<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD><TITLE>RE: [Sis-csi] Limit of Cislunar domain</TITLE>
<META http-equiv=Content-Type content="text/html; charset=us-ascii">
<META content="MSHTML 6.00.2900.2722" name=GENERATOR>
<STYLE>@font-face {
font-family: Tahoma;
}
@page Section1 {size: 8.5in 11.0in; margin: 1.0in 1.25in 1.0in 1.25in; }
P.MsoNormal {
FONT-SIZE: 12pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Times New Roman"
}
LI.MsoNormal {
FONT-SIZE: 12pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Times New Roman"
}
DIV.MsoNormal {
FONT-SIZE: 12pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Times New Roman"
}
A:link {
COLOR: blue; TEXT-DECORATION: underline
}
SPAN.MsoHyperlink {
COLOR: blue; TEXT-DECORATION: underline
}
A:visited {
COLOR: blue; TEXT-DECORATION: underline
}
SPAN.MsoHyperlinkFollowed {
COLOR: blue; TEXT-DECORATION: underline
}
P {
FONT-SIZE: 12pt; MARGIN-LEFT: 0in; MARGIN-RIGHT: 0in; FONT-FAMILY: "Times New Roman"
}
SPAN.EmailStyle18 {
COLOR: navy; FONT-FAMILY: Arial
}
DIV.Section1 {
page: Section1
}
</STYLE>
</HEAD>
<BODY lang=EN-US vLink=blue link=blue>
<DIV dir=ltr align=left><SPAN class=352005603-10102005><FONT face=Arial
color=#0000ff size=2>Mike -</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=352005603-10102005><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=352005603-10102005><FONT face=Arial
color=#0000ff size=2>The thinking at Earth-Moon L2 is to use a halo orbit that
keeps Earth in view at the same time it provides coverage to the lunar
far-side. There are a number of these orbits studied within Exploration as
well as in the SCAWG. No decision has been made whether or not to use the
L2 halo orbit, but its a nice option to have in your
pocket...</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=352005603-10102005><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=352005603-10102005><FONT face=Arial
color=#0000ff size=2>- Jason</FONT></SPAN></DIV>
<DIV> </DIV>
<DIV align=left><FONT face=Arial
size=2>____________________________________________</FONT></DIV>
<DIV align=left><FONT face=Arial size=2>"It's kind of fun to do the impossible."
- Walt Disney</FONT></DIV>
<DIV align=left><FONT face=Arial size=2></FONT> </DIV>
<DIV align=left><FONT face=Arial size=2>Jason A. Soloff</FONT></DIV>
<DIV align=left><FONT face=Arial size=2>Chief Engineer</FONT></DIV>
<DIV align=left><FONT face=Arial size=2>Exploration Communication &
Navigation Systems</FONT></DIV>
<DIV align=left><FONT face=Arial size=2>Constellation Systems</FONT></DIV>
<DIV align=left><FONT face=Arial size=2></FONT> </DIV>
<DIV align=left><FONT face=Arial size=2>NASA / Goddard Space Flight
Center</FONT></DIV>
<DIV align=left><FONT face=Arial size=2>Code 567 / B19 / S046</FONT></DIV>
<DIV align=left><FONT face=Arial size=2>Greenbelt, MD 20771</FONT></DIV>
<DIV align=left><FONT face=Arial size=2></FONT> </DIV>
<DIV align=left><FONT face=Arial size=2>Phone: (301)286-1368</FONT></DIV>
<DIV align=left><FONT face=Arial size=2>Blackberry: (301)356-3708</FONT></DIV>
<DIV align=left><FONT face=Arial size=2>Fax: (301)286-1750</FONT></DIV>
<DIV align=left><FONT face=Arial size=2>E-Mail: <A
href="mailto:Jason.A.Soloff@nasa.gov">Jason.A.Soloff@nasa.gov</A></FONT></DIV>
<DIV align=left><FONT face=Arial size=2></FONT> </DIV>
<DIV> </DIV><BR>
<BLOCKQUOTE dir=ltr
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid; MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> sis-csi-bounces@mailman.ccsds.org
[mailto:sis-csi-bounces@mailman.ccsds.org] <B>On Behalf Of </B>Kearney,
Mike<BR><B>Sent:</B> Sunday, October 09, 2005 9:18 AM<BR><B>To:</B>
sis-csi@mailman.ccsds.org<BR><B>Subject:</B> RE: [Sis-csi] Limit of Cislunar
domain<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV class=Section1>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">I was thinking the
implication was that if L2 is on the far side, it’s not in line-of-sight of
earth. I think that’s the reason radio telescope projects have been
talked about for L2, because the moon shields them from earth’s RF noise.
