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Reusable Rockets Rockets and spacecraft have always been either relatively cheap and disposable . . . or expensive and reusable, meaning that getting to space was out of the reach of all but the richest individuals. That is now changing with SpaceX, Virgin Galactic and Blue Origin leading the charge to develop safe, affordable reusable space vehicles. SpaceX, in particular, has had spectacular success of late. This article describes how they manage to get rockets to land all by themselves – a feat which, until recently, seemed almost impossible. by Dr David Maddison Artist’s concept of the Skylon spaceplane in orbit, with its cargo bay doors open. 14   14   S Silicon Chip Australia’selectronics electronicsmagazine magazine Australia’s siliconchip.com.au O ne of the biggest dreams in space flight is to make it as cheap and accessible to as many people as possible. However, that is only possible if the launch vehicles are reusable, like an airliner. Unfortunately, making a reusable launch vehicle is easier said than done; hence the fact that most space vehicles in use today are still expendable. The Space Shuttle is the most famous reusable space launch vehicle but as we describe below, it was actually more expensive to operate than expendable rockets! But that may have all changed recently, with SpaceX’s multiple successful vertical landings of rocket boosters. They have already reused some rockets more than once. For a video of a “second-hand” rocket launch, see: https://youtu. be/GS8CBmeZ0FY In this article, we look at past, current and future attempts to develop reusable launch vehicles, with particular emphasis on SpaceX. They are currently humanity’s best hope for making space travel affordable and practical. SpaceX SpaceX Falcon 9 SpaceX was founded in 2002 by Elon Musk, with the objectives of lowering the cost of delivering payloads to orbit (Musk believes that US$1100/kg is achievable) and enabling the colonisation of Mars. Musk subsequently co-founded Tesla, Inc – another high-profile manufacturing company. Despite being a relatively young company, SpaceX has achieved a number of “firsts”, such as: • the first private company to deliver a payload to orbit using a liquid fuelled rocket (2008), • the first landing of a commercial rocket under its own power (2015), • the first reuse of a rocket intended for orbital use (2017), • the first private company to launch a payload into orbit around the sun (2018). You may have seen the latter in the news; it was notable in that the payload was Elon Musk’s personal Tesla Roadster. Importantly, SpaceX has also flown 14 resupply missions to the International Space Station (ISS) – something which NASA is no longer capable of doing since the US Space Shuttle was The SpaceX Dragon spacecraft configured as a cargo carrier. siliconchip.com.au retired (more on that later). SpaceX produces both rockets (Falcon) and rocket engines (Merlin and Draco). The Merlin liquid fuel rocket engines are powered by liquid oxygen and kerosene and are the main engines on the Falcon rockets. The Draco engines use monomethyl hydrazine with nitrogen tetroxide as the oxidiser; they are primarily used as thrusters. SpaceX currently offers two launch vehicles, the Falcon 9 and the Falcon Heavy, as well as the Dragon spacecraft. The Falcon 9 is a two-stage rocket which is designed to deliver a payload to space either within a fairing or within the Dragon spacecraft itself. It can also carry humans into space. Payloads can be placed into low earth orbit (up to 22,800kg) or into geosynchronous transfer orbit (8,300kg), or a payload of 4,020kg can be sent to Mars. The vehicle is 70m high, has a diameter of 3.7m and when fuelled has a mass of just over 549 tonnes. Falcon 9 uses nine Merlin engines and a mission can be still completed if up to two engines fail during flight. The thrust developed by Stage 1 at sea level is 7,607kN (equivalent to five 747s at full power) and the first stage burn time is 162 seconds. Stage 2 uses one Merlin engine, optimised for use in the vacuum of space and it develops 934kN with a burn time of 397 seconds. The launch cost for a Falcon 9 with a maximum payload to low earth orbit is US$62 million, which works out to an economical US$2,719 per kilogram. Falcon Heavy The Falcon Heavy consists of a central core and two side-mounted boosters. It is basically a Falcon 9 with two Falcon 9 Stage 1 cores mounted at its sides. Standing 70m tall and 12.2m wide, it is currently the most pow- SpaceX Falcon Heavy The SpaceX Dragon spacecraft in crew-carrying