Comprehensive coverage

How Till was born

Is NASA's Space Launch System (SLS) a flying election bribe, or our best chance to get humans into deep space? David H. Friedman, Scientific American

The SLS launcher has an orange stage in the center, similar to the shuttle boosters. Image: NASA
The SLS launcher has an orange stage in the center, similar to the shuttle boosters. Illustration: NASA

The article was published with the approval of Scientific American Israel and the Ort Israel network

After the cancellation of NASA's Constellation program, which was intended to replace the space shuttle, the US decided to rely on private contractors for access to low Earth orbit, and to build a large rocket, called the "Space Launch System" (SLS), which will be used to fly people and cargo into deep space.

to the program SLS, which is based on components from the shuttle and supported mainly by politicians from countries that will benefit from the development, was given the nickname "missile to nowhere", and it was claimed that it was in fact a purposeless election bribe and had little chance of actually taking off.

But in the meantime, a plan SLS Progressing according to schedule and budget, and the first mission is planned for 2018. Like any program that spans decades, a continuation of a program SLS Depends on future politics. Is this flying election bribe our best chance to get to Mars?

For years, deep inside a huge, undisclosed NASA facility, teams have been staging fake space missions. This is not a theory Michoud) of NASA - the complex in New Orleans where the space agency built its biggest rockets for decades. After the last flight of the space shuttle, in 2011, the huge hangar-like buildings of Michaud were leased to Hollywood studios, for the production of science fiction films such as "Ender's Game" and others.

But recently, a growing group of engineers and other NASA employees are engaged in a new production at these facilities: a "sequel" to the golden age of manned space flight. Mishu returned to the rocket building business, and is now used as a factory to create the largest and most ambitious space vehicle ever built: the Space Launch System (Space launch system), often referred to by its initials SLS.

SLS It is the launch vehicle that will send, so NASA hopes, a team of astronauts from Cape Canaveral, Florida into space, on a journey of about a year to the surface of Mars. The rocket will also bring there the residences, the vehicles and the supplies needed for a few weeks, at least, of wandering in the rusty dust. This mission is 25 years away from us, but for now SLS could bring people to our moon and an asteroid, and send a robotic spacecraft to look for life on Europa, one of Jupiter's moons. This is a groundbreaking interplanetary project, one of the most daring projects NASA has ever undertaken.

So why do so many seem to hate him?

Already in 2016, engineers at NASA's Stennis Space Center in Mississippi intend to conduct an experiment on the SLS core stage, which is about 65 meters high.

replace the shuttle

After the resounding triumph of the Apollo lunar exploration program in the 60s and early 70s, the space shuttle was supposed to make access to low Earth orbit relatively cheap and routine. In practice, each flight cost an average of more than a billion dollars, there were only a few flights a year, and two ferries were lost in disasters. In 2004, a year after the space shuttle Columbia crashed during reentry and seven people died [including Israeli astronaut Ilan Ramon - editors], President George W. Bush ordered NASA to replace the shuttle with a more Apollo-like program that would return us to the moon and beyond Then to Mars.

This plan, called Constellation (Constellation), resulted in the design of two new missiles named Ares Ares, an aircraft for launching a crew, and a rocket that appears to be a giant version of the Saturn 5 (which was used to launch the Apollo spacecraft) whose purpose is to upload a payload. But by 2011, after spending more than nine billion dollars, all Constellation had produced was a crew cabin called Orion, built by Lockheed Martin, and a rocket that had only been launched once as part of a test. President Barack Obama canceled the program and directed NASA to return and focus efforts on the asteroid mission. The agency was asked to contact the private sector to receive crew and equipment launch services for the International Space Station (ISS).

