Conference 7.286::space

    There was an article on this last night on Tomorrow's World (a popular
    science program in the UK).
    
    They announced that a British entry had been judged to be highly
    imaginative, in that it managed to fit its solar sail into a cylinder
    4 metres across. Unfortunately, the presenters of this programme
    are not particularly scientifically literate, and they did not give
    much in the way of details. This was the first I had heard of the
    'Mars race', as they called it.
    
    
    Dave Hazel

From: john@minster.york.ac.uk
Newsgroups: sci.space
Subject: Nina and Columbus 500
Date: 23 Mar 90 10:31:50 GMT
Organization: Department of Computer Science, University of York, England
 
    Last night's UK TV `Channel 4 news' carried a report of an entry
for a proposed (unmanned :-)) solar sailing expedition to Mars in 1992
called `Columbus 500' ("In fourteen hundred and ninety two, Columbus
sailed the ocean blue"). The design for a spacecraft called "Nina",
after one of Columbus's ships, was suggested by a group of British
inventors. JPL has reportedly judged it to be the most promising of
the design proposals submitted. The German company Messerschmitt has
apparently expressed interest in building the craft. 
 
    The innovative feature is the shape of Nina's solar sail. It is a
circular fan which wraps up into a toroid, thus solving the problem of
how such a sail can be compactly stored and cleanly deployed by a
spacecraft. The inventor claims that this geometry is original, and
had been prompted by his interest in, and experience with, Origami. 
 
    Does any one have any further information? Where will the group
find a launch vehicle? Funding? What instruments will the space probe
carry? What research has been carried out into the (formidable?)
problems of controlling a solar sail `in flight'?  
--------------------------------------------------------------
John A. Murdie			+44 904 432752
Dept. of Comp. Sci.		ukc!minster!john
University of York
England

From: henry@utzoo.uucp (Henry Spencer)
Newsgroups: sci.space
Subject: Re: Nina and Columbus 500
Date: 25 Mar 90 06:13:08 GMT
Organization: U of Toronto Zoology
 
    In article <638188310.14538@minster.york.ac.uk> john@minster.york.ac.uk 
writes: 

>Does any one have any further information? Where will the
>group find a launch vehicle? Funding? What instruments will
>the space probe carry? What research has been carried out into
>the (formidable?) problems of controlling a solar sail `in flight'?
 
    The Columbus Quincentennial people are trying to organize a solar
sail race, with one entry apiece from the Americas, Europe, and Asia. 
I don't know how the European and Asian entries are being run, but the
Americas entry was meant to be a multi-phase design competition, with
the number of entries being thinned down progressively.  This may get
revised a bit, because apparently the number of actual phase-one
entries was rather less than expected.  (One of the groups that *did*
submit an entry was the Canadian Space Society, which is how I know
something about this... Note, though, that I'm not seriously involved
with the CSS entry and do not speak for the team.) 
 
    Launch vehicles are as yet a murky area.  Last I heard, various
people were willing to offer piggyback launches, but it would really
be best to have a dedicated launch to get the entries above the Van
Allen belts. (Solar sails work poorly at low altitudes, and the main
piggyback-launch opportunity to high orbit gets you into GTO, which
means radiation trouble because of all the Van-Allen-belt passes.)  A
dedicated launch would carry all three entries, probably, but what can
be done with piggybacking is anybody's guess. 
 
    The Q.C. people are providing some modest funding, although
donations and sponsors are expected to play a considerable role.  This
is definitely an amateur, or at least spare-time, effort, with little
or no government funding. 
 
    Apart from, possibly, a small camera, nobody is seriously
considering instruments.  Just controlling the sails will be a
sufficiently large challenge.  This is a competition, not a scientific
mission.  If it were a science mission, it wouldn't be going to Mars - 
that goal was chosen for PR, not science value, in my opinion. 
 
    Research into sail control has been limited; one might even say
minimal. It's a hard problem, especially with relatively unorthodox
designs that haven't been looked at before. 
-- 
    Henry Spencer at U of Toronto Zoology
    uunet!attcan!utzoo!henry henry@zoo.toronto.edu

    the latest issue of new scientist carries an article 24th March pp10
    
    pretty small but at least there is a picture.
    
    Over all I think the idea is pretty good. It'll cause interest and
    maybe lead a return to thinking upwards. If enough small but smart
    things happen around the same time - what with, space tethers, sky
    channel, and what not the PR will flow through into the
    industry in a postive way..
    
    At least it's smarter and more interesting than 12 meter racing. Though
    if Alan Bond still had a dollar to spend he'd be it.
    
    simon
            

From: jackson@ttidcc.tti.com (Dick Jackson)
Newsgroups: sci.space
Subject: Sailing Race to Mars - is it True?
Date: 27 Apr 90 22:58:36 GMT
Organization: Citicorp/TTI, Santa Monica
 
    Some quotes from an article in the March 24 New Scientist magazine:
 
"The British entry for a planned race to Mars has been judged the most
technically advanced and imaginative of entries submitted from around the
world. (The NS mag. is British by the way, in case you couldn't tell :->).
The Columbus 500 Space Sail Cup, for solar-powered spacecraft, will start
in 1992 as a celebration of Columbus's voyage to America 500 years earlier."
 
"Cambridge Consultants Ltd won the approval of the committee organising the
race with a circular sail 250 metres in diameter."
 
"Cambridge Consultants is looking hard for sponsorship. Italy is
determined not to be left out this time - many firms have promised
financial assistance."
 
This is great if true.  Reading between the lines it seems perhaps only
a half baked project.  Does anyone know the scoop?  Especially -- who is
going to launch the sailing craft (the CC sail is said to fold into a
cylinder 4 x 4 meters)?
 
