[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Re: starship-design: Interstellar Probes
In a message dated 8/11/98 11:37:56 AM, firstname.lastname@example.org wrote:
>Gene Marlin wrote:
>> Using current and near-term technology, how fast could we get a 2
>> kilogram probe to nearby stars such as Tau Ceti, Epsilon Eridani,
>> Proxima Centauri, and 61 Cygni?
>Depends on what kind of propulsion you use. To get it there fast is
>virtually impossible with current technology.
>To give you an example of how bad it really is, this is how much it
>would take to send a school bus sized payload past Alpha Centauri in 900
>Propellant: Specific Imp.: Fuel mass:
>Chemical 500 10^137kg (not enough mass in
>Nuclear fission 5000 10^17kg (a billion
>Nuclear fusion 10000 10^11kg (a thousand
>Antimatter 50000 10^5kg (ten railway tankers)
>If you want to get there faster that 900 years, it gets worse. If you
>want to actually stop at the destination, it gets even worse. That's why
>I don't believe we will make it with any of these propulsion systems. It
>would be better for a 2 kg probe, but not good.
>Kyle R. Mcallister
Actually the numbers for a couple hundred thousand ton ship with a max speed
of .4 light (with a external Boost to speed) was 25 million tons, not billions
of tons. Thou carrying the accel and decel fuel internally would add several