Lots of missions and mission phases don't require bigger antennas. Look at http://eyes.nasa.gov/dsn/dsn.html http://eyes.nasa.gov/dsn/dsn.html for current usag

Lots of missions and mission phases don't require bigger antennas. Look at http://eyes.nasa.gov/dsn/dsn.html http://eyes.nasa.gov/dsn/dsn.html for current usage of the Deep Space Network. As I type this, 3 smaller dishes in Goldstone are handling 4 Mars missions, all solar powered, Odyssey at 14.22 kb/s. At Canberra, the only active dish is a small one, receiving data at 159 b/s from Voyager 2 (!). Which, I grant, doesn't have a lot to say right now. 3 sites, 1 big dish and 3 smaller ones at each, except for a 4th smaller one at Goldstone, that's a serious investment and I gather enough for now, especially since satellite technology now allows storing massive amounts of data (8 GB for New Horizons) for download as the mission and ground stations allow. Note also that after New Horizons finishes downloading the data from its flyby in November 2016, it won't have a lot to say unless and until its Kuiper belt object flyby.