    Dick Jackson

From: henry@utzoo.uucp (Henry Spencer)
Newsgroups: sci.space
Subject: Re: Sailing Race to Mars - is it True?
Date: 28 Apr 90 23:40:34 GMT
Organization: U of Toronto Zoology
 
    In article <12756@ttidca.TTI.COM> jackson@ttidcc.tti.com (Dick
Jackson) writes: 

>This is great if true.  Reading between the lines it seems perhaps only
>a half baked project.  Does anyone know the scoop?
 
It's a real project.  The Columbus Quincentennial Commission is sponsoring
it.  The original plan was to have one entry from each of Europe (where
C.C. started from), Asia (where he thought he was going), and the Americas
(where he actually ended up).  That attractive scheme sort of went down in
flames when Europe submitted more proposals than Asia and the Americas put
together (indeed, the response from both Asia and the Americas was very
disappointing), and I don't know just how it was resolved.
 
I know a little bit about this because one of the Americas proposals is from
a team at the Canadian Space Society who are friends of mine.  (NB, I am
not seriously involved, and do not speak for the team.)
 
>Especially -- who is going to launch the sailing craft...
 
Last I heard, this was still somewhat vague.  Ideal would be a dedicated
donated launch, which could put all the entrants into a high orbit outside
the worst of the Van Allen belts.  Starting from a low orbit is out, there
is too much trouble with air drag.  Starting from GTO is not ideal, because
the sails would make many passes through the Van Allen belts before they
worked their perigees up high enough to avoid them.  Unfortunately, most
opportunities to piggyback on existing non-low-orbit launches involve
comsat launches which end up in GTO.
 
There have been offers of piggybacking for free, and of dedicated launches
for money, but not the right combination yet. :-)  The C.Q.C. has money
for the race, but not an unlimited supply, and it's mostly earmarked to
support sail development.  They'd prefer not to have to buy a launch.
 
There is also a possibility of "extra" entries, because the Italian team,
for one, has its government and its aerospace industries solidly behind
it, and is going ahead independently regardless of what the C.Q.C. does.
They're planning to piggyback on an Ariane launch of an Italian comsat.
-- 
    Henry Spencer at U of Toronto Zoology
    uunet!attcan!utzoo!henry henry@zoo.toronto.edu

From:	DECWRL::"KEVIN@a.CFR.CMU.EDU" 11-JUN-1990 10:40:59.90
To:	space-tech@CS.CMU.EDU 
Subj:	Re: Orbital Mechanics revisited 

> Problems of calculating low-thrust spiraling orbits, particularly in 
> regards to the Moon getting in the way...
 
    This weekend I saw a presentation by the Canadian Solar Sail
Project, discussing among other things the planned orbits.  Solar
sailing is as low-thrust as anything else, such as ion propulsion,
with even more limitations due to the reliance upon sun angle.  They
showed plots of an orbit spiraling up and away from earth (starting
from a 1000km orbit, which they calculate is the minimum needed to
prevent air friction from overcoming solar propulsion), and using the
moon for a gravitational assist.  They aren't certain if they can
control the sail closely enough yet - they would need to get within
~100km for best effect, with a 120m sail, but they're checking on it. 
Apparently using a gravity assist will cut ~20 days off travel time to
Mars.  The Moon is a help, not a hindrance. 
 
    The Canadian project is one of about 14 entrants proposed for the
1992 Columbus memorial Mars race.  There are entrants from MIT
(heliogyro style, very small at 80kg projected weight), Italy (_very_
well funded), I believe John Hopkins has two, although I might be
wrong, Britain has one (the folding of the sail was designed by an
origami expert - 200 meters across), Canada (rated the most
manuverable), etc.. The competition is to race a solar sail ship,
500kg maximum, to Mars. Start is hoped to take place in 1992, only
required payload is a 1kg plaque. 
 
						kwr
 
Internet: kr0u+@andrew.cmu.edu
 

Date: 8 Aug 90 21:10:37 GMT
From: sam.cs.cmu.edu!vac@PT.CS.CMU.EDU  (Vincent Cate)
Subject: Solar Sail References
  
Below are a few references for papers on topics related to solar sails.  
If you know any other such references please post them or send them to 
me or my father.
 
Thanks,
         Vince Cate    vac@cs.cmu.edu
         Henry Cate    hpda!cate@hplabs.hp.com
 
------------------------------------------------------------------
 
Subject: Solar Sail References
From: Henry Cate <cate@hpdblpy.cup.hp.com>
 
>[some stuff deleted]
 
References from World Space Foundation ($25/year membership - P.O.
Box Y, South Pasadena, California 91031)
 
1.  Escape from Planetary Gravitational Fields by Use of Solar Sails
    Norman Sands.  ARS Journal, April 1961, pp 527-533+/-.
    Analytic solution for sub-optimal (but good) algorithm for the
    angle of the sail versus position in orbit.  Used Runge-Katta
    numerical methods for numerical solution.  This is an approximation
    method with error estimation.  It should use less CPU than simple
    simulation - since the steps can be larger at apogee, when the curve
    is open, the orbit is slow.
 
    Good data.  Slight confusion due to angle to sun and angle of sail
    use different reference axis.  Also K is net acceleration of 
    sail * initial orbit / radius of planet.  I think he assumed
    a constant initial orbit radius - but results didn't identify
    what that was - suspect it may be 1000 Km altitude (7300 km r)
 
    Good introduction to the problem of escape from planetary orbit.
    I believe use of velocity angle is superior to use of position
    angle.  (Sands uses position angle - which is easy to work with,
    but not the maximum acceleration from the sail)
 
2.  "Optimum Solar-Sail Interplanetary Trajectories", Carl G. Sauer,Jr.
    Paper 76-792, AIAA/AAS Astrodynamics Conference, San Diego Ca.
    August 1976.
 
    This takes over after escape from a planet - attacks the problem
    with Calculus of Variations.  Provides several examples of trips
    to Mars, Venus, Mercury, and the asteroid Eros.  (departures in the
    1988 time frame)
 
    Equations are also provided, should be a good basis for doing your
    own analysis.
 
