Aeronautics Archives

September 12, 2016September 17, 2016 by David Dickinson

Bloostar: Launching Satellites via Balloon

AistechSat-1 — The recent flight of Aistechsat-1. Image credit: Zero2Infinity.

Is there a better way to get to space? Current traditional methods using expendable rockets launching from the surface of the Earth are terribly inefficient. About 90% of the bulk and mass of what you see on the launch pad is expended in the first few minutes of the mission, just getting the tiny payload above the murk of Earth’s atmosphere and out of the planet’s gravity well.

One idea that’s been out there for a while is to loft a launch platform into the upper atmosphere, and simply start from there. One Spanish-based company named Zero2infinity plans to do just that.

Recently, on May 20^th, 2016, Zero2infinity lofted Aistech’s first satellite into the upper atmosphere, aboard its Sub-Orbital Platform in Near Space balloon system. Zero2infinity uses these Near Space balloons to carry client payloads up above 99% of the Earth’s atmosphere. This is a cheap and effective way to get payloads into a very space-like environment.

These near Space Balloon platforms typically reach an altitude of 28 kilometres (17 miles) above the surface of the Earth. For reference, the Armstrong Line (where the boiling point of water equals human body temperature) starts 18 kilometers up, and the Kármán line — the internationally recognized boundary where space begins — starts at an altitude of 100 kilometers, or 62 miles up.

Most satellites in Low Earth Orbit (LEO) go around the Earth 300 to 600 kilometers up, and the International Space Station resides in a 400 by 400 kilometer standard orbit.

The mission of Aistechsat-1 is to “provide thermal images of the Earth and also help with maritime and aeronautical tracking,” Zero2infinity representative Iris Silverio told Universe Today via email. Zero2infinity plans on conducting another balloon test with Aistechsat-1 later this month on an as yet to be announced date. The final decision all hinges on the weather and the wind speeds aloft.

Aistech envisions a constellation of 25 such nanosatellites encircling the planet.

Zero2infinity also has a grander vision: eventually launching satellites into Low Earth Orbit via balloon. Known as Bloostar, this system would loft a three stage rocket with the company’s existing and proven Near Space balloon technology. The ‘launch’ would occur high in the upper atmosphere, as the engines take over to get the payload into orbit.

Getting there; the Bloostar approach to low Earth orbit. Image credit: Zero2Infinity.

The idea is certainly attractive. Dubbed a ‘shortcut to space,’ the three engine booster rings depicted are a fraction of the size of typical rocket stages. The toroid ring-shaped stages are simply nestled one inside the other, like Russian dolls. Zero2infinity also envisions scaling its ‘Bloon’ platform for micro and nano payloads… and I’ll bet that a Bloostar atmospheric launch will be an interesting spectacle to watch with binoculars from the ground, especially around dawn or dusk.

Another possible advantage includes a much more spacious payload nose cone, meaning no more folding of satellites for launch and unfolding them in orbit. More than a few payloads have suffered setbacks because of this, including the Galileo mission to Jupiter, whose main antenna failed to unfurl completely in 1990.

According to an email discussion with Zero2infinity representative Silverio, the first commercial Bloostar launch is set for 2019, with possible orbital trials starting as early as 2018. Bloostar deployments will occur off the coast of the Canary Islands in the Atlantic. The initial Bloostar launcher will deploy payloads up to 75 kilograms in a 600 kilometer orbit around the Earth.

Rise of the Rockoons

The idea of conducting launches via balloon, known as a ‘rockoon,’ has been around for a while. Thus far, only sub-orbital launches have been conducted in this manner.

A Deacon rockoon shortly after a U.S. Navy shipboard launch. Public Domain image.

The first balloon-based launch of a rocket occurred on August 9^th, 1953, when a Deacon rockoon successfully carried out a sub-orbital launch high over the Atlantic Ocean. Though several companies have kicked around the idea of launching an orbital satellite via balloon-based platform, Zero2infinity might just be the first to actually accomplish it. The United States Department of Defense has considered the idea of launching satellites (and satellite-killing missiles) via the U.S. Air Force’s high flying F-15 Eagle aircraft. Orbital Sciences does currently use its Pegasus-XL rocket carried aloft by a L1011 aircraft to place satellites in orbit. That’s how NASA’s NuSTAR X-ray telescope got into space in 2012.

