AppleLink in Space
The upcoming flight of the space shuttle Atlantis, which has been delayed a couple of times this month, will be a first for the information age. NASA’s astronauts will be carrying aboard a Macintosh Portable that has been outfitted with an off-the-shelf modem and a customized version of the AppleLink software, and they’ll be connecting to AppleLink and sending electronic mail from space.
While this isn’t the first time e-mail has been sent or received from space (earlier missions have included packet radio BBS experimenting), it will certainly be the first use of Apple’s online service from space (assuming everything works as planned). Not only will the astronauts be able to exchange data files and mission reports with ground control personnel, but they’ll also be able to communicate with their families during the trip. Unfortunately for us, but fortunately for the astronauts and their sanity, the shuttle’s AppleLink address is being kept confidential.
Connections to AppleLink already involve a complex data network, but this time things will be a bit more convoluted. Here’s the path as described by Apple’s Michael Elliot Silver:
The digital X.25 packet goes through the GE IS ww network to a modem pool (converts to analog) which is connected to a ROLM telephone switch (converts back to digital), then to a data phone at Johnson Space Center.
The data phone is connected to a Mac Portable through its Printer port. The packet then goes through a ‘Data Forwarder’ application written by our own Byron Han (the genius behind this project) which sends the packet out the Modem port using ‘NASALink,’ a CTB tool specially written for this event (also by Byron).
The packet then goes through a PSI Fax Modem (back to analog) operating in v.27 terr (half duplex, ungodly, and evil) and is then routed through an ATU (Audio Terminal Unit) which digitizes the signal (converts to digital).
The packet is then sent up to an orbiting CommSat (Commercial Satellite) then back down to White Sands, New Mexico TDRSS (Tracking and Data Relay Satellite System).
It is then sent up again to another TDRSS Satellite which is orbiting geosynchronously with the space shuttle, and that satellite sends the packet to the space shuttle (still digital) which sends it through its voice subsystem and converts it back to analog.
It is sent through another ATU to another PSI Fax modem (back to digital) through the modem port, through the NASALink CTB tool and finally into AppleLink 6.0.2s1 (a special version of AppleLink 6.0.2).
Rick M. Holzgrafe — [email protected]
Michael Elliot Silver