3.  "Solar Sail Mission Applications", Jerome L. Wright and Janice M.
    Warmke.  Paper 76-808, AIAA/AAS Astrodynamics Conference, San Diego
    Ca.  August 1976.
 
    This paper describes the JPL/World Space Foundation solar sail and
    extensions to use solar sails to haul cargo to Mars, etc.  There are
    a lot of tables about sizes, mass of sails, cargo mass that would
    be reasonable for both inner planet and outer plant missions.
 
    No math to duplicate the tables.  Refers to Sauer - appears to use
    his optimum trajectory analysis.
 
------------------------------------------------------------------------
Date:          Wed, 8 Aug 1990 16:48:40
From:          LIS USER VAC <LC65@VMA.CC.CMU.EDU>
Subject:       890100 MATHEMATICAL BASIS OF THEORY OF ORBITAL CORREC
To:            VAC%SAM.CS.CMU.EDU@VMA.CC.CMU.EDU
 
 IDNUM     03570708
 TYPE      Journal paper
 DATE      890100
 AUTHOR    Polyakhova, E.N.; Shmyrov, A.S.
 TITLE     Mathematical basis of theory of orbital correction with a solar sail
 SOURCE    Kosmicheske Issledovaniya; vol.27, no.1; Jan.-Feb. 1989; pp. 54-63;
           Translated in:  Cosmic Research; vol.27, no.1; Jan.-Feb. 1989; pp.
           47-54
 SUBJECT   aerospace control; artificial satellites; celestial mechanics;
           optimal control; position control; space vehicles; space vehicles
           orbital correction; correction time optimisation; sail angular
           position variation; control system efficiency; apse line
           orientation; sail pull force; elliptical orbit dimensions; solar
           sail; two-dimensional problem; optimal orbital correction;
           geocentric ecliptic orbit; spacecraft; correctable elements;
           mathematical formulation; nonlinear fourth-order equations;
           controllable system; averaging; small parameter method;
           approximately optimal solution; approximation analytical methods
           Class codes: A9510C; B7610; C3360L; C3120C; C1330
 CODEN     KOISAW; CSCRA7
 ABSTRACT  The two-dimensional problem of optimal orbital correction is
           considered for the geocentric ecliptic orbit of a spacecraft, where
           correction is performed by varying the angular position of a solar
           sail. There are three correctable elements. The correction time is
           optimized, which makes it possible to estimate the efficiency of
           using a solar sail as a control system. The mathematical formulation
           of the problem involves analysis of nonlinear fourth-order equations
           of a controllable system, but a combination of averaging and the
           small parameter method allows for an approximately optimal solution.
           Estimates of the closeness between the optimal and obtained
           solutions serve as the mathematical basis of approximation
           analytical methods for analyzing the problems of sail correction of
           a geocentric orbit. Initial conditions are considered related to the
           orientation of the apse line and the dimensions of the elliptical
           orbit for given restrictions on the pull force of the solar sail
 MISCELLANEOUS
           Treatment: theoretical/mathematical
           Kosm. Issled. (USSR)
           Cosm. Res. (USA)
           Abstract number(s):  A90037629; B90019094; C90019483
           ISSN: 0023-4206
           ISSN: 0010-9525
           U.S.Copyright Clearance Center Code: 0010-9525/89/2701-0047$12.50
           Refs: 8
 
 
Date:          Wed, 8 Aug 1990 16:49:03
From:          LIS USER VAC <LC65@VMA.CC.CMU.EDU>
Subject:       890000 HALO ORBITS FOR SOLAR SAILS-DYNAMICS AND APPLI
To:            VAC%SAM.CS.CMU.EDU@VMA.CC.CMU.EDU
 
 IDNUM     03593027
 TYPE      Journal paper
 DATE      890000
 AUTHOR    McInnes, C.R.; Simmons, J.F.L.
           Dept. of Phys. & Astron., Glasgow Univ., UK
 TITLE     Halo orbits for solar sails-dynamics and applications
 SOURCE    ESA Journal; vol.13, no.3; 1989; pp. 229-34
 SUBJECT   celestial mechanics; solar absorber-convertors; solar sail dynamics;
           corotating reference frame; heliocentric orbit; stationary
           solutions; equations of motion; ecliptic plane; halo orbits;
           inertial frame; interplanetary communications; astronomical
           observations
           Class codes: A8630S; A9510C
 CODEN     ESAJDW
 ABSTRACT  The dynamics of a high-performance solar sail in heliocentric orbit
           are investigated in the context of a co-rotating reference frame
           with an arbitrary angular velocity. In this reference frame,
           stationary solutions are found for the equations of motion out of
           the ecliptic plane, which correspond to halo orbits as viewed from
           an inertial frame. Since the angular velocity of corotation is
           arbitrary, the period of the halo orbit may be chosen at will. Such
           halo orbits may have wide applications for interplanetary
           communications and for astronomical observations
 MISCELLANEOUS
           Treatment: theoretical/mathematical
           ESA J. (Netherlands)
           Abstract number(s):  A90056894
           ISSN: 0379-2285
           Refs: 5
 
 
Date:          Wed, 8 Aug 1990 16:49:18
From:          LIS USER VAC <LC65@VMA.CC.CMU.EDU>
Subject:       891100 THE HOLLOW BODY SOLAR SAIL
To:            VAC%SAM.CS.CMU.EDU@VMA.CC.CMU.EDU
 
