NASA’s ST-5 (Space Technology 5) mission has launched on its second attempt on an Orbital Sciences Pegasus XL rocket from Vandenberg Air Force base today.
During the first launch attempt on March 15, the Pegasus starboard flight control surface fin pin did not retract resulting in an aborted attempt.
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Initial contact with ST5 was made at 9:27 a.m. EST, as the spacecraft passed over the McMurdo Ground Station in Antarctica.
Art Azarbarzin, ST5 project manager at NASA’s Goddard Space Flight Center, Greenbelt, Md., described next week’s planned activities for the spacecraft.
“During the first day, we ensure the three craft are correctly operating. During the next few days, we deploy and test the magnetometer booms. Finally we prepare them for the science demonstration and make any necessary orientation adjustments,” Azarbarzin said.
NASA and Orbital Sciences completed an engineering analysis, but the exact cause of the malfunction could not be determined. The most likely reason was the pin retractor system failed to operate due to the formation of ice.
The mechanism was removed and replaced in case there were other contributing causes. Steps have also been taken to mitigate potential water intrusion that could form ice during captive carry.
ST-5 Mission Background
The innovative ST5 mission was due to launch on Feb. 28, but has now suffered two delays in quick succession. Officially NASA has slated the new launch date as NET March 6, but sources have indicated this has now been pushed back to March 11.
The ST5 mission is in itself part of an exciting move towards micro-satellites. The benefit of proving the micro-satellite technology works could open up the market for a new range of similar spacecraft, launched on much smaller – and thus cheaper – rockets. Each of the ST5 satellites has all the features of is full-sized cousin.
On this mission, three ST5 satellites – not much larger than a portable television set – will be launched using a Pegasus XL to a near-Earth polar elliptical orbit that will take them to between from 300 kilometres to 4,500 kilometres above the Earth.
Once in orbit, the ST5 micro-satellites will be placed in a row about 40-140 km (about 25-90 miles) apart from each other to perform coordinated multi-point measurements of the Earth’s magnetic field using a highly sensitive miniaturized magnetometer built by University of California, Los Angeles. 
This type of measurement is useful for future Sun-Earth Connection missions that will study the effect of solar activity on the Earth’s magnetosphere, a protective magnetic ‘bubble’ that surrounds the planet and helps protect it from harmful space radiation.
The Cold Gas Micro-Thruster (CGMT), built by Marotta Scientific Controls of Montville, New Jersey, will provide propulsion for orbit maintenance. The X-Band Transponder Communication System, built by Aero Astro, will support two-way communications between the ST5 micro-satellites and the ground stations.
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