configuration. Australia’s electronics magazine October 2018  15 Like something out of an old science fiction movie, the two side boosters from the Falcon Heavy landed almost simultaneously at Kennedy Space Center on February 6th, 2018. The central core was also supposed to land (on a drone ship at sea) but it did not have enough ignition fluid to re-ignite the motors for landing. This test flight launched Elon Musk’s personal Tesla Roadster into orbit around the sun. See videos: https://youtu.be/u0-pfzKbh2k and https://youtu.be/ A0FZIwabctw You can track its position at www.whereisroadster.com erful rocket in production in the world. It can lift 63,800kg into low earth orbit, 26,700kg into a geosynchronous transfer orbit, 16,800kg to Mars or 3,500kg to Pluto. Compare its lifting capability into low earth orbit to the retired Space Shuttle (24,000kg), Delta IV Heavy (22,560kg), Ariane 5ES (20,000kg) and the Atlas V 551 (18,510kg) and you will see that it is a monster. See a video of a Falcon Heavy launch at: https://youtu.be/BBA7su98v3Y The cost of a Falcon Heavy launch is US$90 million which for a 63,800kg payload into low earth orbit amounts to US$1,410 per kilogram. The Falcon Heavy was first launched on February 6th, 2018. While this is an amazing rocket, what is perhaps even more astounding is that its two booster rockets came back to Earth on their own, landing gently on their tails and they both went on to power other rockets! (See photo above.) But before we get onto the technology which allowed this incredible feat, we should mention Dragon – SpaceX’s spacecraft, designed to deliver payload and crew into orbit. It can be configured in three different ways: for carrying crew to the ISS, for carrying cargo to the ISS or as an orbiting lab, independent of the ISS. It can also be fitted with a non-pressurised “trunk” to hold extra equipment or cargo. By the way, the Draco thruster engines we mentioned earlier also form part of the launch escape system for the Dragon crew module; for this role, they are upgraded to SuperDraco configuration. The challenges of rocket reuse Readers would be aware of the fact that the now-retired US Space Shuttle was assisted in its launch by two solid rocket boosters, which fell away from the vehicle after they 16 Silicon Chip burned out, deployed parachutes and landed in the ocean. They were then picked up by ships, refurbished and reused for later launches. But liquid-fuelled rockets are preferred for most tasks because of their greater efficiency (higher specific impulse), lower fuel cost and simplicity of fabrication in the outer casing. Liquid-fuelled rockets are not suitable for recovery by the means described above. For a start, their complex engines will not take kindly to being immersed in salt water. You can’t always predict where a spacecraft using a parachute system will land; hence, they are typically brought back over the ocean. The water also cushions the impact. Trying to bring a rocket back safely onto land using parachutes would be much more difficult. Also, when a solid rocket burns out, it is little more than a (very strong) shell, whereas a liquid-fuelled rocket still has the heavy motor(s) attached and its structure exists mainly to support the fuel and oxidiser tanks and subsequent stages, so it may not survive such a re-entry. And due to the weight of the motor(s), even if it does survive re-entry, it will tend to land motor-first, which is not ideal. So that explains why SpaceX chose to use the rocket motor itself to perform a controlled re-entry. However, this is a much trickier task than merely deploying a parachute and requires some clever technology, as we shall see. The pitfalls of reusability Even if the technology to recover rockets is feasible (and clearly it is), that doesn’t necessarily mean it’s a good idea. Disposable rockets can potentially be cheaper, even though you have to build a new one for each launch. Rocket engines have to handle extreme pressures and Australia’s electronics magazine siliconchip.com.au temperatures and they can only withstand these conditions for a limited time before they wear out. In the case of a disposable rocket, the engine only has to survive one launch – typically around two and a half minutes of burn time. That means they can be made lighter and less expensively. In rockets, lightness is essential. The same is true of the rocket itself. A rocket which can survive the stress of re-entry and can then be relaunched is likely to be more expensive to build and heavier, too. And costs tend to go up exponentially with weight. Then there is the fact that a rocket