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发表于 2006-9-8 09:35:46
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2006年9月6日
What's next -- how do you work with a $200 million collector?
(Very carefully!)
接下来是什么？——怎样处理价值2亿美元的收集器？（非常的小心！）
The Stardust@home collaboration has now identified several candidate features in the aerogel that may be the tracks of the first contemporary interstellar dust particles ever brought back to Earth for study (or, they may be something else). We have examined several of these as well as we can through the microscope in the Cosmic Dust Laboratory. Several have passed this cut -- that is, they are still very promising -- and we can't wait to find out what they really are.
Stardust@home 的协作已经在气凝胶中挑出了一些候选特征，或许就是首次被带回地球研究得星际尘埃的轨迹（也可能什么都不是）。一旦我们能使用彗星尘埃实验室的显微镜，便检查了其中的一些。有些已经通过了此次筛选——的确，它们很有希望，我们已经等不及要知道他们究竟是什么东西了。
Unfortunately, it is very difficult to get good images of tracks in the aerogel tiles while they are still in the flight tray (as many of you have pointed out). So to make further progress, we will need to remove the tracks from the collector.
不幸的是（如同许多人指出的那样），由于凝胶块还在收集器的盘子里所以很难得到轨迹在凝胶中的好图像。为进一步的处理，我们需要从收集器中取出这些轨迹。
We are considering two options. The first is to extract the tiles containing these candidate tracks from the collector. This will enable us to examine the tracks in transmitted light, which gives much improved visibility, particularly at very high magnification (we currently have to use reflected light illumination). There are two principal risks in doing this. First, because the aerogel may be somewhat distorted during extraction, we may partially lose the ability to accurately determine where on the sky the particle originated. This could compromise our ability to distinguish between interstellar dust and interplanetary dust. Second, the aerogel is very fragile; it could just fall apart if we try to remove it from the tray. We do have a flight spare that we could practice with, but we know from our experience with the cometary aerogel that it has changed somewhat in space; it has become more brittle. We don't think that either of these issues is very serious, but they have to be considered carefully.
我们考虑了两种方案。第一个方案是从收集器中把包含轨迹的块取出。这将使我们能在透射光中检查这些轨迹，那将大大提高可视性，尤其是在很高的放大倍数下（我们现在使用的反射光照明）。这么做有两个主要的风险。首先，凝胶在取出时可能会受到一些损坏，将使我们部分的丧失测定微利来自天空的哪个方向的能力。这有可能危及我们区分星际尘埃和太阳系内尘埃的能力。其次，气凝胶非常易碎，可能在把它从碟子里弄出来的时候会碎成块儿。我们确实有大量可供练习的备用品，但是我们从彗星尘埃的凝胶那里得到的经验是：凝胶在太空里发生了一些变化，变得更加易碎了。我们不认为这些结果会很严重，但是它们必须被认真考虑。
The second option is to extract the track directly from the aerogel in a "keystone", using an extraction technique that we developed here at Berkeley specifically for Stardust and have been using successfully for several months on the cometary collector. Here we use robotically-controlled micromanipulators and extremely sharp glass needles to machine the aerogel, and extract tracks in tiny doorstop-shaped wedges of aerogel that we call "keystones". The visibility of tracks in these tiny keystones is superb (see picture below). But we would be doing the keystone microsurgery either over or next to the entire collector. We would have to build in numerous safeguards to be absolutely sure that nothing could endanger the collector.
第二种方案是直接从气凝胶中提取出含有轨迹的楔形块，用的是我们在伯克利特别为 Stardust 开发并在数月前成功用在彗星收集器上的提取技术。在此我们用自动控制的显微操作器和极其尖锐的玻璃针来加工气凝胶，并取出含有轨迹的一小块楔形凝胶，我们称之为“楔石”。这些小楔石中的轨迹其可视性非常的好。但是做这样的显微手术差不多要覆盖整个收集器上空。我们要建立众多的安全机制确保收集器的绝对安全。
If this were almost any other project, we could afford to take risks and try some things out. But the interstellar collector is practically priceless(well, not exactly priceless, but it would cost at least $200 million to get another one). So we have to be incredibly careful, and we have to make sure that we've thought this through extremely thoroughly.
