Update: March 14, 2007

ROBOTS DOCKING

By Pam Eastlick for THE DEEP on line

Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.

Last week, I told you about a robot that was all set to explore the deepest cenote on the planet, and that the really big innovation about this robot is that it will explore on its own without wires or tethers or human intervention.  It can build and follow 3D maps, explore and map unknown territory, and return home using its own maps, without any aid from a GPS system.  Its name is DEPTH-X.

And it’s not the only autonomous robot out there.  Last weekend DARPA launched Orbital Express a payload that carried six different satellites.  So, what country uses the acronym DARPA?  Your own.
Most of us think that everything up there in space was launched by NASA, but that’s far from the case.  There are many satellites launched by other countries and consortiums.  The European Space Agency is building its own GPS system and China and Russia certainly aren’t out of the race.  India is also getting ready to launch communications satellites and other space-based research payloads.  LEO (low Earth orbit) is getting to be a VERY busy place.

But a surprising number of satellites that whiz over your heads were put there by the various branches of the US military.  There’s normally not a lot of publicity about these satellites and their purposes.  Most of them are spy satellites and most spy satellites orbit in polar orbits because you can scan the entire planet from a polar orbit.  If you look in the sky shortly after sunset or before sunrise (within two hours of either event) and you see a ‘star’ that’s slowly moving from south to north or north to south, you haven’t found a star or a planet or the International Space Station; you’ve just spotted a military spy satellite.  And the odds are that it just took your picture.

Although the development phases of spy satellites and what they’ll be used for may be hush-hush on the ground; once they’re launched they aren’t so hush-hush anymore because all you have to do to spy on them, is look up.  But what if an enemy nation launched a satellite that was designed to do more than spy on the populace?  Or what if the US did?

The acronym DARPA stands for Defense Advanced Research Projects Agency and they are the military satellite people.  Most of the spy birds up there call home to DARPA.  Last weekend DARPA launched a rocket that they actually wanted a little publicity for.  The mission was called Orbital Express and it carried six different satellites.  Two of them are teammates and this is where the robot science comes in.

The satellites are the Autonomous Space Transport Robotic Operations (ASTRO) service vehicle and the other is the Next generation serviceable Satellite (NextSat).  (One of my favorite sources of hilarity is the military’s (and NASA’s) obsession with acronyms, but that’s the subject of a whole other column!).  NextSat and ASTRO will orbit close to each other for the next three months (the duration of their mission) and during that time; they’ll conduct approach and docking maneuvers from staring points of 4 to 5 miles away.  While they’re docked, they will swap fuel (a prelude to refueling operations in space) and trade and install batteries.  This will be the first robotic component exchange in space history.

An artist’s concept of ASTRO & NextSat just before docking.

So, how will they dock without a human pilot?  They will use the Advanced Video Guidance System (or AVGS for short, you knew it was coming, right?).  The AVGS is mounted on ASTRO and it shoots infrared laser beams (shades of Star Wars!) at retroreflectors mounted on NextSat. Whoa!  What’s a retroreflector?  Well, you don’t get lost in the middle of the word so bad if you hyphenate it and make it retro-reflector.  So are we using it to look back into the past or what?  Retro-reflector is simply the three dollar word for something you see everyday.  A retroreflector is a device that sends light or other radiation back where it came from regardless of the angle of incidence, unlike a mirror, which does that only if the mirror is exactly perpendicular to the light beam.

An artist’s conception of the ASTRO satellite with NextSat successfully docked (Credit: Boeing)

And they’re everywhere.  The strips mounted on safety vests are retroreflectors.  They’re on most tennis shoes, especially if people wear the shoes to jog at night and they’re on the median strip bumps on Guam’s roads. 

Retroreflectors have a long history in space; they were placed on the Moon at every lunar landing site and they have had lasers reflected from them several times.  (A marvelous refutation, by the way for the “We never went to the Moon” people.  If we never went there, how did the retroreflectors get there?)
ASTRO will analyze the pattern of reflections from the retroreflectors on NextSat and will use the data to adjust its speed and angle of approach so it can dock safely with NextSat.

So, why is this important?  Well, if the Orbital Express mission is a success, it could signal the advent of autonomous rendezvous and docking systems.  Satellites could be repaired and upgraded without having to utilize those pesky and incredibly expensive humans.  No more worries about space sickness and bone loss and diapers.  Just let the robots do it!

I for one hope that the robots don’t take over entirely.  Humans need that new frontier!
And speaking of new frontiers, what of the other four spacecraft that were launched aboard the Orbital Express spacecraft?  One payload aboard the Orbital Express was STPsat, designed to collect atmospheric data and demonstrate other spacecraft technologies for the Air Force’s Space Test Program.  There’s not a lot available on this bird and what there is, is buried deep in governmentese.  It’s a typical military launch, in other words.

There’s more information available on the Cibola Flight Experiment from Los Alamos.  They are testing several new technologies including inflatable boom antennas, a new power supply system and a prototype supercomputer designed to process raw data aboard rather than sending the information directly to Earth.

But the last two are really interesting and allude to those new frontiers.  The fourth New Horizons payload is FalconSat3.  It weighs only 119 pounds, but it carries five experiments to study the plasma environment near Earth and test other new hardware.  It also has a Micropropulsion Attitude Control System that the builders hope will be successful.  And who are the builders.  FalconSat3 was built by cadets at the U.S. Air Force Academy.

FalconSat3 under construction

The sixth payload is the MidStar 1 microsatellite.  This 265-pound satellite carries several experiments.  One will test electrochemical membranes in space, another will test the performance of computers in space and a third carries a prototype microdosimeter; which measures radiation.  What makes this satellite special?  It was built by midshipmen at the US Naval Academy including Erin Brewster, a former Guam resident. Robots and students.  New frontiers indeed.  Look up tonight.  You just might see one of Orbital Express’s satellites whizzing over your head while it’s building your future in space.

Drawing of MidStar1