Even so, many in Congress are fighting to continue building heavy payload rockets that could get humans to the moon and Mars. The resulting compromise is SLS - One large rocket, for both humans and cargo, which will rely mainly on the engines, accelerators and tanks of the space shuttle instead of the new technology designed for Ares. SLS He is actually cheap poison.

from the first moment stuck toSLS The perception that this is an invention of Congress, whose purpose is to preserve jobs at NASA and its major contractors. The editors of the Economist newspaper wrote, in December 2014, that "this is the first missile designed by a committee of politicians, instead of scientists and engineers." There were critics who called the SLS Under the name "Missile Jobs" or "Launch System for the Senate". And indeed, senators from the southern US, in whose states there are large facilities of NASA and its contractors, were the loudest supporters ofSLS in congress. Supporters include, for example, Senator Richard Shelby from Alabama, where about 6,000 people are employed in the project SLS at NASA's Marshall Space Flight Center in Huntsville, and Senator David Vitter from Louisiana, where the Michou facility is located. The Boeing Company, the main contractor for the core phase of the project, already employs about 1,500 people at this facility.

The missile development schedule

And the plan, like the missile, is very big. To-SLS There will be a lower core stage, powered by four engines RS-25 of the space shuttle, which use conventional fuel of liquid hydrogen and oxygen. A solid fuel rocket booster will be attached to each side of the core stage, which will provide the extra boost needed to launch the heavy rocket [see figure]. The second stage, which rides on top of the first, will take command at an altitude of about 50 kilometers to push the rocket into orbit, while the Orion crew compartment will be located at the top of the entire structure. The rocket, which is about 98 meters high, will be slightly shorter but more powerful than Saturn 5, which was responsible for all manned flights to the moon, and it will be able to carry a payload three times larger than that of the space shuttle. None of the missile parts are intended for reuse. In the next decade, upgrades toSLS will include more powerful engines and boosters. Tilly SLS Future ones, which will be able to bring a spacecraft to Mars, will include an even more powerful second stage, which will give them double the thrust of the first version.

Critics argue that by deciding to rely on components from the Space Shuttle, Congress ensured that the shuttle's major contractors would continue to profit. "Once again, Boeing is acting like a highwayman," said Peter Wilson, a senior analyst in defense research at the corporation. RAND. Others argue that the approach of the Space Shuttle cycle will reverse the SLS The rocket is a problematic Frankenstein, resurrected from parts of a dead plan sewn together. For example, the choice of shuttle boosters already led to the problem of gaps in the heat insulation.

The estimates as to the final cost of SLS Many and varied. According to NASA's public announcement, 18 billion dollars will be required until the first launch: ten billion for the rocket itself, six for the Orion crew compartment, and another two for the adaptation of Cape Canaveral for the launch of missiles SLS (Incidentally, Senator Bill Nelson of Florida is also an ardent supporter of SLS). But according to a leaked internal study, the cost will be more than 60 billion in the next ten years. Others claim that sending an expedition to Mars will cost up to a trillion dollars. NASA's stated goal is 500 million per launch, but others, who include in the calculation the costs of the entire program, reached up to 14 billion.

According to critics, the administration and the public will never translate their enthusiasm for space research into the hundreds of billions of dollars that the great missions of SLS. According to several analyses, including one internal study done at NASA, it is possible to reach deep space and Mars without a rocket for heavy loads. Some argue that it would be cheaper to rely on small rockets, such as the Delta-4 that has been used for the past decade to put satellites into orbit. With such rockets it will be possible to bring the fuel, the systems and the materials needed to build a large spacecraft into deep space to a low orbit, and build it there. If we still need a huge rocket, as many say, why not turn to the "new space"? company SpaceX, founded by Silicon Valley star Elon Musk, has already won contracts to launch NASA's highly regarded Falcon-9 rockets into orbit. "SLS offers only minor improvements to a technology developed 40 years ago,” says James Pora, president Space Frontier Foundation - a group whose goal is to promote space exploration. "NASA should tell private industry what types of payloads it wants to bring into deep space, offer a certain amount of money for the work and give companies like SpaceX build it.”

currently, SpaceX develops a missile in style SLS For heavy cargo, with 27 engines. It is also working on new, more powerful engines, which, if implemented, would allow the rocket to lift more thanSLS The biggest by design. Plus, all the major components of Tilly SpaceX are intended for reuse, compared to a system SLS which is entirely intended for one-time use.

