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LLRV


The Lunar Landing Research Vehicle’s (LLRV), humorously referred to as “flying bedsteads,” were created by a predecessor of NASA’s Dryden Flight Research Center to study and analyze piloting techniques needed to fly and land the tiny Apollo Lunar Module in the moon’s airless environment. (Dryden was known as NASA’s Flight Research Center from 1959 to 1976.)

Success of the LLRVs led to the building of three Lunar Landing Training Vehicles (LLTVs) used by Apollo astronauts at the Manned Spacecraft Center, Houston, TX, predecessor of NASA’s Johnson Space Center.

Apollo 11 astronaut Neil Armstrong, — first human to step onto the moon’s surface, —said the mission would not have been successful without the type of simulation that resulted from the LLRVs and LLTVs.

When Apollo planning was underway in 1960, NASA was looking for a simulator to profile the descent to the moon’s surface. Three concepts were developed: an electronic simulator, a tethered device, and the ambitious Flight Research Center (FRC) contribution, a free-flying vehicle. All three became serious projects, but eventually the FRC’s LLRV became the most significant one. Hubert Drake is credited with originating the idea, while Donald Bellman and Gene Matranga were senior engineers on the project, with Bellman the project manager.

After conceptual planning and meetings with engineers from Bell Aerosystems, Buffalo, NY, a company with experience in vertical takeoff and landing (VTOL) aircraft, NASA issued Bell a $50,000 study contract in December 1961. Bell had independently conceived a similar, free-flying simulator, and out of this study came the NASA Headquarters’ endorsement of the LLRV concept, resulting in a $3.6 million production contract awarded to Bell on Feb. 1, 1963, for delivery of the first of two vehicles for flight studies at the FRC within 14 months.

Built of aluminum alloy trusses and shaped like a giant four-legged bedstead, the vehicle was to simulate a lunar landing profile. To do this, the LLRV had a General Electric CF-700-2V turbofan engine mounted vertically in a gimbal, with 4,200 lb of thrust. The engine got the vehicle up to the test altitude and was then throttled back to support five-sixths of the vehicle’s weight, simulating the reduced gravity of the moon. Two hydrogen peroxide lift rockets with thrust that could be varied from 100 to 500 lb handled the LLRV’s rate of descent and horizontal movement. Sixteen smaller hydrogen peroxide rockets, mounted in pairs, gave the pilot control in pitch, yaw, and roll. As safety backups on the LLRV, six 500-lb rockets could take over the lift function and stabilize the craft for a moment if the main jet engine failed. The pilot had a zero-zero ejection seat that would then lift him away to safety.

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Neutral Buoyancy Lab training facility

NASA - Neutral Buoyancy Lab

Neutral Buoyancy Laboratory at NASA is 202 feet (62m) long, 101 feet (31m) wide and 40 feet (12m) deep and is used to train personnel for spacewalks.

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Atlas V

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The Atlas V 401 Launch Vehicle is a part of the flight proven Atlas V 400/500 family that is being operated by United Launch Alliance. Atlas V rockets are flown since 2002 and have a near-perfect success rate (one flight was a partial failure, however the mission was catalogued as a success). The Vehicle is operated from Launch Complex 41 at the Cape Canaveral Air Force Station, Florida and Launch Complex 3-E at Vandenberg Air Force Base, California. The vehicle is assembled in Decatur, Alabama; Harlingen, Texas; San Diego, California; and at United Launch Alliance's headquarters near Denver, Colorado.

Atlas V 401 is the smallest of the Atlas V Launcher Family featuring no Solid Rocket Boosters and a 4.2-meter Payload Fairing. The 401 configuration has two stages, a Common Core Booster and a Centaur Upper Stage. Centaur can make multiple burns to deliver payloads to a variety of orbits including Low Earth Orbit, Geostationary Transfer Orbit and Geostationary Orbit,

Every Atlas V version has a three digit ID-Number:
First Digit: Payload Fairing diameter: 4XX - 4m Diameter; 5XX - 5.4m Diameter
Second Digit: Number of Solid Rocket Boosters (0-5)
Third Digit: Number of RL-10A Engines on Centaur (1 or 2)

Launch Vehicle Description

Atlas V 401 stands 58.3 meters tall and has a main diameter of 3.81 meters. With a liftoff mass of 334,500 Kilograms, it is the light-weight of the Atlas V Fleet as the 401 version does not feature any Solid Rocket Boosters. The Launcher uses the conventional Atlas V design with a Common Core Booster and a Centaur Upper Stage on top of it. Atlas V 401 features a 4.2-meter payload Fairing under which it can carry payloads of up to 10,470 Kilograms to Low Earth Orbit. Geostationary Transfer Orbit Capability is 4,750 Kilograms.