There is one main problem facing balloon-based space launches: weather. Unlike aircraft, balloons are often at the whims of the winds aloft, and sometimes stubbornly refuse to go where you want them to. Often, an orbital launch will need to target a precise azimuth heading, a tricky sort of pointing to do from underneath a balloon. Still, we’ve already seen precedent for overcoming this in the effective pointing of balloon-based telescopes, such as the BLAST telescope.

Bloostar might just provide an innovative and cost-effective way to head into orbit, very soon.

-Check out this 2014 article from Universe Today on Zero2Infinity.

-Zero2Infinity also caught last year’s total solar eclipse over the Arctic from aloft.

July 12, 2016April 8, 2018 by Evan Gough

ESA Prepares Revolutionary Air Breathing Rocket Engine

The SABRE (Synergistic Air-Breathing Rocket Engine) could revolutionize access to space. Image: Reaction Engines

If new rocket engines being developed by the European Space Agency (ESA) are successful, they could revolutionize rocket technology and change the way we get to space. The engine, called the Synergistic Air-Breathing Rocket Engine (SABRE), is designed to use atmospheric air in the early flight stages, before switching to conventional rocket mode for the final ascent to space. If all goes well, this new air-breathing rocket could be ready for test firings in about four years.

Conventional rockets have to carry an on-board oxidizer such as liquid oxygen, which is combined with fuel in the rocket’s combustion chamber. This means rockets can require in excess of 250 tons of liquid oxygen in order to function. Once this oxygen is consumed in the first stages, these used up stages are discarded, creating massive waste and expense. (Companies like SpaceX and Blue Origin are developing re-usable rockets to help circumvent this problem, but they’re still conventional rockets.)

Conventional rockets carry their own oxygen because its temperature and pressure can be controlled. This guarantees the performance of the rocket, but requires complicated systems to do so. SABRE will eliminate the need for carrying most on-board oxygen, but this is not easy to do.

SABRE’s challenge is to compress the atmospheric oxygen to about 140 atmospheres before introducing it into the engine’s combustion chambers. But compressing the oxygen to that degree raises its temperature so much that it would melt the engines. The solution to that is to cool the air with a pre-cooling heat exchanger, to the point where it’s almost a liquid. At that point, a turbine based on standard jet engine technology can compress the air to the required operating temperature.

This means that while SABRE is in Earth’s atmosphere, it uses air to burn its hydrogen fuel, rather than liquid oxygen. This gives it an 8 x improvement in propellant consumption. Once SABRE has reached about 25 km in altitude, where the air is thinner, it switches modes and operates as a standard rocket. By the time it switches modes, it’s already about 20% of the way into Earth orbit.

Like a lot of engineering challenges, understanding what needs to be done is not the hard part. Actually developing these technologies is extremely difficult, even though many people just assume engineers will be successful. The key for Reaction Engines Ltd, the company developing SABRE, is to develop the light weight heat exchangers at the heart of the engine.

Heat exchangers are common in industry, but these heat exchangers have to cool incoming air from 1000 Celsius to -150 Celsius in less than 1/100th of a second, and they have to do it while preventing frost from forming. They are extremely light, at about 100 times lighter than current technology, which will allow them to be used in aerospace for the first time. Some of the lightness factor of these new heat exchanges stems from the wall thickness of the tubing, which is less than 30 microns. That’s less than the thickness of a human hair.

Reaction Engines Limited says that these heat exchangers will have the same impact on aerospace propulsion systems that silicone chips had on computing.

A new funding agreement with the ESA will provide Reaction Engines with 10 million Euros for continued development of SABRE. This will add to the 50 million Pounds that the UK Space Agency has already contributed. That 50 million Pound investment was the result of a favorable viability review of SABRE that the ESA performed in 2010.

In 2012 the pre-cooler, a vital component of SABRE, was successfully tested at Reaction Engines facility in Oxfordshire, UK. Image: ESA/Reaction Engines

IN 2012, the pre-cooler and the heat exchangers were tested. After that came more R&D, including the development of altitude-compensating rocket nozzles, thrust chamber cooling, and air intakes.

Now that the feasibility of SABRE has been strengthened, Reaction Engines wants to build a ground demonstrator engine by 2020. If the continued development of SABRE goes well, and if testing by 2020 is successful, then these Air Breathing rocket engines will be in a position to truly revolutionize access to space.

