion: 
  4.48 km / s for a trip of 91 days (eg. 26.6.2003 / 25.9.2003)
• When Mars is near its aphelion: 
  6.72 km / s for travel in 92 days, value totally prohibitive
  5.02 km / s for 122 days (4 months), yet interesting time.

Performance of the New Configuration

The additional capacity introduced by the thrust increase, which results not only in the interplanetary shuttle but to the mothership, she can reach or approach these performances?

Calculated trajectory (approximate optimization, non-algorithmic). PGR: losses by gravity; Pae: aerodynamic losses.

By distributing 2166 T GLOW won almost optimally between the propellant mass of the first floor (and 4% for the increased mass of tanks) and the shuttle (which acts as a second stage for setting LEO) the trajectory calculations lead to the following masses for operational flight:

• Propellant 1st floor (useful reserve + return): 7810 T
• Propellant 1st floor (useful): 7100 T
• Shuttle rocket: 1300 T
• Load placed in LEO (300 km): 547 T
• Including propellant remaining shuttle: 295 T

And, for refuelling in flight LEO, for which the mass of the shuttle, automatic, volume residential or rescue capsule is supposed reduced from 109 to 89 T, we get:

• Remaining propellant refuelling after setting LEO: 458 T

After refuelling, assuming 5% loss (load the replenishment) in the transfer operation, the interplanetary shuttle is therefore provided with 730 T of propellant.

The Isp of 380 s [1] retained matching engines adapted to empty, with deployable diverging.

The mass transfer calculated in the study was 244 T, for a CU 90 T and a long journey (8–9 months). We would return to the CU 100 T, so the bulk transfer is 254 T.

Note that the reduction of travel time reduces the stock of food and from water that can not be recycled at a rate of 2 kg / day / passenger. These ingredients should not however be counted as payload, even if the final waste (organic waste, dirty water) will be received with happiness and recycled by the colony.

With these data, the following maximum DV is obtained:

• DV = g 0 Isp Ln (1 + propellant mass / Final Mass)
• DV = 9.81 x 380 x Ln (1 + 730/254) = 5.05 km / s

The calculated configuration therefore meet the requirements 3 months of travel (4 in the extreme case). Ipso facto,the dose of ionizing radiation is divided by 2 !

And to bypass weightlessness?

6 months in zero gravity stays are common in the ISS and cause no long-term health effects. Nonetheless, especially for transport of passengers “en masse”, it would be desirable to recreate artificial gravity (Martian) on board, so that visitors arrive at their best. Now there is an easy way to get there, inspired by the one already proposed in Mars Direct.

Settlement patterns, such as the one we are studying (1000 Colony residents built in 20 years) require several MCT flights by synodical window (6 in this case). By connecting two by two the transfer shuttles, it is possible to recreate a Martian gravity (0.38g) by rotating the set (eg, at 2 rev / min, well tolerated value) for a distance between the two centers of mass 170 m.

A couples shuttles transfer flotilla, even in artificial gravity configuration, approaching its destination. mass centres of the two vehicles are at a distance of 170 m and the coupling rotates 2 revolutions / minute about an axis allowing solar panels remain illuminated perpendicularly.

Thus the two main negative environmental factors to the physical condition of travellers are under control!

Dimensional Evolution

With the increase in the mass of propellant and the passage diameter of 12.5 to 15 meters, the first stage sees its total height spend 71 to 64 m, making it a fairly stocky floor and could light the rumour that kind feet deployable Falcon necessary given the considerable slenderness of this rocket could be replaced with retractable legs , leaving longitudinally behind.

The shuttle itself could, in our project, see also the width to 15 m, which would house the propellant tanks, whose capacity has increased from 1100 to 1600 about T (to meet the extreme requirements DV). The integration of engines would also be greatly facilitated.

The total height of our attempt to MCT (without feet) is itself of nearly 110 m. It was the size of Saturn5 — Apollo. But here the diameter is 50% larger and the take-off mass 3.4 times larger.

Image giving an idea of ​​the proportions of an MCT of 15 m in diameter and about 10000 T on takeoff, powered by 17 engines of 700 Tm. The real MCT will he neighbour, or SpaceX us he will surprise again with its innovations?

Other Sounds

(Note: information not verified; given for guidance only).