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Common Core Booster


The first Stage of the Atlas V 401 is an Atlas Common Core Booster that is 32.46 meters long and has a diameter of 3.81 meters. With an inert mass of 21,054 Kilograms, the Common Core booster can hold up to 284,089 Kilograms of Rocket Propellant-1 and Liquid Oxygen that are consumed by the single RD-180 Main Engine of the vehicle. RD-180 is being manufactured by NPO Energomash. It is a two-chamber staged combustion engine that provides 3,827 Kilonewtons of liftoff thrust and 4,152 Kilonewtons of vacuum thrust. RD-180 maintains a high-pressure staged combustion cycle employing an Oxygen-rich preburner. It runs with an oxidizer to fuel ratio of 2.72. The drawback of an oxygen-rich combustion is that high pressure, high temperature gaseous oxygen must be transported throughout the engine. The nominal chamber pressure is 267 bar. RD-180 is capable of being throttled from 50% to 100% of rated performance. The engine is based on the RD-170 engine that features four combustion chambers. First Stage control is accomplished by gimbaling the RD-180 nozzles by up to 8 degrees. Engine gimbaling is achieved via the vehicles hydraulics system. The first stage propellants are held inside aluminum isogrid tanks; tank pressurization is accomplished with high-pressure Helium that is stored in Helium Bottles on the Common Core Booster. Tank pressurization is computer-controlled. The Common Core Booster is equipped with a Flight Termination System that can be used to destroy the vehicle in the event of any major malfunction. Also, the CCB is outfitted with redundant Rate Gyros to acquire navigation data. Internal Batteries provide power during powered ascent and an independent telemetry system is utilized for data downlink. First stage separation is initiated by pyrotechnics and the core stage ignites eight retro rockets to drop away from the launcher.

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Interstage Adapter

The first and second stage of the Atlas V launch vehicle are connected by a Interstage Adapter (400-ISA) that is used to join the two stages of the vehicle that feature different diameters. It consists of a cylindrical section that is 3.05 meters in diameter and 2.52 meters in length as well as a conical section with a maximum diameter of 3.81 meters and a length of 1.61 meters. The composite structure is equipped with Aluminum Ring Frames (forward and aft) and weighs 947 Kilograms.

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Centaur Upper Stage

The Upper Stage of the Atlas V 401 is a single-engine Centaur Stage. Centaur is 3.05 meters in diameter and 12.68 meters in length with an inert mass of 2,243 Kilograms. Centaur is a cryogenic rocket stage using Liquid Hydrogen and Liquid Oxygen as propellants. A total of 20,830 Kilograms of propellants can be filled into the vehicle's pressure stabilized stainless steel tanks. The LOX and LH2 Tanks are separated by a common ellipsoidal bulkhead. Centaur is powered by a RL-10A-4-2 engine that is manufactured by Pratt & Whitney Rocketdyne and provides 99.2 Kilonewtons of thrust. The engine uses an expander cycle and operates at a chamber pressure of 39 bar. It is 3.53 meters in length, 1.53 meters in diameter and features a Nozzle Extension. RL-10 has a certified burn time of up to 740 seconds and can make multiple engine starts. It has a dry weight of 166 Kilograms and an expansion ratio of 84:1 achieving a thrust to weight ratio of 61:1. RL-10 can be gimbaled with a electromechanical system to provide vehicle control during powered flight. During Coast Phases, the vehicle's orientation is controlled by Centaur's Reaction Control System. Eight lateral 40-Newton Thrusters and four 27-Newton Thrusters are used for attitude control. The System uses Hydrazine propellant. The Centaur Upper Stage houses the Atlas V Flight and Guidance Computers that are capable of autonomously performing the mission controlling all aspects of the flight. The fault-tolerant inertial navigation unit is located on the Centaur forward equipment module.

In the aft section of the Centaur Upper stage is an ASA - Aft Stub Adapter that is 3.05 meters in diameter and 0.65 meter in length. ASA has a mass of 181.7 Kilograms and consists of a Aluminum Monocoque. It is separated by a Frangible Joint Assembly Separation System.

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Payload Adapter

Payload Adapters interface with the vehicle and the payload and are the only attachment point of the payload on the Launcher. They provide equipment needed for spacecraft separation and connections for communications between the Upper Stage and the Payload. The separation system can be based on either the traditional pyrotechnical-initiated bolt cutters/separation nuts or Low-Shock Marmon Type Clamp Band Separation System. For Atlas V, a Launch Vehicle Adapter interfaces with the SIP (Standard Interface Plane) of the Launcher and connects to the Standard Payload Adapter or custom-made adapters. Four off-the-shelf adapters are available to accommodate various payloads. Also, custom made fairings can be fitted atop the Launch Vehicle Adapters to accommodate a variety off different payload requirements.

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Payload Fairing

The Payload Fairing is positioned on top of the stacked vehicle and its integrated Payload. It protects the spacecraft against aerodynamic, thermal and acoustic environments that the vehicle experiences during atmospheric flight. When the launcher has left the atmosphere, the fairing is jettisoned by pyrotechnical initiated systems. Separating the fairing as early as possible increases launcher performance. The Atlas V 401 Rocket features fairings with a diameter of 4.2 meters. Three different fairing lengths are available: 12.0, 12.9 and 13.8 meters. Major sections of these payload fairings are the boattail, the cylindrical section, and the nose cone that is topped by a spherical cap. Both fairing and boattail sections consists of Aluminum Skin Stringers and Frame Clampshells. The fairing is separated by pyro bolts and spring jettison actuators that push the two halves away from each other. Payload Fairings are outfitted with acoustic panels, access doors and RF windows. Optional fairing hardware includes thermal shields and ECS doors. Also, the Payload Fairing is connected to a purge air system to ensure a controlled environment

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GRAIL


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Mission Overview

The GRAIL mission will place two spacecraft into the same orbit around the Moon. As they fly over areas of greater and lesser gravity, caused both by visible features such as mountains and craters and by masses hidden beneath the lunar surface, they will move slightly toward and away from each other. An instrument aboard each spacecraft will measure the changes in their relative velocity very precisely, and scientists will translate this information into a high-resolution map of the Moon's gravitational field.
This gravity-measuring technique is essentially the same as that of the Gravity Recovery And Climate Experiment (GRACE), which has been mapping Earth's gravity since 2002.