In ESA’s words, “ESA are confident that a ground test of a sub-scale engine can be successfully performed to demonstrate the flight regime and cycle and will be a critical milestone in the development of this program and a major breakthrough in propulsion worldwide.”

Bring it on.

June 18, 2016September 20, 2016 by Nancy Atkinson

NASA Brings Back the X-Plane, and This One’s Electric

An artist's concept of NASA's X-57 Maxwell aircraft, a new electric X-plane that is quieter, more efficient and more environmentally friendly. Credits: NASA Langley/Advanced Concepts Lab, AMA, Inc

While NASA has had a long and storied history of building and testing experimental aircraft – called X-planes — it has been almost a decade since the space agency has developed any new aircraft. But an initiative announced earlier this year as part of the new budget has NASA back designing, building and flying a new series of X-planes, with the goal of creating more “green” aviation technologies that can then be utilized by the aeronautics industry.

NASA unveiled the first plane in the new X series, an electric aircraft with 14 motors integrated into a new wing design. This experimental airplane has been designated the X-57, with the nickname of “Maxwell,” to honor James Clerk Maxwell, the 19th century Scottish physicist who did groundbreaking work in electromagnetism.

“With the return of piloted X-planes to NASA’s research capabilities – which is a key part of our 10-year-long New Aviation Horizons initiative – the general aviation-sized X-57 will take the first step in opening a new era of aviation,” said NASA Administrator Charlie Bolden, speaking at an annual forum of theAmerican Institute of Aeronautics and Astronautics (AIAA).

This artist's concept of NASA's X-57 Maxwell aircraft shows the plane's specially designed wing and 14 electric motors. Credits: NASA Langley/Advanced Concepts Lab, AMA, Inc. — This artist’s concept of NASA’s X-57 Maxwell aircraft shows the plane’s specially designed wing and 14 electric motors. Credits: NASA Langley/Advanced Concepts Lab, AMA, Inc.

Other new X-plane designs include larger transport-scale aircraft that will use less fuel and create less noise, and a business-jet-sized supersonic vehicle that burns low carbon bio-fuels and generates only quiet sonic booms that people on the ground will barely hear. The main goals of the new X-planes will be to demonstrate how airliners can burn half the fuel, saving airline companies money, while generating 75 percent less pollution during each flight as compared to now. They’ll also be much quieter than today’s jets.

The X-57 Maxwell has newly designed long, skinny wings embedded with 14 electric motors – 12 on the leading edge for take offs and landings, and one larger motor on each wing tip for use while at cruise altitude. The idea is that distributing electric power across a number of motors integrated with an aircraft will result in a five-time reduction in the energy required for a private plane to cruise at 175 mph.

The Bell X-1, in which Chuck Yeager “broke” the sound barrier in 1947. Credit: NASA

NASA’s first X-plane was the X-1, which in 1947 became the first airplane to fly faster than the speed of sound. It was flown by Chuck Yeager and was featured in the book and movie “The Right Stuff.” While many of the aircraft were well known — like the X-15 that became the fastest piloted aircraft of the X-plane program — other aircraft were developed clandestinely. Other experimental aircraft included research on lifting bodies and other wing designs or unique engines like the scramjet. Other experimental aircraft didn’t carry the “X” designation, like the Navy’s D-558-II Skyrocket, but was flown by Scott Crossfield in 1953 to become the first airplane to travel twice the speed of sound, or Mach 2.

“Dozens of X-planes of all shapes, sizes and purposes have followed – all of them contributing to our stature as the world’s leader in aviation and space technology,” said Jaiwon Shin, associate administrator for NASA’s Aeronautics Research Mission Directorate. “Planes like the X-57, and the others to come, will help us maintain that role.”

What Is Air Resistance?

Space Travel — Atlantis Breaks Through the Clouds

Here on Earth, we tend to take air resistance (aka. “drag”) for granted. We just assume that when we throw a ball, launch an aircraft, deorbit a spacecraft, or fire a bullet from a gun, that the act of it traveling through our atmosphere will naturally slow it down. But what is the reason for this? Just how is air able to slow an object down, whether it is in free-fall or in flight?

Because of our reliance on air travel, our enthusiasm for space exploration, and our love of sports and making things airborne (including ourselves), understanding air resistance is key to understanding physics, and an integral part of many scientific disciplines. As part of the subdiscipline known as fluid dynamics, it applies to fields of aerodynamics, hydrodynamics, astrophysics, and nuclear physics (to name a few).