which uses its engine(s) to assist in landing – as the Falcon boosters do – also need to carry extra fuel for this job. That adds to the weight, meaning they have to carry even more extra fuel so that they can bring that fuel with them! There is also the cost of refurbishing a rocket after it has been used once – checking it over to make sure it’s safe to launch again, cleaning, refuelling and so on. That can add up to a significant portion of the cost of a new rocket. So there are hurdles to be overcome before a reusable rocket makes sense. For an in-depth analysis of the pros and cons of launcher reuse, primarily focused on SpaceX’s technology, see: https://youtu.be/NY2ZVCA2Sno SpaceX’s reusable rocket technology As explained above, parachutes are not a practical way to recover a liquid-fuelled rocket. So it makes sense to use the motor itself to control the re-entry and cushion the impact. But this means the rocket needs extra fuel to complete recovery. A Falcon rocket carrying its maximum payload could not be recovered as it cannot carry that extra fuel. The payload capacity is reduced by around 30% if the boosters are to be recovered, to allow for the extra fuel needed for manoeuvering and landing. Carrying that extra fuel means that the launch is more expensive but this is offset by the savings from not having to build new boosters for the next launch. It isn’t just fuel either; on the Falcon 9, the landing legs alone weigh 2.1 tonnes. That’s 2.1 tonnes extra weight that must be carried until the second stage separates and 2.1 tonnes less payload capacity, just to allow the rocket to land. However, the high payload capability and high efficiency of the Falcon rockets means that they can still carry a significant payload to orbit while also retaining enough fuel for controlled landings. It is also necessary to have the ability to vary the engine thrust over a wide range, to allow for precisely controlled acceleration both to provide stabilisation upon re-entry and also cushioning for the touchdown. And the engines must be able to be restarted multiple times. This is not that easy to achieve; early rockets had difficulty restarting due to fuel and oxidiser moving around in the (almost-empty) tanks. Small thrusters are needed to orientate the rocket correctly and to provide a small acceleration to force the liquids into the lower end of the tanks (accomplished by gravity at launch) to keep the fuel pumps fed. Reliable, multi-use igniters are required to provide a controlled re-start; ignition has to be carefully sequenced with activation of the turbo-pumps which feed in fuel and oxidiser to prevent the engines from exploding. The engines must be carefully designed to avoid instability and possisiliconchip.com.au Reusable or Refurbishable? The ideal reusable launch system is much like a passenger aircraft, in that the only work required between flights is some basic maintenance and refuelling. No reusable launch system has achieved that yet but the situation has improved dramatically between the now-retired US Space Shuttle and the SpaceX Falcon 9. The Space Shuttle took 650,000 hours of labour to refurbish between flights – this figure increased after the Challenger accident in 1986, due to more rigorous NASA policies which involved thoroughly checking everything between every flight. Figures are hard to come by for SpaceX but it is thought that for the Falcon 9 Block 3 and 4 boosters require about 1000 to 10,000 labour hours to be refurbished, ready for reuse. You can see the “used” nature of some of the Falcon 9 boosters because they still have soot marks on them from their landing when the rocket is flying through its own exhaust plume. That suggests that the boosters are not entirely remanufactured, as was required for the Space Shuttle main engines. Falcon 9 rockets also need much less refurbishment and checking because they see less heat than the Shuttle did during re-entry and therefore they don’t have an extensive thermal protection system to check and maintain. SpaceX has a stated goal that the boosters should be able to be turned around between flights in 24-48 hours with inspections only, and the plan is to reuse Block 5 boosters ten times before major refurbishment is required. ble failure at lower thrust levels. Digital engine control can be used to avoid unstable thrust levels; it is tough to design a rocket engine that is efficient at 100% thrust while still being stable at much lower thrust levels but if there are particular combinations of conditions that lead to instability, the engine controller can be programmed to avoid those