Objectives

GRAIL's engineering objectives are to enable the science objectives of mapping lunar gravity and using that information to increase understanding of the Moon's interior and thermal history. Getting the two spacecraft where they need to be, when they need to be there, requires an extremely challenging set of maneuvers never before carried out in solar system exploration missions.

Mission design


The two GRAIL spacecraft will be launched together and then will fly similar but separate trajectories to the Moon after separation from the launch vehicle, taking about 3 to 4 months to get there. They will spend about 2 months reshaping and merging their orbits until one spacecraft is following the other in the same low-altitude, near-circular, near-polar orbit, and they begin formation-flying. The next 82 days will constitute the science phase, during which the spacecraft will map the Moon's gravitational field.

Spacecraft and payload

The two GRAIL spacecraft are near-twins, each about the size of a washing machine, with minor differences resulting from the need for one specific spacecraft (GRAIL-A) to follow the other (GRAIL-B) as they circle the Moon.

The science payload on each spacecraft is the Lunar Gravity Ranging System, which will measure changes in the distance between the two spacecraft down to a few microns - about the diameter of a red blood cell. Each spacecraft will also carry a set of cameras for MoonKAM, marking the first time a NASA planetary mission has carried instruments expressly for an education and public outreach project.

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From which Apollo mission is this pic?

Honestly, I'm not sure, it's probably from Apollo 17 though. I pluck the pic from NASA.gov, I'll track down its info for you.

Vandenburg AFB - these are military launches

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Hubble Reveals Fascinating and Chaotic Properties of Pluto's Moons

Hubble Reveals Fascinating and Chaotic Properties of Pluto’s Moons « AmericaSpace

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Using a set of archival data that were taken with the Hubble Space Telescope. astronomers were able to conduct the most comprehensive and detailed study to date of Pluto’s four smaller moons, Nix, Hydra, Kerberos and Styx. This artist’s illustration shows the scale and comparative brightness of these small satellites, as discovered by Hubble over the past several years. Pluto’s binary companion, Charon, is placed at the bottom for scale. Two of the moons (Nix and Hydra), are highly oblate. The reflectivity among the moons varies from dark charcoal to the brightness of white sand. Hubble cannot resolve surface features on the moons and so the cratered textures seen here are purely for illustration purposes.

Some of the best things come in small packages, as the saying goes, and that certainly holds true for Pluto and its system of moons. A new comprehensive analysis of archival observations of the Pluto system, undertaken with NASA’s Hubble Space Telescope during the last decade, have revealed the dwarf planet and its moons comprise a fascinating mini planetary system of their own which is entirely unique in the Sun’s planetary family, while also providing many important insights not only about the physical processes that take place in our own Solar System, but about those that govern extrasolar ones as well.

Discovered in 1930 by American astronomer Clyde Tombaugh, Pluto was originally thought to be the long-sought-for hypothetical massive Planet X in the outskirts of the Solar System, which astronomers had extensively searched for many decades during the mid-19th and early 20th century. As telescopes were becoming steadily more powerful in the years following the discovery of Pluto, it was eventually determined that the latter was in reality just a diminutive world no more than 2,300 km across, which was also found in the late 1970s to be accompanied by a comparatively large moon named Charon that had a diameter of approximately 1,200 km, almost half that of Pluto. The Hubble Space Telescope completed the picture of Pluto’s moon system by detecting an additional four much smaller satellites around the planet, Nix and Hydra in 2005, as well as Kerberos and Styx in 2011 and 2012 respectively.

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A composite image from the Hubble Space Telescope, showing Pluto’s entire system of known moons. The four smaller moons, Nix, Hydra, Kerberos and Styx, were imaged with 1000x longer exposure times because they are far dimmer than Pluto and Charon.

One of the more interesting aspects of Pluto and Charon is the fact that, due to their comparative sizes and close distance between them, both objects orbit their common center of mass thus comprising a double-planet system with the rest of the smaller moons revolving around the latter, essentially making Pluto and Charon the only binary planet in the entire Solar System, with the exception of the Earth and the Moon, whose own center of mass lies within our home planet. Ever since Pluto’s smaller moons were discovered, astronomers have been actively studying their fascinating orbital dynamics with the help of Hubble, which is currently the only space telescope capable of observing their motions from a distance of more than 5 billion km away. Now, in a new paper which is being published today (June 4) in the journal Nature, planetary astronomer Mark Showalter, a senior research scientist at the SETI Institute in California and co-discoverer of Kerberos and Styx, and Dr. Douglas Hamilton, a professor of astronomy at the University of Maryland, present the results of a comprehensive four-year study of the entire Pluto system, based on archival Hubble data collected by the orbiting observatory between 2005 and 2012. The analysis of the data revealed quite unexpected and fascinating findings that were contrary to previous theoretical predictions, including the extremely small surface brightness of Kerberos compared to that of other satellites in the Pluto system, as well as the chaotic nature of the orbital revolutions of Nix and Hydra.