Definition:

By definition, air resistance describes the forces that are in opposition to the relative motion of an object as it passes through the air. These drag forces act opposite to the oncoming flow velocity, thus slowing the object down. Unlike other resistance forces, drag depends directly on velocity, since it is the component of the net aerodynamic force acting opposite to the direction of the movement.

Another way to put it would be to say that air resistance is the result of collisions of the object’s leading surface with air molecules. It can therefore be said that the two most common factors that have a direct effect upon the amount of air resistance are the speed of the object and the cross-sectional area of the object. Ergo, both increased speeds and cross-sectional areas will result in an increased amount of air resistance.

This picture shows a bullet and the air flowing around it, giving visual representation to air resistance. Credits: Andrew Davidhazy/Rochester Institute of Technology — *Picture showing a bullet and the air flowing around it, giving visual representation to air resistance. Credits: Andrew Davidhazy/Rochester Institute of Technology*

In terms of aerodynamics and flight, drag refers to both the forces acting opposite of thrust, as well as the forces working perpendicular to it (i.e. lift). In astrodynamics, atmospheric drag is both a positive and a negative force depending on the situation. It is both a drain on fuel and efficiency during lift-off and a fuel savings when a spacecraft is returning to Earth from orbit.

Calculating Air Resistance:

Air resistance is usually calculated using the “drag equation”, which determines the force experienced by an object moving through a fluid or gas at relatively large velocity. This can be expressed mathematically as:

$F_D\, =\, \tfrac12\, \rho\, v^2\, C_D\, A$

In this equation, FD represents the drag force, p is the density of the fluid, v is the speed of the object relative to sound, A is the cross-section area, and CD is the the drag coefficient. The result is what is called “quadratic drag”. Once this is determined, calculating the amount of power needed to overcome the drag involves a similar process, which can be expressed mathematically as:

$P_d = \mathbf{F}_d \cdot \mathbf{v} = \tfrac12 \rho v^3 A C_d$

Here, Pd is the power needed to overcome the force of drag, Fd is the drag force, v is the velocity, p is the density of the fluid, v is the speed of the object relative to sound, A is the cross-section area, and Cd is the the drag coefficient. As it shows, power needs are the cube of the velocity, so if it takes 10 horsepower to go 80 kph, it will take 80 horsepower to go 160 kph. In short, a doubling of speed requires an application of eight times the amount of power.

*An F-22 Raptor reaching a velocity high enough to achieve a sonic boom. Credit: strangesounds.org*

Types of Air Resistance:

There are three main types of drag in aerodynamics – Lift Induced, Parasitic, and Wave. Each affects an objects ability to stay aloft as well as the power and fuel needed to keep it there. Lift induced (or just induced) drag occurs as the result of the creation of lift on a three-dimensional lifting body (wing or fuselage). It has two primary components: vortex drag and lift-induced viscous drag.

The vortices derive from the turbulent mixing of air of varying pressure on the upper and lower surfaces of the body. These are needed to create lift. As the lift increases, so does the lift-induced drag. For an aircraft this means that as the angle of attack and the lift coefficient increase to the point of stall, so does the lift-induced drag.

By contrast, parasitic drag is caused by moving a solid object through a fluid. This type of drag is made up of multiple components, which includes “form drag” and “skin friction drag”. In aviation, induced drag tends to be greater at lower speeds because a high angle of attack is required to maintain lift, so as speed increases this drag becomes much less, but parasitic drag increases because the fluid is flowing faster around protruding objects increasing friction. The combined overall drag curve is minimal at some airspeeds and will be at or close to its optimal efficiency.

*Space Shuttle Columbia launching on its maiden voyage on April 12th, 1981. Credit: NASA*

Wave drag (compressibility drag) is created by the presence of a body moving at high speed through a compressible fluid. In aerodynamics, wave drag consists of multiple components depending on the speed regime of the flight. In transonic flight – at speeds of Mach 0.5 or greater, but still less than Mach 1.0 (aka. speed of sound) – wave drag is the result of local supersonic flow.

Supersonic flow occurs on bodies traveling well below the speed of sound, as the local speed of air on a body increases when it accelerates over the body. In short, aircraft flying at transonic speeds often incur wave drag as a result. This increases as the speed of the aircraft nears the sound barrier of Mach 1.0, before becoming a supersonic object.