conditions. Attitude control After the successful separation of the second stage, the first stage is still on an upwards trajectory. A disposable rocket follows a parabolic path, re-entering the atmosphere (likely tumbling) and partially burning up before falling into the ocean or on an unoccupied area of land (launch sites are chosen to avoid burnt out rockets falling on people). So the first part of recovering a reusable rocket is to use thrusters to rotate and stabilise the rocket and to push the fuel to the bottom of the tanks. The main engine(s) are then restarted and run for a time to ensure that the rocket re-enters the atmosphere cleanly and that it is heading to the planned recovery location. For the Falcon rocket, this is the pad where it is to land. The engines are then shut off and the rocket allowed to continue under gravity’s influence until it is within the atmosphere. It must then be stabilised using the thrusters and/or controlled aerodynamic surfaces (fins/wings) when the engine is fired again, to slow it down. Stability is vital at this point, not just to prevent the rocket burning up but also because if the fuel is sloshing around in the tank(s) too much, the main engines may not be able to be restarted. Too much spin can cause the fuel to stick to the outside of the tanks, like a centrifuge; this was the reason for at least one failure to recover a Falcon 9 rocket. Australia’s electronics magazine October 2018  17 The SpaceX Dragon spaceship delivering 3175kg of cargo to the ISS on April 10th, 2016. On the same trip, it returned cargo to earth. While it is capable of carrying astronauts, it has not been used for that purpose yet. The final part of the descent requires careful computer control of the engine thrust and the various manoeuvring devices, to bring the rocket gently down onto its landing pad. Legs deploy just before landing, so it does not tip over when it touches down. Thrusters are not normally used during the final descent, partly because they would not have enough fuel but also because aerodynamic surfaces provide much more authority (ie, provide a wider range of control) once the rocket is within the lower part of the atmosphere, where the air is thicker. All this control requires numerous thrusters and control surfaces, motors and valves to drive them, a computer to control those motors and valves, accelerometer and gyroscopes for feedback and positioning feedback – either from an aerospace grade GPS receiver (or several), and/or from ground radar stations tracking the rocket(s) and relaying their position and velocity information via radio links. Position and velocity information for the final stages of landing is likely to come from a source very close to the landing pads to ensure the rockets slow down just before reaching the ground and then touch down in precisely the right spot. Augmented GPS could be used to provide accurate position data; see our article in the September 2018 issue (siliconchip.com.au/Article/11222) for more details on that. The software required to perform all these tasks, especially the final stages of landing, needs to be written very carefully and the control systems must all be well-characterised to prevent instability in the algorithms. Because of the possibility that the rockets may crash when attempting landing (which has happened a few times), SpaceX decided initially to land their rockets on a floating platform at sea. Once they had successfully landed a few 18 Silicon Chip rockets on that platform, they got government approval for bringing the rockets back to land-based pads. Rapid development SpaceX announced the reusable rocket program in 2011 and testing with purpose-built prototypes took place from 2012 through to 2014, with four landings over water. Six landing tests were carried out with Falcon 9 rockets in 2014 and 2015, with the first landing on a ground pad in December 2015. The first commercial SpaceX launch to successfully recover a booster was on April 8, 2016 and since then, there have been 20 successful booster recoveries. Of these, 14 have already been reused. The plan is to also recover the Falcon 9 Heavy core; however because it would be much further downrange than the boosters (which can return to their launch site) it could land at sea, on a drone ship. The fact that this program progressed from initial testing to full commercial use in just five years is quite astounding. Space programs have progressed quickly in the past; for example, the Apollo program which landed men on the moon took around eight years from President John F Kennedy’s famous exhortation