Systems architect and administrator Christopher Murtagh is developing the server that will block ports for applications that simply could not work on the Moon or Mars (e.g. web, Instagram, Twitter) due to the inherent light travel-time delay, and manage the unique SAM email addresses each team member will use, to which they will have forwarded their personal or work email prior to entering SAM. This is due to the fact that we cannot capture, store, and then release Gmail, Yahoo, or any other email but can introduce a time delay on a server that we control.
Wait. Did you say there is no internet on the Moon or Mars?! But how will I post to Instagram when I am take that first, bold step for all of human kind? How will I tell the world what I ate for breakfast? Where will I post the dozens of selfies my fans have been waiting for?! Surely, there is a way!
When Mars is near its closest point to the sun (perihelion) and Earth is at its farthest (aphelion), as the two planets were in 2003, there is 34.8 million miles (56 million km) between them. Earth and Mars are farthest apart when both are at their farthest from the sun, and at opposite sides of our host star, up to 250 million miles (401 million km) apart. SAM management will program the respective delay for each mission, from ~1.3 seconds for the Moon to 3 minutes one-way to Mars at its closest position and ~20 minutes one-way at its maximum.
While web (HTTP) and file transfers (FTP) have their own dedicated protocol, they all share something in common — the ability to send large files in smaller pieces, or packets. And with each of these packets is a checksum, a means of making certain that the packets arrived complete, without corruption due to a poor connection or cosmic ray strike, and ideally without having been hacked along the way. This means that each packet is prepared, and a mathematical value (checksum) assigned to the packet that represents the complete, unaltered data. When it is received, the checksum is compared to the contents of the packet, a response is generated and sent to the origin, and the next packet is sent. This is true for live video streaming, YouTube downloads, Instagram and Facebook posts, and direct file transfers from your computer to Google Drive or Dropbox, etc.
There are hundreds or thousands of packets sent every second, and if any one of these is stalled, even for a small fraction of a second, the entire system stalls too. The packets must be sent and received in order, or the photo or video gets completely scrambled (which we’ve all experienced). Therefore, even the relatively short distance to the Moon (~1.3 seconds) is too great a delay for one, let alone tens of millions of packets. And to Mars? Forget it. Under the current web protocol, there is simply no way.
So how did the Apollo astronauts send their live video broadcast? Analog radio signals that carried the video data were sent from their base to receiving antennae on Earth, and then rebroadcast to the world. Today, very few of these TV radio stations remain. Radio stations continue to broadcast analog signals with digital counterparts to improve the quality and provide information about the stations, newscast, or song.
“Broadcast” literally means “casting to the wide world” without concern for the receiving end. There is no means to guarantee that the information arrived safely. It’s just thrown out there, clear channel or encrypted, it’s a one-way delivery.
With our modern digital communications, your mobile phone or computer is conducting a private, secure, point-to-point dialog with a receiving station, and every packet MUST be accounted for, or the system stalls.
So how will we send data from the Moon or Mars?
Stay tuned …