Crashing Planets Together

Hi,

I went through the figures last night for moving planets out of orbit and
crashing them into other planets to make them easier to terraform. There
were four different sceanrios:

(1) Move Mercury to a Venus orbit and combine the two planets into one.
This would require 3.52 x 10^32 Joules to change the orbit of Mercury. When
combined: the planetary radius would increase by 129.3 km; the gravity will
increase from 90.3% to 92.5% earth-standards; the atmospheric pressure will
decrease from 90 to 89.46 earth-standard atmospheres; the D-value will
increase from 1.552 to 1.622; the H-value will increase from 0.777 to 0.812
so it still couldn't hold Hydrogen-1 over a long timescale. Conclusion: not
really worth the effort.

(2) Move Mars to a Venus orbit and combine the two planets into one.
This would require 4.14 x 10^32 Joules to change the orbit of Mars (to slow
it down). When combined: the planetary radius will increase by 434.45 km;
the gravity will decrease from 90.3% to 88.98% earth-standards (as Mars is
less dense than Venus); the atmospheric pressure will decrease from 90 to
78.2 earth-standard atmospheres; the D-value will increase from 1.552 to
1.645; the H-value will increase from 0.777 to 0.823 so it still couldn't
hold Hydrogen-1 over a long timescale. Mars will have to move through
Earth's orbit to get to Venus which could be hazardous. Conclusion: not
really worth the effort or risk to Earth.

(3) Move Mercury and Mars to a Venus orbit and combine the three planets
into one. This would require 7.66 x 10^32 Joules to changes their orbits.
When combined: the planetary radius will increase by 451.9 km; the gravity
will increase from 90.3% to 93.8% earth-standards; the atmospheric pressure
will decrease from 90 to 77.9 earth-standard atmospheres; the D-value would
increase from 1.552 to 1.739; the H-value would increase from 0.777 to
0.870 so its still couldn't hold Hydrogen-1 over long time-scales. Mars
will have to move through Earth's orbit to get to Venus which could be
hazardous. Conclusion: not really worth the effort or risk to the Earth.

(4) Move Mercury and Venus to a Martian orbit and combine the three planets
into one. This will require 3.70 x 10^33 Joules to change their orbits.
When combined: the planetary radius will increase by 451.9 Km; the gravity
will increase from 90.3% to 93.8% earth-standards; the atmospheric pressure
will decrease from 90 to 77.9 earth-standard atmospheres; the D-value will
increase from 1.552 to 2.388 and the H-Value from 0.777 to 1.195 so it
could easily hold Hydrogen-1 and could be terraformed. Mercury and Venus
will have to move through Earth's orbit to get to Mars which could be
doubly hazardous. Conclusion: it's a possibility if the technology and
energy are available, and if the risk is acceptable.

Michael
http://www.geocities.com/alt_cosmos/index.html