# Talk:Sub-orbital spaceflight

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## I'm confused...

So any vehicle that travels higher than 100 km yet slower than orbital speed is said to be in Sub-orbital spaceflight.

I don't understand why it is slower than orbital speed. According to the definition of the Karman line, shouldn't it be faster ? In fact, are suborbital flights such as those performed by SpaceShipOne slower or faster than orbital speed ? --Scroteau96 21:28, 25 February 2007 (UTC)

Suborbital flights are almost always slower than orbital speed. SpaceShipOne was much slower than orbital speed. If you can achieve orbital speed (which is very expensive), then you might as well inject into orbit, otherwise you have wasted a lot of money. Charles 16:09, 25 March 2007 (UTC) The only known cases of suborbital flights exceeding orbital velocities were mission failures, e.g. Pioneer-1. Nobody intentionally flies an orbital speed suborbital trajectory (i.e. nobody has money to burn).Charles 16:20, 25 March 2007 (UTC)

Has anyone done the math to show that the successful lunar impactor missions weren't on sub-orbital trajectories? Intuitively, an object impacting the face of the moon following a direct tracjectory had little angular velocity.... Sdsds 20:47, 25 March 2007 (UTC)

Earth escape missions do not fit the generally accepted defintion of suborbital. I think we are splitting hairs here Charles 03:05, 26 March 2007 (UTC)

You are right -- we're splitting hairs. Even so, a lunar impact doesn't imply an Earth escape. What matters is that this article is a great opportunity to explain a bit of orbital mechanics, and it isn't clear the article does that very well yet, given that readers describe themselves as "confused". Sdsds 03:29, 26 March 2007 (UTC)
Fair enough. Over the weekend I will try to write a few words on parabolic trajectories versus elliptical orbits, linking to other content on Wikipedia which covers it in more detail.Charles 13:33, 30 March 2007 (UTC)

### The definition

So which is it? Suborbital Spaceflight or suborbital flight? The dictionary definition of suborbital says it's anything that does not complete an orbit around the world. This would include all regular planes which are very much suborbital. Surely it should be suborbital spaceflight only and use of the other term should be demoted to 'often mistakenly called' status? John 13:33, 30 March 2007 (UTC)
You could be on a suborbital trajectory and not be in space though; anything above about 35 km is in very thin air, and momentum dominates.WolfKeeper (talk) 01:25, 30 November 2007 (UTC)
The difference between suborbital and ordinary flight is largely arbitrary. The government bureaucrats in the USA haggled over it in a jurisdiction fight and came up with a definition that states that something is a suborbital flight if the thrust/weight ratio of the aircraft is greater than one over more than half the powered portion; at least something like that last time I checked.WolfKeeper (talk) 01:25, 30 November 2007 (UTC)

## Flight duration

I restored some text mentioning the duration of the Pioneer 1 sub-orbital flight (43 hours). If you can find a real-world (not theory) example with a longer duration, please use it instead. (On the theory side: if a flight exits the Hill sphere, can we agree it would be non-orbital even if tangential velocity were zero?) Sdsds 15:35, 12 March 2007 (UTC)

## Why were Categories removed?

Why did User:Ksyrie remove lots of categories on 19 March 2007. What was wrong with them? Charles 16:14, 25 March 2007 (UTC)

## Suborbital as in electron orbits?

Suborbital redirects here... will move as soon as I find the right article. W1k13rh3nry 23:47, 24 April 2007 (UTC)

ah... never mind. W1k13rh3nry 23:48, 24 April 2007 (UTC)

## I'm confused too...

This article says that flights in low Earth orbit "attain orbit but deorbit after less than one full orbital period," but the article on orbital spaceflight defines orbital spaceflight as "a spaceflight in which a spacecraft is placed on a trajectory where it could remain in space for at least one orbit," and then lists low Earth orbit as an orbit area. Does this mean that a spacecraft in low Earth orbit deorbits before completing the circle, but remains in outer space for the full circle? Not going in a full circle but going in a full circle doesn't make any sense. Someone the Person 00:07, 15 November 2007 (UTC)

there's a difference between a trajectory that would do an orbit, and a trajectory that wouldn't. There's also a difference between being on a trajectory that is orbital and completing it, to being on an orbital trajectory, but doing retrorocket firing that reenters you before you've actually completed an orbit.WolfKeeper 06:57, 15 November 2007 (UTC)

## Talk:Sub-orbital spaceflight/Intercontinental flight

I've moved a recently created page about Intercontinental flight here because it was too focused on space travel, when in fact any flight between continents is intercontinental. Please merge what you can (with proper credit to the original creator in the edit summary if you wish to delete the page) - Mgm|(talk) 00:36, 8 February 2009 (UTC)

I think I was logged out when I made the edit, but I removed the following section from the 'Tourist' section of the article. It's nothing more than an advertisement.

In 2008, Xcor Aerospace partnered with Rocketship Tours to offer the most affordable tourist access to the edge of space (less than half the price of existing competition). For more information contact Robert Miller at (928) 704-8000 or visit www.rocketshiptours.com.