to Congress (May 25, 1961), to Neil Armstrong’s equally famous “Tranquility base here: The Eagle has landed” on 20 July, 1969. But these days, major aerospace programs can take decades, even when they are using proven technology. This suggests that the move from government-managed space programs to private industry had resulted in muchimproved efficiency, as predicted by many proponents of the aerospace industry. For more details on SpaceX’s reusable rocket development program, see: https://en.wikipedia.org/wiki/ Australia’s electronics magazine siliconchip.com.au The Blue Origin “New Shepard” (named after Alan Shepard, the first US Astronaut in space), just after blast-off. It is a race between Jeff Bezos’ Blue Origin and Sir Richard Branson’s Virgin Galactic as to who will be the first to put tourists into space! SpaceX_reusable_launch_system_development_program The journey to Mars Elon Musk’s greatest vision for SpaceX is to establish a colony on Mars (and beyond). The proposed SpaceX Mars transportation infrastructure consists of reusable launch vehicles, passenger spacecraft, orbital refuelling tankers and the production of propellants on Mars for return journeys: methane and oxygen, to be made from atmospheric CO2 and underground ice. The goal is to have the first humans on Mars by 2024. This involves the BFR or Big Falcon Rocket, which is currently in development. The BFR is intended to replace the Falcon 9, the Falcon Heavy and the Dragon with a single vehicle that is suitable for insertion into Earth orbit, lunar orbit and interplanetary missions. They even want to use it for suborbital flights to allow Size comparison of various rocket systems, including several currently in use and some still in development. Note particularly the difference in size between the SpaceX Falcons, the Blue Origin New Glenn and the Saturn V, the latter of which sent men to the moon. The three-stage New Glenn will be the third-tallest rocket ever built after the Saturn V and the Soviet N1 (not Antares Soyuz Ariane pictured), at 99m tall 5 and 7m in diameter. siliconchip.com.au passengers to go from one place on Earth to any other in one hour or less. The BFR will be nine metres in diameter, 106m tall, with a total mass of 4400 tonnes. It will have a payload capacity to low Earth orbit of 150 tonnes, to Mars of 150 tonnes (with in-orbit refuelling) and a return payload from Mars of 50 tonnes. It will be powered by liquid methane and liquid oxygen and have two reusable stages. The second stage will have three configurations: cargo, passenger or tanker. Because the cargo version will have such a high payload, it will be used to deliver a large number of satellites at once to reduce costs. For Moon and Mars missions, the BFR would be refuelled in Earth orbit by the tanker version of the BFR, sent up on a separate flight. The following videos are relevant to the BFR: https://youtu.be/XcVpMJp9Th4 and https://youtu.be/0qo78R_yYFA Atlas V Vulcan Falcon V 9 Falcon Heavy Delta IV Heavy Australia’s electronics magazine New Glenn 2-stage New Glenn 3-stage New Glenn landed booster Saturn V October 2018  19 A history of reusable space vehicles Apart from early experimental rocket designs which were recovered and rebuilt by their designers, the first vehicle that could fly to the edge of space in suborbital flights (considered to be 80km for the purpose of qualifying as an astronaut) and was reusable was the North American Aviation X-15 rocket-powered hypersonic plane, which first flew in 1959 until its retirement in 1968. An X-15 spaceplane at the moment of launch from its B-52 mothership. The X-15 was designed as an experimental platform to investigate: spacecraft control in a near vacuum; the hypersonic flight regime (speeds above Mach 5); aircraft construction using advanced materials such as titanium, nickel steel alloys and ablative materials; the space environment; human factors; atmospheric re-entry and spacecraft systems. But the X-15 was suborbital and needed to be carried aloft by a B-52 bomber. It also had a short flight time and no real payload – just the pilot. However, the X-15 deserves its place in history as to this day it continues to hold the title for the fastest manned “aircraft” ever flown, at 7274km/h; (2021m/s), set in October 1967. The US Space Shuttle The first reusable system to reach orbital flight (and capable of carrying a payload) was NASA’s Space Shuttle which flew from 1981 to 2011. It was designed to be cheaper than expendable launch systems but it turned out to be far more expensive, primarily due to substantial costs for refurbishment between