In supersonic flight, wave drag is the result of oblique shockwaves formed at the leading and trailing edges of the body. In highly supersonic flows bow waves will form instead. At supersonic speeds, wave drag is commonly separated into two components, supersonic lift-dependent wave drag and supersonic volume-dependent wave drag.

Understanding the role air frictions plays with flight, knowing its mechanics, and knowing the kinds of power needed to overcome it, are all crucial when it comes to aerospace and space exploration. Knowing all this will also be critical when it comes time to explore other planets in our Solar System, and in other star systems altogether!

We have written many articles about air resistance and flight here at Universe Today. Here’s an article on What Is Terminal Velocity?, How Do Planes Fly?, What is the Coefficient of Friction?, and What is the Force of Gravity?

If you’d like more information on NASA’s aircraft programs, check out the Beginner’s Guide to Aerodynamics, and here’s a link to the Drag Equation.

We’ve also recorded many related episodes of Astronomy Cast. Listen here, Episode 102: Gravity.

March 15, 2016March 18, 2016 by Evan Gough

90 Years Ago Goddard’s Liquid-Fuelled Rocket Launched Spaceflight

Dr. Robert H. Goddard and a liquid oxygen-gasoline rocket in the frame from which it was fired on March 16, 1926, at Auburn, Massachusetts. Image: NASA/Clark University Robert H. Goddard Archive

The invention of the rocket changed space science forever. The Universe could only be inspected from the surface of the Earth, with all that atmosphere in the way, until rockets were invented. And as far as the modern age of rocketry goes, it all started 90 years ago with Robert Goddard’s liquid-fuelled rocket.

Goddard was a dreamer. He envisioned rocket-powered spacecraft plying the solar system. Obviously, he passed away before interplanetary travel materialized, but his work on rocketry certainly laid the groundwork for that eventual achievement. The Goddard Space Flight Center is named after him, and it’s doubtful that any engineering or technology student in the world doesn’t know who he is.

Goddard’s first liquid-fuelled rocket was modest by today’s standards, of course. But he had to solve several technical challenges to achieve it, and his ability to solve these challenges led to not only this first flight, but to a total of 34 rocket flights in 15 years, from 1926 to 1941. His rockets reached the altitude of 2.6 km (1.6 miles) and speeds of 885 km/h (550 mph.) He also patented 214 inventions.

Goddard is considered the father of modern rocket science, but he is actually one of three men who are considered the main contributors to modern rocketry. Russian Konstantin Tsiolkovsky (1858-1935) and German Hermann Oberth (1894-1989) are the other founding fathers of modern rocketry.

Goddard didn’t invent rocketry, of course. The Chinese used rockets as far back as the 13th century, and rockets made appearances throughout history as weapons and fireworks. But Goddard’s success at liquid-fuelled rocketry, and the capabilities that came with it, is when rocketry really got off the ground. (Sorry.)

Nowadays, Goddard is understood to be a driven and highly-intelligent person, the type of person who is responsible for advancing science and technology. But back in his time, before he had successful flights, he and his ideas were ridiculed. Check out this criticism from the New York Times, January 13th, 1920:

“That Professor Goddard, with his ‘chair’ in Clark College and the countenancing of the Smithsonian Institution, does not know the relation of action to reaction, and of the need to have something better than a vacuum against which to react — to say that would be absurd. Of course he only seems to lack the knowledge ladled out daily in high schools.”

Stinging words, to be sure, but people who know anything about the history of science are familiar with this kind of condemnation of brilliant people, coming from those who lack vision.

Now of course, we have huge rockets. Great thundering beasts that lift enormous loads out of Earth’s gravity well. And we’re so accustomed to rocket launches now that they barely make news. But I always get a kick out of imagining what people like Goddard would feel if they were able to view a launch of one of today’s behemoths, like the Ariane 5. I’m sure his chest would swelled with pride, and he would be amazed at what people have accomplished.

But his vindication wouldn’t just come from the huge leaps we’ve made in rocket technology, and the huge rockets we now routinely launch. It would also come from this retraction, delivered decades too late but with class, by the New York Times, on July 17 1969, the day after Apollo 11 launched:

Further investigation and experimentation have confirmed the findings of Isaac Newton in the 17th Century and it is now definitely established that a rocket can function in a vacuum as well as in an atmosphere. The Times regrets the error.

