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interplanetarypodcast · 8 years ago

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Podcast 21

Nebula and Asparagus

Inspired by a Tweet from the International Association of Astronomical Artists. IAAA

What is asparagus Staging?

People playing Kerbal Space program know and use asparagus staging because it gives you a better mass ratio

Two or three similar stages are stacked side by side, and burn in parallel. Using crossfeed, the fuel tanks of the orbital stage are kept full, while the tank(s) in the booster stage(s) are used to run engines in the booster stage(s) and orbital stage. Once the boosters run dry, they are ejected, and (typically) glide back to a landing. The advantage to this is that the mass ratios of the individual stages is vastly reduced due to the way cross feed modifies the rocket equation. Isp*g*ln(2MR^2/MR+1) & Isp*g*ln(3MR^2/MR+2)[clarification needed] respectively.[original research?] With hydrogen engines, a triamese only needs an MR of 5, as opposed to an MR of 10 for a single-stage equivalent vehicle.[citation needed]

An early concept of Asparagus Staging was the MUSTARD

The Multi-Unit Space Transport And Recovery Device or MUSTARD was a concept explored by the British Aircraft Corporation (BAC) around 1968

MUSTARD was a delta-winged three-stage reusable vehicle which used the triamese concept , which is a type of Aspargus staging

The three components of the design were three largely identical lifting bodies (each similar to the Northrop HL-10), stacked back-to-belly.

The units would be stacked for launch, and two of them would act as boosters to launch the third into Earth orbit. The booster units would feed any excess fuel to the unit which was to be the spacecraft. At 150,000 to 200,000 ft. (45,750 to 60,960 m), at around 30 nautical miles, the booster units would separate and land like aircraft.

The spacecraft would place its payload into orbit at around 1000 nautical miles, after 10 minutes from launch, and then return in a like manner.

Picture is a beauty from a book with recently declassified art of the secret British space shuttle.

Falcon Heavy had originally been designed with a unique propellant crossfeed capability, where some of the center core engines are supplied with fuel and oxidizer from the two side cores, up until the side cores are near empty and ready for the first separation event. This allows engines from all three cores to ignite at launch and operate at full thrust until booster depletion, while still leaving the central core with most of its propellant at booster separation The propellant crossfeed system, nicknamed "asparagus staging", comes from a proposed booster design in a book on orbital mechanics by Tom Logsdon. According to the book, an engineer named Ed Keith coined the term "asparagus-stalk booster" on Page 143 for launch vehicles using propellant crossfeed. Elon Musk has stated that crossfeed is not currently planned to be implemented, at least in the first Falcon Heavy version.

The cross-feeding scheme used by Space X apparently does not pump fuel into the tanks of the core stage. Instead, the three core-stage engines next to each side booster are fed directly from the side booster’s tanks. This is very similar to how the shuttle’s external tank feeds the shuttle main engines (SMEs). In the case of the Falcon Heavy, of course, the two side booster’s tanks are feeding propellant to 12 engines instead of 9, so they run out of propellant faster. At some point after liftoff, of course, you do not need the full thrust of all 27 engines to maintain acceleration, as much of the mass (propellant) has already been used. The core stage engines will then apparently be throttled down while the side stages continue to burn at full thrust. Presumably, only the center three engines in the core stage are using propellant from the core stages tanks. Thus, when the side stages separate, most of the core stage’s propellant is still there, and then all the core stage engines can burn at full thrust. Assuming that the core stage is going several thousand miles an hour at separation and is perhaps 30 miles high or more, it is as if an entire stretched Falcon 9 rocket starts its liftoff at separation. Separation of fuel lines like this occurred every time the external tank separated from the space shuttle and when the old original Atlas shed its two side booster engines.

COOL!!!

NEBULAE

What are they?

A nebula (Latin for "cloud";pl. nebulae, nebulæ, or nebulas) is an interstellar cloud of dust, hydrogen, helium and other ionized gases. Originally, nebula was a name for any diffuse astronomical object, including galaxies beyond the Milky Way. The Andromeda Galaxy, for instance, was once referred to as the Andromeda Nebula (and spiral galaxies in general as "spiral nebulae") before the true nature of galaxies was confirmed in the early 20th century by Vesto Slipher, Edwin Hubble and others.

Most nebulae are of vast size, even millions of light years in diameter.

Contrary to fictional depictions where starships hide in nebulae as thick as cloud banks, in reality a nebula that is barely visible to the human eye from Earth would appear larger, but no brighter, from close by.

The Orion Nebula, the brightest nebula in the sky that occupies a region twice the diameter of the full Moon, can be viewed with the naked eye but was missed by early astronomers.

Check out my EPIC shot here!!!

