NEA trajectory / relative velocity

Hi Ryan,

So far as I am aware, while there do appear to be literally thousands of
asteroids of various sizes in similar orbit to ours, only 3 of those
that have been found so far, need less delta V to get there and get
back, than our Moon does. This is due not so much to differences in
orbit as differences in orbital velocities. Indeed, some folk have tried
to use this as an argument for forgetting asteroids and going to Mars,
failing to realize that there are indeed many asteroids that need less
delta V to get to than even the Martian moons, let alone Mars itself.

Best wishes, Andy.

Ryan Healey wrote:

> Are you refereing to the dV required to get off this rock?
>
> Because if you are then it is also a problem for the moon and anywhere
> else you
> plan to go, once your in HEO your pretty much right next door in terms
> of dV.
>
> --- andy-nimmo wrote:
> > Hi Al,
> >
> > No argument re your physics, but a major one with your
> interpretation of
> > the result. If Earth's mass is as domininant re the asteroid's mass
> as
> > the Sun's is to ours, then as far as we humans' rocket engineering
> and
> > fuel are concerned the velocity differences will indeed amount to a
> high
> > delta V - even if for general astronomical puposes there may seem
> little
> > difference.
> >
> > Best wishes, Andy.
> >
> > Al Globus wrote:
> >
> > > andy-nimmo wrote:
> > >
> > > > Hi John,
> > > >
> > > > You say, "Quite the contrary: Its orbit is very like ours
> > > (definition
> > > > of NEA). Similar mean distance from the Sun necessarily means
> that
> > > its
> > > > velocity around the Sun is similar to ours around the Sun.
> Hence,
> > > low
> > > > Delta-V requirement." This is simply untrue. For its velocity to
> be
> > > > similar to ours in a similar orbit it would have to have similar
>
> > > mass
> > > > to us, and none of these do.
> > >
> > > What matters is the ratio between the mass of the Sun and the
> object
> > > orbiting about it. If the masses are reasonably similar they each
>
> > > orbit
> > > about.in between them. As long as the sun's mass is sufficiently
> > > dominant, the satellite effectively orbits around the center of
> the
> > > sun
> > > regardless of its mass.
> > >
> > > The equation is: GmM/r^2. So if m <<<< M variations in m don't
> > > matter
> > > much.
> > >
> > > > --
> > >
> > > Al Globus
> > > aglobus@..., (650) 604-4404
> > > http://www.nas.nasa.gov/~globus/home.html
> > >
> > > The dinosaurs weren't spacefaring. We are. I don't think that's an
>
> > > accident.
> > > Maybe we are life's taxi to the stars.
> > >
> > > I think we should:
> > >
> > > 1. Devote half of NASA's budget ($7 billion) to reaching NASA's
> 2020
> > > goal of
> > > reducing launch costs to Low-Earth-Orbit to $220/kg with a 0.01%
> > > failure
> > > rate.
> > > This should enable space tourism. The resulting orbital hotels
> will
> > > need
> > > to
> > > develop efficient orbital life support and other necessary
> > > technologies.
> > >
> > > 2. Build orbital space colonies. The materials in the largest
> asteroid
> > >
> > > are
> > > sufficient for orbital colonies with a combined surface area about
> 500
> > >
> > > times
> > > greater than Earth's. Eros alone could make over ten thousand
> space
> > > colonies,
> > > each with about about 10 square kilometers of 1g living area.
> > >
> > > 3. After a few generations of orbital living, people won't need
> their
> > > colony
> > > to be near Sol. Then small groups of colonies with populations in
> the
> > > tens-of-thousands can set out on multi-decade journeys to nearby
> > > stars.
> > >
> > > Except the launch goals, none of this is even a little bit
> official.
> > >
> > [www.newaydirect.com]
> >
> Service.
> >
[www.debticated.com]