|"14-281-KuiperBeltObject-ArtistsConcept-20141015" by ASA, ESA, and G. Bacon (STScI)|
I’m sure that observant readers have noticed that the distance part of the post header has changed. We’ll now display the distance we are from Earth in AU, or Astronomical Units. An AU is the average distance between the Earth and the Sun and is a fraction under 150 million km.
We’ve now reached the outer regions of the solar system, otherwise known as the Kuiper Belt. We entered the belt after passing beyond Neptune’s orbit. Pluto is the most famous object known within the belt, and it is the largest of many hundreds, if not thousands of bodies.
The belt is formed primarily from planetesimals. These are small bodies of ice and rock remnants from the protoplanetary disk that the planets and their moons were formed from. The belt is much denser than the asteroid belt situated between Mars and Jupiter and has been traversed by only a handful of probes in the last century of space travel.
Even so, the density isn’t such that it poses a significant risk. Statistically speaking, there’s too much space and too little mass. However, we do have to be careful as we only need to be hit once by a large enough object to jeopardise the mission. There was considerable debate about whether the flight path for the Venti probe should follow this course. But the opportunity to map the Kuiper Belt, or at least part of it, was compelling and it also offered the opportunity to test our threat avoidance systems.
We’re now travelling at 1200 km/s and when we enter interstellar space we will be moving at over 30 times that speed. We don’t expect to encounter any objects of appreciable mass in deep space, however a small rock of only a kilogram could destroy the probe if we hit it at that speed.
The sail is even more vulnerable. It’s designed to be able to operate effectively even if punctured dozens of times, but it is the primary source of propulsion for the mission and a major power source when close enough to a star, so its loss would be catastrophic.
To avoid any collisions, the probe is equipped with a powerful radar system and laser tracking which scans the direction of travel. This is tied into the navigation system so it can automatically make adjustments if a threat is detected. The system is capable of 360 degrees of scanning and is the main tool for mapping the belt. We also use the optical and other sensors to look for objects farther away.
We’ve gathered some excellent data on our flythrough and have transmitted it back to the research teams on Earth. While we haven’t made any immediate discoveries, they have a large amount of new data to analyse. This is the last time we’re likely to see any bodies bigger than pebbles until we reach Tau Ceti. It’s hard to comprehend how empty it is out here.
We had another glitch with the Primary Command Module. The error followed the same pattern as the corrupt data we saw before. Once again a reboot fixed the problem, but with the error in the same place, we might have a hardware issue. The spiderbots will examine the hardware and see if they can find the cause.
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