# 14618 byrmenich@... on April 10, 2001, 9:29 a.m.
Member since 2022-08-22
(See attached file: top 50 neas.zip)
I've attached a file 'top 50 neas.zip', which in turn contains 'top 50
neas.xls'. Columns B through V are taken directly from the
Aten/Apollo/Amor close-approach lists at
http://cfa-www.harvard.edu/iau/lists/Unusual.html.
Columns W through AF implement an Earth-to-NEA delta-V calculation, based
on my very rudimentary knowledge of orbital mechanics. I've tried to do a
Hohmann transfer with plane change at the aphelion. I know that there may
be lower energy transfers such as bi-elliptic, but I am not fluent in those
calculations yet. Based on my calculations, I sorted the 1154 objects in
ascending order of column AF "total delta-V", and have retained only the
top 50 in this spreadsheet to minimize the size of the file for the
discussion group.
Does anyone here have enough knowledge to send an updated spreadsheet back
to me with corrected formulas for the minimum energy transfer delta-V? If
so, I thank you in advance. Don't worry about potential gravity assists by
the Moon or other objects, unless it is trivial to do so.
(BTW, already in 2001 there have been what appear to me to be a few low
delta-V discoveries; c.f., 2001 FR85 and 2001 CQ36.)
Ron Menich
# 14619 byRobert.Clements@... on April 11, 2001, 2:59 a.m.
Member since 2022-08-22
>
> (See attached file: top 50 neas.zip)
>
> Hopefully this site accepts small attachments...
the original .xls? We aren't working in quite the fashion you are -
are shortterm goal is flybys - & really shocking the hell out of the
advertising industry - of large, hopefully scientifically interesting
objects; but are keeping our eyes are open for second generation
rendezvous & sample return objects as we do so.
Robert
# 14620 byrmenich@... on April 11, 2001, 7:48 a.m.
Member since 2022-08-22
(See attached file: top 50 neas.xls)
are able to read it now.
I missed quite a few of the Apollo asteroids for some unknown reason
yesterday, so even if you were able to read the version I sent yesterday,
please discard it and use this updated one instead.
I added a column AG for the synodic period of the (Earth,NEA) pair.
As I said, my knowledge of orbital mechanics is rudimentary, so these calcs
are probably not as exact as they could be.
But I think they're fairly reasonable because the following asteroids "in
the news" bubble up to my top 50:
* 1999 AO10 / 2000 AG6 / 1998 UQ, the three targets for the Hera mission
(c.f., http://www.uark.edu/misc/hera/)
* 1998 KY26, imaged via radar and thought to contain water (c.f.,
http://www.academicpress.com/solar/Contents/chap33.htm)
* 2000 SG344, the NEA that might perhaps be a discarded Saturn IVB stage
that failed to impact the Moon (c.f.,
http://www.spacescience.com/headlines/y2000/ast06nov_2.htm)
Ron Menich
Robert.Clements@
AM
Please respond
to ssi_list
>
> (See attached file: top 50 neas.zip)
>
> Hopefully this site accepts small attachments...
The .zip didn't with this network. Is it possible for you to send me
the original .xls? We aren't working in quite the fashion you are -
are shortterm goal is flybys - & really shocking the hell out of the
advertising industry - of large, hopefully scientifically interesting
objects; but are keeping our eyes are open for second generation
rendezvous & sample return objects as we do so.
Robert
# 14621 byrmenich@... on April 11, 2001, 9:38 a.m.
Member since 2022-08-22
Someone requested explanations of terms, units, etc., related to the
spreadsheet:
mu Product of GM for the Sun
_1au Distance of Earth from Sun in meters
v_earth Velocity of Earth in meters/second
r_earth Same as _1au
Sheet 'all!':
Columns B through V See
http://cfa-www.harvard.edu/iau/lists/Unusual.html for more details
Column W, "a_transfer" Semi-major axis of transfer orbit from Earth
to NEA, measured in AU
Column X, "dv_transfer_init" Delta-V required to shift from Earth orbit to
the transfer orbit, in meters/second
Column Y, "v_transfer_term" Velocity in meters/second at aphelion of
transfer orbit
Column Z, "v_aster_term" Velocity in meters/second of asteroid orbit at
aphelion, in m/s
Column AA, "dv_transfer_aph" Delta-V required to more from Earth-to-NEA
transfer orbit to NEA orbit
Column AB, "out of plane" Velocity component of asteroid normal to
ecliptic plane
Column AC, "in plane" Velocity component of asteroid orbit in
ecliptic plane
Column AD, "dv in plane" Difference b/n velocity component of NEA in plane
and orbit of spacecraft
Column AE", dv plane change" Delta-V required to crank orbit from the
ecliptic to the inclination of the NEA
Column AF, "total delta V" Total delta-V required for the three impulses
Column AG, "synodic period" Length of time in years between Hohmann
transfer launch windows
The computation is based on three impulses
1.) Transfer from Earth orbit to Earth-to-NEA transfer orbit
2.) Transfer from Earth-to-NEA transfer orbit to an orbit having the same
q/Q/a/e values as the NEA, at aphelion, but in ecliptic plane.
3.) Plane change to crank orbit from ecliptic plane to inclination of Incl
degrees. Plane change at NEA aphelion.
As I said, there are probably better ways to do this, and that's what I'd
like someone to tell me.
Ron Menich
rmenich@...
08:43 AM
Please
respond to
ssi_list
(See attached file: top 50 neas.xls)
I've attached the Excel (version 97 SR2) file directly. I hope that you
are able to read it now.
I missed quite a few of the Apollo asteroids for some unknown reason
yesterday, so even if you were able to read the version I sent yesterday,
please discard it and use this updated one instead.
I added a column AG for the synodic period of the (Earth,NEA) pair.
As I said, my knowledge of orbital mechanics is rudimentary, so these calcs
are probably not as exact as they could be.
But I think they're fairly reasonable because the following asteroids "in
the news" bubble up to my top 50:
* 1999 AO10 / 2000 AG6 / 1998 UQ, the three targets for the Hera mission
(c.f., http://www.uark.edu/misc/hera/)
* 1998 KY26, imaged via radar and thought to contain water (c.f.,
http://www.academicpress.com/solar/Contents/chap33.htm)
* 2000 SG344, the NEA that might perhaps be a discarded Saturn IVB stage
that failed to impact the Moon (c.f.,
http://www.spacescience.com/headlines/y2000/ast06nov_2.htm)
Ron Menich
Robert.Clements@
ssi_list@...
Delta-V formula
AM
Please respond
to ssi_list
>
> (See attached file: top 50 neas.zip)
>
> Hopefully this site accepts small attachments...
The .zip didn't with this network. Is it possible for you to send me
the original .xls? We aren't working in quite the fashion you are -
are shortterm goal is flybys - & really shocking the hell out of the
advertising industry - of large, hopefully scientifically interesting
objects; but are keeping our eyes are open for second generation
rendezvous & sample return objects as we do so.
Robert
(See attached file: top 50 neas.xls)