The planning of a mission SLS applied despite the objections. The first flight, in 2018, will launch an unmanned Orion spacecraft beyond the moon. A second launch, the date of which has not yet been determined, will send a human crew a few years later on a similar trajectory, to a greater distance from Earth than humans have ever reached. What happens next depends largely on Congress and the president-elect, but the current plan is to send humans to an asteroid in the mid-2020s, and a manned mission to Mars in the 2030s.

The missile factory

NASA tests its largest rockets at the Stennis Space Center, nestled in a network of lakes, rivers, marshes and canals at the southern tip of the Mississippi. We wear safety helmets and vests, and Tom Byrd - who was the facility's deputy administrator on behalf of NASA until his retirement in January 2015 - tells me that there are three reasons for the facility's proximity to water. The activity at Stennis requires access to large rigs, expertise in assembly work of the type carried out on vessels, and an available way to cool huge blocks of metal, which are exposed to temperatures close to those on the surface of the sun.

Indeed, an experiment here is a huge structure of metal and concrete, somewhat reminiscent of a slice cut across the width of a large cargo ship. We climb up to one of the shafts, and on the way Byrd shows me a control room that would have fit a Soviet power plant from the 50s: mainly steam gauges and large, clunky dials. I ask why they haven't upgraded this to digital panels, and the answer turns out to be a show mantra SLS The whole thing: it took decades to overcome the enormous forces at work and the many malfunctions and make this thing work, so why bother with it?

Rounded sections are stacked on top of each other and welded together to form a tall cylinder, which will serve as a sheath for the SLS core stage. Inside this sheath there will be two tanks that will carry the fuel for the rocket, one of liquid hydrogen and one of liquid oxygen. At NASA's Mishu assembly facility, engineers are now building "safety" cylinders to test the strength of the parts.

From the front, however, I can see that Stannis is full and loaded with upgrades. Canals and roads are adapted to handle larger loads, and the test stands themselves are being strengthened and renovated, because a system SLS Put them under greater pressures than any missile that preceded it. "The forces that are produced here are greater than the forces that operate during the launch, because the missile in the test cannot escape from its own flames," explains Bird. In a test operation that lasts about nine minutes, thousands of hoses spray jets of water at high pressure against the walls of the pedestal - not for cooling, but to weaken the wild vibrations that could tear the pedestal apart. Even before a period SLS The construction of private buildings within a 13-kilometer radius of the tunnels was prohibited, because the sound waves from the experiments could collapse buildings on their own. motorized SLS will produce the most powerful rocket thrust ever.

Across the Mississippi-Louisiana border, a few hours by waterway (or in my case, 45 minutes by car), there is a Michou facility that I visited the next day. In contrast to the isolation of Stennis, the facility is located in the heart of an industrial area, on the outskirts of New Orleans. In some ways, it is a factory like any other factory, with welding stations, forklifts, cranes and parts boxes. Everything is just done on a much larger scale.

From the inside, a sparkling miche. On a tour of the factory, you see how it is filled, minute by minute, with new equipment: large robotic arms that can move at breakneck speed, platforms on wheels and crane-like devices that quickly bring parts weighing tens of tons from one station to another, and systems for organizing components that ensure that there is no missing or excess component in the engines , consisting of hundreds of thousands of parts. He who builds a machine as powerful as a rocket engine SLS Must have a very low tolerance for deviations in the assembly process. "If the parts tracking system told us that one of the tiny rings here was redundant, we would stop all work until the cause was discovered," says Patrick Whipps, one of NASA's Mishu administrators.

