Statement by Pete Worden, Peterson AFB, CO, July 10, 2002
MILITARY PERSPECTIVES ON THE NEAR-EARTH OBJECT (NEO) THREAT
"
There is an interesting concept to consider. If we can find the
right small object in the right orbit we might be able to nudge it
into an orbit "captured" by the earth. This would make a NEO a
second natural satellite of earth. Indeed, there is at least one NEO
that is close to being trapped by the Earth now, 2002 AA29. If such
an object were more permanently in earth orbit it could not only be
more closely studied but might form the basis for long-term
commercial exploitation of space. Moreover, a very interesting next
Ron
Greetings,
There is another near-earth asteroid, 3753 Cruithne, which is closer to
being a natural satellite of Earth. It orbits the Sun with the same average
period as Earth does, and Earth's mass perturbs its orbit, but it does not
directly orbit Earth. There are many web sites, for example,
www.astro.queensu.ca/~wiegert/3753/3753.html, where you can find more about
it. Search for Cruithne on Google.com for the others.
I believe it would be cheaper to use the Moon than to change the orbits
of these objects, though. And the Moon has plenty of mass and water (ice,
at the poles). Just staying on less massive objects would be a problem,
where if one kicked up some dust, owing to the low gravity, it would take
months to "settle out".
Cheers, Jay Huebner
MILITARY PERSPECTIVES ON THE NEAR-EARTH OBJECT (NEO) THREAT
"
There is an interesting concept to consider. If we can find the
right small object in the right orbit we might be able to nudge it
into an orbit "captured" by the earth. This would make a NEO a
second natural satellite of earth. Indeed, there is at least one NEO
that is close to being trapped by the Earth now, 2002 AA29. If such
an object were more permanently in earth orbit it could not only be
more closely studied but might form the basis for long-term
commercial exploitation of space. Moreover, a very interesting next
"
Ron
>
> Greetings,
> There is another near-earth asteroid, 3753 Cruithne, which
> is closer to
> being a natural satellite of Earth. It orbits the Sun with
> the same average
> period as Earth does, and Earth's mass perturbs its orbit,
> but it does not
> directly orbit Earth. There are many web sites, for example,
> www.astro.queensu.ca/~wiegert/3753/3753.html, where you can
> find more about
> it. Search for Cruithne on Google.com for the others.
mean that transitioning it to become a true satellite - or targetting it
with any kind of return mission - would be easy. It might be (given the
chaotic nature of the orbit); but i wouldn't bet on it. 2002 AA29 - which
has interested me ever since it's discovery was annouced earlier this year -
makes six monthly returns to terrestrial space; never gets very far away
from the Earth even at apogee; & has a very small relative velocity - if it
wasn't so (apprently) large, i think a lot of people would assume that it
was just a bit of space flipping round, taunting us.
> I believe it would be cheaper to use the Moon than to
> change the orbits
> of these objects, though.
Don't need it: you just use a lot of very precisely designed corrections; &
the mass of the Earth itself will do a lot of the work. 2002 AA29 is
apparently transitioning in (or out) of a temporary Earth orbit already; so
the job is already half done. It currently appears to be one of the best
targets for a cost effective manned miision beyond Earth orbit,a s Pete
Worden notes in his piece.
> And the Moon has plenty of mass
> and water (ice,
> at the poles). Just staying on less massive objects would be
> a problem,
> where if one kicked up some dust, owing to the low gravity,
> it would take
> months to "settle out".
Very definitely an unproven, on several levels. Dust wasn't any kind of
issue for the NEAR landing; & given that electromagnetic forces are likely
to have a greater influence on particulate matter in microgravity
environments like this, any models based on gravitational action are likely
to be wrong. Anyway: given that this >is< a microgravity environment, it
will be easy to move above the surface without significantly throwing up
dust. Swimming (ie, floating above the surface, using your hands to pull
yourself along in a swimming-style motion) should be feasible; maximising
directional control & minimise surface disturbance.
Live in peace
Robert.Clements@...
endeavour2 project http://www.geocities.com/robtclements/endeavour2.html>
I am confused by your message. I am not sure what you think is unproven.
