Astrophysicists working with ground-based detectors at the South Pole and balloon-borne instruments are closing in on such structures, and may report their findings soon.

【翻译】天体物理学家们使用南极陆基探测器和球载仪器，正越来越靠近这些构造（具体指什么，不详），也许不久会报告他们的观测结果。

【分析】

1. ground-based detectors：陆基探测器

2. balloon-borne instruments：球载仪器

3. working with ground-based detectors at the South Pole and balloon-borne instruments：现在分词短语作定语，修饰Astrophysicists。因为太长，可以当作谓语来理解和翻译。

4. close in on：“接近；逼近；靠近”。