Tiny probes launched to test advanced technologies
BY JUSTIN RAY
Posted: March 22, 2006
Three trail-blazing satellites were fired into Earth orbit this morning to prove if TV-sized probes can serve as formation-flying buoys for monitoring the weather of space and the enormous storms spawned by the sun.
"ST5 is the first step in developing missions of tens or hundreds of small spacecraft that would look at phenomena such as space weather," said deputy project manager Candace Carlisle.
The storms in this "weather" are solar flares and massive eruptions on the sun called coronal mass ejections that churn across space and impact life on Earth by disrupting communications, interfering with spacecraft and knocking out power grids.
"Space weather is becoming quite important to us because of our increasing utilization and dependence upon space-based systems," said Jim Slavin, the ST5 project scientist.
"Space-based assets, GPS satellites, communications satellites, all sorts of commercial and governmental systems, they are growing every year. Because they are very high altitude they often take the brunt of the space weather."
But researchers still are trying to understand the fundamentals of space weather, such as why a storm starts when it does and why some storms miss the Earth while others head right for us, Slavin said.
"For the purposes of space weather, we need to deploy literally tens or even a hundred space weather buoys in Earth orbit at a variety of distances in order to be able to arrive at a mature understanding of exactly what are the physical processes behind space weather, and then to use that understanding to be able to forecast it and eventually to mitigate against its effects. We are a space-based society whether we realize it all of the time or not."
The three ST5 micro-sats were hauled into a highly elliptical orbit aboard an air-launched Pegasus rocket made by Orbital Sciences. The winged rocket was ferried off the coast of California and dropped from the belly of a modified L-1011 jet at 1403 GMT (9:03 a.m. EST; 6:03 a.m. PST) this morning.
With the push of a button in the aircraft's cockpit, the rocket was cast free to fall 300 feet in five seconds before the first stage motor ignited to begin the trek to space.
It took just over six minutes for the 37th Pegasus booster to fire all three of its solid-fueled stages to achieve an approximate orbit of 187 by 2,838 miles, inclined 105.6 degrees to the equator.
Release of the 55-pound micro-sats from the launcher occurred one by one from a special rack that supported them during the ride to space. The forward-most craft jettisoned about nine-and-a-half minutes into flight, followed by the middle and then the aft-most during three-minute intervals.
NASA's Deep Space Network tracking stations in Madrid, Spain and Canberra, Australia were scheduled to establish contact with the micro-sats later in the day to determine their health and status.
Designers have packed several advanced technologies into the identical probes including:
"There are 10 specific technologies on ST5. Each one is actually very generally applicable to a broad range of missions, and as a consequence spacecraft designers have 10 new tools to work with. And tools that are not only smaller, lower power and less expensive, but because of ST5 they will have been proven in space. Therefore, they can be used with a high degree of confidence in future missions," said Ray Taylor of the Science Mission Directorate at NASA Headquarters.
"We're not narrowly focused on enabling one specific mission capability but rather investing our technology money in validation of technologies that are broadly applicable...to future missions," added Chris Stevens, manager of NASA's New Millennium Program that encompasses the ST5 mission. NMP is best known for its first mission, Deep Space 1, which carried a dozen advance technologies including an ion engine.
But the most immediate use for swarms of tiny intelligent micro-sats working together in a constellation will be space weather studies, mission officials predict.
"When you look up at the sun and see the visible light that gives us daytime and feel the warmth against your skin, fortunately at those wavelengths the sun is a relatively steady star. But as soon as you start looking at other wavelengths -- X-ray, gamma-ray -- or the charged particles in the hot the gas that comes off the sun at times it can be extremely violent," said Slavin.
"ST5 is going to measure the intensity, stability and motion of electric currents that flow in and out of certin regions of Earth's ionosphere that power the Northern and Southern Lights."
The micro-sats will explore Earth's magnetic field using highly sensitive magnetometers. But officials stress that ST5 is just testing whether the technologies will work, while serving as the catalyst to spur later missions that would perform the scientific research.
"As part of the demonstration, I believe ST5 will produce some unique scientific measurements, and depending on what those measurements show it is possible there could be a discovery made. But the primary purpose is the technology validation. If we do make a scientific discovery or see something that is very surprising, which is possible, it will just be a serendipitous event and certainly it'd be a very nice bonus," Slavin said.
Each micro-sat has a deployable boom with a magnetometer, which Slavin called a "proxy" for a more complete suite of particles and fields instruments that would be needed on operational space weather probes.
The ST5 micro-sats are "full-service" spacecraft with propulsion, communication and control systems. They were constructed to be "magnetically clean" to prevent interfering with the science measurement tests. And each have built-in intelligence to fly for a week in "lights out" mode while operating autonomously without human interaction.
"The focus is on reducing the risk -- the cost risk, the schedule risk, as well as understanding the performance risk for these advance technologies," Stevens said.
"The first one is always harder to build because you are learning all of these new things. But from now on all of the smaller satellites of this size will be much, much easier to build because of the lessons learned from ST5," added Art Azarbarzin, the ST5 spacecraft project manager.
Slavin anticipates the advances made by ST5 and later steps to understand space weather will pave the way for a solar storm alert network.
"I expect there will be some constellations deployed that are basically warning systems. You can think of them almost as the tsunami buoys they are putting out in the Indian Ocean right now."
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