Dust was a terrible problem for the joints in the space suits on early
Apollo missions to the Moon. Also electrostatic charges on dust particles,
apparently from solar UV ionizing the dust (driving electrons off), keeps
some dust suspended above the lunar surface. This must be happening also
for all other bodies with regolith and without atmospheres in the inner
solar system.
NEAR landed on Eros, but did nothing after that, so how could dust have
been a problem for it?
Swimming in the vacuum of space is not likely to do anything but give the
swimmer some exercise. It won't propel them.
And then there is the issue of water, which you didn't respond to.
I also think potential investors would like investing in projects on the
Moon so they would at least know where their investments were.
Sincerely, Jay Huebner
> Greetings,
> There is another near-earth asteroid, 3753 Cruithne, which
> is closer to
> being a natural satellite of Earth. It orbits the Sun with
> the same average
> period as Earth does, and Earth's mass perturbs its orbit,
> but it does not
> directly orbit Earth. There are many web sites, for example,
> www.astro.queensu.ca/~wiegert/3753/3753.html, where you can
> find more about
> it. Search for Cruithne on Google.com for the others.
Cruithne is temporarily a mathematical satellite of Earth; but that doesn't
mean that transitioning it to become a true satellite - or targetting it
with any kind of return mission - would be easy. It might be (given the
chaotic nature of the orbit); but i wouldn't bet on it. 2002 AA29 - which
has interested me ever since it's discovery was annouced earlier this year -
makes six monthly returns to terrestrial space; never gets very far away
from the Earth even at apogee; & has a very small relative velocity - if it
wasn't so (apprently) large, i think a lot of people would assume that it
was just a bit of space flipping round, taunting us.
> I believe it would be cheaper to use the Moon than to
> change the orbits
> of these objects, though.
Don't need it: you just use a lot of very precisely designed corrections; &
the mass of the Earth itself will do a lot of the work. 2002 AA29 is
apparently transitioning in (or out) of a temporary Earth orbit already; so
the job is already half done. It currently appears to be one of the best
targets for a cost effective manned miision beyond Earth orbit,a s Pete
Worden notes in his piece.
> And the Moon has plenty of mass
> and water (ice,
> at the poles). Just staying on less massive objects would be
> a problem,
> where if one kicked up some dust, owing to the low gravity,
> it would take
> months to "settle out".
Very definitely an unproven, on several levels. Dust wasn't any kind of
issue for the NEAR landing; & given that electromagnetic forces are likely
to have a greater influence on particulate matter in microgravity
environments like this, any models based on gravitational action are likely
to be wrong. Anyway: given that this >is< a microgravity environment, it
will be easy to move above the surface without significantly throwing up
dust. Swimming (ie, floating above the surface, using your hands to pull
yourself along in a swimming-style motion) should be feasible; maximising
directional control & minimise surface disturbance.
Live in peace
Robert.Clements@...
endeavour2 project http://www.geocities.com/robtclements/endeavour2.html>
> I believe it would be cheaper to use the Moon than to change the orbits
> of these objects, though.
the orbit of the whole body, you can almost certainly chip
bits off. So what could you use it for?
Well, ISS could do with a radiation shield for one thing.
Some rock could do that nicely. The delta-v to return that
to LEO is probably <100m/s per second with a bit of luck.
Getting stuff from the moon needs atleast 2.5 km/s. That's a
huge, huge difference. The space junk people would have
kittens though ;-)
Second, if the rock could be used in any way to provide
propellent, the ISS could be reboosted up into a higher orbit-
it wouldn't take much and then it would never decay- the
reason they don't do that now? a) Not enough fuel b) the
Van Allen belts- oh look we just solved that one already
;-)
Actually come to think of it- using a tether to lower
the rock down towards the earth is one way to reboost the ISS.
>
> I am confused by your message. I am not sure what you
> think is unproven.
> Dust was a terrible problem for the joints in the space suits on early
> Apollo missions to the Moon. Also electrostatic charges on
> dust particles,
> apparently from solar UV ionizing the dust (driving electrons
> off), keeps
> some dust suspended above the lunar surface. This must be
> happening also
> for all other bodies with regolith and without atmospheres in
> the inner
> solar system.
phenomenom) will be a problem on all worlds; but what you were claiming
(without any evidence to back your position up) was that this problem would
be worse on microgravity bodies like 2002 AA29. It's possible that you're
right; but the only evidence we have to date (the NEAR landing) doesn't
support your case - when we have more data on the issue (from MUSES-C on the
first level; & perhaps some of the ESA, NASA & PRC asteroid recon missions
currently under study - despite the valuable data that its multiple flybys
will add to our knowledge, Dawn won't help us on this one), we'll know for
sure; but at this point, you can't argue that it will necessarily be a
threat.