More specifically, the researchers studied the brightness variations of Pluto’s moons throughout their entire orbital periods, under the assumption that the latter were locked in synchronous orbits around Pluto, as is the case with Charon and most of the other moons in the Solar System, which causes them to constantly point one hemisphere toward their respective planets. Since Pluto’s smaller moons are irregularly shaped due to their very small sizes, the researchers expected that their brightness would change in a predictable manner during their orbital revolutions around Pluto, if they were indeed locked in such a synchronous rotation. Yet what Showalter and Hamilton found to their great surprise was there appeared to be no correlation whatsoever between the moons’ brightness and their position along their orbits, indicating that Nix and Hydra definitely weren’t locked in a synchronous rotation around Pluto. After running a series of numerical simulations based on these observations, the researchers soon realised that these orbital wobbles of Nix and Hydra were the result of the irregular gravity field they were embedded in, which was caused by the Pluto-Charon binary planet system itself, leading the smaller moons to exhibit a fundamentally chaotic and unpredictable orbital spins over longer periods.

“[Pluto and Charon] whirl around each other rapidly, causing the gravitational forces that they exert on the small nearby moons to change constantly,” says Hamilton. “Being subject to such varying gravitational forces makes the rotation of Pluto’s moons very unpredictable. The chaos in their rotation is further accentuated by the fact that these moons are not neat and round, but are actually shaped like rugby balls! Like good children, our Moon and most others keep one face focused attentively on their parent planet. What we’ve learned is that Pluto’s moons are more like ornery teenagers who refuse to follow the rules.”

These chaotic orbital dynamics elevate Pluto and its moons from the status of just a set of inconspicuous lesser bodies in the outskirts of the Solar System, to that of a very unique and fascinating mini planetary system in its own right. “Prior to the Hubble observations, nobody appreciated the intricate dynamics of the Pluto system,” adds Showalter. “Our research provides important new constraints on the sequence of events that led to the formation of the system.”

As for the results of these strange orbital dynamics, the view from Nix and Hydra would be unlike anything seen anywhere else in the Solar System. “You would literally not know if the Sun is coming up tomorrow,” explained Showalter during the presentation of the study’s results at a NASA teleconference that was held yesterday at the agency’s headquarters, in Washington, D.C. “For that matter, the Sun might rise in the west and set in the east. In fact, if you had a real estate on the north pole of Nix you might suddenly discover one day that you’re on the south pole instead. This is the environment we’re talking about for Nix and Hydra and we believe for the other moons as well, although we don’t [currently] have the data to show that.”

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Years-worth of studies with the Hubble Space Telescope have revealed that the Jupiter and Pluto systems have much in common regarding their structure and that the moons of Pluto are not small in the relative sense. Seen at left is a montage of Jupiter and its four large Galilean moons as photographed by NASA’s Voyager 1 spacecraft in 1979. Scaling Pluto and its moons up to the size of Jupiter creates a system very similar to the Jupiter system we already know (seen at right), with the exception of Charon, which is the primary driver of the chaos that has been observed with Hubble in the Pluto system.

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One key question that naturally arose out of these findings is how the Pluto system is kept stable over long periods of time without having its moons fly apart or collide with one another due to these orbital instabilities. The answer came when Showalter and Hamilton determined through their numerical simulations that all four moons are being kept in a surprising near-3:4:5:6 orbital resonance relative to Charon, while Nix, Styx, and Hydra are tied together in a near-1:2:3 three-body orbital resonance, where for each orbital revolution that Nix makes around Pluto, Styx makes two and Hydra makes three, similar to the near-resonances that are shared between Io, Europa, and Ganymede around Jupiter. “What this relationship does, is to prevent these moons from ever getting very close together all at the same time and that helps to stabilise the system,” explains Hamilton. “The resonant relationship between Nix, Styx and Hydra makes their orbits more regular and predictable, which prevents them from crashing into one another. This is one reason why tiny Pluto is able to have so many moons.”

The brightness variation measurements which led the researchers to study orbital dynamics of Pluto’s smaller moons allowed them to make another important discovery about the latter as well. More specifically, by studying the light curves of the smaller moons, Showalter and Hamilton were able to determine that Nix and Hydra both shared an albedo (surface reflectivity) of approximately 40 percent, similar to that of Charon, which indicated they are all fairly bright objects. Yet the albedo of Kerberos, whose orbit lies between that of Nix and Hydra, was found to be no greater than 4 percent, indicating it was a surprisingly dark object. Such surface darkening has been observed on various Solar System moons as well and is thought to result from meteorite dust debris that covers the moon’s surfaces over time. But the fact that the surfaces of the neighboring moons Nix and Hydra are so bright presents an unexpected enigma for astronomers, who had theorised that due to the close locations, the surfaces of all three moons should have been coated with dark debris material in similar proportion. “Think of a charcoal briquette orbiting between two dirty snowballs,” says Showalter. “Now, that’s a very, very strange result.”

