This creates a zone of electromagnetic disturbance that no radio waves can penetrate. For 17 or more minutes, the shuttle is out of contact. It loses three feet in height for every 15 feet it covers. This is a descent far steeper than made by any powered aircraft. At around , feet - about 30 miles - the craft's navigational equipment should pick up beacon signals from its landing strip, and begin to slalom in a series of wide swings to slow its speed further.
At 40, feet, while still travelling at one and a half times the speed of sound, it executes a degree turn and takes a bearing on its runway. At 13, feet, its speed begins to drop to mph; its landing gear drops 11 seconds before touchdown and it hits the runway at more than mph.
It would have no shortage of power with such a large area of solar panels. It has no internal girders. Its outer shell covers an interior of many large bags of hydrogen to give it rigidity and to stop the gas bunching up at its nose. It also has inflatable trusses, with nitrogen filling the gaps in between these components. The nitrogen is vented if necessary and then replaced from liquid nitrogen tanks. It is balanced to float at , feet altitude in the atmosphere. But since it is aerodynamic, it also behaves like a glider on the way down.
It doesn't look much like a glider to our eyes perhaps, but that big voluminous V shape makes a great glider in the very tenuous upper atmosphere during re-entry. So what keeps it up is partly aerodynamic lift and partly buoyancy. The aerodynamic effects keep it higher in the atmosphere for longer, and so keep it cooler on the way down. On page they say: "By losing velocity before it reaches the lower thicker atmosphere, the reentry temperatures are radically lower This makes reentry as safe as the climb to orbit.
Instead, every stage along the way pays for itself. At present they pay for the tests through pongsats and other ways to lift material to the edge of space. Their tests involve high altitude balloons and V-shaped airships rated for the lower atmosphere. They have also tested a high altitude balloon-based airship design.
JP Aerospace holds the altitude record for an airship , propeller driven, remotely controlled from the ground, and flying at a height of 95, feet above sea level. It gets the name because at that height the sky will be dark even in daytime, as for the Moon. Next, they plan small airships doing test hypersonic glides back to Earth. Finally, they do test flights to orbit with smaller airships, then the first human pilots to orbit, and then huge orbital airships with passengers and cargo.
The idea started off as a US Air Force contract for a near space reconnaissance airship. It was only rated as sturdy enough for launch in a 2 mph wind at the time an airship is particularly vulnerable in the short time it takes to launch it from the ground. They did this with some reluctance - and it blew apart in the strong winds, causing some minor injuries.
The inventor himself sustained three broken ribs. That was enough for the US Air Force to cancel the contract. JP Aerospace have now solved the problem and can launch their lower atmosphere V-shaped airships in any wind conditions.
You can read their account of this story here. You might wonder what happens if the airship is hit by a meteorite or orbital debris. From page of the book:. A balloon pops because the inside is at a higher pressure than the air on the outside. The inner cells of the airship are "zero pressure balloons". There is no difference in pressure to create a bursting force. All a meteorite would do is to make a hole. The gas would leak out staggeringly slowly The JP Aerospace orbital airships are so lightweight they could never survive at ground level.
The slightest wind would tear them apart. If you want to fly all the way down to ground level on Earth in one go, then you need a more massive airship.
It still gets quite hot during the descent. It inflates before it enters the atmosphere see patent for details , and rather similarly to the JP Aerospace idea it decelerates slowly in the upper atmosphere, so generating much less heat because of its low ballistic coefficient. They hope it can be used for Venus, and also Titan, and possibly Mars. It would only descend as far as the Venutian upper atmosphere, at the cloud tops, where temperatures and pressures are the same as on Earth.
The cloud tops also have natural protection from cosmic radiation, and nearly all the ingredients for life. Indeed there are suggestions that it could be a good place for humans to settle outside of Earth. Some astrobiologists think there may be life in the upper Venus atmosphere, already, which could have migrated there long ago when Venus was more habitable. The Russians are interested to search for this life, and may include an unmanned aerial vehicle, possibly VAMP in their Venera D mission to Venus in the mid s.
So it could also be used for Earth re-entry. It might be useful for surveillance, photographing the Earth from above, and also for scientific studies of the upper atmosphere. Can this be improved on? This absorbs most of the heat, all the way through the early stages of re-entry, until the spacecraft is traveling slowly enough to drop the aeroshell and deploy parachutes. The spacecraft hits the atmosphere at many kilometers per second, so there is a lot of heat to dissipate.
The main methods they use to keep the temperatures within reasonable bounds are:. They reached rather higher temperatures for the Apollo return from the Moon, as their re-entry was at a higher velocity.
It is useful, as it is also good at conducting heat and electricity. Titanium and zirconium diboride have similar properties. You might wonder why the astronauts returned from the Moon at such a high speed. After all, it orbits the Earth at a speed of only 1. If you come back in a transfer from the Moon you hit the atmosphere at Starting from a higher orbit just makes things worse for you. The one thing you can do to help with re-entry speed is to orbit the Earth in the same direction that it spins.