> NEAR landed on Eros, but did nothing after that, so how
> could dust have
> been a problem for it?
It wasn't a problem; but more importantly, it didn't detect this great cloud
of swirling dust you believe will derail any mission. True: had it followed
the backup plan of taking off & again & making a second landing, we might
have found something closer to your picture of the surface; but on one
landing it didn't happen.
> Swimming in the vacuum of space is not likely to do
> anything but give the
> swimmer some exercise. It won't propel them.
You use your hands to push against the surface, as you would in any other
microgravity environment. I admit that swimming is probably not the best
analogy i could have used (it's more accurately a slow frog's leap); but
you'll move (slowly, admittedly; but the opposite is uncontrollable leaps,
because your legs are two powerful for the environment). People forget that
these objects have so little directional gravity that they basically are a
microgravity environment.
> And then there is the issue of water, which you didn't respond to.
Not relevant, unless you choose an asteroid without water. Carbonaceous &
icy asteroids are swimming in the stuff (if you pardon the expression);
although closed loop life support could send people to & from plenty of NEAs
without the need for in situ supplies. More accurately, though, the polar
areas of the Moon has plenty of H ions (>not< necessarily water; although
there is enough O in the lunra rocks that water could be developed if you
could successfully mine the H ions) - something i chose not to stress last
time.
> I also think potential investors would like investing in
> projects on the
> Moon so they would at least know where their investments were.
Having dealt with space investors in the past, i know that the last thing
they are concerned about is orbital mechanics - they're interested in
internal rates of return; competitive product; & cost minimisation... which
explains why discussions with space investors tend to be very short. As
such, what investors think really doesn't have much relevance to anything
related to human flights beyond LEO in the near term; because none of the
three essentials apply to any of the get-rich-slow schemes sometimes
described as space business opportunities.
Live in peace
Robert.Clements@...
endeavour2 project http://www.geocities.com/robtclements/endeavour2.html>
See attached note from baalke@...
baalke@...
10/21/02 01:52 PM
Please respond to neo-owner
http://news.bbc.co.uk/1/hi/sci/tech/2347663.stm
Earth's little brother found
The asteroid was found almost by accident
By Dr David Whitehouse
BBC News
October 21, 2002
Astronomers have discovered the first object ever that is in a companion
orbit
to the Earth.
Asteroid 2002 AA29 is only about 100 metres wide and never comes closer
than 3.6 million miles to our planet.
But it shares the Earth's orbit around the Sun, at first on one side of
the Earth
and then escaping to travel along our planet's path around the Sun until
it
encounters the Earth from the other side. Then it goes back again.
Researchers are speculating that 2002 AA29 could be visited by astronauts
or
used to understand the threat to our planet posed by such rocks from
space.
Analysis of 2002 AA29's motions have revealed a remarkable event that
happens to it every few thousand years.
In 550AD, and again in 2600AD and 3880AD, for a while it will become a
true satellite of our planet, in effect Earth's second moon, although
technically it will remain under the gravitational control of the Sun.
It remains a second moon to Earth for about 50 years until it escapes.
Full story here:
http://news.bbc.co.uk/1/hi/sci/tech/2347663.stm
rmenich@...
07/18/02 05:45 PM
Statement by Pete Worden, Peterson AFB, CO, July 10, 2002
MILITARY PERSPECTIVES ON THE NEAR-EARTH OBJECT (NEO) THREAT
"
There is an interesting concept to consider. If we can find the
right small object in the right orbit we might be able to nudge it
into an orbit "captured" by the earth. This would make a NEO a
second natural satellite of earth. Indeed, there is at least one NEO
that is close to being trapped by the Earth now, 2002 AA29. If such
an object were more permanently in earth orbit it could not only be
more closely studied but might form the basis for long-term
commercial exploitation of space. Moreover, a very interesting next
"
Ron