Hello Chanrobt,
The most commonly described term for an interplanetary orbit transfer is
"Hohmann transfer orbit"
Walter Hohmann published the details of this method in 1925.
The Hohmann Transfer Orbit from Earth to Mars is an elliptical orbit
with the following characteristics:
- Perihelion (closest to the Sun) is at Earth orbit
- Aphelion (farthest from the Sun) is at Mars orbit
- Launch from Earth to Mars is done so that Mars and the spacecraft
arrive at the same time
- Is an orbit where minimum energy is consumed
There are a number of good references describing transfer orbits and
related issues. Some use additional terms such as "leads the motion of
the target planet" but a phrase like that is used much less frequently
than a "transfer orbit" or "Hohmann transfer orbit".
http://kosmoi.com/Science/Physics/Mechanics/tpecp3.shtml
Scroll down to the third major section titled "Interplanetary
Spacecraft Transfer Orbits" for a text esplanation of transfer orbits.
Uses the phrase "leads..." mentioned above.
http://www.marsacademy.com/traj/traj6.htm
Titled "From Low Earth Orbit to Mars", one of a series of sections
that describe how to get efficiently from Earth to Mars.
http://www.polaris.iastate.edu/EveningStar/Unit6/unit6_sub3.htm
Titled "Launch Windows to Other Planets", has a pair of nice
animations showing a "miss" and a "hit" for spacecraft travel to
another planet. Uses the phrase "when to head in the right direction"
as the general term to decide how to reach the planet.
http://me.queensu.ca/courses/MECH497/CD/htmlmods/orbital/rv/rv.html
Another document on transfer orbits, scroll down to see a description
and formulas to compute the "lead angle".
As mentioned at the start - the more proper term would be Hohmann
Transfer Orbit, but if you need a simple phrase perhaps "lead angle"
would be as good as any.
Search phrases used included:
orbital mechanics leading target
lead transfer orbit
these first two lead me to conclude that "lead" was used in many
different ways without any consistent usage.
Earth to Mars orbit
transfer orbit
Hohmann transfer orbit
This last phrase brought up a focused list of sites - all related to
spacecraft. Note also that even though I did not use
"Hohmann transfer orbit"
as the phrase - this phrase appears on all the sites in the first page.
If you would like some additional references or if the answer is not
clear, please use a clarification request so I can fix the answer.
--Maniac |
Request for Answer Clarification by
chanrobt-ga
on
20 May 2004 16:43 PDT
Thanks. I appreciate this very much.
One question, is there any other word, term, or phrase that sounds
more like what it is defining than "Hohmann transfer orbit" or even
"orbit transfer". But with a little more scientific "spin" than
"leading the target".
I remember from Apollo Project broadcasts that term "trans lunar
injection". You pretty much knew what it meant without translation.
But, it was defintiely not colloquial speech.
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Clarification of Answer by
maniac-ga
on
20 May 2004 17:28 PDT
Hello Chanrobt,
Well, the phrase
"transfer orbit"
would certainly be somewhat descriptive but would require some
additional background just like TLI (Trans Lunar Injection) did back
in the Apollo era. Let's see what a few additional searches brings up.
Hmm. A quick search of trans lunar injection brings up a pretty
interesting series of pages that apparently describe an Apollo
simulator. Look at the list of topics on the left and TLI is just one
of several topics. From the description, TLI basically refers to the
boost phase to set up the transfer orbit (to the Moon) and followed by
Lunar Coast for the coasting duration. Farther down, there is an TEI
(Trans Earth Injection) description that covers the return boost.
That would imply that the phrase
Trans (your destination here) Injection
may be an appropriate for describing the boost to travel to another
planet. A quick search of
"trans vars injection"
finds about 313 references - all describing travel to Mars. However, note that
"trans venus injection"
"trans saturn injection"
did not match any documents and
"trans jupiter injection"
had only one hit so it might not be a term that can be generalized freely.
I also did a check at NASA's Mars Rover site
http://marsrovers.jpl.nasa.gov/mission/timeline.html
where there is a timeline. The phrases used here are terms such as
"launch" (covering all steps up to cruise), or "inject the spacecraft
onto a trajectory to mars". Hmm. Not much here to help your quest. You
may be best with a TLI derivative.
--Maniac
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Request for Answer Clarification by
chanrobt-ga
on
21 May 2004 15:52 PDT
Ian, thanks for your follow-up on the "leading the target" question.
In re-reading your original answer, I found the phrase "lead angle"
which I had missed the first time. That may prove useful.
In any event, I appreciate both your orginal detailed answer and the
informative clarification.
thanks
-robert c.
|
Clarification of Answer by
maniac-ga
on
24 May 2004 09:51 PDT
Hello Chanrobt,
Thanks for the kind words and glad to be of help.
--Maniac
|