So if your satellite is orbiting in the same direction as the Earth in an equatorial orbit, West to East, it has 0.
This makes re-entry just a little easier. An orbit in this direction also makes the launch easier. You need around 0. This is why it was such a major gaffe for the Gravity film when it showed all the orbital debris orbiting Earth from East to West, as Neil deGrasse Tyson tweeted. But you can achieve a much gentler re-entry using a ballute - a cross between a balloon and a parachute.
It works like an aeroshell but decelerates much higher in the atmosphere. It combines some of the approaches of the previous ideas. The space engineers in the early s explored many other such ideas detailed here: Rescue. Some seem rather hair-raising, including the Paracone —the astronaut just sits in a seat, with their back towards the Earth, and aims towards the center of a large continent, as its margin of error is kilometers.
When it re-enters, then a large inflatable aeroshell deploys with a crushable cone. There is no parachute—it relies on the aeroshell crushing during landing to protect the astronaut. The astronaut has an inflatable aeroshell stowed away in the seat. During re-entry this deploys.
Unlike the Paracone, you do have a parachute as well, for the landing. This is another idea originally developed for Gemini in the early s. For a while, before they settled on the familiar parachutes, the engineers thought that after the fiery stage of re-entry, the capsules would glide down to Earth beneath a parasail or paraglider.
Those tests were quite promising, though they ran into many issues; for instance, getting the glider to unfold. Eventually this line of research ended in when they changed to the parachutes as used by Apollo. The Russians also used parachutes for the Soyuz flights.
For details of the paraglider research, see: Coming Home. Anyway, at around the same time in , the engineers came up with the idea of using the same paraglider approach to go all the way from orbit right down to the surface, without an aeroshell.
It could be folded up into a small cylindrical package that would be kept docked to a space station, much as our modern Soyuz TMA is. In an emergency, the crew enter this cylinder, and separate. The paraglider then inflates and deploys. It would re-enter at an angle of 1 degree, with the paraglider angle of attack of 70 degrees. It would approach the speed of sound at 43 km altitude, and from there it would be able to glide km horizontally before eventually landing.
The Spaceship-One uses a different idea for re-entry. This is only for a sub-orbital hop at present. The first demonstration of the feather system was in The Virgin Galactica crash in was a result of the pilot accidentally unlocking the feathering system too soon. It then deployed by itself and changed the shape of the rocket far too early, when it still needed to be streamlined. What about returning a final stage? That also is low mass and it presents a large cross section if you fly it backwards, rocket motors first, with supersonic retropropulsion.
First, some background. Every time a spaceship goes into orbit, it needs a final stage, a thin container full of fuel which is burnt right at the end, to get it to orbital velocity. It has to do that, because the spaceship itself is far too small to have enough fuel to get to orbit by itself, even with the help of the first and sometimes second stage. It then discards the final stage, which normally orbits Earth a few times and finally falls back to Earth apart from interplanetary missions and missions to the Moon, which often use a more powerful final stage, for instance nearly every mission to Mars also sends a final stage in the general direction of Mars too.
So, could a final stage be returned to Earth in the same way that SpaceX have returned the Falcon first stage? Well, when SpaceX returns the first stage of the Falcon 9, it slows down partly through friction in the upper atmosphere. Asked 6 years, 1 month ago. Active 3 years, 3 months ago. Viewed 31k times. And that got me thinking: How does the Space Shuttle reduce speed during the re-entry process? Does the Space Shuttle have flaps, spoilers and reverse thrust capabilities?
Can the Space Shuttle make a go-around? Where does it land? I know that when it is on the ground the Space Shuttle can deploy parachutes to reduce speed.
Improve this question. Rodrigo de Azevedo 1, 1 1 gold badge 9 9 silver badges 26 26 bronze badges. Gabriel Brito Gabriel Brito 6, 17 17 gold badges 49 49 silver badges 79 79 bronze badges.
Same result, different execution. At any rate, Simon did specify after re-entry , and the deorbit burn was definitely before re-entry. Pointing backwards whilst within atmosphere would be Point well taken.
Show 7 more comments. Active Oldest Votes. First, the two easy questions, which were answered well by other questions, but I'll include here as well for completeness: Could the shuttle perform a go-around? The OMS engines are too weak to make a difference in the atmosphere, and the main engines which would be powerful enough are only fueled by the orange external tank which is jettisoned after launch.
Where did it land? There were other landing sites designated for emergencies, but none were ever used. Now, for the really big question of how the shuttle reentered and landed.
Orbital Mechanics First, a real quick lesson in orbital mechanics. This illustrates the effect: Starting from the circular orbit black , if you slow down at point A, you might end up with something like the red orbit, and if you speed up you might end up with something like the blue orbit.
Deorbit Burn Because of the nature of orbital mechanics, as described above, you want to perform your deorbit maneuver on the opposite side of the planet from your intended landing site. S-Turns Some answers have claimed that the shuttle used S-turns for the purpose of slowing down.
