Accidental Orion?

Henry Spencer opined


This process can be greatly accelerated, if you want to badly enough. A
salvo of large nuclear explosions at medium-high altitude -- preferably
over some remote area! -- will bulge the Earth's atmosphere upward quite a
bit in that area for an hour or two. Any LEO object passing through the
bulge will be de-orbited.

Somehow I don't think that this plan will go over well with Canadians.


-ash
for assistance dial MYCROFTXXX

In article ,
Timothy McDaniel wrote:
...Any object whose orbit was
last *changed* at a point on Earth's surface will have an orbit that
intersects Earth's surface...

Due to air drag, if a projectile is fired upwards from the surface of
the Earth, the orbit was not last changed at the surface, but rather
in the upper atmosphere. Is that an insignificant factor -- does that
just mean that such an object in a closed orbit will intersect the
upper atmosphere again (and thereby just reenter a little more slowly)?

That's one issue. The other is that the orbit changes introduced while
passing through the upper atmosphere are generally not of a helpful kind.
It's unlikely that a practical design can get substantial lift during such
an ascent -- just staying intact at such velocities is hard enough -- and
drag makes orbits lower, not higher.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |

In article ,
Timothy McDaniel wrote:
Due to air drag, if a projectile is fired upwards from the surface of
the Earth, the orbit was not last changed at the surface, but rather
in the upper atmosphere. Is that an insignificant factor -- does that
just mean that such an object in a closed orbit will intersect the
upper atmosphere again (and thereby just reenter a little more
slowly)?

But you still have the last trajectory change inside the atmosphere,
which means that when you complete the orbit, you'll be back in enough
atmosphere to affect your trajectory again ... earthwards ...

-- don

In article ,
Don Stokes wrote:
In article ,
Timothy McDaniel wrote:
Due to air drag, if a projectile is fired upwards from the surface of
the Earth, the orbit was not last changed at the surface, but rather
in the upper atmosphere. Is that an insignificant factor -- does that
just mean that such an object in a closed orbit will intersect the
upper atmosphere again (and thereby just reenter a little more
slowly)?

But you still have the last trajectory change inside the atmosphere,
which means that when you complete the orbit, you'll be back in enough
atmosphere to affect your trajectory again ... earthwards ...

That's what I said. The last trajectory change was not at the
surface, but rather in the upper atmosphere. So when you complete the
orbit, it'll intersect the upper atmosphere again, and thereby reenter
... earthwards ...

--
Tim McDaniel, ; is my work address

Timothy McDaniel wrote:
In article ,
Don Stokes wrote:
In article ,
Timothy McDaniel wrote:
Due to air drag, if a projectile is fired upwards from the surface of
the Earth, the orbit was not last changed at the surface, but rather
in the upper atmosphere. Is that an insignificant factor -- does that
just mean that such an object in a closed orbit will intersect the
upper atmosphere again (and thereby just reenter a little more
slowly)?

But you still have the last trajectory change inside the atmosphere,
which means that when you complete the orbit, you'll be back in enough
atmosphere to affect your trajectory again ... earthwards ...

That's what I said. The last trajectory change was not at the
surface, but rather in the upper atmosphere. So when you complete the
orbit, it'll intersect the upper atmosphere again, and thereby reenter

There is a special case, if you have "significant" hypersonic lift, and
a bit of extra apogee.
As you'r about to exit the atmosphere, you flatten the trajectory a bit,
and as you come down again, use lift to continue raising perigee.

Repeat until the wings are a net loss.
However, if this can be done lighter than a kick motor is debatable.
Deploying wings in well under a second that have to function well at
mach 30, and take thousands of G on launch well...

In article ,
Ian Stirling wrote:
As you'r about to exit the atmosphere, you flatten the trajectory a bit,
and as you come down again, use lift to continue raising perigee.

You still can't raise the perigee out of the atmosphere that way. The
highest it can ever go is the last altitude where you had significant
lift, which by definition must be within the atmosphere.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |

Henry Spencer wrote:
In article ,
Ian Stirling wrote:
As you'r about to exit the atmosphere, you flatten the trajectory a bit,
and as you come down again, use lift to continue raising perigee.

You still can't raise the perigee out of the atmosphere that way. The
highest it can ever go is the last altitude where you had significant
lift, which by definition must be within the atmosphere.

If you get rid of the wings, this might significantly decrease the
frontal area, and allow a reasonable orbital life (for some things).

It's a tradeoff between the wing size and the size of the kick motor.

The optimal point may of course be with no wings.