Ham Hears Mars Orbiter 45 Million Miles From Earth

Richard L. James writes "As reported on the Mars-net email list Flight Refuelling Amateur Radio Society's resident satcom + WLAN guru Paul J. Marsh (M0EYT) has managed to detect and receive NASA's Mars Reconnaissance Orbiter on X band at a staggering range of 45 million miles from Earth using a home made receiver setup and a RFspace SDR-14 software radio."

Comments

Re:Security risk?

[user9918277462]

All NASA communications are encrypted. One of the highest priorities during recovery of the Columbia wreckage was to find and secure the NSA "black box" that encrypted radio traffic between the shuttle and ground control.

Can you imagine the damage some antisocial radio vandal could do to the Mars Rovers, for instance, if the command traffic was sent in the clear?

Not quite

[slightlyspacey]

As with most things in life, the correct answer is "it depends". All NASA communcations to/from the shuttle are NOT necessarily encrypted but can be. Uplink from the ground to the shuttle always is encrypted (we don't want someone sending bogus commands). In addition, the crew has the option of disabling all commands coming from the ground. Direct downlink from the shuttle to the ground can be encrypted but that is not always done. It depends on the mission configuration. DOD-based classified missions back in the 80s always were encrypted on both the uplink and downlink.

There are also other communications paths between the shuttle and the ground. Indirect communications, known as forward and return links via, TDRSS are always encrypted.

Re:Power being wasted?

[NixieBunny]

Perhaps you meant to say "some random microwave receiver expert", not "some random dude". This is not everyday work - I build stuff like this for radiotelescopes. But I'm surprised that he used a tiny 1 meter diameter dish to receive the signal - I was expecting at least a standard old-fashioned 3 meter satellite dish to have been used to improve the signal level at the receiver.

I am waiting patiently for the equipment webpage to load so that I can see what sort of filters he used. That's the main tricky part for doing such an experiment - you need to build a custom filter to reject everything that isn't in the spacecraft's frequency band. The rest of the equipment is apparently a modified satellite TV receiver and a generic software radio.