Author Topic: Missions to Callisto  (Read 3813 times)

Offline Warren Platts

Missions to Callisto
« on: 01/11/2012 03:07 PM »
In the Europa thread it was suggested that maybe a new thread on missions to Callisto might be a good idea.

Advantages:

1. Radiation not nearly the problem that it is for the inner Galilean Moons.

2. More volatiles than the other Galilean Moons.

Disadvantage:

1. Chances of finding signs of life on Callisto are considered by some to be somewhat less than Europa or Ganymede.

Here is a NASA study that looked into it. It called for a series of robotic missions culminating in an actual human crewed mission. Of all places in the Jovian system, probably Callisto would be the most suited for a human station with ISRU propellant production. Thus, Callisto might be a useful way station for points even further out. Gravity there is 1/8g; escape velocity is 2.44 km/sec.

The mission requirement was that the humans get returned back to Earth within 5 years. They seemed to think the radiation issues were manageable.

They proposed that nuclear rockets (either nuclear thermal or nuclear electric) be used, but perhaps SEP (possibly combined with solar sails?) could also be used.

Also, single stage, reusable, chemical MTV's are capable of up to 11 km/sec delta v. Maybe these might also be a viable alternative to going nuclear?

http://www.nasa-academy.org/soffen/travelgrant/bethke.pdf
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline Warren Platts

Re: Missions to Callisto
« Reply #1 on: 01/13/2012 04:06 PM »
Another advantage of Callisto is that the delta v to get there is substantially less than Europa or Ganymede:

If I did this right:

Europa:
dV LEO ---> Europa orbit = 9.5 km/sec
dV orbit ---> surface = 2.0 km/sec
Total dv = 11.5 km/sec

Callisto:
dV LEO ---> Callisto orbit = 7.7 km/sec
dV orbit ---> surface = 2.4 km/sec
Total dV = 10.1 km/sec

(These figures assume coplanar Hohmann transfer orbits, and chemical propulsion.)

cf. Hop David's Hohmann.xls

If staged from an L2 depot, the delta V's to the surface of Europa and Callisto would be 8.4 km/sec and 7.0 km/sec, respectively.
« Last Edit: 01/13/2012 04:08 PM by Warren Platts »
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci