There is none. This spacecraft doesn't even have an onboard computer. The only reason people don't routinely hack spacecrafts like this is because you need a worldwide network of huge dish antennas to communicate with it. Right now, outside of the Deep Space Network, only the Aricebo dish is capable of transmitting to it. Once it gets closer to earth (within a few million miles), the 20 meter dish at Moorehead in Kentucky will be used.

You could use multiple, smaller dishes than Aricebo; coordination is required though.

http://en.wikipedia.org/wiki/Astronomical_interferometer

Example: The VLA http://www.vla.nrao.edu/

I think you just needed one of these http://imgur.com/soLoTRs

I don't get the reference. Please elaborate for us newbs.

Using a Capt. Crunch whistle, you could recreate the tones telcoms used to initiate long distance calling. Meaning you could blow the whistle and get free long distance. http://en.wikipedia.org/wiki/John_Draper

It's a plastic whistle, like the ones that were found in some cereal boxes forty years ago.

It emits a note at 2600Hz, which coincidentally was the frequency for carrier control on the Bell phone network at the time.

See: http://en.wikipedia.org/wiki/John_Draper#Phreaking

It's a reference back to John Draper's work on the blue box. You could trick AT&T pay phones into thinking you had deposited money by playing tones which were reproducible on toys that came out of Captain Crunch boxes.

In the early early days of telephone hacking (phone phreaking) a guy named John Draper discovered that the toy whistle found in a box of Cap'n Crunch cereal would emit a tone at precisely 2600 Hz. This frequency was used by The Bell System to issue call routing instructions. With it, you could make free long-distance calls around the world. Some via satellite.