 IDNUM     03583445
 TYPE      Journal paper
 DATE      891100
 AUTHOR    Strobl, J.
 TITLE     The hollow body solar sail
 SOURCE    Journal of the British Interplanetary Society; vol.42, no.11; Nov.
           1989; pp. 515-20
 SUBJECT   aerospace propulsion; radiation pressure; space vehicles; sunlight;
           solar sail force transfer; near-Sun solar sail; payload
           acceleration; gas-filled sail; payload masses; solar radiation
           pressure; piloted space missions; sunlight; spacecraft models;
           perihelion distance; hollow body solar sail; highly stressed solar
           sail; terminal speeds; unmanned missions; 1 to 50 Mg; 320 to 430
           km/s; 1.7 to 2.0 solarradii; H/sub 2/ filled hollow body
           Numerical data: mass 1.0E+03 to 5.0E+04 kg; velocity 3.2E+05 to
           4.3E+05 m/s; heliocentric distance 7.9E-03 to 9.3E-03 AU
           Chemical indexing: H2/el H/el
           Class codes: A9555P
 CODEN     JBISAW
 ABSTRACT  A proposed solution for the problem of transferring force from a
           highly stressed solar sail operating close to the Sun to a payload
           is discussed. Models of spacecraft are evaluated for payloads
           between 1000 kg and 50000 kg, which reach terminal speeds of ca. 430
           km/s and 320 km/s respectively. Applications for such spacecraft in
           both manned and unmanned missions are mentioned
 MISCELLANEOUS
           Treatment: theoretical/mathematical
           J. Br. Interplanet. Soc. (UK)
           Abstract number(s):  A90050175
           ISSN: 0007-084X
           Refs: 11
 
 
Date:          Wed, 8 Aug 1990 16:49:31
From:          LIS USER VAC <LC65@VMA.CC.CMU.EDU>
Subject:       891007 40TH INTERNATIONAL ASTRONAUTICAL FEDERATION CO
To:            VAC%SAM.CS.CMU.EDU@VMA.CC.CMU.EDU
 
 IDNUM     03669696
 TYPE      Conference proceedings
 DATE      891007
 TITLE     40th International Astronautical Federation Congress. Next 40 Years
           in Space
 SOURCE    Acta Astronautica; vol.22; 1990
           40th International Astronautical Federation Congress. Next 40 Years
           in Space; Malaga, Spain; 7-13 Oct. 1989
 SUBJECT   aerospace computing; aerospace engines; aerospace propulsion; space
           vehicles; aerospace; Launch vehicles; single stage to orbit; Space
           Station Freedom; control; crews; Columbus; microgravity; expert
           systems; design; Meteosat-P2; large structures; solar sail; comet
           encounters; SIGHT; lunar base power; propulsion; Hipparcos; star
           trackers; Mars exploration; Phobos mission; manned spaceflight;
           optical space communications; global change; remote sensing; GIST
           Class codes: B0100; B7610; B7640; C7460
 CODEN     AASTCF
 ABSTRACT  The following topics were dealt with: Launch vehicles, single stage
           to orbit, Space Station Freedom, control, crews, Columbus,
           microgravity, expert systems, design, Meteosat-P2, large structures,
           solar sail, comet encounters, SIGHT, lunar base power, propulsion,
           Hipparcos, star trackers, Mars exploration, Phobos mission, manned
           spaceflight, optical space communications, global change, remote
           sensing, GIST
 MISCELLANEOUS
           Acta Astronaut. (UK)
           Abstract number(s):  B90048570; C90048770
           ISSN: 0094-5765
           U.S.Copyright Clearance Center Code: 90/$3.00+0.00
 
  
Date:          Wed, 8 Aug 1990 16:51:18
From:          LIS USER VAC <LC65@VMA.CC.CMU.EDU>
Subject:       820200 SAILING ON SUNLIGHT MAY GIVE SPACE TRAVEL A SE
To:            VAC%SAM.CS.CMU.EDU@VMA.CC.CMU.EDU
 
           ARTICLE AVAILABLE ON CARTRIDGE 14M, FRAME 4703
 DATE      820200
 AUTHOR    Drexler, Eric
 TITLE     Sailing on sunlight may give space travel a second wind.
 SOURCE    Smithsonian v12 p52(10) 1982 Feb
 SUBJECT   solar energy--aeronautic use
           sails--aeronautic use
           space vehicles--technological innovations
           metallic films--aeronautic use
           Solar Sail Project--aims and objectives
           aluminum films--aeronautic use
           World Space Foundation--research
 GRAPHICS  photograph
 CODEN     SMSNA
 

From: neufeld@physics.utoronto.ca (Christopher Neufeld)
Newsgroups: sci.astro
Subject: Re: Solar sail race???!!??
Date: 18 Dec 90 16:55:59 GMT
Organization: University of Toronto Physics/Astronomy/CITA
 
In article <52033@eerie.acsu.Buffalo.EDU> v056q3g5@ubvmsd.cc.buffalo.edu writes:

>  Does anyone know is there any truth to the rumor that there is going to
>be a unmanned solar sail race in 1992 from Earth to Mars??
 
   I hope so, since I'm helping to design one of the spacecraft. The
race was set up by the American government to commemorate the 500th
anniversary of Columbus' departure from Europe. The goal is to get a
spacecraft to Mars using only solar pressure (obviously, you're allowed
to use a chemical launcher to get off the ground), and the spacecraft
should weigh no more than 500 kg.

   Last I heard there were five serious teams, and a few who were
building steam. There's the World Space Foundation's sail, the one to
beat, since the WSF was founded by the engineers who first worked on the
space sail concept for NASA and were upset that the agency didn't go
ahead with a sailcraft. The Italian sail is getting a lot of publicity
in Italy, Columbus' native soil. The president (prime minister?) has a
figuredhead position on the design board. Japan's entry fell off track,
but seems to be straightened out again. There is a very late entry from
Israel, though apparently nobody in that country has heard of it. The
Israeli team has hired an adman in the States to publicize their
project, but that's the only real evidence of its existence. The British
team seemed to be having trouble, and I haven't heard if they are back
in the race or not.

   Sails will launch in late 1992, around Columbus day (I think that's
in September or October, what do I know, I'm just working on
electronics?). Handicaps will be/have been established for things like
proximity to the planet Mars (as opposed to just reaching the orbit),
time spent in Earth-escape mode, lunar gravity assists (which are very
difficult when your acceleration is measured in mm/s^2), and similar
considerations.

