自然通讯文章"到地核的任务-一个谦虚的建议"，建议在裂缝中放置大量液态铁，让它一直下沉到地核，携带一个可以使用地震波传输数据的探测器。这是一个有趣的想法。虽然可能有许多技术问题，但我觉得似乎没有什么是不可克服的，值得一试。但是，我想知道为什么作者建议使用液态铁而不是液态铅。我希望铅更便宜，也需要更小的体积来实现相同的断裂应力(由于密度更高)。此外，较低的熔点有利于裂纹在表面附近扩展。

铅会溶解在周围的岩浆中吗?它会发生化学反应变成更轻的化合物吗?

由于原文是在付费墙后面，我在这里复制正文:

我之前已经评论过了这里。不管这是铁、铅还是其他什么东西，都不会起作用。发表在《自然》杂志上的事实并不意味着它就是真的，永远记住这一点。

A 10⁸ kg的铁球将有大约< A href="https://www.wolframalpha.com/input/?i=1E8%20kg%20of%20iron" rel="nofollow noreferrer">直径30米，与地球尺度相比，这不是很多。下面是为什么它不会起作用:

1. 我们在地表上有非常大质量的物体。它们被称为建筑物。它们不会下沉。尽管它们没有那么密集，但建筑物建立在基础上，将其质量集中到一个小区域，产生非常大的压力。地基的作用是将建筑物固定在坚固的岩石上，这样它们就不会下沉。作者建议用炸药引爆裂缝。也许是核爆炸。我们过去有很多核爆炸——它们不会产生裂缝。 They make craters.
2. Crack propagation is only relevant in the lithosphere. Once you get to the asthenosphere, about 200 kilometres deep, cracks don't propagate any more and the equations the author presents are meaningless. Plastic behaviour of rocks is achieved much earlier anyway.
3. Even if there is a crack, it will have smaller cracks radiating from it. The liquid iron, being liquid, will fill those smaller cracks and lose from the mass of the main liquid blob. With time, the blob will get smaller and smaller until it will not be able to do anything any more.
4. The melting point of iron is more than 1500 °C, this higher than the temperature of the ambient rocks. It will lose heat quicker than it gains by gravitational potential and solidify.
5. The iron will react with the rocks around it. Particularly if it is liquid, because these things are highly reactive. It will start dissolving things into it (which will counter point 5), but it will also lose iron to the surrounding rocks. It will dissolve oxygen, carbon, sulfur, possibly alkalis like sodium, maybe silicon. These are light elements that will overall lower the density of the ball of iron, bringing it to a stop.
6. The oxygen fugacity of the crust and upper mantle is higher than iron-wustite, which will be imposed by the equilibrium with iron. Therefore, it will leach oxygen from the surrounding rocks, essentially turning some of the liquid iron into "rock". This will also decrease the mass of the blob of iron.

You were specifically asking about lead. All points above (except 5) are equally applicable to lead.