navigation of spaceships

I wonder how did they calculate the travel plan of the Mars Rover? or any
spaceships?

how did they hit the target with such precision after travelling months or
years from millions of miles away? there must be a formula, yes? they
must have a piece of computer program that does the calculation? Is the
source code in public domain? I want to learn how they do it.

thank you
-kc

"KC" wrote in message
news:fn7Kb.223348$8y1.911937@attbi_s52...
|
| there must be a formula, yes?

Many of them. Orbital mechanics is a rich science. A good beginner's text
is "Fundamentals of Astrodynamics" by Roger Bate.

| Is the source code in public domain?

The current rover's code likely is not, but there are quite a few orbital
mechanics software toolkits available.

http://cdeagle.tripod.com/omcdrom1.html


--
|
The universe is not required to conform | Jay Windley
to the expectations of the ignorant. | webmaster @ clavius.org

"KC" wrote in message
news:fn7Kb.223348$8y1.911937@attbi_s52...
I wonder how did they calculate the travel plan of the Mars Rover? or any
spaceships?

how did they hit the target with such precision after travelling months or
years from millions of miles away? there must be a formula, yes? they
must have a piece of computer program that does the calculation? Is the
source code in public domain? I want to learn how they do it.

Once the type of transfer orbit is decided upon, the approximate
times of launch and entry into the transfer orbit can be determined
by the known locations of the planets over time. There are usually
short "launch windows" that occur when the planets will be situated
advantageously (you wouldn't want the spacecraft to arrive at its
destination only to find that the target planet wasn't there, and
you'd like to choose a time when the total distance traveled is
minimized).

The lowest energy practical transfer orbit is known as a Hohmann
Transfer. You can look that up.

Once the approximate times are evaluated, it requires precise
computer modeling to pin down the details. The model has to
take into account the perturbations caused by all of the various
bodies of the solar system acting on the spacecraft as it travels.
Nasa, for example, has very accurate ephemerides of the planets
and other solar system bodies which it calculates. You can look
up DE200, DE405, and DE406, for example.

With the accurate positions of the planets given for any point
in time, an accurate model of possible spacecraft trajectories
can be had by way of numerical simulations using what are called
orbit integration codes. These are similar to the codes that
provided the planetary ephemerides in the first place. It may
take a great many test runs to determine the optimum trajectory
that uses the minimum fuel and number of course corrections.

Fancy trajectories can employ gravitational assist maneuvers, where
some energy is "stolen" from a planet to give a boost to the
spacecraft without expending a lot of fuel. Again, approximate
calculations can be done by hand, but it takes computer
simulation to pin down the specifics.

If you're interested in the tinkering with orbits and such on
your computer, you might be interested in The Orrery newsletter.
A number of like-minded individuals subscribe:

http://members.attcanada.ca/~gneill/

It's a question that I've pondered.

I suppose the secret is in the ability to finely tune rocket thrust/burn
duration.

I've heard that a moon shot is analogous to a dart player throwing at a
dartboard which is
swinging like a pendulum, whilst the player rotates quickly. I suppose a
shot to Mars
would require the player to do somersaults as well !

People may look upon the Beagle mission as a failure. Considering the
distance
and the accuracy required, I don't. :-)

The apparent lack of communication is a technical hitch. That's all.


"KC" wrote in message
news:fn7Kb.223348$8y1.911937@attbi_s52...
I wonder how did they calculate the travel plan of the Mars Rover? or any
spaceships?

how did they hit the target with such precision after travelling months or
years from millions of miles away? there must be a formula, yes? they
must have a piece of computer program that does the calculation? Is the
source code in public domain? I want to learn how they do it.

thank you
-kc

Grunt wrote:
It's a question that I've pondered.

I suppose the secret is in the ability to finely tune rocket
thrust/burn duration.

I've heard that a moon shot is analogous to a dart player throwing at
a dartboard which is
swinging like a pendulum, whilst the player rotates quickly. I
suppose a shot to Mars
would require the player to do somersaults as well !

People may look upon the Beagle mission as a failure. Considering the
distance
and the accuracy required, I don't. :-)

Now *that's* the way we should be thinking! I mean, they *did* get it to
Mars! Besides, something can and should be learned even from failures, looks
like NASA learned their lesson from 1999 well :-)


The apparent lack of communication is a technical hitch. That's all.

--
The butler did it.