The Mars Balloon (or Aerobot) is proposed to be launched from a low cost system, such as the Pegasus rocket. While using Pegasus means less infrastructure is needed, it also limits the size of the capsule and cruise stage combination.
The capsule plus cruise stage will then follow a trajectory to Mars. Upon reaching Mars, the capsule will detach, enter the atmosphere, slow down, inflate the balloon, and the probe is on it’s way. To be worth the expenditure, the mission should be operational for at least ten days. On Earth, long duration balloon flights have lasted 100 or more days. That would produce an awesome science return from such a modest investment.
The entry sequence would be very similar to that shown here.
Rather than using airbags or skycranes, the aerobot will inflate a 10 meter (or slightly larger) balloon while descending slowly using a parachute. The balloon will then float for 10 or more days over the surface, imaging the surface, taking meteorological readings, and also checking for atmospheric gasses.
Data from the aerobot will be relayed to the orbiting probes such as the Mars Reconnaissance Orbiter and Odyssey. The MRO is equipped with the UHF radio to talk to rovers (and balloons!) and the Xband radio to talk t the DSN on Earth.