Many of the components that will be used here to build the missile originate from other vehicles. "We won't have many one-of-a-kind components inSLS,” says William Gerstenmeier, NASA administrator who leads the agency's manned space research. However, he adds, new manufacturing methods and tools should greatly reduce the production cost of these components. The upgrades in this area include a rotary friction welding machine, which is sized like a municipal water tower. Large aluminum alloy missile parts are inserted whole into this monster, and there special drills fuse two parts together. This is the largest machine of its kind in the world.

system SLS advancing in many ways beyond the technologies of the space shuttle. To analyze the air pressure on SLS When flying through the atmosphere, and other unsteady aerodynamic factors, NASA turns to the most advanced fluid dynamics analysis software available. Without this software, the engineers would have had to redesign the missile to withstand a greater load, to compensate for a much larger margin of error. Additionally, SLS It uses aviation systems and digital controllers that are based on advanced computer chips several generations older than those used in the space shuttles. This will allow the automatic control of the engines and the flight to react many times faster to sudden changes and dangerous situations.

The engines left over from the space shuttle program will be used in the first four flights of SLS, but starting in 2020 new versions of them will be required. For this, NASA uses machines that create thousands of turbine blades the size of a coin. The machines create the blades by laser welding metal powder into the correct shape, instead of engraving each blade individually. This will reduce the blade production time of an entire engine from one year to just one month. "We use computer control everywhere, to minimize labor costs and improve accuracy," says Gerstenmeier.

for SLS

when a plan SLS At full swing, it should produce at least two missiles a year, maybe even four. In the space launch world this is considered mass production. But if NASA fails to convince the public that it is worth building the SLS, the program will hang.

There are two main objections to the plan. One, 18 billion dollars is too much money for a rocket, and the second is the claim that to explore space scientifically one should concentrate on sending autonomous spacecraft and robots, not humans. These two objections can be approached as a matter of perspective. Eighteen billion isn't too much for the ability to send humans to another planet and back, and it's only a third more than it used to take to improve the flow of traffic in Boston through the underground traffic artery, the “"Big Dig. It is easy to argue that there are cheaper ways, but the success and safety achievements of NASA in the past set a high bar, and it is unlikely that the American public would want to save a few thousand from the federal budget in exchange for a higher risk of disaster.

As for robots vs. humans, it is often said that the scientific contribution of manned expeditions is greater than that of a research spacecraft or robotic vehicle, but the real justification for manned spaceflight is the advancement of the human race itself towards the settlement of new places.

To-SLS There are many fans, including current NASA executives, some space experts, and a growing part of the American public, who were excited in December 2014 at the sight of the perfect orbital flight of the Orion spacecraft, the spacecraft that will be placed atop rockets in the future SLSWhen they take off into deep space. The experts among these supporters can easily respond to reviews, individually.

Is it worth using smaller rockets to lift components and fuel for on-orbit assembly? According to Gerstenmeier's calculations, a manned mission to Mars would require 500 tons of material. editorial board SLS You could do this in four launches, but the best Delta-4 missiles would need at least 24 launches. Each such launch increases the program's risk a bit, Gerstenmeier argues, because the first minute of each mission has the greatest likelihood, relatively speaking, of serious malfunctions. This approach is also more vulnerable to delays, which will accumulate and affect the next launches in the queue. "We used this approach in the space shuttles to build the International Space Station," he says, "and it ended up taking decades for the mission."

However, he said, the biggest drawback of the multiple launch approach is the enormous amount of work required to assemble in space, while orbiting the Earth, the habitable structures, interplanetary vehicles and fuel tanks, given our limited experience with such complicated assembly tasks. "There will be many things to the friend," he says, "in fact it will be a production line in space. Some parts will inevitably not work as required, and it will be difficult to make repairs there. It adds a tremendous amount of complexity and risk.” Thanks to the diameter of SLS It will be possible to pack large payloads in a variety of shapes, up to ten meters in size, such as solar panels and antenna arrays, which in any other form of launch would have to be folded - a complex process in itself, which makes these parts more vulnerable to damage and malfunctions.

Another advantage of the method of launching heavy loads: it is possible to convert part of the thrust of the large rocket into speed, which will bring the spacecraft to its destination more quickly. This is a critical consideration for a manned flight to Mars, because exposure to cosmic radiation and the issue of supplies place unequivocal limits on the duration of the flight. Long-range robotic missions will also benefit from this, because in order to get the most out of follow-on missions, their planning must wait for information to arrive from the missions that preceded them. The raw power of SLS Allows missions to be sent into deep space using fuel, as opposed to the gravitational slingshot effect around planets used by missions such as Voyager and Galileo.