A numerical simulation of the orientation of Nix as seen from the center of the Pluto system. It has been sped up so that one orbit of Nix around Pluto takes 2 seconds instead of the actual 25 days. Large wobbles are visible, and occasionally the pole flips over. This tumbling behavior meets the formal definition of chaos; the orientation of Nix is fundamentally unpredictable. Video Credit: STScI and Mark Showalter, SETI Institute

The overall findings to come from this new study by Showalter and Hamilton not only help to shed more light to the intricate dynamics of the Pluto system, but they can help astronomers gain important insights to the inner workings of extrasolar planetary systems as well. “What if Pluto were the size of our Sun? Then Charon would be a small [neighboring] star, forming a double star system,” commented during yesterday’s teleconference Heidi Hammel, a planetary astronomer and executive vice president of the Association of Universities for Research in Astronomy in Washington, D.C. “And we actually know from many telescopic searches that double stars are ubiquitous throughout our galaxy. And thanks to NASA’s Kepler spacecraft and many other telescopic searches , we know that many of these double stars do host planets, so Pluto and its complex and chaotic moon system can provide a direct analog to these planetary systems we see around other stars … Everything we have learned about the Pluto system, we actually learned without resolving these moons – they are just points of light. And we’re developing now the capabilities in astronomy, of seeing exoplanets around other stars as points of light separated from their host stars … So, thanks to this very interesting moon system of Pluto, we will one day be able to apply the same kinds of tools and techniques for probing those moons, to study exoplanetary systems around other stars and learn about the characteristics of those planets in that kind of detail that you are hearing [about Pluto] today. And all of this is grounded in our knowledge of these four tiny moons travelling in their chaotic orbits and chaotic rotations around the distant around the binary Pluto and Charon system, as seen with the Hubble Space Telescope.”

“We are learning chaos may be a common trait of binary [exoplanetary] systems,” adds Hamilton. “It might even have consequences for life on planets if it is found in such systems.”

Despite its superior capabilities, Hubble can only reveal so much about Pluto and its menagerie of fascinating and chaotic moons. More detailed observations are bound to come just 40 days from now, when NASA’s New Horizons spacecraft will speed through the Pluto system on 14 July, for its eagerly anticipated and historic flyby of this distant realm of the Solar System. “Hubble has provided a new view of Pluto and its moons revealing a cosmic dance with a chaotic rhythm,” says John Grunsfeld, associate administrator of NASA’s Science Mission Directorate in Washington, D.C. “When the New Horizons spacecraft flies through the Pluto system in July we’ll get a chance to see what these moons look like up close and personal.”

And if there ever was a need to come up with a reason to make the upcoming New Horizons flyby more interesting than it already is, then the promise of a more detailed view of exoplanetary systems in the vast reaches of our Milky Way galaxy would be a fine reason indeed.
 
SLS Main Engine Test Fire Round Two Ignites With 450-Second Burn at Stennis Space Center

SLS Main Engine Test Fire Round Two Ignites With 450-Second Burn at Stennis Space Center « AmericaSpace

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NASA’s Space Launch System (SLS) rocket is quickly manifesting into reality. Its solid rocket booster was test fired just a couple months ago, NASA’s Pegasus transport barge is being made larger to support moving the colossal rocket, acoustic sound-suppression testing is occurring, F-18 Hornet fighter jets are carrying out flight tests for SLS flight software development, test stands are being built or modified, KSC’s iconic Vehicle Assembly Building (VAB) is being upgraded to support SLS, launch pad 39B is being prepared, the rocket’s Mobile Launch Platform (MLP) and Crawler Transporter are being prepared, and both qualification and flight hardware for the first SLS vehicle itself are being constructed for an inaugural 2018 launch on the Exploration Mission-1 (EM-1) flight with NASA’s Orion deep-space multi-purpose crew capsule (which itself conducted its first flight test last December).

The latest happening on America’s “Journey to Mars” occurred yesterday (May 28, 2015), as the space agency conducted a second test fire of the RS-25 main engine that will help power the 320-foot-tall SLS off its launch pad 39B at Kennedy Space Center, where astronauts will ascend from to escape Earth’s orbit for destinations farther from home than any human in history has ever been.

The 450-second test fire, carried out by development engine [HASHTAG]#0525[/HASHTAG] on the historic A-1 test stand, went off without issue—something that has come to be expected of the RS-25 engine, which formerly powered NASA’s now-retired space shuttle fleet uphill on 135 missions. The RS-25 was the first reusable rocket engine in history, as well as being one of the most tested large rocket engines ever made, having conducted more than 3,000 starts and over one million seconds (nearly 280 hours) of total ground test and flight firing time over the course of NASA’s 30-year space shuttle program.

The engines proved their worth time and time again, but the RS-25 now requires several modifications to meet the giant rocket’s enormous thrust requirements.

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Yesterday’s test fire will provide engineers with critical data on the engine’s new state-of-the-art controller unit—the “brain” of the engine, which allows communication between the vehicle and the engine itself, relaying commands to the engine and transmitting data back to the vehicle. The new controller also provides closed-loop management of the engine by regulating the thrust and fuel mixture ratio while monitoring the engine’s health and status, thanks to updated hardware and software configured to operate with the new SLS avionics architecture.

