Can we change Earth's orbit with modern technology? It is well known that, according to Newton's 3rd law, spacecrafts entering or leaving Earth provoke tiny (insignificant) changes to Earth's orbit (see related question here).
My question is about significant changes. For instance, say we would like to shift the Earth's orbit closer to that of Mars (forget about the ecological consequences of this). Do we currently have the technology capable of doing this? For instance, something like a huge nuclear explosion? This question only deals with &quot;natural&quot;, non-human ways to change a planet's orbit. I am interested about technology-based changes.
No, we cannot.
It's relatively simple math to show that we are a very long shot from changing Earth's orbit by anything significant at all: consider the kinetic energy of Earth in its current orbit, and do the same math for that in the desired orbit:
$ E_{kin} = \frac{m_E}{2}v^2 \approx \frac{m_E}{2}\frac{GM_S}{a}$
where $m_E = 6\cdot 10^{24}$kg is Earth's mass, $M_S=2\cdot 10^{30}$kg is the solar mass and $a=150\cdot 10^9$m is the distance from Earth to sun. I used the approximation in calculating orbital velocity $v = \sqrt{\frac{GM_S}{a}}$ that the Earth mass, is much smaller than the Sun's mass. So current orbital velocity is (using numbers as above) $29822$m/s.
Now, changing oribital distance outward by 1%, thus by $1.5\cdot 10^9$m, to $151.5\cdot 10^9$m yields a speed of $29674$m/s - and in energy that subsequently gives a difference of $2.64\cdot 10^{31}$J to move Earth's orbit about 1% to further from the Sun.
Annual world primary energy production currently is around $10^{20}$J - so we &quot;just&quot; need to produce 100.000.000.000 times the yearly energy production of the entire world to change Earth's orbit about 1%. And that implies that we have a technique to transfer energy 100% into Earth orbital velocity - something which cannot exist either due to simple thermodynamic argument.
Edit to add: Another way to argue is the rocket way: typical speed of conventional rocket exhausts are a few km/s, which is less than needed to leave Earth's orbit - that's why you need multi-stage rockets to get anything into orbit. But if you want to move the whole Earth with a rocket motor, you need a propellant which is fast enough that it directly leaves Earth's gravitational field - or you will not be able to create any effective change of momentum and only move around mass in the Earth system itself. So you need to make some substantial technological advances here, too - or some entirely different technique.