"SLS You will shorten the travel time to visit Europa's moon, from six years or more to two and a half," says Scott Heard, professor of aeronautics and astronautics at Stanford University. "This will allow us to carry out a great scientific mission." If you add to this the larger payload masses and the additional flexibility in packaging, you get a very convincing argument in favor of a missile for heavy loads. This also explains why both China and Russia are working on developing similar launchers SLS.

And the same is true for SpaceX. The "new space" domain encourages more transportation to the space station and back, and fewer rockets to deep space: beyond the handful of missions that NASA has prepared in general terms for SLS, there is no market for such missiles, nor is it planned to be. company SpaceX You will not be able to spread the development costs of a heavy payload missile over different commercial customers as you did with the smaller missiles. Scott Przynski, a former NASA astronaut who flew the space shuttle five times and now works at the University of Arizona, explains that without this advantage, SpaceX is in exactly the same position as Boeing, Lockheed-Martin and other traditional contractors of space projects. "These are excellent contractors," he explains, "and I don't see a significant difference in favor SpaceX. "

Relying on the familiar and the tested instead of innovation can be a recipe for failure in the automotive, cell phone or software market, but when it comes to flying a team of heroes into deep space on the wings of a poorly controlled explosion, a certain amount of conservatism is not necessarily a bad thing. Some of the early rockets of SpaceX Exploded or lost control, as always happens in the development of new tools. In October 2014, a crew member was killed in a test flight of a spacecraft developed by a company Virgin GalacticTo bring "space tourists" to sub-orbital altitude. This happened only three days after the explosion of an unmanned missile built by the private company Orbital Science and was supposed to arrive at the International Space Station.

These accidents are a reminder that even after decades of experience, the missile field is a difficult field, and there is a high risk of major disasters. This is one of the reasons why my head Inspiration Mars Foundation, a privately funded organization trying to advance a mission to Mars, join supporters atSLS After initially expressing a skeptical position. Other Mars experts agree. ",plan SLS It received criticism from the first day, as a 'missile to nowhere'," says the bard, "but today it has clear and justified tasks, and it's time for everyone to join in and help think, how to ensure that everything will be run for the best."

Escape speed

On a chilly night in January 2015, for 500 seconds, one of the huge engine test facilities at the Stennis Space Center turned into a ball of fire. It was the first test since 2009 of an engine R-25 of the space shuttle, and it was perfect. If the experiments continue to be successful, time will work in favor SLS. The longer the program lasts, assuming it meets the budget goals and schedules, the better it will prove its feasibility. In the first three years of its existence, the program has progressed quickly and smoothly, easily passed the design review stage, and is now entering initial production stages. For a brand new rocket designed for humans, that's a dizzying pace. Only a few glitches were discovered. The gaps in the insulation were the most serious fault, and they were also quickly repaired with a layer of adhesive.

In the coming years anything can happen, with new presidents and congresses. Says Joan Johnson-Fris, a professor at the US Naval War College, who specializes in space. A new general consensus may emerge in the US administration that we should leave Mars for now and concentrate on building a base closer to home. According to her, "Some people in Washington have a nostalgia for the moon that borders on crime." Others believe that NASA should forget about Mars and the Moon all together and focus on asteroids, not only because they might provide answers to important questions about the formation of the solar system, but also because we might be able to learn how to deflect or destroy an asteroid that approaches Earth.

However, the attraction to Mars is still strong, and it has intensified recently, as more and more people have realized that we can reach the red planet in our lifetime. "We all want to see the human race get there," Przezinski says. "Other tasks will only distract." He has certain misgivings about SLS: He doesn't think it's a problematic way to get to Mars, but worries that the price and schedule of the program will cause it to be abandoned before we get there.