“We’ve made modifications to the RS-25 to meet SLS specifications and will analyze and test a variety of conditions during the hot fire series,” said Steve Wofford after the first test fire earlier this year, manager of the SLS Liquid Engines Office at NASA’s Marshall Space Flight Center in Huntsville, Ala., where the SLS Program is managed. “The engines for SLS will encounter colder liquid oxygen temperatures than shuttle; greater inlet pressure due to the taller core stage liquid oxygen tank and higher vehicle acceleration; and more nozzle heating due to the four-engine configuration and their position in-plane with the SLS booster exhaust nozzles.”

For shuttle flights the engines pushed 491,000 pounds vacuum thrust during launch—each—and shuttle required three to fly, but for SLS the power level was increased to 512,000 pounds vacuum thrust per engine, and the SLS will require four to help launch the massive rocket and its payloads with a 70-metric-ton (77-ton) lift capacity that the initial SLS configuration promises.

The pace for SLS engine testing at Stennis is expected to pick up this summer. After the first test fire on Jan. 9, upgrades were needed on the A-1 test stand’s high pressure industrial water system, which provides cool water for the test stand during a hot-fire engine run. Engine 0525 will carry out a total of seven test fires in this first series of tests and will fire for a grand total of 3,500 seconds, followed by another 10 test fires with another development engine, which will be put through its paces for a grand total of 4,500 seconds.

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To put the power of the Aerojet Rocketdyne-built RS-25 engines into perspective, consider this:

  • The fuel turbine on the RS-25’s high-pressure fuel turbopump is so powerful that if it were spinning an electrical generator instead of a pump, it could power 11 locomotives; 1,315 Toyota Prius cars; 1,231,519 iPads; lighting for 430 Major League baseball stadiums; or 9,844 miles of residential street lights—all the street lights in Chicago, Los Angeles, or New York City.
  • Pressure within the RS-25 is equivalent to the pressure a submarine experiences three miles beneath the ocean.
  • The four RS-25 engines on the SLS launch vehicle gobble propellant at the rate of 1,500 gallons per second. That’s enough to drain an average family-sized swimming pool in 60 seconds.
The next RS-25 test fire is currently scheduled to take place sometime between June 10-12.


Four previously-flown RS-25 engines will be attached to the first SLS core stage, which will be manufactured at Michoud Assembly Facility in New Orleans, and test fired together atop the B-2 test stand at Stennis as a stage before being approved for the first SLS launch, planned for late 2018.

NASA currently has 16 RS-25 engines in their SLS inventory, 14 of which are veterans of numerous space shuttle missions. Aerojet Rocketdyne just recently finished assembly of the sixteenth engine, engine 2063, one of the space agency’s two “rookie” RS-25’s. It will be one of four RS-25 engines that will be employed to power the SLS Exploration Mission-2 (EM-2), the second SLS launch currently targeted for the year 2021.

“There is nothing in the world that compares to this engine,” said Jim Paulsen, vice president of Program Execution Advanced Space & Launch Programs Aerojet Rocketdyne. “It is great that we are able to adapt this advanced engine for what will be the world’s most powerful rocket to usher in a new space age.”

The SLS program also kicked off its Critical Design Review (CDR) earlier this month at NASA’s Marshall Space Flight Center in Huntsville, Ala., which demonstrates that the SLS design meets all system requirements with acceptable risk and accomplishes that within cost and schedule constraints. The CDR proves that the rocket should continue with full-scale production, assembly, integration, and testing, and that the program is ready to begin the next major review covering design certification. The SLS CDR is expected to be completed by late-July.

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Acoustic Testing


 
New Oxygen Preburner Firings a Major Step Toward Rekindling US Hydrocarbon Rocket Engine Leadership

New Oxygen Preburner Firings a Major Step Toward Rekindling US Hydrocarbon Rocket Engine Leadership « AmericaSpace

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The U.S. Air Force (USAF) and its rocket engine contractor Aerojet Rocketdyne (AJRD) have achieved a major milestone toward a new U.S. state-of-the-art capability to develop powerful next generation hydrocarbon rocket engines. The achievement involves completion of the first in a series of hot-fire tests on a sub-scale oxygen-rich pre-burner, built by ARJD for the USAF’s Hydrocarbon Boost Technology Demonstrator (HBTD) program.

While America once led the world in kerosene and RP-fueled rocket engine technology, the U.S. has lost such hydrocarbon rocket infrastructure and lags behind Russia, specifically with the Energomash RP-1/liquid oxygen RD-180 that powers the proven and reliable United Launch Alliance (ULA) Atlas-V.

There are two major rocket engine cycles. One is called a “gas generator cycle,” where gases used to drive an engine’s turbopump are exhausted by the pump, giving a somewhat ragged looking rocket plume due to this flaming exhaust vented beside more distinct rocket nozzle plumes.

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As this diagram shows, the oxygen-hydrogen powered Space Shuttle RS-25 Main Engine has pre burners, but no powerful U.S. hydrocarbon engine does, a deficiency the USAF program seeks to correct.