JZelazny (talk) 04:52, 16 March 2009 (UTC)

## First Man-made Object in Space

This article first says the first man-made object in space was the V2 rocket in 1942 (under the ballistic missile section). Later (under the Notable unmanned sub-orbital spaceflight title) its says the first suborbital spaceflight was the V2 rocket in 1944? So which was it 1942 or 1944? Thanks! Jlenthe (talk) 21:15, 21 February 2010 (UTC)

## First manned sub-orbital space flight

Is this really worth noting, when the first manned orbital space flight had already occured? — Preceding unsigned comment added by 24.180.55.166 (talk) 01:19, 15 September 2011 (UTC)

## Space gun

Any sources for the statement guns have been used for suborbital flight? I find it hard to believe. Martijn Meijering (talk) 16:10, 23 September 2011 (UTC)

Never mind, found a reference. Martijn Meijering (talk) 16:39, 23 September 2011 (UTC)

## Dubious

The list of unmanned suborbital spaceflights currently includes a V-2 strike on London. I do not contest that this flight happened, but AFAIK it never crosssed the Karman line, and thus was not a spaceflight and doesn't belong here. The other V-2 flight listed is known to have crossed the Karman line and does belong, but it did not hit London; it was a test flight. If you have a proof that the London strike did also cross the Karman line, please add a citation. 31.18.251.154 (talk) 23:32, 13 September 2012 (UTC)

## Speed, range, altitude

In the section "Speed, range, altitude", it says, "Note that an intercontinental flight at an altitude of 300 km would require a larger delta-v than that of a LEO." Why is that? Even though I understand many things about physics, including the physics of spaceflight, I don't understand why said statement would be true. Or is it a mistake? If not, it sohuld be explained why.--Solomonfromfinland (talk) 23:30, 17 October 2012 (UTC)

## Factor 2 error

" ${\displaystyle {\text{semi-major axis}}=(1+\sin \theta )R}$ " is wrong, this looks like the whole major axis. - Patrick (talk) 07:26, 25 November 2015 (UTC)

## Gagarin's Vostok 1

The introduction to the present article indicates that Vostok 1 de-orbited before completing an orbit (but says this is still not considered sub-orbital, because it was on an orbital trajectory, i.e. could have completed). However the Vostok 1 article says nothing about this, and indicates a completed orbit; it explicitly mentions that "the landing point is west of the takeoff point because of the Earth's eastward rotation" but does not state the angular displacement achieved in the non-rotating frame (i.e. does not explicitly show that the orbit overlapped itself). How are orbits conventionally counted, or is this controversial? Either way, the two articles should be clear and consistent about this. — Preceding unsigned comment added by 163.1.246.64 (talk) 11:16, 9 February 2016 (UTC)

Ground trace of Gagarin's flight. Note location of retrofire off the western coast of Africa.
You bring up a couple of very good points with which we (WP:WikiProject Spaceflight) need to deal. NASA has developed a very precise terminology, in which an orbit is defined in fixed space; they have always described the Gemini, Apollo, Space Shuttle, and I believe Mercury as well, in revolutions, which take the Earth's rotation into account and are defined as completed when the spacecraft passes over the same longitude where it started. The period of a revolution is thus longer than the period of an orbit, which is complete when the spacecraft passes its starting lattitude. We do not account for this difference in Template:Infobox spaceflight. We should discuss this at Template talk:Infobox spaceflight.
As for Vostok 1, I agree the commonly accepted "fact" it was a complete orbit is not well verified. The map has been shown to be inaccurately drawn.(The "cartoony" drawing was recently fixed. JustinTime55 (talk) 14:51, 22 April 2016 (UTC)) Gagarin obviously made less than a complete revolution, but since his landing site was north of the launch site, one might conclude he completed an orbit. However, his retro-rocket fired to take him out of orbit over the west coast of Africa (about 9° south latitude). Therefore, he technically did not stay in orbit for one complete period. They are playing a bit loose by counting the re-entry path as part of the orbit. We should discuss this at Talk:Vostok 1 and it probably should be explained more clearly there.
That being said, it's not accurate to call Gagarin's flight suborbital either, because a suborbital flight is properly defined as one which doesn't have enough energy to stay in orbit (or complete an orbit that doesn't intersect the ground or its atmospheric entry interface.) JustinTime55 (talk) 15:34, 9 February 2016 (UTC)

## Problematic recent edit

In the autumn of 1945, the group M. Tikhonravov K. and N. G. Chernysheva at NII-4 rocket artillery Academy of Sciences technology on its own initiative the first stratospheric rocket project was developed by BP-190 (ru) for vertical flight two pilots to an altitude of 200 km based on captured German ballistic rocket V-2[1].

There are (at least) two things wrong with this edit:

• Occuring in 1945, it does not belong in the Tourist flights section
• Does not at all conform to standard English grammar, which makes it hard to read.

I have moved it here for discussion, rather than deleting it outright. JustinTime55 (talk) 14:45, 22 April 2016 (UTC)

1. ^ Anatoli I. Kiselev; Alexander A. Medvedev; Valery A. Menshikov (December 2012). Astronautics: Summary and Prospects. Translated by V. Sherbakov, N. Novichkov, A. Nechaev. Springer Science & Business Media. pp. 1–2. ISBN 9783709106488.