In the meantime, there is noSLS Stops in sight. This fact alone, which is not valid for any other plan to reach Mars, may ensure the progress of the project. It may be based on the interests of members of Congress, it may lack the innovative fervor of alternative plans, but the signs are that it will go ahead as planned, and it has funding for the foreseeable future. This should be enough toSLS Will be the rocket that takes us to Mars. And if that happens, the review will soon be forgotten.


10 תגובות

  1. Voyager nuclear core for power generation thermocouples.
    It's not enough to propel a large spaceship even if you duplicate it a million times.
    How has Voyager moved on from the 70s? If you remember Newtonian mechanics in the absence of friction you move at equal speeds in a vacuum i.e. without propulsion. When you want to change direction, you activate the correcting and stopping engines. There is a difference between probing propulsion and propelling a large manned spacecraft. The modern concept speaks of movement at an acceleration up to a significant part of the speed of light, or less than that when driving an ion engine. You can laugh until tomorrow, but nuclear engines in submarines, in airplanes and in power plants need steam in my opinion to turn a turbine. A combined cycle in a gas turbine is when: the steam from cycle A is used while only increasing the temp for the second cycle and this results in a 26% improvement in efficiency. Here the heat source is the nuclear core, but the steam source cannot be regenerated. Therefore, it is necessary to solve the problem of reusing water with a very high efficiency or find another liquid, or another source of circulation. The one problem I present as a solution is that it doesn't make sense that as the road gets longer you have to take a train car of fuel with more and more cars, and the other: there is no need for a modern concept to turn off the engines, there is no lack of energy.

  2. As soon as the proof of the feasibility of returning an entire launcher to a soft landing arose, a few weeks ago, those who think linearly should have immediately stopped any investment in any other launch technology. Just what - the US Congress and Senate do not think linearly.

  3. "Without having water that will turn into steam and drive a turbine in space"


    If there is a hole in the ship's radiator, the water spills into the space and the ship falls.

  4. Yossi, how has Voyager 2 been moving in space for 30 years with a plutonium core without water to turn into steam and drive a turbine in space? The plutonium produces all heat...

  5. Construction of such a spacecraft is suitable for execution in space and of course the use of rockets - to transport the building blocks into space. Perhaps this is why the Americans are returning to missiles. They don't want to possibly transport modules to a spacecraft to Mars on Russian rockets.
    If they reach Mars first, and alone, they plant a flag of ownership. Both the journey to Mars and the settlement there will create a technological advantage for them for years.

  6. What is said below - I saw it on the NASA website: the method of escaping a body outside the fall range to Earth, turning off engines and arriving with engines off to Mars is outdated. It is suitable at most for escape from the earth. Recently, experiments were reported on propulsion with a laser at speeds close to the speed of light - as a means of propulsion for a large spaceship, and there are also ion engines that use electrons in a plasma state - as in lightning or a fluorescent lamp. A method that until today has worked for small probes like Philae. With these two methods, significant momentum generation from an increasing mass of fuel is converted into particles that move at the speed of light and their momentum is large due to the speed. The amount of fuel required for carrying is small. The second part of the puzzle in propulsion that does not consume an increasing volume of fuel with the distance, is, in my careful estimation, a nuclear reactor that will produce electric energy as in power plants on Earth and as in airplanes and submarines. From here you know how to raise to a high voltage and from here you know how to operate a laser on the one hand or an ion engine on the other hand. Here there was opposition due to the fear of irreversible pollution of the atmosphere due to a malfunction - a problem that I believe is solvable. The size of a nuclear reactor core for a submarine is an orange. The challenge here is an integrated cycle not only of the steam but of the water since, in a submarine and an aircraft carrier and a power plant - there is a source of water. In space there is no. These two methods will provide spacecraft with propulsion that will last over a decade, and without the urgent need to turn off engines and if it is a laser and the laser is successful in the experiments - with reaching Mars in a few days.

    Another principle that is required is in my opinion

Leave a Reply

Email will not be published. Required fields are marked *

This site uses Akismat to prevent spam messages. Click here to learn how your response data is processed.