The other cycle is the “staged combustion cycle,” where a share of the propellant—be it kerosene or oxygen or both—is first burned in a pre-burner. The resulting hot gas is first used to power the engine’s turbines and pumps, then, instead of being dumped as with the gas generator cycle, that exhausted gas is injected into the main combustion chamber, along with the rest of the propellant to generate powerful thrust. The two stages that make up the staged cycle propulsion are from the pre-burner stage, then combustion chamber stage.

A key advantage of staged combustion is that it gives an abundance of power, which permits very high chamber pressures and the use of high expansion ratio nozzles. These nozzles give better efficiencies at low altitude critical to the flight in the moments after liftoff.

The disadvantages of staged cycle engines include harsh turbine conditions, exotic plumbing to carry the hot gases, and complicated feedback and control. The U.S. mastered all of these for the Space Shuttle RS-25 Main Engine design that used cryogenic oxygen and hydrogen propellants and a preburner for each.

According to Aerojet Rocketdyne an oxidizer preburner combusts hydrogen and oxygen at an extremely fuel-rich mixture ratio, and thus supplies hot gas at variable rates to drive the engines high-pressure oxidizer turbo pump. The operating level of the oxidizer preburner is controlled by regulating the oxidizer flowrate by means of the oxidizer preburner oxidizer valve. Welding the injector into the top of the engine’s Hot Gas Manifold forms the combustion area and places it immediately above the pump turbine.

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“Throughout the sub-scale fabrication and facility checkouts, we’ve documented a number of lessons learned that have directly influenced a full-scale pre-burner design. We are looking forward to what more we will learn during the hot-fire test series,” said Joe Burnett, program manager of the Hydrocarbon Boost Technology Demonstrator program at Aerojet Rocketdyne.

AJRD states, “In coming months, multiple injector configurations will be tested to evaluate the performance and stability parameters that are critical for a high-performance, high-reliability liquid oxygen/kerosene rocket engine.”

According to the USAF, typical parameters for an oxygen preburner are:

  • Mixture: A full 100 percent of the engine’s oxygen flow will be be mixed with 4 percent of the RP flow.
  • Losses: There are no secondary gas flow losses en route to the thrust chamber.
  • Performance: The resulting high pump and turbine speeds will equate to higher combustion chamber pressures producing higher thrust.
The sub-scale test series will be used to aid the design and development of the full-scale pre-burner and engine development. An oxygen-rich pre-burner is one of the enabling technologies of the Oxygen-Rich Staged Combustion (ORSC) cycle needed to provide high thrust-to-weight and performance regardless of hydrocarbon fuel type, both USAF and AJRD documentation says.

Under program direction of the Air Force Research Laboratory (AFRL), Aerojet Rocketdyne is designing, developing, and testing the HBTD engine. Its technologies are directed at achieving the goals of the Rocket Propulsion for the 21st Century (RP21) program, formally known as Integrated High Payoff Rocket Propulsion Technology, or IHPRPT.

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Russian RD-180 being checked out near Moscow, Russia. It and the four-chamber RD-170 are only large hydrocarbon engines given more thrust with preburners.

Designed to generate 250,000 pounds of thrust, the engine technology uses liquid oxygen and liquid kerosene (RP-2) in the first U.S.-developed demonstration of the ORSC cycle. It has been designed as a re-usable engine system, capable of powering up to 100 flights, and features high-performance long-life technologies and modern materials, said the Air Force and its contractor.

Burn-resistant, high-strength alloys, manufactured using novel technologies, will be used throughout the engine. Manufacturing parameters of some of the alloys have been developed under a joint effort with the Air Force, known as the Metals Affordability Initiative or MAI, said AJRD.

These advanced technologies will be matured sufficiently throughout the program to support the next generation of expendable launch system development efforts. It also will help in the rapid turn-around usability for future re-usable launch systems.

The data from this test effort will be used by other Air Force development programs such as the Advanced Liquid Rocket Engine Stability Tools program (ALREST) to further advance the state-of-the-art capabilities in combustion stability modeling.

Previously, Aerojet Rocketdyne designed and supplied the oxygen-rich and fuel-rich pre-burners for the Air Force’s Integrated Powerhead Device (IPD) demonstration engine, the world’s first full-flow staged combustion rocket engine.

“The design lessons learned and test approach from the IPD pre-burners have been leveraged for the HBTD pre-burner architecture,” Aerojet Rocketdyne believes.
 
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Flying (Mostly) Friendly Skies: Northrop Grumman Developing Airplane to Cruise Atmosphere of Venus

Flying (Mostly) Friendly Skies: Northrop Grumman Developing Airplane to Cruise Atmosphere of Venus « AmericaSpace

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With so much attention now on the rovers and spacecraft at Mars, Saturn, Ceres, comet 67P/Churyumov-Gerasimenko, and, soon, Pluto, it may seem like Earth’s closest planetary neighbor Venus has been forgotten again. But no, Venus is still very much on the minds of researchers who are busy developing a concept airplane which could cruise for years in the hellish planet’s atmosphere.

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Prototype wing built for the Rapid Eye drone concept. A much larger version will be used for VAMP.

