This is only a preview of the October 2018 issue of Silicon Chip. You can view 40 of the 112 pages in the full issue, including the advertisments. For full access, purchase the issue for $10.00 or subscribe for access to the latest issues. Items relevant to "GPS-synched Frequency Reference Pt.1":
Items relevant to "Arduino-based programmer for DCC Decoders":
Items relevant to "Low-voltage, high-current DC Motor Speed Controller":
Items relevant to "Opto-Isolated Mains Relay":
Items relevant to "Intro to programming: Cypress' System on a Chip (SoC)":
Purchase a printed copy of this issue for $10.00. |
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
|