And if the comm relay at L2 is not in RF line-of-sight, then another
relay would be needed anyway. But I’m not a celestial mechanics guy, I’m
just going from diagrams I’ve seen. </SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">In any case, I think
it’s safe to say that lunar missions could have some TBD elements at L2, hence
extending our definition of Cislunar to that point. </SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">But another source
says that L2 is 92,000 Km past the moon.</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><A
href="http://www.projectpluto.com/interest.htm">http://www.projectpluto.com/interest.htm</A></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">The earth-moon
distance is 385,000 Km, and the round trip time delay for earth-moon is 2.5
sec, I would think that the L2 round trip time would be only 3.5 sec or
so. Not the 10 sec in your table. </SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">385+92= 477,000 Km
for earth-moon L2, not the 1,500,000 Km that you listed. I wonder if you
got the distance for earth-sun L2 instead of earth-moon L2?
</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">I’m still confused
about who wrote this table up to begin with. Was it Chris or Keith
(Hogie)? It’s a great way to define the cislunar domain, IMHO, anyway.
</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<DIV>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"> -=-
Mike</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Mike
Kearney</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">NASA MSFC
EO-01</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">256-544-2029</SPAN></FONT></P></DIV>
<DIV>
<DIV class=MsoNormal style="TEXT-ALIGN: center" align=center><FONT
face="Times New Roman" size=3><SPAN style="FONT-SIZE: 12pt">
<HR tabIndex=-1 align=center width="100%" SIZE=2>
</SPAN></FONT></DIV>
<P class=MsoNormal><B><FONT face=Tahoma size=2><SPAN
style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Tahoma">From:</SPAN></FONT></B><FONT
face=Tahoma size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma">
Krupiarz, Christopher [mailto:Christopher.Krupiarz@jhuapl.edu] <BR><B><SPAN
style="FONT-WEIGHT: bold">Sent:</SPAN></B> Saturday, October 08, 2005 10:15
PM<BR><B><SPAN style="FONT-WEIGHT: bold">To:</SPAN></B> Kearney, Mike;
sis-csi@mailman.ccsds.org<BR><B><SPAN
style="FONT-WEIGHT: bold">Subject:</SPAN></B> RE: [Sis-csi] Limit of Cislunar
domain</SPAN></FONT></P></DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"></SPAN></FONT> </P>
<P style="MARGIN-BOTTOM: 12pt"><FONT face="Times New Roman" size=2><SPAN
style="FONT-SIZE: 10pt">Mike,<BR><BR>L2 being on the far side of the Moon is
what makes it nice as a comm relay for assets that are also on the far
side. I'm not sure about L4 and L5, but I'm with you about not being
confident in my knowledge of how these points could be used. Off-hand if
you're using relays to save power/mass on a lander, it would seem using L4
& L5 wouldn't help much. However, L4 & L5 would give some
coverage of the far side. <BR><BR>Chris<BR><BR><BR>-----Original
Message-----<BR>From: sis-csi-bounces@mailman.ccsds.org on behalf of Kearney,
Mike<BR>Sent: Sat 10/8/2005 10:10 PM<BR>To:
sis-csi@mailman.ccsds.org<BR>Subject: RE: [Sis-csi] Limit of Cislunar
domain<BR><BR>Keith (Hogie): I was plugging your table below into
section 2...<BR><BR><BR><BR>0000.1 sec - Interaction between rovers, landers,
(e.g. local<BR>environment)<BR>0000.1 sec - Low-Earth orbit ( a few