Although denser than the space surrounding them, most nebulae are far less dense than any vacuum created on Earth – a nebular cloud the size of the Earth would have a total mass of only a few kilograms. Many nebulae are visible due to their fluorescence caused by the embedded hot stars, while others are so diffuse they can only be detected with long exposures and special filters. Some nebulae are variably illuminated by T Tauri variable stars. Nebulae are often star-forming regions, such as in the "Pillars of Creation" in the Eagle Nebula. In these regions the formations of gas, dust, and other materials "clump" together to form denser regions, which attract further matter, and eventually will become dense enough to form stars. The remaining material is then believed to form planets and other planetary system objects

Around 150 AD, Claudius Ptolemaeus (Ptolemy) recorded, in books VII-VIII of his Almagest, five stars that appeared nebulous. He also noted a region of nebulosity between the constellations Ursa Major and Leo that was not associated with any star. The first true nebula, as distinct from a star cluster, was mentioned by the Persian astronomer, Abd al-Rahman al-Sufi, in his Book of Fixed Stars (964). He noted "a little cloud" where the Andromeda Galaxy is located. He also cataloged the Omicron Velorum star cluster as a "nebulous star" and other nebulous objects, such as Brocchi's Cluster. The supernova that created the Crab Nebula, the SN 1054, was observed by Arabic and Chinese astronomers in 1054

In 1715, Edmund Halley published a list of six nebulae.

Jean-Philippe de Cheseaux compiling a list of 20 (including eight not previously known) in 1746.

From 1751–53, Nicolas Louis de Lacaille cataloged 42 nebulae from the Cape of Good Hope,

Charles Messier then compiled a catalog of 103 "nebulae" (now called Messier objects, which included what are now known to be galaxies) by 1781; his interest was detecting comets, and these were objects that might be mistaken for them

William Herschel and his sister Caroline Herschel. Their Catalogue of One Thousand New Nebulae and Clusters of Stars was published in 1786.

Beginning in 1864, William Huggins examined the spectra of about 70 nebulae. He found that roughly a third of them had the emission spectrum of a gas. The rest showed a continuous spectrum and thus were thought to consist of a mass of stars.

A third category was added in 1912 when Vesto Slipher showed that the spectrum of the nebula that surrounded the star Merope matched the spectra of the Pleiades open cluster. Thus the nebula radiates by reflected star light.

About 1922, following the Great Debate, it had become clear that many "nebulae" were in fact galaxies far from our own.

Great debate- Shapley was arguing in favor of the Milky Way as the entirety of the universe, Curtis on the other side contended that Andromeda and other such "nebulae" were separate galaxies, or "island universes" (a term invented by the 18th-century philosopher Immanuel Kant, who also believed that the "spiral nebulae" were extragalactic)

Slipher and Edwin Hubble continued to collect the spectra from many diffuse nebulae, finding 29 that showed emission spectra and 33 that had the continuous spectra of star light.

In 1922, Hubble announced that nearly all nebulae are associated with stars, and their illumination comes from star light. He also discovered that the emission spectrum nebulae are nearly always associated with stars having spectral classifications of B1 or hotter (including all O-type main sequence stars), while nebulae with continuous spectra appear with cooler stars.

Both Hubble and Henry Norris Russell concluded that the nebulae surrounding the hotter stars are transformed in some manner

TYPES

Diffuse nebulae can be divided into 1. emission nebula, 2. reflection nebulae and 3. "dark nebulae."

Examples from Matt Russell’s Work

1. Pacman Nebula

2. Pleiades

3. Horsehead

Planetary nebulae form when low-mass asymptotic giant branch stars nova. A star that novas pushes the outer layers of the star's mass outward forming gaseous shells, while leaving behind the star's core in the form of a white dwarf. The hot white dwarf illuminates the expelled gases producing emission nebulae with spectra similar to those of emission nebulae found in star formation regions

example: Dumbbell Nebula (also known as Apple Core Nebula, Messier 27, M 27, or NGC 6853)

A protoplanetary nebula (PPN) is an astronomical object which is at the short-lived episode during a star's rapid stellar evolution between the late asymptotic giant branch (LAGB) phase and the following planetary nebula (PN) phase

Supernova remnants A supernova occurs when a high-mass star reaches the end of its life. When nuclear fusion in the core of the star stops, the star collapses. The gas falling inward either rebounds or gets so strongly heated that it expands outwards from the core, thus causing the star to explode.[19] The expanding shell of gas forms a supernova remnant, a special diffuse nebula. Although much of the optical and X-ray emission from supernova remnants originates from ionized gas, a great amount of the radio emission is a form of non-thermal emission called synchrotron emission.This emission originates from high-velocity electrons oscillating within magnetic fields.