   In order to be eligible, sails must be privately sponsored. This
generally means corporate sponsors, since the expendable launcher used
to get the sail above the atmosphere runs in the tens of millions of
dollars. A solar sail can't fight air drag below roughly 1000km altitude.
  
-- 
 Christopher Neufeld....Just a graduate student  | "Shtarker! Zis is KAOS!
 neufeld@helios.physics.utoronto.ca    Ad astra! | Vee do not 'yippee yo
 cneufeld@{pnet91,pro-micol}.cts.com             | kye aye' here!"
 "Don't edit reality for the sake of simplicity" |      Siegfried of KAOS

So are the participants generally paying (via sponsors) for the launch services
as opposed to getting put into a launch as ballast like Amsat often does?

Burns

    There was a piece on NPR this morning about the Columbus Handicap (as
    it is being called).
    
    They mentioned the team from MIT (most data), whose entry features a 
    spacecraft of about .25 acre sale made of a durable plastic the
    thickness of kitchen plastic wrap.
    
    They also mentioned that the British entry is being designed by Arthur
    D Little.
    
    The cost per team is $15-30 million, most of which is probably due to
    launch costs. Many teams are short on funding.
    
    The race will start in October, 1992 (they said). The piece pointed out
    that in January, 1490, Columbus was looking for funding, which he did
    not receive until early 1492 - the point being that all those teams
    that are behind on funding still have a chance of finding a 
    benefactor and being able to join the race.
    
    					-**Ted**- 

From: henry@zoo.toronto.edu (Henry Spencer)
Newsgroups: sci.space,sci.space.shuttle
Subject: space news from Jan 21 AW&ST
Date: 6 Mar 91 05:48:13 GMT
Organization: U of Toronto Zoology
 
    Soviets reveal details of their "Regatta" satellite project,
intended for near-Earth solar and magnetospheric science and using
solar-sail technology for attitude control and stabilization. 
Basically it's a fairly ordinary satellite with a very large skirt
sticking out nearly at right angles from the spaceward end, and
several little rectangular "solar rudders" mounted on the rim of the
skirt for control.  The intent is to provide an unusually clean
environment for experiments by avoiding attitude thruster firings. 
IKI [the Space Research Institute], the developers, are also offering
it to the NOAA/electrical-utilities consortium that wants a
solar-storm warning satellite. 
 
"But this *is* the simplified version   | Henry Spencer @ U of Toronto Zoology
for the general public."     -S. Harris |  henry@zoo.toronto.edu  utzoo!henry

Article: 38255
From: roberts@CMR.NCSL.NIST.GOV (John Roberts)
Newsgroups: sci.space
Subject: Re: light-emitting drives
Date: 6 Dec 91 01:22:57 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: National Institute of Standards and Technology
 
>From: wl1807@sarah.albany.edu (William F. Laviolette Jr.)
>Newsgroups: sci.space
>Subject: light-emitting drives and "tachyon"drives
>Date: 5 Dec 91 17:41:13 GMT
>Organization: State University of New York at Albany
 
>It is my understanding that advanced scientific circles are already working
>on systems known as light-emitting drives....
 
I sent a message over the weekend that apparently evaporated. 
 
A light-emitting drive would work, but the problem is that they are
horribly inefficient in terms of energy consumption. It's almost
always better to use your energy source to drive some matter out the
back as reaction mass. (Similarly, you *could* power your car by
letting the gasoline run out of the tank and turn a little water wheel
before it pours onto the street, but then your "gas mileage" would be
only a few inches per tankful. It's far more efficient to use the
gasoline a different way. :-) 
 
I believe a beam of light exerts a force equal to the power of the
beam in watts divided by the speed of light. This is for a directed
beam, like that from a laser or a spotlight. (The coherence of the
laser beam doesn't really get you anything if you bring the laser
along with you.) 
 
Non-directional radiation from a flat glowing surface (i.e. a
radiator) gives half the thrust per unit energy, according to
calculations Christopher Neufeld and I made.  Of course, such a
radiator might be considerably more efficient than a laser overall,
especially if you put baffles along the sides of the plate to direct
most of the light "back". 
 
Interestingly, the wavelength of the electromagnetic radiation doesn't
have anything to do with the thrust - it's just a simple energy equivalent. 
 
Solar sails can be practical because they do not carry their power
source along with them. You also get the benefit that reflection
approximately perpendicular to the surface gives you double the "kick"
per photon (simple momentum transfer equation). 
 
I tend to favor solar sail plans that get their light from the Sun,
since you get that free.  Of course, if you try to use it to sail to
another star system, you won't get there very fast, because outside of
the inner solar system, the available energy is very limited.  There
has been mention of building huge lasers to drive solar sails to other
star systems - it has been stated that the technology has not been
developed yet, which is true, but what's often not stated is the
horrendous amount of power required, even assuming other problems can
be overcome. 
 
Consider the following example:

 - Lightsail craft mass 100 metric tons (a little on the light side)

 - Power source: Huge laser in solar system, reflecting perpendicularly
    from sail on craft

 - Assume 100% efficient laser operation and transmission of power to
    sail - both extremely unrealistic

 - Final delta-V of sailcraft = 1/10 speed of light (most commonly cited
    figure)

 - Ignore energy loss caused by redshifting (relatively minor at 0.1 c)
 
Since using a mirror effectively doubles the thrust of the light beam,
the energy required to perform this maneuver is:
 
          E = c * m * (delta V) / 2
 
or about 4.5E20 Joules. If power is priced at 5 cents per
kilowatt-hour, this launch will then require about six and a quarter
trillion dollars for power, still neglecting cost of design and
construction of all the parts, inefficiencies of making and receiving
the laser beam, etc. 
 
If we become rich enough to pay the price, or if the price of power
goes down enough to make this practical then that's fine, but in the
meantime, we may well have found a better way to do it. 
 