hundred kilometers one-way)<BR>0000.1 sec - Low-Lunar orbit ( a few hundred
kilometers one-way)<BR>0000.1 sec - Low-Mars orbit ( a few hundred
kilometers one-way)<BR>0000.5 sec - Earth geosync orbit (36,000
kilometers one-way)<BR>0002.5 sec - Earth-to-Moon (384,000 kilometers
one-way)<BR>0010.0 sec - Earth to L1 or L2 (1,500,000 kilometers
one-way)<BR>------------------Limit of Cislunar domain<BR>0366.0 sec - Earth
to Mars (closest = 55.000.000 kilometers one-way, 6<BR>minute, RTT)<BR>2673.0
sec - Earth to Mars (farthest = 401,000,000 kilometers one-way,<BR>45 minute
RTT)<BR><BR><BR><BR>But I started wondering about the usage of L1 and
L2. L1 is closer to<BR>earth than the moon, so it would really not be a
factor in establishing<BR>the boundary of cislunar missions in terms of time
delay. L2 is on the<BR>far side of the moon and wouldn't have much value
for comm relays. Did<BR>you have some other mission in
mind? <BR><BR><BR><BR>In terms of comm relays, I was wondering if L4 or
L5 (preceding or<BR>following the moon in earth orbit) have more value as comm
relays. And<BR>I started wondering if anyone what Exploration was
considering as<BR>possible uses for those Lagrangian points. I'm not
confident in my<BR>understanding, and I just want whatever text that goes into
the Cislunar<BR>GB to be credible. <BR><BR><BR><BR>Anyone have any
insight into that? <BR><BR><BR><BR>I ask the question, because a better
description of what might be done<BR>at the Lagrangian points would help the
"mission characteristics"<BR>section. <BR><BR><BR><BR> -=-
Mike<BR><BR><BR><BR>Mike Kearney<BR><BR>NASA MSFC
EO-01<BR><BR>256-544-2029<BR><BR>________________________________<BR><BR>From:
sis-csi-bounces@mailman.ccsds.org<BR>[<A
href="mailto:sis-csi-bounces@mailman.ccsds.org">mailto:sis-csi-bounces@mailman.ccsds.org</A>]
On Behalf Of Keith Hogie<BR>Sent: Thursday, September 08, 2005 12:55 AM<BR>Cc:
sis-csi@mailman.ccsds.org<BR>Subject: Re: [Sis-csi] IP Header
Compression<BR><BR><BR><BR>Adrian J. Hooke wrote:<BR><BR>At 01:40 PM 9/6/2005,
Keith Hogie wrote:<BR><BR><BR><BR> I agree we need to consider issues
with small packets and low rates,<BR>but how low do we need to go. In
all of the missions I have seen (non<BR>deep space), the lowest data rates are
125 bps. This is over an order<BR>of magnitude difference from your 10
bps. <BR><BR> For the Cislunar environment, we need to figure out
what some of our<BR>limits are. Do we really want to burden the Cislunar
design with issues<BR>that only relate to Deep Space?<BR><BR><BR>Aren't the
Lunar missions supposed to be "training" for going to Mars?<BR>For critical
emergency commanding operations, shouldn't we be developing<BR>a robust,
unified, reliable, tested system that works wherever you go?<BR><BR><BR>
For emergency commanding I don't see any difference between Cislunar<BR>or
Deep Space. In both cases the solution is to send a string of
bits<BR>that gets decoded by hardware and do not need any protocol.
The<BR>critical hardware commands are their own frame sync, authentication,
and<BR>command all packed into a highly unique string of bits. Most
hardware<BR>decoders pick off the bits they are looking at directly from
the<BR>receiver and don't involve any flight software. This means that
there<BR>is no complex packet processing and the hardware is just looking
for<BR>particular sequence of bits. The length of this sequence is not
a<BR>function of any CCSDS or IP headers. Getting the command to
the<BR>spacecraft just requires radiating the proper string of bits.
