This week saw the launch of a new project - the Horizon program. As promised, a probe has left Kerbin orbit and is currently on an intercept course for the planet Eve. Horizon I was launched on top of a new Houndstone IIA launch vehicle (which is a modified version of the Houndstone II used to launch Observer) just days after the Ranger long-distance communication satellites were put into orbit.
The popular Union A-2A, which has been the primary launch-vehicle for the on-going Celestia Mun missions, was not powerful enough for this operation. The Houndstone IIA lifted the probe to a 500km orbit before the second-stage propelled Horizon I to an intercept course with the planet Eve. Unlike the Union launch-vehicles, the Houndstone does not have re-usable boosters.
Dawn Launch. The morning light begins to slide down the new Houndstone IIA launch vehicle that carried the new Horizon probe to Eve
Horizon I will take around forty days to travel to our nearest planetary neighbour. As it flies past Eve, it will capture colour images of the planet as well as some basic measurements. The probe is expected to come within 300km of the planet. Once it has flown past Eve, it will enter an heliocentric orbit where it will be retired.
As the craft accelerated away from our planet it took some test photographs to prove the on-board imaging system. The probe will return colour images to Mission Control thanks to it's large and powerful communications dish. This will allow us to view this mysterious world up front for the first time in detail. Because the planet orbits closer to our star than Kerbin, it is not easy to see the face of the world. Horizon I will solve that problem.
Horizon I's imaging system, the first colour camera to be fitted to a space probe, is put to the test and yields some great results. This is roughly the expected distance the craft will pass Eve. One of it's solar panels is in view to the right, while the top of the booster that propelled the probe to Eve can be seen in the bottom left.
A view of the Houndstone IIA booster before the probe detached. Once jettisoned, the booster was controlled remotely to steer away from Horizon I and return to Kerbin's atmosphere.
The staff at the KSC had to perform various tests to the craft once it had separated from it's booster. An attitude test was one particular area that needed a run-though. The problem with the craft as it speeds further and further away from Kerbin is the communication delay.
'We input a command to the craft,' Gene Kerman explained, 'and it takes several seconds to get there. At great distances, operations become tricky. At present, Horizon is about two-and-a-half million kilometers from us travelling at ten kilometers per second. This means that our signals take about twelve seconds to reach the probe, and then twelve seconds for a signal to come back. So when we send a command to the craft, it's at least thirty seconds before we know it's done what we asked it to do. Everything has to be preempted.'
An impression of Horizon I speeding towards Eve. The probe weighs just less than a ton and carries only enough propellant to ensure a fly-past of the planet.
Horizon I has already brought back a stunning image. After completing a thorough test of it's propellant systems, the staff at the KSC decided to turn the probes' camera for one final glance of it's home planet.
Farewell Kerbin. Horizon I looks back one last time at the world it shall never see again. This image was taken at a distance if 65,000km, just over a day after launch
Although not the first probe to leave the orbit of Kerbin, it is the first probe to leave and remain under control. The probe is currently in a state of hibernation after performing trajectory adjustments a few days ago. Only basic house-keeping and system monitoring tasks are being undertaken. The probe is expected to make one final orbital correction in a weeks time before all it's systems will be activated for the Eve encounter.
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