EWTN and Difference between sub-orbital and orbital spaceflights: Difference between pages

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There sometimes appears to be confusion among the general public about the '''difference between sub-orbital and [[orbit]]al spaceflights'''. This article is an attempt to clarify this issue. It also elaborates on the technical implications of the differences between orbital and sub-orbital spaceflights.

'''EWTN''' - or The Eternal Word Television Network - is a [[television]] and [[radio]] operation that broadcasts [[Catholic]] [[religious]] programming, via [[satellite]] and [[shortwave]] radio.

A [[spaceflight]] is a [[flight]] ''into'' or ''through'' [[outer space|space]]. The craft which undertakes a spaceflight is called a [[spacecraft]].

EWTN began in [[1981]] and transmits 24 hour programming to 104 million homes in 110 countries and 16 territories on [[cable]], satellite, and [[LPTV|low power TV]].

The general public often thinks of [[orbital spaceflight]]s as spaceflights and of [[sub-orbital spaceflight]]s as "something less than actual spaceflights". This is not accurate; both orbital and sub-orbital spaceflights are true spaceflights.

==In the beginning==

The founder of EWTN, [[Mother Angelica]], founded [[Our Lady of Angels]] Monastery near [[Birmingham, Alabama]] and began developing short written religious teachings. As these short books became more popular, Mother Angelica's fellow [[nun]]s looked at technology to enable worldwide distribution.

Strictly speaking, the term ''orbit'' means any [[trajectory]] in general. In common usage the term ''orbit'' refers to a closed trajectory around the Earth (or another central body). The term ''sub-orbital'' refers to a trajectory which intersects the central body before a complete orbit is achieved. An ''orbital spaceflight'' is one which completes an orbit fully around the central body.

==Television==

Mother Angelica began receiving requests for speaking engagements, which turned into a [[video]] series of her talks taped at a local Birmingham television station. Eventually, she built a TV studio on monastery property in [[Irondale, Alabama]], a suburb of Birmingham. This developed into the worldwide brodcast center that EWTN is today.

For a flight from Earth to be a spaceflight, the spacecraft has to ascend from Earth and at the very least go past the [[edge of space]]. The edge of space is, for the purpose of space flight, often accepted to lie at a height of 100 km (62 miles) above mean [[sea level]].

==Radio==

Any flight that goes higher than that is by definition a spaceflight. Where the [[Earth's atmosphere]] ends space begins but the atmosphere fades out gradually so the precise boundary is difficult to ascertain - hence the need for an arbitrary altitude for the [[edge of space]].

In 1992, EWTN established the largest privately owned [[short wave radio]] station in the Birmingham area. The station broadcasts Catholic programming 24 hours a day in English and Spanish. In 1996, EWTN launched a free satellite-delivered AM/FM radio network to stations worldwide, also in English and Spanish.

==Angular velocity==

In 2004, EWTN announced an agreement with [[Sirius Satellite Radio]], which allows Sirius to carry EWTN programming.

An orbital spaceflight is achieved when the spacecraft travels around the Earth in space at sufficient lateral velocity (or equivalently, enough [[angular velocity]]) to "miss" the Earth, even though [[gravity]] is still effecting it, and "free-fall" forever. Lateral velocity is the speed of something around an object and it is this which is the critical factor. Although the angular velocity required is a function of the height of the orbit, orbital spaceflight is possible at any altitude beyond the edge of space.

==News==

The EWTN News department produces a daily news service for the television and radio network, featuring news sources including [[Vatican Radio]].

A body which does not have sufficient angular velocity cannot orbit the Earth. The actual speed of a sub-orbital spacecraft could exceed that of an orbital one and the height that a sub-orbital spacecraft attains may even exceed that of an orbital one, but the critical difference between the two - the achieving of an orbit - depends crucially on the angular velocity. Travelling straight up will never result in an orbit, doing so faster than [[escape velocity]] will have the obvious effect and orbit is still not attained.

==Criticism==

EWTN is criticized by many for its portrayal of [[Protestants]], [[Atheists]], [[Homosexuals]], [[New Age]] groups, and others. EWTN programs for example will call Protestants heretics, and there are several EWTN programs directed at countering Protestant beliefs. Despite this, EWTN will call Protestants [[anti-Catholic]] if a Protestant group criticizes Catholicism. [[Genocides]] in [[Communist]] countries are attributed to [[Atheism]], but EWTN will call groups or individuals anti-Catholic if those groups point out Catholic inspired killing, such as the [[Inquisition]]. EWTN programs, including Benedict Groeschel's program on the [[Ten Commandments]], have even made statement that Atheists do actually believe in God, and simply will not admit it to themselves. New Age groups are associated with [[Satanism]]. And [[Judaism]] is portrayed as an incomplete religion, such as on programs like the Journey Home where former Jews who have appeared on the show have said that Judaism is fulfilled in Catholicism. The network also broadcasts a show called Defending Life, in which [[pro-choice]] advocates are portrayed as murderers.

==Difference in the real world==

==Programming==

*''[[Mother Angelica Live]]

*''Daily [[Mass (liturgy)|Mass]]

*''Life on the Rock with [[Fr. Francis Mary]]

*''EWTN Live with [[Fr. Mitch Pacwa]]

*''The Journey Home with [[Marcus Grodi]]

*''The World Over with [[Raymond Arroyo]] - News

That said, typical sub-orbital craft need go only just past the accepted edge of space at 100 km (62.5 miles) for the flight to be a spaceflight. At this arbitrary boundary there is still too much atmosphere present for a long term stable [[low earth orbit]] (LEO). In order to be stable for more than just a few weeks or months the satellite or spacecraft is placed in orbit at an altitude where drag from the atmosphere truly is negligible. A stable LEO is usually at least 350 km up.