John Roberts
roberts@cmr.ncsl.nist.gov

As an old sailboater myself, I find the idea of light-powered sails to
be fascinating, but I don't think it'll ever be tried outside of an
experiment.  Within the last month, a British group has reported a
breakthrough in the area of containment of a fusion reactor, and the
superconditivity researchers are not far behind (I don't kow if the
Brits used superconductivity).  By the time we get ready to set sail
for Mars, say, around the turn of the millenium, fusion will be a done
deal and that is my vote for the power source.

Of course, we will never really get anyplace until we learn how to
harness gravity into a power source.

    There's a SF book that I read recently (but forget the name/author)
    about a race which goes around the galaxy in light sail ships as
    traders. They set up trade with a civilization and get them to build a
    launch laser. If the civilization proves too backward to be able to
    build the laser, they cause the sun to go nova to give them that extra
    boost to get to the next place. Not much repeat business...
    
    May have been a short story in Niven's N-Space.

re .14:

Your guess was right.  It is a Niven short, though I don't remember the name.
The guy who finds out owns a bar, and an ET was in his bar sampling his
wares and got drunk.

But back to reality...

There's another note that this could be talked about, but since non-chemical
reaction energy sources have been brought up, a number of recent issues of
Aviation Week and Space Technology have had articles on nuclear thermal
propultion and nuclear electric propulsion, which seem to have promise.
						-- Tom

    What good is a solar sail for the round trip?
    
     I can see how you would use it to move away from the sun, but how can
    you use it to get back to earth?
    
    Gregg

Use a gravity slingshot to get headed back toward the sun, then use the sail to
brake.

One can also accelerate toward the light source using a light sail by making the
sail multipart-detachable.  When you want to accelerate toward the light, you
detach the outer segment of the sail along with some static lines.  The lines need
need to connect to some small mass to keep everything shaped right.  Use the
released sail to focus light back at you.  It is, of course, going to accelerate
away from the light source (and you).  You turn around with the inner portion of
the sail.  That inner section is now facing toward the sun, but that side is
painted black, so photons are absorbed, not reflected.  The inner side of the
sail is shiny, so photons from the released sail are reflected off the payload's
sail.  If you do it all right, the reflected photons give more energy then the
absorbed photons and boom---acceleration.  Of course it only works for as long as
you can keep the released sail focussed on the payload sail.

Burns

RE: <<< Note 604.18 by DECWIN::FISHER "I *hate* questionnaires--Worf" >>>

>One can also accelerate toward the light source using a light sail by making the
>sail multipart-detachable.

There's a reasonable science-fiction story which uses this technique. I can't
recall the author or title; "Roche World," maybe.
						-- Tom

re .13
    
>Within the last month, a British group has reported a breakthrough in the area
>of containment of a fusion reactor, and the superconductivity researchers are
>not far behind (I don't kow if the Brits used superconductivity).
    
    See DECWET::PHYSICS topic 242 for details.
    
>By the time we get ready to set sail for Mars, say, around the turn of the
>millenium, fusion will be a done deal and that is my vote for the power
>source.
    
    I think that assuming a viable fusion reactor by the year 2000 may be
    optimistic, granted even that for our purposes it may not have to be
    commercially viable just energetically. The abovementioned group of
    researchers are talking "decades".
    
    As nice as nuclear fusion is as a source of energy, you still need
    reaction mass to expel which reduces useful payload. Score one for
    solar sails.
    
    Before we consider nuclear fusion for use in spacecraft, I would be
    interested in the mass of the whole device. These things tend to be big
    and heavy. Anyone have any figures?
    
    Also, do you ignite before or after launch? If after, you need an
    on-orbit energy source to get the reaction going or do you carry it
    with you? Or what? Ideas welcome!

From:	DECPA::"usenet-space-news-request@ames.arc.nasa.gov" 18-JAN-1992 
        01:19:31.37
To:	sci-space-news@rutgers.edu
Subj:	* SpaceNews 20-Jan-92 *

SB NEWS @ AMSAT < KD2BD $SPC0120
* SpaceNews 20-Jan-92 *

Bulletin ID: $SPC0120

                              =========
                              SpaceNews
                              =========

                       MONDAY JANUARY 20, 1992

SpaceNews originates at KD2BD in Wall Township, New Jersey, USA.  It
is published every week and is made available for unlimited distribution.

* SOLAR SAIL NEWS *
===================
An international scientific "solar sail" expedition and race to the
Moon is planned for 1994, with participants from the United States,
Europe, and Japan presently working to complete their spacecraft for
launch on an Ariane 4 rocket.  All three satellites will use sails
having areas of 400 square meters, and use solar radiation pressure
against the sail for propulsion.  The first spacecraft to return an
image of the Moon's far side wins the competition.  In addition, the
spacecraft sponsored by AMSAT-NA and the World Space Foundation, will
have interplanetary capability, and will proceed to the planet Mars if
its lunar encounter goes well. 

The imaging payload carried on the solar sail expedition will be based
on the color CCD camera carried on WEBERSAT-OSCAR-18.  A beacon
transmitter is proposed for operation on 145.825 MHz, the same
frequency used by UoSAT-OSCAR-11 and DOVE-OSCAR-17.  Communication
links with the spacecraft will probably use Mode S, with a 1.2 GHz
uplinks and 2.4 GHz downlinks. Manchester encoding with HDLC
formatting is expected to be used for the uplink data stream (similar
to MicroSat uplinks).  The spacecraft transmitter will use binary
phase shift keying (BPSK) AX.25 level 2 packet data protocol (similar
to MicroSat downlinks) in the 2.4 GHz amateur satellite band. 