The<BR>length of the hardware command is just a function of how many bits
you<BR>think you need to make sure your command doesn't occur in normal
data<BR>transfers. <BR><BR> My main concern is for all the other
operational modes there is a very<BR>large disconnect between things that will
work in a Cislunar environment<BR>and a long haul link to Mars. If you
consider the following round trip<BR>times (RTT):<BR><BR>0000.1 sec -
Interaction between rovers, landers, (e.g. local<BR>environment)<BR>0000.1 sec
- Low-Earth orbit ( a few hundred kilometers one-way)<BR>0000.1 sec -
Low-Lunar orbit ( a few hundred kilometers one-way)<BR>0000.1 sec - Low-Mars
orbit ( a few hundred kilometers one-way)<BR>0000.5 sec - Earth
geosync orbit (36,000 kilometers one-way)<BR>0002.5 sec - Earth-to-Moon
(384,000 kilometers one-way)<BR>0010.0 sec - Earth to L1 or L2 (1,500,000
kilometers one-way)<BR>------------------Limit of Cislunar domain<BR>0366.0
sec - Earth to Mars (closest = 55.000.000 kilometers one-way, 6<BR>minute,
RTT)<BR>2673.0 sec - Earth to Mars (farthest = 401,000,000 kilometers
one-way,<BR>45 minute RTT)<BR><BR> When you look at distances like these
there is a huge break between<BR>Cislunar ones and Mars. In the
Cislunar area it is actually possible<BR>to do interactive things like
interactive audio, video, and data access.<BR>You can consider security
protocols that negotiate security details. At<BR>L1 and L2 things get a
bit uncomfortable at 10 seconds RTT but that is<BR>still manageable. At
Lunar distances you can do most anything you do on<BR>Earth. A 2.5
second delay is a bit long for some interactive operations<BR>but it is not
really any longer than what happens when you surf the open<BR>Internet and hit
a bit of congestion. The main point is that out to L1<BR>and L2 you can
actually do interactive operations This also applies to<BR>systems on
Mars and orbiting around Mars. <BR><BR> However, when you move to
the long haul link between Earth and Mars,<BR>the RTT jumps up to over 100 or
1,000 times that of the Earth and Moon.<BR>With a 6 to 45 minute RTT, you
can't carry on an interactive voice or<BR>video conversation and lots of
interactive data access just doesn't<BR>work. On a Earth-to-Mars link
you are forced to shift to an operations<BR>concept of two one-way
links. Operations must shift into email-like<BR>file store-and-forward
or one-way streaming of data. <BR><BR> So I don't see any
real problem with using the same hardware<BR>commanding solution in Cislunar
or Earth-to-Mars scenarios. Some file<BR>store-and-forward and one-way
streaming operations will also work for<BR>both environments. Of course
any acknowledgments on the file-store-and<BR>forward will take lots
longer. <BR><BR> My concern is that other there are lots of
protocols and applications<BR>that will work fine in an interactive Cislunar
environment but just<BR>don't work for Earth-to-Mars. We don't want to
limit our Cislunar<BR>solutions to only those that will also work for
Earth-to-Mars. I think<BR>we need to develop our Cislunar solutions and
then see if any of them<BR>will also work in a Earth-to-Mars
scenario. <BR><BR><BR><BR>----------------------------------------------------------------------<BR>
Keith
Hogie
e-mail: Keith.Hogie@gsfc.nasa.gov<BR> Computer Sciences
Corp. office: 301-794-2999 fax:
301-794-9480<BR> 7700 Hubble Dr.<BR> Lanham-Seabrook, MD
20706 USA 301-286-3203 @
NASA/Goddard<BR>----------------------------------------------------------------------</SPAN></FONT></P></DIV></BLOCKQUOTE></BODY></HTML>