flights. It took around 25,000 people (costing US$1 billion per year) nine months to refurbish each Shuttle after a flight. Also, it was not completely reusable. The components reused were the two solid rocket boosters and the orbiter itself; the giant external fuel tank was jettisoned to burn up during re-entry over the ocean. The Space Shuttle program cost over its lifetime around US$210 billion (2010 dollars) for 135 flights or an average of over $1.5 billion per flight, although different costs are claimed according to the accounting methodology used. The original estimated cost for the Space Shuttle delivering a payload to orbit was US$54 per kilogram (about US$300 in today’s money). In 2011, the estimated actual cost per kilogram of payload delivered to orbit was about $18,000 per kilogram. It was also initially estimated to be capable of being launched every week but after the first flights, it soon became apparent that this was unrealistic and there was only one launch every three months on average for the entire fleet; individual orbiters took nine months to The Space Shuttle main engines were “reusable” – but had to be rebuilt after each flight at great expense. An expendable engine may have been much cheaper over the life of the program. 20 Silicon Chip An F-1 Rocket engine, one of five used on the first stage of the Saturn V used to send men to the moon. These could have been adapted to be used on the Space Shuttle, as an expendable alternative to the reusable main engines. refurbish, as mentioned above. Part of the reason it was so expensive was due to the cost of rebuilding for the main liquid fuel engines (attached to the orbiter) after each launch. The cost was so high that it would likely have been cheaper to build expendable engines for each launch. For example, the Saturn V main engines were proven technology before the first shuttle launch and could have been used instead. The total thrust developed by the three main engines and the two solid rocket boosters on the Shuttle was 28,900kN while the Saturn V F-1 engines developed 6,676kN, so the Shuttle could have been launched with four F-1 engines alone with no solid boosters. Note that the F-1 engines would have to have been modified for Shuttle operation since they were designed to operate for around two minutes, before the next stage took over, versus the Shuttle engines which had to operate for around 8.5 minutes until orbital insertion. Soviet Buran shuttle The Soviet Union also developed a competing reusable launch system from 1980, similar to the Space Shuttle. It was called the Buran but it made only one unmanned flight, in 1988 and then the program was effectively cancelled, with the collapse of the Soviet Union, in 1991. Australia’s electronics magazine siliconchip.com.au Aborted attempts Rockwell X-30 Apart from the Shuttle, there have been many other programs to develop reusable launch systems which have either been unsuccessful or cancelled for one reason or another. These include: • Sea Dragon, a sea-launched reusable booster which was the biggest rocket ever proposed and would have been able to carry 550 tonnes into low earth orbit. It would have used a single enormous motor with fuel fed by pressurised gas (1962; see video: https://youtu.be/6e5B7EKVg48) • Douglas DC-X, a single-stage-toorbit rocket which was part of the US Strategic Defense Initiative “Star Wars” program (1991-1996). • Sea Dragon Douglas DC-X • BAC MUSTARD or Multi-Unit Space Transport And Recovery Device (1964-1970); see video: https://vimeo.com/66870958 BAC MUSTARD • Lockheed Martin X-33 (1996-2001) – a one third scale prototype for the • Lockheed Martin VenturStar, a proposed single-stage-to-orbit (SSTO) replacement for the Space Shuttle Lockheed Martin X-33/ .VentureStar • • XCOR Lynx, which was to fly suborbitally with a pilot and single paying passenger or payload (2003-2017). XCOR Lynx • BAE HOTOL or Horizontal Take-Off and Landing (1982-1989) BAE HOTOL • Airbus Adeline, a reusable rocket first stage (2010-18) These unsuccessful or cancelled examples all contributed to scientific and engineering knowledge. But it is clear that a major problem with developing reusable launch systems is that they are significantly more complex and expensive to build initially than expendable launch systems and are not necessarily cheaper in the long run either. Shockingly, since the demise of the Shuttle, NASA has no ability to put astronauts in space and they contract rides at great expense on the Russian Soyuz spacecraft, to get crew to the International Space Station (ISS). In 2017, Russia charged the USA