[ExI] question re "honkin' big cannon" space launch

G P SINGH girindra at isac.gov.in
Wed Mar 4 08:20:53 UTC 2009

Being a space engineer in general and spacecraft systems engineer in  
perticuler with experience of two completed big spacecrafts and third  
one in progress. I am bringing out some technical issues here   
(Assuming infinite money and reasonable medical or QOL spinoffs) in  
cannon/gun launch of spacecrafts

Whether a spacecraft is launched by surface magentic rail or baloon  
magnetic rail, the required orbital velocity for a satellite will be  
around 8-9 Km/S. So how can the accelaration be achieved ? In addition  
to challenge of material strength which I assume can be solved by use  
of Nanomaterials and nano process technology. There are

additional following challenges in this proposition -

	a.  Fastest levitation train runs at speed of around 15-16 metre/sec.  
How can the multiplication of 800-900 can come? Normally rails are  
passive and trains are active device in trains. But here situation is  
different, we need to have active rails and active spacecraft.

	b.  Point of Keith Henson of giving 1g acceleration... if we assume  
1G for about 1000 second then 5000 km is nearing radius of earth ,  
even 1G accelaration can not be given for that much distance because  
the required power should be there in spacecraft (correct me if i am  
wrong) or if the power of 50 GW should be there in tunnel/rail then it  
will resemble nuclear particle accelarator. Presently Normal highest  
power level of a spacecraft has never gone beyond around 15000W  
(barring space station)

	c. How the acceleration will take care of circularity of earth for  
that which will change the desired orbit after exit even for a smaller  
mass of 5 ton ?  At present Mass of high power satellite of around  
10000W will be arounf 4000 Kg. How will even this mass of 4 Ton can be  
accelerated to achieve any desired orbit by?

	d. At present satellites are having only one liquid apogee motor of  
around 500 newton. So we need to accomodate more number of motors to  
correct the orbit after exit shock. In current configuration of  
spacecrafts thrusters, LAM, fuel lines and Power supply for propulsion  
takes lot of weight then mass of payload will reduce.

	e. Design of satellite of such kind will be complex. If i assume  
normal ARIANE launch as standard. Then what shall be configuration  
changes in spacecraft. Most severe shock will come at exit. So worst  
case design fo 30G shock will change structural design. Its interface  
with rails should be through magnetic levitation then what will be  
source of powers inside the tunnel/rails ? And what will be change in  
design of solar panel & batteries. And big question is that... The  
payload either infrared observatory or communication repeater or a  
optional spy camera electronics will interact heavily with magnetic  
power supply.  And such EMI/EMC design of components will be an issue.

	g. It may appear simple, Access to 100 Kms up in the air from surface  
  will be either by means an elevator ( Aircraft is rules out,  
helicopter will still work) so +g and -g shocks need to be accounted  
in design margins.


Girindra Pratap Singh
Indian Space Research Organization
Department of Space, Government of India
Bangalore INDIA

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