After Unity, New Shepard gets into SpaceFollow article
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New Shepard heads for the Kármán Line: the maximum theoretical altitude at which a true aircraft can fly. This height above sea-level is recognised by most of the world as the beginning of ‘Space’.
Image credit: Blue Origin
It always happens: you wait for a tourist bus into Space and two come along at once. After the first passenger flight of Virgin Galactic’s VSS Unity on July 11th, Blue Origin’s New Shepard went beyond the Kármán Line on July 20th. For an account of Unity’s flight and subsequent grumbling amongst professionals concerning the labelling of tourist passengers as ‘Astronauts’, see The new Space Tourist: Astronaut or Astronaut*?
A ‘Real’ rocket this time….
Unlike Unity which hitched a ride to the upper atmosphere on a relatively conventional jet aircraft, New Shepard went the whole way, there and back using rocket power. Like Unity though, it started out as a single-vehicle but came back as two. It consists of a single-stage booster with one BE-3 engine developing about 110,000 lbf (490 kN) of thrust using cryogenic fuel: liquid hydrogen and liquid oxygen (LH2/LOX). In principle, it’s much more environmentally friendly than some other designs as the only emissions are heat and water. The same cannot be said of the engines used in Virgin Galactic’s system. Unity has a hybrid motor: it burns solid fuel with a liquid oxidiser. Solid fuel is a lot easier and safer to handle than cryogenic types and a liquid oxidiser allows the motor to be shut-down by the pilot – an essential feature for Unity. The fuel is rubber-based and goes by the name Hydroxyl-Terminated Polybutadiene (HTPB). It works well, but does tend to leave a trail of Carbon Black (soot) particles in the upper atmosphere, something of great concern to climate-change scientists . The oxidiser, Nitrous Oxide (N2O) has its issues too: it can be misused as a recreational drug with fatal consequences and it’s a powerful ‘greenhouse’ gas contributing to global warming. That said, its use in rocketry should cause no problems unless the spacecraft develops a leak in the upper atmosphere (It can damage the ozone layer as well). Emissions from the jet-powered mothership Eve have also got to be factored in. All in all, this suggests that New Shepard is likely to have less environmental impact than Unity, should Space Tourism really ‘take-off’ in the future.
The booster stage of New Shepard returns to Earth seven minutes after lift-off. At this point, the capsule is still on its way down and is just about to deploy parachutes.
Image credit: Blue Origin
Flight profile - Sub-Orbital
A round trip with Unity takes over 90 minutes thanks to the initial leisurely cruise to high-altitude with mothership Eve and the glide to a runway landing at the end. Your ‘Space experience’ starts with the ignition of Unity’s rocket motor, followed soon after MECO by a few minutes of weightlessness until the spaceship becomes an aircraft and glides back to the spaceport. Perhaps the ride should have been billed as the X15 Experience, but without all the discomfort, high risk of death, etc!
On the other hand, a trip with New Shepard lasts just 10 minutes, but all of it can loosely be described as ‘astronaut-type experience’. A simplified view of its flight profile is shown in Fig.1.
You can see straight away that the ‘core’ of the experience is the same as Virgin Galactic’s - without the aircraft/glider phases. You do get a ride on a recognisable rocket launched vertically, capsule separation and a parachute ‘splashdown’. Though I think they’ll soon run out of customers able and willing to spend a vast amount of money for such a quick thrill. Either the price will have to come down a lot, or more will have to be offered. A stay in an orbiting hotel perhaps?
Getting into orbit
Question: Could Unity or New Shepard be adapted to achieve orbital flight? Answer: Not a chance. In order to get into a 220-mile orbit, for example, a rocket has to:
- Accelerate from rest on the Earth’s surface to about 17,000 mph at the orbital altitude.
- Start pitching over after lift-off so that it’s moving ‘horizontally’ at orbital speed at the desired altitude. See Fig.2.
New Shepard has just enough thrust to reach an altitude of about 60 miles going straight up. By the time it gets there its vertical speed is just about zero and so is its ‘horizontal’ speed. In other words, it’s essentially a giant firework rocket, albeit man-rated. It does the job, but if you want to get into orbit, a rocket with an order of magnitude more thrust is needed. Blue Origin does have such a vehicle in the pipeline called New Glenn, but for the moment SpaceX have nearly cornered the market in re-usable orbital boosters with their Falcon 9.
A SpaceX Falcon 9 two-stage rocket lifts-off carrying supplies, or indeed a crew, to the orbiting International Space Station.
Image credit: SpaceX
Compare the above with the picture of New Shepard lifting-off with just one engine. There’s a lot more power on display with the Falcon for a start: nine Merlin RP-1/LOX engines producing 190,000 lbf (845 kN) of thrust each. All that power produces deafening noise and vibration capable of wrecking the launch pad. Hence the clouds of steam from the sound-deadening water deluge. New Shepard doesn’t need one of those. Also, notice the almost colourless exhaust from New Shepard and the intense flame from the Falcon: RP-1 (Kerosene) unfortunately tends to produce carbon particulates amongst other things and is thus not so environmentally friendly.
Flight profile – Earth Orbit Insertion
It was realised back in the 1950s that using one enormous rocket to place an object in Earth-orbit or go to the Moon was not practicable. The only sensible approach was to stack two or more rockets on top of each other creating one big rocket that flew in stages. The lowest or first stage would still have to be pretty massive to lift the whole rocket, but only part of the way into orbit before being detached and falling back to Earth. This simplified flight profile for a Falcon 9 rocket delivering a payload into Low-Earth Orbit (LEO) shows that despite all that engine power, the first stage barely makes it any higher than New Shepard. But it will be moving considerably faster on an upward curving trajectory; a second stage then takes over to move the payload into its correct orbit while the first returns to Earth to be re-used.
The second stage is nothing like as impressive as the first, having only a single Merlin engine optimised for operation in the vacuum of Space. In fact, New Shepard has a similar performance to that of Falcon’s second stage. The big difference between first and second stages is due to:
- The massive reduction in weight after the first stage has separated and fallen away.
- A large reduction in air resistance above the Kármán Line.
- The second stage is already moving at speed when its engine ignites.
SpaceX normally launches rockets from Cape Canaveral on the US east coast, sending them eastwards out over the Atlantic. This means that a rocket heading for orbit gets an assist from the Earth itself as the latter is spinning in the same direction. The returning booster can either continue in the same direction to land on an automated barge, or execute a series of burn manoeuvres to take it back to the Cape.
Mere stepping stones to the planets?
It would be feasible for SpaceX to provide the full ‘orbital experience’ for well-heeled tourists using their existing Crew Dragon craft, but even millionaires might baulk at the cost of a few 90-minute laps around the Earth. Not to mention the need for serious astronaut training. Unquestionably, a destination in Space is required, and by that, I mean something rather more comfortable than the ISS. Both SpaceX and Blue Origin have their sights set on Mars; both are developing huge rockets, Starship and New Glenn respectively for the trip, and I’m sure there will be no shortage of customers, if the price is right. I have no doubt: anyone undertaking that trip will definitely have earned the right to the title, Astronaut.
 Potential Climate Impact of Black Carbon Emitted by Rockets, Martin Ross, Michael Mills and Darin Toohey, GEOPHYSICAL RESEARCH LETTERS, 2010.
For more information on how the physical laws first described by Sir Isaac Newton explain what keeps an object in orbit, see my article: The Scourge of Space Junk, Part 1: Orbital Mechanics.
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