March 1, 2016March 18, 2016 by Evan Gough

NASA’s New X-Plane Program to Bring Quiet Supersonic Flight

An illustration of what a quiet supersonic passenger aircraft might look like. Image: Lockheed Martin.

NASA has plans to develop new supersonic passenger aircraft that are not only quieter, but also greener and less expensive to operate. If NASA’s 2017 budget is approved, the agency will re-start their X-Plane program, the same program which was responsible for the first supersonic flight almost 70 years ago. And if all goes according to plan, the first test-model could be flying as soon as 2020.

The problem with supersonic flight—and the reason it’s banned— is the uber-loud boom that it creates. When an aircraft passes the speed of sound, a shockwave is created in the air it passes through. This shockwave can travel up to 40 kilometres (25 miles), and can even break windows. NASA thinks new aircraft designs can prevent this, and it starts with abandoning the ‘tube and wings’ model that current passenger aircraft design adheres to. It’s hoped that new designs will avoid the sonic booms that cause so much disturbance, and instead produce more of a soft thump, or supersonic ‘heartbeat.’

Another illustration of what a quiet supersonic aircraft might look like. Image: NASA/Boeing.

The image above shows what a hybrid wing-body aircraft might look like. Rather than a tube with wings attached, this design uses a unified body and wings built together. It’s powered by turbofan engines, and has vertical fins on the rear to direct sound up and away from the ground. (Just don’t ask for a window seat.)

Lockheed Martin Aeronautics has been chosen to complete a preliminary design for Quiet Supersonic Technology (QueSST.) They will have about 17 months to produce a design, which will then lead to a more detailed designing, building, and testing of a new QueSST jet, about half the size of a production aircraft. This aircraft will then have to undergo analytical testing and wind-tunnel validation.

After the design and build of QueSST will come the Low Boom Flight Demonstration (LBFD) phase. During the LBFD phase, NASA will seek community input on the aircraft’s performance and noise factor.

But noise reduction is not the only goal of NASA’s new X-Plane program. NASA administrator Charles Bolden acknowledged this when he said, “NASA is working hard to make flight greener, safer and quieter—all while developing aircraft that travel faster, and building an aviation system that operates more efficiently.”

NASA has been working in recent years to reduce aircraft fuel consumption by 15%, and engine nitrogen oxide emissions by 75%. These goals are part of their Environmentally Responsible Aviation (ERA) project, which began in 2009. Other goals of ERA include reducing aircraft drag by 8% and aircraft weight by 10%. These goals dovetail nicely with their revamped X-Plane initiative.

It’s hard to bet against NASA. They’re one of the most effective organizations on Earth, and when they set goals, they tend to meet them. If their X-Plane program can achieve its goals, it will be a win for aircraft design, for paying customers, and for the environment.

For a look at the history of the X-Plane project, look here.

January 27, 2016January 27, 2016 by Evan Gough

Blue Origin Reaches Another Milestone: Reusable Rocket Launches and Lands Safely

Blue Origin's New Shepard rocket has successfully launched and landed a second time. Image: Blue Origin

On Friday, January 22nd, commercial space company Blue Origin successfully launched and landed its reusable rocket, New Shepard, at their launch facility in Texas. This is the second flight for New Shepard, showing that reusable rockets are on their way to becoming the launch system of choice. New Shepard launched, travelled to apogee at 101.7 kilometres, (63.19 miles) and then descended to land safely at their site in West Texas. This is the first successful reuse of a rocket in history.

Reusable rockets are an important development for space travel. Rockets are enormously expensive, and having to trash each rocket after a single use makes commercial space flight a real challenge. Blue Origin—and other companies like SpaceX—are blazing a trail to cheaper space flight with their reusable designs. This is great, not only for all the good sciencey reasons that we love so much, but because eventually civilian space enthusiasts may be able to travel past the Karman Line without having to sell all their possessions to do so. (Reserve your ticket here.) Continue reading “Blue Origin Reaches Another Milestone: Reusable Rocket Launches and Lands Safely”

December 30, 2015January 27, 2016 by David Dickinson

Space Stories to Watch in 2016

An artist's conception of Juno in orbit around Jupiter. image credit: NASA

2015 was an amazing year in space, as worlds such as Pluto and Ceres snapped into sharp focus. 2015 also underlined the mantra that ‘space is hard,’ as SpaceX rode the roller coaster from launch failure, to a dramatic return to flight in December, complete with a nighttime landing of its stage 1 Falcon 9 rocket back at Cape Canaveral. Continue reading “Space Stories to Watch in 2016”