[Info via K8OCL]

* FEEDBACK/INPUT WELCOMED *
===========================
Mail to SpaceNews should be directed to the editor (John, KD2BD) via any
of the following paths:

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-- 
John A. Magliacane                 FAX  : (908) 747-7107
Electronics Technology Department  AMPR : KD2BD @ NN2Z.NJ.USA.NA
Brookdale Community College        UUCP : ...!rutgers!ka2qhd!kd2bd
Lincroft, NJ  07738  USA           VOICE: (908) 842-1900 ext 607

Article: 61313
From: ajjb@adam4.bnsc.rl.ac.uk (Andrew Broderick)
Newsgroups: sci.space
Subject: Re: Solar Sail Data
Date: 20 Apr 93 16:11:43 GMT
Sender: news@inf.rl.ac.uk
Organization: Rutherford Appleton Lab, UK
 
In article <1993Apr15.051746.29848@news.duc.auburn.edu>
snydefj@eng.auburn.edu writes: 

>I am looking for any information concerning projects involving Solar
> Sails
 
I was at an interesting seminar at work (UK's R.A.L. Space Science
Dept.) on this subject, specifically on a small-scale Solar Sail
proposed as a student space project. The guy giving the talk was keen to
generate interest in the project. I'll typein the handout he gave out at
the meeting. Here goes : 
 
			The Microlight Solar Sail
			-------------------------
 
1. Introduction
The solar sail is a well-established concept. Harnessing the pressure of
sunlight, a spacecraft would have unlimited range. In principle, such a
vehicle could explore the whole Solar System with zero fuel consumption.
 
However it is more difficult to design a practical solar sail than most
people realize. The pressure of sunlight is only about one kilogram per
square kilometer. Deploying and controlling the large area of aluminized
fabric which would be necessary to transport a 'conventional' type
spacecraft is a daunting task. This is why, despite the potential of hte
idea, no such craft has actually been launched to date.
 
2.Design
Recent advances in microelectronics make possible a different concept: a
tiny sail just a few metres in diameter which could be controlled purely
be electronics, with no mechanical parts. Several attitude control
methods are feasible: for example the pressure sunlight exerts on a
panel of solar cells varies according to whether power is being drawn.
 
The key components of the craft will be a minute CCD camera developed at
Edinburgh University which can act as both attitude sensor and data
gathering device; solar cells providing ~1 watt power for control and
communication; and a directional radio antenna etched onto the surface
of the sail itself. Launched as a piggyback payload, the total cost of
the mission can be limited to a few tens of thousands of dollars.
 
3.Missions
The craft would be capable of some ambitious missions. For example:

a) It could rendezvous with a nearby asteroid from the Apollo or Amor
groups. Closeup pictures could be transmitted back to Earth at a low bit
rate.
b) It could be steered into a lunar polar orbit. Previously unobserved
areas around the lunar poles could be viewed. By angling the sail to
reflect sunlight downwards, polar craters whose bases never receive
sunlight could be imaged. Bright reflections would confirm that
volatiles such as water ice have become trapped in these
locations.[Immensely valuable information for setting up a manned lunar
base, BTW]
c) It could be sent to rendezvous with a small asteroid or comet
nucleus. Impacting at low speed, a thin wire probe attached to the craft
causes it to rebound while capturing a tiny sample is a sharp-edged
tube, like performing a biopsy. Returning to Earth, the sail acts as an
ideal re-entry parachute: load per unit area 20 gm/m2 ensures that heat
is reradiated so efectively that the sail temperature cannot exceed ~300
deg C. The material sample is recovered, enclosed in a small insulating
container.
 
Contact: Colin Jack                              Tel. 0865-200447
Oxford Mathematical Designs, 131 High Street, Oxford OX1 4DH, England
 
--------------------------------
 
This guy would love to hear from anyone interested in this project or
seeking details or anything, and would be most happy to send you more
information.
 
	Andy
-- 
                                  ----------------------------------- 
Andy Jonathan J. Broderick,      | "I have come that they might have |
Rutherford Lab., UK              |  life, and have it to the full"   |
Mail : ajjb@adam2.bnsc.rl.ac.uk  |  - Jesus Christ                   |

Article: 61319
From: higgins@fnalf.fnal.gov (Bill Higgins-- Beam Jockey)
Newsgroups: sci.space
Subject: Re: Solar Sail Data
Date: 20 Apr 93 20:26:48 GMT
Organization: Fermi National Accelerator Laboratory
 
In article <1993Apr15.051746.29848@news.duc.auburn.edu>,
snydefj@eng.auburn.edu (Frank J. Snyder) writes: 

> I am looking for any information concerning projects involving Solar
>  Sails. [...]
> Are there any groups out there currently involved in such a project ?
 
Sure.  Contact the World Space Foundation.  They're listed in the sci.space
Frequently Asked Questions file, which I'll excerpt.
 
    WORLD SPACE FOUNDATION - has been designing and building a solar-sail
    spacecraft for longer than any similar group; many JPL employees lend
    their talents to this project. WSF also provides partial funding for the
    Palomar Sky Survey, an extremely successful search for near-Earth
    asteroids. Publishes *Foundation News* and *Foundation Astronautics
    Notebook*, each a quarterly 4-8 page newsletter. Contributing Associate,
    minimum of $15/year (but more money always welcome to support projects).
 
	World Space Foundation
	Post Office Box Y
	South Pasadena, California 91301
 
WSF put together a little paperback anthology of fiction and
nonfiction about solar sails: *Project Solar Sail*.  I think Robert
Staehle, David Brin,  or Arthur Clarke may be listed as editor.
 
Also there is a nontechnical book on solar sailing by Louis Friedman,
a technical one by a guy whose name escapes me (help me out, Josh),
and I would expect that Greg Matloff and Eugene Mallove have something
to say about the subject in *The Starflight Handbook*, as well as
quite a few references.
 
Check the following articles in *Journal of the British Interplanetary
Society*:
 
V36 p. 201-209 (1983)
V36 p. 483-489 (1983)
V37 p. 135-141 (1984)
V37 p. 491-494 (1984)
V38 p. 113-119 (1984)
V38 p. 133-136 (1984)
 
(Can you guess that Matloff visited Fermilab and gave me a bunch of
reprints? I just found the file.)
 
