[FPSPACE] Dual Orion capsules studied for manned asteroid missions

Tue Aug 25 12:18:20 EDT 2009

 Very well, back in 1998 Bill Bottke wrote the following
 about such rubble piles:

 "There is no easy way to determine the internal makeup of
 an asteroid. Remote sensing techniques can, at best, only
 probe the top layers of an asteroid's surface. More elaborate
 methods, such as deep core drilling and sample return,
 staging and observing a moderate-sized impact event, or
 setting up an in situ network of seismometers, could provide
 more diagnostic information, but they would require spacecraft
 funded at a level comparable to or higher than NASA's current
 generation of Discovery-class missions." 

 As I see it, the higher one rates the probability that Apophis
 is indeed a rubble pile, the more urgent one would necessarily
 judge the call for a transponder mission to ascertain both its
 orbit and makeup, since a rubble pile leaves us with only light
 tools - such as the VASIMR ion engine - to avert a collision,
 should Apophis in 2029 be bound to enter the 600m wide keyhole
 leading to a 2036 direct hit over North America. 

--
Jens Kieffer-Olsen
Slagelse, Denmark

> -----Original Message-----
> From: Michael K. Heney [mailto:mike at heney.net] 
> Sent: Monday, August 24, 2009 3:47 PM
> 
> er - 21,000,000 tonnes - dropped a set of zeroes.
> 
> 21,000,000 tonnes - asteroid
>     156,000 tonnes - supertanker
> 
> On Mon, 24 Aug 2009, Michael K. Heney wrote:
> 
> >
> > Hmmm - interesting. The mass of Apophis (per Wikipeda) is 
> > 21,000 tonnes - or 
> > about 150 times the mass of that supertanker.  Sounds like 
> > imparting 
> > non-trivial delta-V is not an unreasonable proposition - 
> > assuming the rock is not a rubble pile ...
> >
> >
> > On Mon, 24 Aug 2009, Jens Kieffer-Olsen wrote:
> >
> >>  Although Apophis is very much more massive than Messenger
> >>  its orbit needs less change to enter Earth orbit than does that
> >>  spacecraft to enter orbit around Mercury.
> >>
> >>  In both cases the bulk of the change will stem from slingshot
> >>  effects, whereas nudging is merely the mechanism to fine-tune
> >>  the slingshots.
> >>
> >>  The size of planets makes the difference in size between Messenger
> >>  and Apophis unimportant. Just as Larry Ellison's yacht Rising Sun
> >>  and the world's largest container ship Emma Maersk ( with a
> >>  deadweight of 156,000 tonnes ) obey the same principles of
> >>  hydromechanics.
> >>
> >>  The 2029 pass of Apophis within GEO distance provides a strong,
> >>  natural slingshot effect. Just as there exists a 
> so-called 'keyhole'
> >>  passing through which in 2029 Apophis will be able to target Earth
> >>  for a direct hit in 2036, other keyholes exist that will 
> permit Apophis
> >>  to repeat its close encounters with Earth in later years, and thus
> >>  allow us to plan a chain of slingshots, just like Messenger goes
> >>  through a series of such.
> >>
> >>  Attaching ion engines to Apophis well before 2029 will enable the
> >>  desired fine-tuning of the pass, directing the asteroid through a
> >>  pre-calculated keyhole. The exercise is similar to the deflection
> >>  required, if we wanted instead to prevent Apophis from passing
> >>  through the keyhole causing a 2026 collision.
> >>
> >>  --
> >>  Jens Kieffer-Olsen
> >>  Slagelse, Denmark
> >> 
> >>
> >>  -----Original Message-----
> >>  From: Michael K. Heney [mailto:mike at heney.net]
> >>  Sent: Sunday, August 23, 2009 4:44 PM
> >>
> >>  Take a look at J002E3 - initially thought to be a NEO 
> when discovered in
> >>  September 2002, it turned out to be the S-IVB from Apollo 
> 12.  The stage
> >>  entered a heliocentric orbit after sending Apollo 12 on 
> its way to the
> >>  moon; in 2002, it was recaptured into a chaotic orbit as 
> it passed near
> >>  the Earth-Sun L1 point; it was ejected back into 
> heliocentric orbit in
> >>  July 2003, and may do it again sometime in the 2030-2040 
> timeframe...
> >>
> >>  So, nudging Apophis (an exercise left to the reader...) 
> to interact with
> >>  the L1 (or L2 point) for capture into an unstable orbit, 
> and then tweaking
> >>  that orbit to something more stable would do the trick.
> >>
> >>  Of course, there IS a wee difference in situations 
> (ignoring mass) ...
> >>  The S-IVB is in an earth-grazing orbit - with an eccentricity only
> >>  slightly different than Earth's.  It approaches gently, 
> on a tangent to
> >>  the L-1 point.  Apophis is an Earth-crossing asteroid, with an
> >>  eccentricity of about .19 - it's movin' on through as it 
> approaches Earth.
> >>  You'd want to bump it's aphelion down from 1.1 AU to 
> closer to 1, raise
> >>  the perihelion from .75 to something much closer to 1, 
> and do it in such a
> >>  way so that it still ends up near the Earth so it can be captured.
> >>
> >>  That's a lot of noodging on a good-sized (350m) rock ...
> >> 
> >>
> >>  On Fri, 21 Aug 2009, David R. Woods wrote:
> >> 
> >> >  Jens,
> >> > 
> >> >  Do you know of any references that describe how that 
> capture process 
> >> >  could
> >>  take place?
> >> >  Typically, with conservation of momentum, there is too 
> much energy for
> >>  something to be captured
> >> >  if it comes in from beyond Earth's gravitational well.  
> I could see a
> >>  sling shot maneuver using
> >> >  the Moon to somehow put it into a retrograde orbit, but 
> that seems 
> >> >  bazaar
> >>  and dangerous if you
> >> >  did not get it exactly right.
> >> > 
> >> >  Dave
> >> > 
> >> >  -------- Original Message --------
> >> >  Subject:
> >> >  Re: [FPSPACE] Dual Orion capsules studied for manned 
> asteroid missions
> >> >  Date:
> >> >  Fri, 21 Aug 2009 21:58:17 +0200
> >> >  From:
> >> >  Jens Kieffer-Olsen <dstdba at post4.tele.dk>
> >> >  Reply-To:
> >> >  dstdba at post4.tele.dk
> >> >  Organization:
> >> >  Indian Red
> >> >  To:
> >> >  <fpspace at friends-partners.org>
> >> > 
> >> >  <snip>
> >> > 
> >> >  Only by knowing the precise orbit of Apophis
> >> >  can the necessary combination of nudges and slingshots 
> be calculated 
> >> >  that
> >>  will eventually
> >> >  deliver the asteroid into GEO.
> >> > 
> >> >  <snip>
> >> >  Jens Kieffer-Olsen
> >> >  Slagelse, Denmark
> >> > 
> >> > 
> >> 
> >> 
> >> 
> >