November 25, 2015December 23, 2015 by David Dickinson

Spotting Asterix: France Marks 50 Years of Space Exploration

Author’s note: In the wake of the November 13th terrorist attacks, the French Space Agency CNES canceled the celebration of the 50^th anniversary of the launch of Asterix. This post commemorates the launch of France’s first satellite 50 years ago this week, and pays a small tribute to the noblest of human endeavors, namely the exploration of space and the pioneering spirit of humanity exemplified by a heroic nation.

A milestone in space flight occurred 50 years ago tomorrow, when France became the sixth nation—behind the U.S.S.R., the United States, Canada, the United Kingdom and Italy—to field a satellite. The A1 mission, renamed Asterix after a popular cartoon character, launched from a remote desert base in Algeria a few hours after dawn at 9:52 UT on November 26^th.

Though France was 6^th nation in space, it was 3rd—following the Soviet Union and the United States—to launch a satellite atop its very own rocket: the three stage Diamant-A.

P12108 — The launch of Asterix into the blue desert skies over Algeria.

The satellite launch was intended mainly to test the ability of the French-built rocket, which flew 11 more times before its retirement in 1975. Asterix did carry a signal transmitter, and was due to carry out ionospheric measurements during its short battery-powered life span. With a high elliptical orbit, Asterix won’t reenter the Earth’s atmosphere for several centuries to come.

The launch occurred from the remote desert air base of Hammaguir, located 31 degrees north of the equator in western Algeria. Then as today, the site is a forlorn and austere location with very few creature comforts, though we can personally attest from our deployment to a similar French Air Base in Djibouti that the French military does serve wine in their mess hall…

The French space program started in 1961 under president Charles de Gaulle and centered around the construction and use of the Diamant rocket. Three variants were built, including the one used to place Asterix in orbit. One of the stranger tales of the early space age involved the first—and thus far only—sub-orbital launch of a cat into space from the same Algerian site in 1963, though Iran recently made a vague statement that it would do the same in 2013.

Contact with Asterix was lost due to a damaged satellite antenna shortly after launch. Founded in 1961, the French space agency CNES (The Centre National d’Etudes Spatiales, or National Centre for Space Studies) now partners with NASA and the European Space Agency on missions including micro-gravity studies on the International Space Station, Rosetta’s historic exploration of comet 67P Churyumov-Gerasimenko and more. And although the Hammaguir space facility in Algeria is no longer in use, CNES operates out of the Kourou Space Center in French Guiana and the Toulouse Space Center in southern France today.

A stamp series commemorating the Diamant rocket and Asterix.

Tracking Asterix

Though inoperative, Asterix still orbits the Earth once every 107 minutes in an elliptical low Earth orbit. Asterix ranges from a perigee of 523 kilometers to an apogee of 1,697 kilometers. In an orbit inclined 34 degrees relative to the Earth’s equator, Asterix isn’t expected to reenter for several centuries.

A 42 kilogram satellite approximately a meter across, Asterix is visible worldwide from about 40 degrees north to 40 degrees south latitude. Essentially a binocular object, you can nonetheless see Asterix from your backyard if you know exactly where and when to look for it in the sky. Asterix will appear brightest on a perigee pass directly overhead.

Asterix’s NORAD ID satellite catalog number is 01778/COSPAR ID 1965-096A.

The orbital trace of Asterix. Image credit: Orbitron

When it comes to hunting for binocular satellites, you need to now exactly where it’ll be in the sky at what time. We use Heavens-Above to discern exactly when a given satellite will pass a bright star, then simply watch at the appointed time with binoculars. We also run WWV radio in the background for a precise audio time hack. This allows us to keep our eyes continuously on the sky. This simple method is similar to that used by Project Moonwatch volunteers to track and record satellites starting in the late 1950s.

Other satellite challenges from the early Space Age include Alouette-1 (Canada’s first satellite), Prospero (UK’s first and only indigenous satellite) and the oldest of them all, the first three Vanguard satellites launched by the United States.

Don’t miss a chance to see this living relic of the early space age, still in orbit. Happy 50^th to the CNES space agency: may your spirit of space exploration continue to soar and inspire us all.