Ranging Obviously, the ultimate goal of reentry is to reach your intended runway at an appropriate speed for landing. Entry Guidance Phases I'm not going to go into detail about entry guidance, but I will say that the primary considerations change as speed and altitude changes, and the entry guidance is broken up into phases to reflect this. Temperature Control : Begins at closed loop guidance and ends at a velocity of Mach Tries to maintain a constant temperature within the design limits of the orbiter.
Equilibrium Glide : Simply provides a bridge between temperature control and constant drag phases. It's named as such because its shape is similar to that of the equilibrium glide profile. Transition : Designed to transition from the high drag and high alpha of entry to the lower drag and lower alpha required for the orbiter to fly more like an airplane. This phase terminates at Mach 2. Again, I'm not going to go into a ton of detail feel free to ask other questions if you want , but here's the gist: If all went well in the entry stage, TAEM will begin at about 82, feet and 60 nautical miles from the runway intended ground track, not straight-line distance.
Acquisition : Turns the orbiter towards a point of tangency on the heading alignment cone HAC and then flys wings-level until it intercepts the HAC.
The tangency point is referred to as "waypoint 1" WP1. During this phase, the orbiter slows to below Mach 1, at which point the commander takes CSS control-stick steering , which is the closest thing the shuttle has to a "manual" mode. Heading Alignment : Guides the orbiter around a virtual "cone" see diagram below until it is in alignment with the runway. It's not really a cone, mathematically speaking, but it's the easiest way to visualize it.
Prefinal : Establishes the orbiter on the outer glide slope. Approach and Landing The final guidance phase is called "Approach and Landing". Control e. Mach 10, the speedbrake opens on a pre-programmed schedule to act as pitch trim. Mach 5, rudder becomes active, initially acting primarily as aileron trim. Mach 1, RCS yaw jets are disabled.
Navigation e. Below feet, the orbiter was also able to use a radar altimeter for altitude information. Improve this answer. Community Bot 1. Bret Copeland Bret Copeland 9, 3 3 gold badges 56 56 silver badges 60 60 bronze badges. Add a comment. Source: zlutykvet. Source: quest. Source: spaceshuttleguide. The steep banks in particular are used to control the vertical component of the lift vector. Without them, the shuttle will still reenter, but it will follow a 'skip reentry' profile, essentially bouncing off the upper atmosphere until it bleeds off a large amount of energy, then sinking like a rock, resulting in reentry heating and loads beyond design limits.
The bank angle is varied to control the rate of energy dissipation, and the banks are reversed to keep the cross range deviation from getting too large. My reading from NASA's site 2nd quote in my answer seems to indicate that the S turns are done once in the atmosphere to bleed speed. They strike me as aerodynamically controlled turns, not steering jet turns 3rd quote. It should be noted that the concept of "in" or "out" of the atmosphere is not well defined -- the density varies continuously from entry interface to the surface.
These were not "S-turns" per se -- they were banks to control the lift vector and, correspondingly, the rate of descent. The S is just a consequence of having to roll back over to correct crossrange drift. The shuttle was never flown with a negative AoA. S-turns aren't really to slow down. The flip maneuver was pitch up , not down.
And a few other minor things. I've written a very detailed answer below. All quotes sourced from NASA To reduce speed once in the atmosphere To use up excess energy, the orbiter performs a series of four steep banks, rolling over as much as 80 degrees to one side or the other, to slow down.
To make a go-around During reentry and landing, the orbiter is not powered by engines. Emphasis mine i. Where does it land: On the ground, of course! Edwards was also the primary landing site for the first several 10 or more? Other locations were emergency abort destinations for use before the shuttle left the Earth's atmosphere. FreeMan FreeMan In most cases, they have been flying nose-first and upside down, so they then fire the RCS thrusters to turn the orbiter tail first.
Once the orbiter is tail first, the crew fires the OMS engines to slow the orbiter down and fall back to Earth; it will take about 25 minutes before the shuttle reaches the upper atmosphere. During that time, the crew fires the RCS thrusters to pitch the orbiter over so that the bottom of the orbiter faces the atmosphere about 40 degrees and they are moving nose first again. Finally, they burn leftover fuel from the forward RCS as a safety precaution because this area encounters the highest heat of re-entry.
Todd Wilcox Todd Wilcox 7 7 silver badges 12 12 bronze badges. This is a quite common misconception actually. See en. I never knew that but it makes sense. I'll edit. Dreamer Dreamer 1 1 silver badge 5 5 bronze badges. Here are some images that illustrate what it looks like. The re-entry generates a lot of heat and the underside has special heat-resistant tiles to cope with this.
During re-entry the shuttle isn't really 'flying' so much using its underside to slow down. At that stage the usual flaps, spoilers and reverse thrust wouldn't do much. Re-entry refers normally only to the portion where the shuttle is coming into the atmosphere. After a while, when the speed is reduced sufficiently, the shuttle starts to fly more like a normal plane, and uses normal controls. That phase isn't normally called re-entry.
0コメント