#107 July 1997
Section 184.108.40.206.107.of the Artemis Data Book
We have been reporting extensively in recent issues of MMM on the flagship project of the Huntsville, Alabama L5 Society (HAL5, NSS chapter) - its history, plans, attempts, and ultimate successful first launch. Success did not come according to textbook script. The event had real drama and so here we bring you "the rest of the story."
At 8:25 AM EDT, on a record cold Mother's Day morning on Sunday, May 11, a small group of space enthusiasts made amateur rocketry history by launching the first amateur rocket from a high altitude balloon, a concept known as a "rockoon".
A rocket launched at 100,000 feet is above 99% of the atmosphere where it is subjected to only 1% of the drag that a similar ground based launch would experience. Launched at high altitude, it can also operate much more efficiently, because there is less back pressure on the nozzle exit to oppose the rocket thrust. This translates to a higher thrust for a given amount of fuel consumed per second, a term in rocketry known as "specific impulse". In lay terms it is analogous to a car's miles per gallon.
The HALO rocket uses hybrid propulsion - an inert solid fuel, asphalt, is kept safely away from a liquid oxidizer until ignition. The Space Launch 1 rocket was fired at 60,000 feet from a large high-altitude helium balloon made of clear polyethylene plastic over 100 feet long, but thinner than a sandwich bag (only 0.35 mils thick). At its design altitude of about 130,000 feet, the balloon, which has a volumetric capacity of 141,000 cubic-feet, would have expanded to 65 feet in diameter.
Due to weather concerns for early Saturday, May 10th, and with FAA approval for Monday, HAL5 had decided to delay the second attempt of Space Launch 1 until Sunday, the 11th. It was worth the wait. Sunday morning was perfectly calm, albeit cold, and the balloon launch could not have been better. A slight delay caused by some empty helium bottles resulted in a launch at 6:59 AM EDT just 6 minutes before the end of the FAA extended window.
Wind carried the balloon from its launch point in Hampstead, North Carolina (about 20 miles north of Wilmington) about 110 nautical miles to the east as it rose at an increasing ascent rate from 600 to 700 feet per minute. The rocket ignited at 8:25 AM, with the balloon safely over open ocean.
The balloon gondola carried an amateur television (ATV) camera and transmitted live color video back to earth at a frequency of 434 Mhz. The camera was oriented so that it looked straight up past the side of the gondola towards the balloon. The rocket carried a smaller black and white ATV camera transmitting at 1280 MHz, GPS receiver, and transmitter.
At 8:25 AM, the balloon was at about 60,000 feet altitude when it suddenly opened along a seam line. This was not supposed to happen,even at altitude, as the bottom of the balloon is open to allow helium to vent when necessary. We are still analyzing the video to determine what happened and will be sending a copy to the balloon manufacturer to get their expert advise. With the rocket well clear of land, and well out over international waters, a decision was quickly made to send the command to fire the rocket.
Gondola video was fine throughout the mission and clearly showed the rocket launching past the deflated balloon -- confirming a near vertical launch for the rocket as planned. The color video shows a brilliant flash from the rocket exhaust followed by an expanding cloud of plastic bits leftover from the plastic wrap. The rest of the gondola appeared intact. The cut-down squibs were fired by remote command shortly afterwards to release the gondola from the balloon and to deploy the gondola parachute.
Altitude verification for the rocket was to be primarily based on signals from an onboard GPS receiver. GPS transmissions faded away, however, while the balloon was only at 30,000 feet. Backup altitude verification was to have come from the B&W camera, which was oriented so that the curvature of the Earth can be measured to estimate the altitude. The rocket video transmissions lasted longer, but also faded away before the rocket reached apogee. The team is confident that the onboard electronics operated properly, but the antennas used were not oriented well or large enough for the signal to reach out past 100 miles. Analysis of available data and video is still being performed to determine the altitude and distance reached.
Without the GPS transmission, HAL5 has no direct measure of rocket apogee altitude. HAL5 would be most grateful to anyone tracking the balloon and/ or rocket by radar, by radio transmissions, or with optical telescopes to send us a copy of your data and conclusions.
The balloon gondola and rocket both splashed down far out in the Atlantic Ocean, well out of reach of our recovery boat. It is possible that they will wash up on shore some day in some country. Rewards and acknowledgment will go to whomever recovers the balloon gondola and/or rocket. If you find either one, please take photographs and make notes of its condition where you find it (on the beach or in the ocean) before picking it up.
Kudos to the entire Project HALO team, including its temporary on-site volunteers. Thanks also to the entire memberships of HAL5 and NSS for their support, to the people of North Carolina for their fine hospitality, encouragement, and support , and to the members of the press for understanding.
More Information about HALO
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