• Cargo flights will be shipped before the first shipment, so that pioneers have everything necessary for their survival and to start installation of the colony. No, the Falcon Heavy flights / Red Dragon, the first being announced in 2018, are not intended primarily for scientific charges but these preparatory cargo missions.
• Among which should be pre sent, it will find the nuclear power generator. This could be 20 T, delivering 5–10 MWe and be able to bury itself in the ground!
• We would have seen at SpaceX whole collection of spacesuits prototypes, which we are still waiting that they may be revealed … But it is unclear whether innovation affects only the design (forget the suits at 20,000 Leagues Under the Sea) also technology.

Financing Capacity

Regardless of the future participation of agencies, training effect, financing the development of the MCT and the introduction to the Martian surface installation means a first permanent settlement may rely mainly the industrial success of Elon Musk. This has also repeatedly made comments that leave no doubt about his “Martian” strategy:

• Refusal, despite pressure from the markets, to SpaceX stock exchange “as the MCT will not be operational,” and this, in order not to impede its progress towards the target in March [2];
• Financing of developments by the profits of the commercial markets;
• Use developments under contract to finance the required technologies and materials (eg Dragon 2.);
• Industrial developments (Tesla Motors, Solar City, but also constellation of satellites Internet, Hyperloop?) essential because “it will take a lot of money to allow colonisation”;
• Creator of a capitalisation of more than $ 45 billion (twelve years) in which it holds about 20%, Elon Musk imagine, due to the synergy solar panels — batteries — electric vehicle that is being created that this empire could one day be worth $ 1 trillion! This ambitious projection is based on its eyes to the fact that the solar industry will now affects 1% of the potential market; one imagines that even with “only” a few hundred billion capitalisation, the profits generated are used to finance the Martian dream of multi-entrepreneur…

An Exciting Business, But its Hallmark Risk

The spectacular successes can reassure stakeholders (shareholders, banks, customers) of this vast industrial construction, including Mars is the pinnacle. But they do not guarantee that the next challenges will be overcome … The adventure plays off the beaten path, face entrenched competitors and fierce, and with the acceptance of an abnormal level of risk. technical risks, of course, the frantic correlative level of innovation at SpaceX and Tesla, but, above all, financial risks, which agonise business circles and will cause serious criticism. And all the more so if the technical challenges are earned, mostly without respect the announced deadlines. The bold decisions have multiplied in recent years, mainly for the development of Tesla:

• Investment of $ 5 billion (Panasonic) in the “Gigafactory” batteries (opening end of July);
• Announced a production target of 500,000 cars in 2020, against 50,000 in 2015 (but the 2016 target was revised mid-year downward …)
• Following the historic success of pre-orders for the Tesla Model 3 decision to advance this goal in 2018, causing disbelief and unpleasant dilution of capital through the issuance of $ 1.4 billion additional shares to fund the increase rate;
• Recent offer of redemption Solar City (also owned approximately 20% by Musk) for $ 2.5 billion transaction deemed a further dilution of capital by the shareholders of Tesla;
• Maintaining persistent red of the main financial indicators of Tesla (recurring losses, high debt, high consumption of capital …), justified in the eyes of the leaders by the size of the future market;
• SpaceX creation within a satellite branch, with the announcement of the goal of starting her own constellation of orbiting satellites dedicated to the universal spread of the Internet; This initiative appeared later abandoned, however SpaceX continues to publish many job offers for specialists in this field … The competitors are very powerful!

Conclusion

The Martian ambition Elon Musk should not be considered as a Utopian dream. On the one hand because the many sensational and successful entrepreneur has its credibility. On the other hand the fact that, as and the realisation of its innovations, the strategy of its approach to the Martian goal is emerging more clearly and convincingly, on the technical course, but also on economic and ethical, what is fundamental.

Indeed, what use to settle on another planet if it did not lead to a useful and viable long-term achievement, that is to say capable of providing benefits and services to prove their utility through the existence of a market and, to ensure the financing of its need for imported goods? This is only a development of the old question: on Mars, to do what? On this point, Elon Musk spoke clearly: for him, the settlement must be a business because it can not be funded in the long term, or be destined for a future without finding its autonomy and purpose.

Many ideas have been issued in the past for goods and services that could market the colony, but not convincing so far.The development of an interplanetary transport inexpensive and massive, like SpaceX aims, completely changes the game. Therefore APM looks at what could be the business model of such a colony. Meanwhile the big announcement of September 27, 2016.

[1] This Isp may be optimistic. However, the value of 386 s was reached by a LOX / motor Russian Methane (soil test).

[2] The entry of Google capital totaling $ 900 million was used to evaluate 12 billion to SpaceX.