Experimental investigation of the formation of dipeptides in the ices of Kuiper Belt Objects

早期地球上怎么会有有机分子？它们是在这里发展的，还是从太阳系的其他地方来的？一个可能的来源是海王星以外的柯伊伯带，到目前为止，在那里已经发现了超过7万个直径超过100公里的物体。大多数这些柯伊伯带天体，或KBO，主要由不同组成的冰组成，Chon是生物体中最常见的元素。例如，夸奥尔上的冰包括氮、甲烷、乙烷和水。由于KBO从太阳系发展的早期就存在，这些冰已经暴露在电离太阳辐射下数十亿年。这种辐射会在冰基质中引发化学反应，可能会导致二肽的形成。二肽在益生菌分子的发展中起着关键作用，它不仅是蛋白质的组成成分，而且是多肽和酶的催化剂。由于KBO被认为是短周期彗星的关键来源，它们可能已经将这些与生物相关的分子送到了早期地球。该项目的目标是通过实验模拟KBO上的物理和化学条件和过程，以确定是否以及在什么条件下可以在那里形成二肽。为此，我们将使用一台新型的超高真空机合成成分和温度方面与KBO冰类似的冰。然后，我们将把冰暴露在电离辐射中，这种辐射模拟了KBO上自然产生的辐射(质子和光子)。在冰的辐射期间和之后，我们将使用一系列专门开发的检测机制来探测复杂的有机分子，特别是二肽键。在第一阶段，为了排除检测到的伪像，我们将首先合成纯冰块，并获得用于稍后比较的测量结果。然后，在第二阶段，冰将分别用每种类型的电离辐射处理，然后同时用光子和质子辐射处理，因为相互作用是可能的。最后，在第三个实验阶段，在辐照之前，将在冰中掺入矿物橄榄石(彗星上发现的几种类似矿物之一)，以测试可能的催化效果。

How did there come to be organic molecules on early Earth? Did they develop here or arrive from elsewhere in the Solar System? One possible source is the Kuiper Belt beyond Neptune, where over 70,000 objects with a diameter larger than 100km have been identified to date. Most of these Kuiper Belt Objects, or KBOs, consist mainly of ice of varying compositions of CHON, the most common elements in living organisms. For example, the ice on Quaoar includes nitrogen, methane, ethane, and water. Because KBOs have existed since the early stages of the Solar System's development, these ices have been exposed to the ionizing solar radiation for billions of years. Such radiation can trigger chemical reactions in the ice matrix, possibly resulting in the formation of dipeptides. Dipeptides play a key role in the development of prebiotic molecules, not only as a building block of proteins but a catalyst of polypeptides and enzymes. Because KBOs are considered to be a key source of short period comets, they may have delivered these biologically relevant molecules to the early Earth.The goal of this project is to experimentally simulate the physical and chemical conditions and processes on KBOs, to determine if, and under what conditions, dipeptides can form there.To do this, we will synthesize ices analogue to KBO ices in composition and temperature, using a novel ultra-high vacuum machine. We will then expose the ices to ionizing radiation that simulates the naturally occurring radiation on KBOs (protons and photons). Both during and after the radiation of the ices, we will use an array of specially developed detection mechanisms to probe for complex organic molecules and for the dipeptide bond in particular. In the first phase, to rule out detection artifacts, we will first synthesize the pure ices and obtain measurements for later comparison. Then, in a second phase, the ices will be treated separately with each type of ionizing radiation, then treated with both photons and proton radiation simultaneously, as interactions are possible. Finally, in a third experimental phase, the ice will be doped with the mineral olivine (one of several similar minerals found on comets) before irradiation, to test for possible catalytic effects.