In the final episode of Season 4, Dev Ayesha, Ed Baldwin and other protagonists hijack the space ship Ranger to drag the wayward Asteroid 2003LC "Goldilocks" into Mars orbit.

In terms of the "real world", is such an asteroid capture vaguely feasible?

The premise is Goldilocks, a 1.1 km wide iron asteroid, is rich in precious metals, specifically Iridium. Goldilocks is a Jupiter Trojan perturbed onto a close approach to Mars. The Mars-7 international alliance want to perform a 20 minute burn using their asteroid tug Ranger to divert the asteroid on a gravity assist path towards Earth, where it can be mined.

Mega-rich Dev Ayesha "hijacks" Ranger's maneuver adding an additional 5 minutes burn and bringing Goldilocks into Mars orbit For All Mankind just for the benefit of Mars.

Assume 2003LC (Goldilocks) has a mass of ~4 billion tonnes.

Some questions that immediately occur to me:

  1. How do I estimate delta-V? What is the minimum required? This is critical to the problem. Here is a Solar System Delta-V Map: https://upload.wikimedia.org/wikipedia/commons/thumb/9/93/Solar_system_delta_v_map.svg/1535px-Solar_system_delta_v_map.svg.png

  2. The Ranger uses some form of plasma propulsion, perhaps based on VASIMR. A fusion reactor is used to generate the electricity with Argon as the propellant. How much Argon would be required?

Thoughts and answers on any of these questions, or more general relevant comments, would be appreciated.

  • 3
    $\begingroup$ Due to how Stack exchange works it would be good to edit this a bit to make it a single question, if need be splitting out some of the 8 points into new questions and keeping this one to be about the DV and possibly fuel needed given your existing answer $\endgroup$ Commented Mar 29 at 7:46
  • 3
    $\begingroup$ if it's a major plot point that they put it into Mars orbit, could you remove it from the title so you don't spoil it for people who don't want to be spoiled? $\endgroup$
    – Erin Anne
    Commented Mar 29 at 8:03
  • 3
    $\begingroup$ I don't know the plot and haven't watched the show, but if a 5-minute burn is the difference between capture and earth redirect, couldn't they just do another 5-minute burn to get the asteroid going back towards Earth? Unless some external force influences the asteroid like atmospheric braking, there shouldn't be a reason why this wouldn't be possible...? $\endgroup$
    – Dragongeek
    Commented Mar 29 at 11:57
  • $\begingroup$ @Dragongeek. Yes they could, but the pirates (Helios) have control of the Ranger tug, which presumably no longer has the Argon fuel for another 5 minute burn. It would take time for Earth to attempt an asteroid recover after this act of piracy. It would also take years if the Ranger tug is one-of-a-kind. Also I suspect over time they would bring the asteroid into a lower Mars orbit, making it harder to recover. $\endgroup$
    – Galerita
    Commented Mar 29 at 15:27

1 Answer 1


These are some of my thoughts. Feel free to correct me!

There's almost no chance of perturbing a Jupiter Trojan into an Mars crossing orbit. That requires a Jupiter-Mars transfer orbit (delta-V ~ 2.7 km/s). It's more believable if 2003LC (Goldilocks) were perturbed by Jupiter in to Mars crossing orbit. Given it is metal rich it was likely ejected from the inner solar system in the distant past.

Calculating delta-V is critical to this problem. Assume perihelion is close to Mars, we are lined up for an insertion into Mars-Sun orbit. We then need to slow it to Mars capture, so 0.67 km/s

At the very least you need an elliptical orbit to a periapsis of say 200 km. If it were a circular orbit that would be a delta-V of 0.67+0.34+0.4+0.7 = 2.1 km/s., but presumably ~1.5 km/s (help!!). (That would make the Earth burn required 1.5*4/5 = 1.2 km/s - 20 min vs 25 min.)

Minimum delta-V is unlikely to point it directly at Earth. If it did more delta-V would required for some sort of braking into a usable Earth orbit. But what is a feasible way to get it into Earth orbit?

A delta-V of 1.5 km/s over 25 min is ~1 m/s^2 ~ 0.1g (no big deal).

At 1.1 km diameter & 7 g/cc, Goldilocks mass is 7x(4pi/3)(1100/2)^3 ~ 4 billion tonnes (4 trillion kg).

  • 3
    $\begingroup$ If you can find exhaust velocity for an argon thermal rocket you can get tonnes of fuel per second to achieve 1 meter per second for 4 Billion tonnes. With 8kms being quoted for Hydrogen envelope math sez 500 tonnes of fuel per second, more once you start using rocket equation properly. A good source for this sort of stuff is projectrho.com/public_html/rocket/enginelist2.php $\endgroup$ Commented Mar 29 at 7:52
  • 6
    $\begingroup$ Accelerating a a multi-billion-tonne object at 0.1g probably shouldn't be described as "no big deal". $\endgroup$ Commented Mar 29 at 12:05
  • $\begingroup$ @Starfish Prime I meant in terms of the effect on the crew of this particular maneuver. BTW I love the name Starfish Prime was the largest nuclear test conducted in space. Few know about these tests. $\endgroup$
    – Galerita
    Commented Mar 29 at 15:30

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.