The network also airs coverage of Church events worldwide, documentaries, music specials, the [[Rosary]], and other [[devotional]] segments.

But again, the difference in height should not be overemphasized: Whether the altitude is 100 km or 350 km the distance from the centre of the Earth is only different by less than four percent.

==External links==

*[http://www.ewtn.com EWTN's website]

The difference between the lowest speeds required for orbital and sub-orbital space flights is substantial: a spacecraft must reach about 29,000 km/h (18,000 mph) to attain orbit. This compares to the relatively modest 4,000-4,800 km/h (2,500-3,000 mph) typically attained for sub-orbital crafts.

[[Category:Birmingham, Alabama]]

[[Category:International broadcasting]]

The important difference in energy requirements between a sub-orbital spaceflight such as that required for the [[Ansari X Prize|X Prize]] and for an orbital spaceflight is that no lateral or angular velocity is required for the sub-orbital flight. The energy required to get to 100 km or even 350 km altitude is dwarfed by the energy required for the necessary lateral velocity of orbital space flight.

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[[Category:Roman Catholic media]]

In terms of energy: accelerating a spacecraft to [[orbital speed]] requires about 31 times as much net energy as just lifting it to a height of 100 km (together 32 times), see [[Specific orbital energy#Examples|computation]].

[[Category:United States television networks]]

But this is the energy which must be imparted to the orbiting mass: For a rocket the fuel and oxygen (and their tanks) must be accelerated as well and so the energy requirement is actually much more than the factor of 32 identified. (See the [[rocket equation]] article for a more detailed treatment).

In terms of the [[semi-major axis|semi-major axes]] <math>a</math> of the [[elliptic orbit]]s: the total [[specific orbital energy]] is {{il|<math>\epsilon=-{\mu\over{2a}}</math>|70}} where <math>\mu\,</math> is the [[standard gravitational parameter]]. Being at rest at the surface of the Earth corresponds to <math>a=R/2</math> (with <math>R</math> the radius of the Earth). Reaching a height of 100 km means an increase of <math>a</math> of 50 km, while a LEO requires an increase of <math>a</math> of more than 3000 km. See also [[orbit equation#Low-energy trajectories|low-energy trajectories]].

A vertical sub-orbital flight with the same energy as a LEO would reach a height of ca. 7000 km above the surface.

===Atmospheric reentry a much bigger challenge with orbital flights===

Because of that speed difference, '''atmospheric reentry is much more difficult for orbital flights than it is for sub-orbital flights'''. Note however, that such considerations only apply to orbital flights where the vehicle needs to return to Earth intact. If the vehicle is, say, a satellite that is ultimately expendable, then there naturally is no need to worry about reentry.

Returning craft though (including all potentially manned craft), have to find a way of slowing down as much as possible while still in higher atmospheric layers and avoid plunging downwards too quickly. To date (as of 2004), the problem of deceleration from orbital speeds has mainly been solved through [[aerobraking]], ie. using the atmospheric drag itself to slow down. On an orbital space flight initial deceleration is provided by the retrofiring of the craft's rocket engines. Aerobraking in turn has so far mainly been achieved through orienting the returning space craft to fly at a high drag attitude coupled with ultra strong heat shields on the space craft, to protect against the high temperatures generated by atmospheric compression and friction caused by passing through the atmosphere at supersonic speeds. The thermal energy is dissipated mainly as infrared radiation. Sub-orbital space flights, being at a much lower speed, do not generate anywhere near as much heat upon re-entry.

This has allowed maverick aircraft designer [[Burt Rutan]] recently (July 2004) to demonstrate an alternative or complementary approach to heat shield dependant [[reentry]] with the suborbital [[SpaceShipOne]]. It may be possible that the concepts utilized in SpaceShipOne's design can be applied to orbital space craft design and result in a markedly reduced need for a massive heat shield. Currently however, the need for an ultra high-performance and ultra reliable heat shield is a major difference between crafts designed for orbital flights (as opposed to sub-orbital ones), demonstrated in the [[Mercury program]] wherein the orbital flights used a typical ablative [[heat shield]] while the sub-orbital flights relied simply on a large metal heat-sink.

If we can transport fuel tanks into orbit, which returning spaceships can use to brake from their orbiting speed to zero or a low speed, re-entry can be made much safer and easier. The big problem now is that spaceships have practically no fuel left when they reach orbit, and have to get home again without being able to slow down before hitting the atmosphere.

==Summary==

* Sub-orbital spaceflights flights are spaceflights just as orbital flights are.

* Both go beyond the atmosphere and past the edge of space.

* A sub-orbital flight may reach a higher height than an orbital one.

* The most important requirement for an orbital flight over a sub-orbital one is speed.

* The [[shock wave]] produced by high speed atmospheric reentry generates lots of heat from which the spacecraft must be protected.

== See also ==

* [[Boundary to space]]

* [[Low Earth orbit]]

* [[Atmospheric reentry]]

* [[Aerobraking]]

[[Category:Birmingham, AlabamaSpaceflight]]