The aircraft design, called the Venus Atmospheric Maneuverable Platform (VAMP), is being developed by Northrop Grumman as an entry in NASA’s next New Frontiers planetary science competition. It will compete for $1 billion in NASA funding, possibly as early as Oct. 1, 2015. The winning mission will need to be ready for launch by 2021, according to Jim Green, NASA’s director of planetary science. VAMP will have to compete against other high-priority New Frontiers destinations such as the lunar poles, Jupiter’s moon Io, Saturn, and trojan asteroids. It is also part of Northrop Grumman’s 2015 Challenge: Lighter Than Air Competition (for the High School Innovation Challenge):

“Northrop Grumman is currently performing research on an unmanned concept vehicle called the Venus Atmospheric Maneuverable Platform (VAMP). VAMP is a very large, but incredibly light inflatable aircraft that integrates Northrop Grumman’s diverse capabilities in deployables, unmanned aircraft, semi-buoyant vehicles, and space exploration into a unique planetary exploration vehicle. Using a combination of powered flight and passive floating, VAMP will be capable of staying aloft for long periods of time collecting vital data about Venus and its atmosphere. After reaching Venus’ orbit aboard a carrier spacecraft, VAMP will deploy and inflate with a buoyant gas. With a wingspan of approximately 150 feet and 100 pounds of payload carrying capability, VAMP will be able to cruise through the Venus skies at altitudes between 31 and 43 miles (55 and 70 kilometers) for several months to a year.”

This year’s challenge uses the VAMP program as inspiration to design and build an airship with agile maneuverability, speed, endurance, and payload-carrying capability.

VAMP will also need to clear some engineering hurdles before that can happen. Nothing like it has ever flown before, on Earth or elsewhere. The closest thing is a pair of ultra-light wings built in 2008 and 2010 by Northrop’s partner L.Garde Inc. of Tustin, Calif., for a defunct Defense Advanced Research Projects Agency initiative called Rapid Eye, which were meant to be collapsible, rocket-deployed drones which could arrive for reconnaissance duties anywhere on Earth an hour after launch. The project was cancelled in 2010. While the wings for Rapid Eye were only 2 meters long, the wings for VAMP would need to be much larger, at 55 meters across.

Right now, the technology is rated a three on NASA’s Technology Readiness Level (TRL) scale, a “proof of concept” level. Once “flight proven,” those technologies are rated at TRL 9. According to Ron Polidan, Northrop’s Redondo, California-based chief architect of civil systems, “The one nice thing for New Frontiers is they would like you to be at TRL 6 by the preliminary design review, so that gives you a few more years.”

“We have a list of a about a dozen instruments that people have proposed we fly… and we convened a science advisory board to help us define both the instruments and where the aircraft needs to be to take the needed measurements,” Polidan said.

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VAMP would fly autonomously, carrying a variety of scientific instruments to study the Venusian environment; there is still a lot about Venus which scientists don’t understand. While the surface of Venus is extremely hot and inhospitable, higher altitudes are more benign, making the aircraft concept feasible. An airplane could fly the (mostly) friendly skies of Venus with little problem.

“Surviving on the surface for any longer than four hours and getting high-resolution data is a challenge,” said Constantine Tsang, a research scientist at the Southwest Research Institute in Boulder, Colo. She is also a member of Northrop’s all-volunteer VAMP science advisory board.

“Not a whole lot different than flying on Earth,” Polidan said. “If you wanna just sprinkle sulfuric acid all over yourself, that would be more like what you have on Venus.”

The acidity at altitude, unlike the unforgiving surface conditions, “we can handle now with a lot of the materials we have,” Tsang added.

A big question is: How much science VAMP could do, being an airborne craft instead of a surface lander or rover? The answer is not everything scientists might want, but still a lot.

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“VAMP could not answer all key questions,” said Robert Herrick, a University of Alaska-based surface specialist. “Primarily, the platform would be for atmospheric science.” Herrick chaired the committee in charge of the NASA-chartered Venus Exploration Analysis Group’s (VEXAG) 2014 science roadmap. Or as VEXAG member Kevin McGouldrick, a research scientist with the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder, noted, VAMP could answer all of the big atmospheric questions, half the questions about surface-atmosphere interactions, and perhaps some of the Venusian surface questions by “remotely sensing the surface.”

According to Tsang, VAMP could remotely study the surface using nadir-facing infrared sensors.

“That would tell you whether the surface is basaltic, has igneous rocks, things like that,” Tsang said. “But you couldn’t do isotopic ratio measurements of minerals, for example, that rovers could be doing.”

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Having a functioning lander in Venus’ brutal surface conditions is difficult enough, never mind a rover. That may be a while in the future yet. The airplane concept would seem to be a good way to study both Venus’ atmosphere and surface, at least for the near future. Venus is thought to have been more Earth-like earlier in its history. VAMP could help answer the question of how it became such an inhospitable place since then.

The design concept might also be well-suited to explore other places in the Solar System such as Saturn’s moon Titan, and similar ideas are also now being proposed. A Titan airplane would provide unprecedented views of Titan’s methane seas, lakes, and rivers, as well as study what clues the moon might offer in terms of astrobiology. Scientists consider Titan to be similar in many ways to the early Earth, when life was just starting to gain a foothold.

If it wins the competition, VAMP could provide a unique opportunity to study our nearest planetary neighbor up close in a way not possible before, and help scientists understand why “Earth’s twin gone bad” changed the way that it did over time.
 

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