US$490 million for six seats on Soyuz. This deficiency will hopefully be solved by SpaceX and Boeing, who are both working on space capsules and associated launch systems. Unmanned tests for both are scheduled late this year (but more likely will happen in 2019). The two designs are quite different; the Boeing CST-100 capsule is more traditional with physical switches while the SpaceX capsule is more “Tesla style” with touchscreens. The Ansari X Prize In 1996, to stimulate development in reusable launch systems, a prize of US$10 million was offered by a private foundation for the first non-governmental organisation that could develop a reusable manned spacecraft, capable of being launched into space twice within two weeks. In 2004, the prize was renamed the Ansari X Prize in recognition of a major donation from an entrepreneur of that name. On 4th October 2004, the prize was awarded to the Tier One team led by Burt Rutan with funding from Microsoft’s Paul Allen, for their SpaceShipOne craft. The date corresponded to the launch anniversary of Sputnik 1 in 1957. Of course, the prize money was not the real incentive, as US$100 million had been invested in the technology to win the prize. Bezos’ Feather • Rockwell X-30, a single-stage-to-orbit passenger spaceplane that was intended to fly between Washington and Tokyo in 2 hours (1986-93) siliconchip.com.au In case you were wondering about the significance of the feather painted on all Blue Origin spacecraft, it’s “a symbol of flight with grace and power.” Australia’s electronics magazine October 2018  21 Current/future reusable spacecraft development Blue Origin Jeff Bezos, of Amazon fame, founded Blue Origin (www. blueorigin.com) in 2000. Blue Origin’s design philosophy is to incrementally improve systems (corporate motto “step by step, ferociously”) and not to move on to the next phase of design until the existing design is perfected. Engineers from the McDonnell Douglas DC-X project were hired to work on the New Shepard spacecraft, which incorporates ideas from that concept. New Shepard, named after Alan Shepard, the first American in space, is intended for space tourism use, with suborbital flights. The first passenger-carrying flight is expected late this year with paying passengers in 2019. It flies at an altitude in excess of 100km. New Shepard has a single booster which detaches from the crew capsule and returns to earth, landing vertically under rocket power with drag brakes to slow it down before the engine fires. The crew capsule continues to coast and then later descends via a parachute. The crew capsule (seen above) seats six and has large windows for viewing. Each flight gives a few minutes of weightlessness. The New Glenn, named after John Glenn, the first American to orbit the earth, is designed to deliver payloads into earth orbit and will be available in either two- or three-stage versions. The three-stage version will be the third-tallest rocket ever built. The two-stage version will be able to lift 45 tonnes to low earth orbit or 13 tonnes to geostationary transfer orbit. It uses the Blue Original developed BE-4 engine which is fuelled by liquid oxygen and liquid methane. Payload figures have not been released for the three-stage version. The New Glenn is not just “vapourware”; as of April 2018, it has seven satellite launches booked and the first launches are expected in 2020. See the video “Introducing New Glenn” at: https://youtu.be/ BTEhohh6eYk The New Armstrong is still being designed and few details have been released but the speculation is that this will take payloads to the moon. That would be consistent with their naming convention and Blue Origin have also published a picture of a lunar lander. You can view a video of the latest New Shepard launch, testing emergency capsule separation on July 18th, 2018. It includes highlights of previous tests and a single “passenger”, Mannequin Skywalker. See: https:// 22 Silicon Chip youtu.be/kgfTDkU0Z-g Another video at https://youtu.be/6ZJghIk7_VA shows the view (and sound) from the crew capsule during the launch. Another video of the same launch, called “Apogee 351,000 Feet”, is at: https:// youtu.be/h6_RvniifL8 You can also watch a space tourism promotional videos for Blue Origin at https://youtu.be/K9GoLD49sQ0 and https://youtu.be/YJhymiZjqc Boeing CST-100 Starliner The Boeing CST-100 Starliner is a reusable spacecraft rather than a launch system and is designed to take astronauts to the ISS and possibly other orbital missions. It is slightly larger than the Apollo command module and will carry up to seven astronauts or fewer