Crab nebula

Hubble Pallette

Hubble Palette (Ha/OIII/SII) replacing Red Green Blue with filtered light

H-alpha (Hα) is a specific deep-red visible spectral line in the Balmer series with a wavelength of 656.28 nm; it occurs when a hydrogen electron falls from its third to second lowest energy level. H-alpha light is important to astronomers as it is emitted by many emission nebulae and can be used to observe features in the sun's atmosphere including solar prominences.

[O III] In astronomy and atomic physics, doubly ionized oxygen (also known as O III) is the ion O2+. Its emission forbidden lines in the visible spectrum, primarily at the wavelength 500.7 nm, and secondarily at 495.9 nm, are known in astronomical spectroscopy as [O III]. Before spectra of oxygen ions became known, these lines once led to a spurious identification of the substance as a new chemical element. Concentrated levels of O III are found in diffuse and planetary nebulae. Consequently, narrow band-pass filters that isolate the 501 nm and 496 nm wavelengths of light, that correspond to green-turquoise-cyan spectral colors, are useful in observing these objects, causing them to appear at higher contrast against the filtered and consequently blacker background of space (and possibly light-polluted terrestrial atmosphere) where the frequencies of [O III] are much less pronounced.

These emission lines were first discovered in the spectra of planetary nebulae in the 1860s. At that time, they were thought to be due to a new element which was named nebulium. In 1927, Ira Sprague Bowen came up with the current explanation of them being due to doubly ionized oxygen

Sulpher can have the same type of emission from it's double ionised state and gives of a red light ( SII)

Pacman

In the News

Astronomers discover the first white dwarf pulsar in history, ending half a century of searching

It's small but it will rip you apart using only magnetism.

AR Sco is only 380 light-years away from Earth, in the Scorpius constellation. It has two stars — a very rapidly spinning former star known as a white dwarf pulsar, and an actual star known as a red dwarf — locked together in a 3.6-hour orbit.

The red dwarf isn’t very noticeable in and of itself. It weighs one-third of a Solar mass (the biggest ones reach one-half of a solar mass). It ‘burns’ helium just like our Sun but at a much slower rate. So it’s not particularly hot or very bright at all. Standard red dwarf across the board.

However, its choice of companions creates some spectacular interaction which brought the scientists’ attention to the system in the first place. Its neighboring pulsar isn’t much bigger than Earth, but it’s an estimated 200,000 times denser. Like all pulsars, it’s a kind of neutron star and very lively celestial body.

JAXA’s mission to fish for space trash thwarted by faulty tether

“We believe the tether did not get released,” leading researcher Koichi Inoue said. “It is certainly disappointing that we ended the mission without completing one of the main objectives.” Before the mission, agency spokespersons said that JAXA planned to take these missions on a regular schedule, and even to “attach one tip of the tether to a targeted object.” Hopefully, this setback won’t disrupt JAXA’s space-cleaning ambitions.

Federal investigators find persistent cracks in SpaceX Falcon 9 rockets

Reports from a Government Accountability Office (GAO) mention a dangerous defect that could compromise the safety of astronauts — namely, “persistent cracking of vital propulsion-system components.”

“We have qualified our engines to be robust to turbine wheel cracks,” John Taylor, a SpaceX representative, tells The Verge. “However, we are modifying the design to avoid them altogether. This will be part of the final design iteration on Falcon 9. SpaceX has established a plan in partnership with NASA to qualify engines for [crewed] spaceflight.”

Company Aims to Launch 2017 Solar Eclipse Balloon Flight, High-Altitude Skydive

A startup near-space ballooning company is hoping to not only capture spectacular footage of this August's solar eclipse over the United States, but also break the high-altitude jump record set by Felix Baumgartner in 2012.

Blue jets studied from Space Station

ESA astronaut Andreas Mogensen during his mission on the International Space Station in 2015 was asked to take pictures over thunderstorms with the most sensitive camera on the orbiting outpost to look for these brief features.

Denmark’s National Space Institute has now published the results, confirming many kilometre-wide blue flashes around 18 km altitude, including a pulsating blue jet reaching 40 km. A video recorded by Andreas as he flew over the Bay of Bengal at 28 800 km/h on the Station shows the electrical phenomena clearly – a first of its kind.Around 150 AD, Claudius Ptolemaeus (Ptolemy) recorded, in books VII-VIII of his Almagest, five stars that appeared nebulous. He also noted a region of nebulosity between the constellations Ursa Major and Leo that was not associated with any star.[6] The first true nebula, as distinct from a star cluster, was mentioned by the Persian astronomer, Abd al-Rahman al-Sufi, in his Book of Fixed Stars (964).[7] He noted "a little cloud" where the Andromeda Galaxy is located.[8] He also cataloged the Omicron Velorum star cluster as a "nebulous star" and other nebulous objects, such as Brocchi's Cluster.[7] The supernova that created the Crab Nebula, the SN 1054, was observed by Arabic and Chinese astronomers in 1054

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