And K. Eric Drexler's paper "High Performance Solar Sails and Related
Reflecting Devices," AIAA paper 79-1418, probably in a book called
*Space Manufacturing*, maybe the proceedings of the Second (?)
Conference on Space Manufacturing.  The 1979 one, at any rate.
 
Submarines, flying boats, robots, talking         Bill Higgins
pictures, radio, television, bouncing radar       Fermilab
vibrations off the moon, rocket ships, and        HIGGINS@FNAL.BITNET
atom-splitting-- all in our time.  But nobody     HIGGINS@FNAL.FNAL.GOV
has yet been able to figure out a music           SPAN:  43011::HIGGINS
holder for a marching piccolo player. 
                     --Meredith Willson, 1948

Article: 61341
Newsgroups: sci.space
From: jbh55289@uxa.cso.uiuc.edu (Josh Hopkins)
Subject: Re: Solar Sail Data
Date: Wed, 21 Apr 1993 01:40:59 GMT
Sender: usenet@news.cso.uiuc.edu (Net Noise owner)
Organization: University of Illinois at Urbana
 
higgins@fnalf.fnal.gov (Bill Higgins-- Beam Jockey) writes:
 
>snydefj@eng.auburn.edu (Frank J. Snyder) writes:
 
>> I am looking for any information concerning projects involving Solar
>>  Sails. [...]
>> Are there any groups out there currently involved in such a project ?
 
Bill says ...
 
>Also there is a nontechnical book on solar sailing by Louis Friedman,
>a technical one by a guy whose name escapes me (help me out, Josh),
 
I presume the one you refer to is "Space Sailing" by Jerome L. Wright.  He 
worked on solar sails while at JPL and as CEO of General Astronautics.  I'll
furnish ordering info upon request.
 
The Friedman book is called "Starsailing: Solar Sails and Interstellar Travel."
It was available from the Planetary Society a few years ago, I don't know if
it still is.
-- 
Josh Hopkins                                          jbh55289@uxa.cso.uiuc.edu
		    "Find a way or make one."
	             -attributed to Hannibal

Article: 79870
From: higgins@fnalo.fnal.gov (Bill Higgins-- Beam Jockey)
Newsgroups: sci.space
Subject: Re: solarsails, references?
Date: 14 Dec 93 23:15:05 -0600
Organization: Fermi National Accelerator Laboratory
 
In article <2elqak$f3j@vixen.cso.uiuc.edu>, jbh55289@uxa.cso.uiuc.edu
(Josh Hopkins) writes: 

> cwisnia@eis.calstate.edu (Cory M Wisnia) writes:
>>I have a rather bright student who is interested in solarsails as they 
>>might apply to space travel,  perhaps using the solar wind. 
> For a beginner I'd recommend  Louis Freidman's  "Starsailing: Solar Sails
> and Interstellar Travel."  [...]
> If you want more
> technical stuff, try  "Solar Sails" (I believe that's the title) by 
> Jerome Wright.  The writing and editing stink, but it does have plenty of
> equations and technical details.  I don't have any journal references handy,
> but I know the Journal of the British Interplanetary Society has had several
> articles in the past.  You local reference librarian can help you find more. 
 
I can add some citations to Josh's list.
 
I've recently completed an "egoscan" on the past year of my sci.space
postings, and as long as people keep asking questions I've answered
before, I hardly have to write anything at all.  Eventually I will
retire and a robot simulation of me will handle my wisecracks.
 
Beyond that, eventually, software simulations of all major sci.space
posters will be developed.  (Should we now say sci.space.*?) 
 
On 20 April of this year, I wrote:
 
>Contact the World Space Foundation.  They're listed in the sci.space
>Frequently Asked Questions file, which I'll excerpt.
>
>    WORLD SPACE FOUNDATION - has been designing and building a solar-sail
>    spacecraft for longer than any similar group; many JPL employees lend
>    their talents to this project. WSF also provides partial funding for the
>    Palomar Sky Survey, an extremely successful search for near-Earth
>    asteroids. Publishes *Foundation News* and *Foundation Astronautics
>    Notebook*, each a quarterly 4-8 page newsletter. Contributing Associate,
>    minimum of $15/year (but more money always welcome to support projects).
>
>        World Space Foundation
>        Post Office Box Y
>        South Pasadena, California 91301
>
>WSF put together a little paperback anthology of fiction and
>nonfiction about solar sails: *Project Solar Sail*.  I think Robert
>Staehle, David Brin,  or Arthur Clarke may be listed as editor.
>
>Also there is a nontechnical book on solar sailing by Louis Friedman,
>a technical one by a guy whose name escapes me (help me out, Josh),
 
[Of course, Josh provided the Friedman and Wright titles above.]
 
>and I would expect that Greg Matloff and Eugene Mallove have something
>to say about the subject in *The Starflight Handbook*, as well as
>quite a few references.
>
>Check the following articles in *Journal of the British Interplanetary
>Society*:
>
>V36 p. 201-209 (1983)
>V36 p. 483-489 (1983)
>V37 p. 135-141 (1984)
>V37 p. 491-494 (1984)
>V38 p. 113-119 (1984)
>V38 p. 133-136 (1984)
>
>(Can you guess that Matloff visited Fermilab and gave me a bunch of
>reprints? I just found the file.)
>
>And K. Eric Drexler's paper "High Performance Solar Sails and Related
>Reflecting Devices," AIAA paper 79-1418, probably in a book called
>*Space Manufacturing*, maybe the proceedings of the Second (?)
>Conference on Space Manufacturing.  The 1979 one, at any rate.
 
I only have the vaguest concept of how Net  | Bill Higgins
News works. I envision it as sort of a      | Fermilab
perpetually orbiting cluster of data,       | higgins@fnal.fnal.gov
somewhat in the nature of the Phoenix       | higgins@fnal.Bitnet
Asteroids in *Dark Star*. --Jacque Marshall