September 24, 2015December 23, 2015 by Nancy Atkinson

Dramatic Imagery from NASA of Supersonic Shock Waves

This schlieren image of a T-38C was captured using the patent-pending BOSCO technique and then processed with NASA-developed code to reveal shock wave structures. Credit: NASA.

NASA is using a 150-year-old photographic technique with a few 21st century tweaks to capture unique and stunning images of the shockwaves created by supersonic aircraft.

Called schlieren imagery, the technique can be used to visualize supersonic airflow with full-scale aircraft in flight. Usually, this can only be done in wind tunnels using scale models, but being able to study real-sized aircraft flying through Earth’s atmosphere provides better results, and can help engineers design better and quieter supersonic planes.

And a side benefit is that the images are amazing and dramatic, creating a little “shock” and awe.

This schlieren image dramatically displays the shock wave of a supersonic jet flying over the Mojave Desert. Researchers used NASA-developed image processing software to remove the desert background, then combined and averaged multiple frames to produce a clear picture of the shock waves. Credit: NASA. — This schlieren image dramatically displays the shock wave of a supersonic jet flying over the Mojave Desert. Researchers used NASA-developed image processing software to remove the desert background, then combined and averaged multiple frames to produce a clear picture of the shock waves.
Credit: NASA.

Earlier this year, NASA released some schlieren imagery taken with a high-speed camera mounted on the underside of a NASA Beechcraft B200 King Air, which captured images at 109 frames per second while a supersonic aircraft passed several thousand feet underneath over a speckled dessert floor. Special image processing software was used to remove the desert background, then combine and average multiple frames, which produces a clear picture of the shock waves. This is called air-to-air schlieren.

“Air-to-air schlieren is an important flight-test technique for locating and characterizing, with high spatial resolution, shock waves emanating from supersonic vehicles,” said Dan Banks, the principal investigator on the project, being done at NASA’s Armstrong Flight Research Center at Edwards Air Force Base. “It allows us to see the shock wave geometry in the real atmosphere as the target aircraft flies through temperature and humidity gradients that cannot be duplicated in wind tunnels.”

But now they’ve started using a technique that might provide better results: using the Sun and Moon as a lit background. This backlit method is called Background-Oriented Schlieren using Celestial Objects, or BOSCO.

The speckled background or a bright light source is used for visualizing aerodynamic flow phenomena generated by aircraft or other objects passing between the camera and the backdrop.

This schlieren image of shock waves created by a T-38C in supersonic flight was captured using the sun’s edge as a light source and then processed using NASA-developed code. Credit: NASA. — This schlieren image of shock waves created by a T-38C in supersonic flight was captured using the sun’s edge as a light source and then processed using NASA-developed code.
Credit: NASA.

NASA explains the technique:

“Flow visualization is one of the fundamental tools of aeronautics research, and schlieren photography has been used for many years to visualize air density gradients caused by aerodynamic flow. Traditionally, this method has required complex and precisely aligned optics as well as a bright light source. Refracted light rays revealed the intensity of air density gradients around the test object, usually a model in a wind tunnel. Capturing schlieren images of a full-scale aircraft in flight was even more challenging due to the need for precise alignment of the plane with the camera and the sun.”

Then, there are variations on this technique. One recent demonstration used Calcium-K Eclipse Background Oriented Schlieren (CaKEBOS). According to Armstrong principal investigator Michael Hill, CaKEBOS was a proof of concept test to see how effectively the Sun could be used for background oriented schlieren photography.

Using the solar disk as a backdrop, its details revealed by a calcium-K optical filter, researchers processed this image to reveal shock waves created by a supersonic T-38C. Credit: NASA. — Using the solar disk as a backdrop, its details revealed by a calcium-K optical filter, researchers processed this image to reveal shock waves created by a supersonic T-38C.
Credit: NASA.

“Using a celestial object like the sun for a background has a lot of advantages when photographing a flying aircraft,” Hill said. “With the imaging system on the ground, the target aircraft can be at any altitude as long as it is far enough away to be in focus.”

Researchers found the ground-based method to be significantly more economical than air-to-air methods, since you don’t have to have a second aircraft carrying specially mounted camera equipment. The team said they can use off-the-shelf equipment.

Schlieren imagery was originally invented in 1864 by German physicist August Toepler.

Find out more about the air-to-air technique here and the BOSCO techniques here.