astronauts and more cargo. It is designed to be reused up to ten times. It can be launched by various rockets such as the Atlas V, Delta IV, Falcon 9 and the Vulcan. It can endure missions of 60 hours of orbital flight and can remain docked for up to 210 days. The first crewed flight is expected to take place in mid-2019. Reaction Engines Skylon Australia’s electronics magazine siliconchip.com.au Skylon (www.reactionengines.co.uk) is a single-stage-to-orbit space plane which starts its journey with air-breathing liquid hydrogen engines in the lower atmosphere and then switches to liquid hydrogen and liquid oxygen when there is insufficient atmospheric oxygen. It is being designed to carry 17,000kg of payload to equatorial low earth orbit, 11,000kg to the ISS or 7300kg to geosynchronous transfer orbit. It is expected to have a two day turn around time between flights. Skylon was developed from HOTOL, mentioned earlier. ShipTwo has two pilots; the rocket motor uses a polyamide fuel (a nylon-like material) and nitrous oxide as the oxidiser. The total flight time will be around 2.5 hours but only a few minutes will be in space. It is a race between Sir Richard Branson’s Virgin Galactic or Jeff Bezos’ Blue Origin as to who will be the first to put tourists into space! The following video is of a test flight on 29th May 2018. The aircraft reached an altitude of nearly 35km and a speed of Mach 1.9. See: https://youtu.be/YQPyZB-cjO4 United Launch Alliance Vulcan A key feature of the Skylon is the SABRE or Synergetic Air-Breathing Rocket Engine which operates much like a conventional jet engine and ramjet up to an altitude of 26km and up to speeds of Mach 5.5, at which point the air intake closes and the engine acts like a rocket. Skylon has the potential to seat up to 30 passengers in a special module instead of cargo. The empty weight of the space plane is expected to be 53,500kg with a fully loaded weight of 325,000kg. SABRE engine testing is expected to start in 2020. However, no date has been provided for construction or testing of the space plane. See the video at: https://youtu.be/2m-oiO_ZwZI SpaceShipTwo SpaceShipTwo is a suborbital spaceplane manufactured by The Spaceship Company which is owned by Virgin Galactic (www.virgingalactic.com). It launches at an altitude of 15000m from a “mother ship” plane, White Knight Two. SpaceShipTwo will be used to carry six fee-paying passengers to suborbital altitudes (around 110km) at a cost of around US$250,000 per ride. Sir Richard Branson, founder of Virgin Galactic said on 29th May this year that they are only two or three flights away from sending passengers into space and he plans to be one of the first. Space- siliconchip.com.au The United Launch Alliance (www.ulalaunch.com) between Boeing Defense, Space & Security and Lockheed Martin Space Systems is intended to provide space launch services to the US Government. They currently use four expendable rockets: the Atlas V, Delta II, Delta IV and Delta IV Heavy. In 2014, they began developing a new launch system with several configuration options to replace both the Delta and Atlas launch systems; the Vulcan. The new first-stage booster will have two Blue Origin BE-4 2400kN thrust engines running on liquid methane and liquid oxygen, to replace the Russian RD-180 engines currently used on the Atlas V. This decision was made due to the perceived supply risks with Russia due to the Ukrainian crisis at the time, and the desire to use US-built engines. The first stage can also accommodate up to six additional strap-on solid rocket boosters to increase thrust (eg, for heavier payloads). The second stage will be the Centaur as used in the Atlas V but they are planning to develop a new second stage later, called the Advanced Cryogenic Evolved Stage. All the above is relatively conventional but the possibility of reusability has not been ignored. They plan to eventually recover the first-stage motors, which will separate from the fuel tank after they burn out. An inflatable heat shield will then be deployed for hypersonic re-entry, followed by a guided descent with a parafoil, to be captured in mid-air by a helicopter. The engines are 24% of the booster weight but 65% of the booster cost and these Blue Origin engines are reusable by design. One advantage of recovering the motors by this method is that fuel does not need to be kept for the landing process, as is the case with SpaceX and Blue Origin; therefore, a larger payload can be put into space. See videos: https://youtu.be/SqCTK7BmLHA and https:// youtu.be/lftGq6QVFFI SC Australia’s electronics magazine October 2018  23