如果是其他的项目,我们可以冒些风险试着做些事情。但是星际尘埃几乎是无价的（好吧、不是无价的，但是要花至少2亿美元才能再弄些来）。所以我们不得不极端小心，确保想到了所有可能的事情。
Fortunately, a situation like this has come up before. In the late 1960's, when the Apollo missions were bringing back rocks from the Moon, NASA recognized that they needed a way to oversee the handling of these incredibly precious samples. So NASA organized a committee of scientists called the Curation and Analysis Planning Team for Extraterrestrial Materials (CAPTEM) to oversee the curation of the Moon rocks -- that is, to advise NASA on how to store and distribute them. Even though it's been nearly 40 years, this committee is still very busy making recommendations to NASA on the curation and distribution of all kinds of extraterrestrial samples to scientists all over the world. These include the Apollo moon rocks, which are still in very heavy demand, but now also include samples from the Genesis mission and now Stardust.
所幸的是，以前有过类似的情形。在上世纪60年代末，当阿波罗计划从月球带回岩石的时候，NASA 认识到需要一种方法来监督对这些无价之宝的处理。因此 NASA 组建了一个称作“掌管与分析地外物质计划编制组”(CAPTEM)的科学家委员会来监督月球岩石的掌管，也就是向 NASA 提供如何对其保存和分发的建议。时至今日已经将近40年了，该小组依然忙碌于向 NASA 提供所有类似的地外样品在掌管以及向全球的科学家分发方面的建议。包括阿波罗带回的岩石——它依然是供不应求，以及如今的“起源”号样品和“星尘”样品。
A subcommittee of CAPTEM has been organized for the oversight and allocation of the Stardust samples. Amazingly, it's called the Stardust Sample Allocation Subcommittee (SSAS). The Stardust@home project director, Andrew Westphal, is on this subcommittee. The SSAS will meet on Sept 18-19 in at the Lunar and Planetary Institute (LPI) in Houston near NASA's Johnson Space Center. (See the ARES website). At this meeting, we will decide on a course of action, then make a recommendation to the CAPTEM committee that will meet at LPI near the end of October. We will keep the Stardust@home collaboration informed as this careful decision-making proceeds.
CAPTEM 的一个下属委员会已经组建起来负责星尘样品的监督及分配。它叫“星尘号样品分配分委员会”（SSAS）。Stardust@home 的项目主管 Andrew Westphal 就在其中。SSAS 将在9月18-19日于休斯敦的月球与行星学会（LPI）集会。离 NASA 的约翰逊航天中心不远。在此次会议上我们将决定行动的方针，然后向 CAPTEM 委员会建议在10月底再次集会。在这个谨慎抉择的过程中我们将保持 Stardust@home 的协作得到最新消息。
This is the frustrating part: this is going to take a while. There is just no other way. We have to be very, very careful with these precious samples. After all, they belong to all the American people, who paid for the mission.
这就是阻力所在，还需要一段时间。别无他途。我们必须非常、非常小心的对待这些珍贵的样品。毕竟，它们属于全体美国纳税人。
Finally, a word about the huge advantage of doing sample-return missions. Stardust, like Apollo and Genesis, brought back samples from space that can be studied simultaneously by hundreds of scientists all over the world. Many, if not most, of the scientific instruments that are now being used to analyze Apollo samples couldn't have even been imagined in the 1960's. Even in the case of Stardust, some of the instruments that are now being used didn't exist when Stardust was launched in 1999. Some other instruments, like the synchrotrons that we mentioned in an earlier news item, are the size of shopping malls, and could never practically be flown in space. As long as we're careful, these same samples will be studied by our grandchildren using instruments that we cannot imagine today. They will be answering questions that we don't even know how to pose.
最后，总结一下取样返回任务的巨大优越性。“星尘”和“阿波罗”、“起源”一样，从太空带回样品使得全球的数百位科学家得以同时对其进行研究。此外、如今用于分析阿波罗样品的科学设备岩石上世纪60年代无法想象的。“星尘”也有同样的情况，一些正在使用的设备在它发射时还不存在。另一些设备，如先前的新闻里提到的购物中心般大小的同步加速器，是几乎可能被发射到太空中的。只要我们处处小心，我们的子孙就能用我们现在无法想象的设备研究这些样品。他们将会回答那些我们无法回答的问题。 |
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发表于 2006-8-4 11:29:58
