ESA's Cluster Spacecraft Makes Shocking Discovery

A recent observation by the ESA's Cluster Spacecraft was able to finally prove a 20-year-old theory. "On 24 January 2001, the four Cluster spacecraft were flying at an approximate altitude of 105 000 kilometres, in tetrahedron formation. Each spacecraft was separated from the others by a distance of about 600 kilometres. With such a distance between them, as they approached the bow shock, scientists expected that every spacecraft would record a similar signature of the passage through this region. Instead, the readings they got were highly contradictory. They showed large fluctuations in the magnetic and electric field surrounding each spacecraft. They also revealed marked variations in the number of solar wind protons that were reflected by the shock and streaming back to Sun."

Poor Wesley...

[gzerphey]

I'm sorry but did anyone else think of a Kolvoord Starburst?

http://en.wikipedia.org/wiki/The_First_Duty [wikipedia.org]

Uh.. yeah

[orclevegam]

Well, I understand more or less what the article is about (although they said it in a very long winded way), but I'm thinking unless you're a astrophysicist, are studying particle physics, or possible electro-magnetic phenomena then this is a rather dry article.

It's my understanding based on the article that what they discovered (or more accurately proved) was that the bow shock produced by the solar wind colliding with earths magnetosphere is not actually a single giant bow shock, but more like a whole bunch of continually reforming bow shocks stacked on top of each other. Of course, I'm not a physicist, so I could be wrong in that interpretation. Also, it doesn't seem as if this discovery has any immediately applicable implications but is more of a hey, that's kind of neat, type thing.

Re:Long-delayed echoes and magnetosphere shock wav

[KutuluWare]

A comment made near the end of TFA may help explain why it's so "shocking":

Although the conditions that cause the reformation of a shock wave are rare around the Earth, they are common around these other celestial objects.

I would interpret this, in context with the rest of the article, to mean that the phenomenon measured by the Cluster doesn't normally happen around Earth. After all, we've been sending spacecraft out past the moon since long before 2001, so these can't be the first to get a chance to measure the region. I believe the point of the article was that these fluctuations were predicted in 1985, but until 2001, none of the measurements of Earth's bow shock supported the theory. The ESA was fully expecting similar readings this time around, but "shockingly" got readings that proved the 20-year-old theory. --K

Data Analysis and Peer Review Take Time

[Anonymous Coward]

The data discussed in the article were from 2001, but the final analysis was only just published this year.

Before the data from the spacecraft could be analyzed by the scientists, the data had to be calibrated and checked for anything weird that could have been introduced when they were transmitted from the spacecraft to the ground. The scientists who did this study probably used data from several instruments on board the spacecraft - the magnetic field instrument, electric field instrument, electron detectors, ion detectors, and plasma wave instruments. In order to get access to these data sets, the scientists had to contact the institutions that built the various instruments on board the spacecraft to get permission to use the data in their study.

Once the scientists assembled all the necessary data sets, they had to screen the data for bow shock crossings. Spacecraft like the Cluster satellites can record data 24 hours a day, 7 days a week, so there are a lot of data to search for events. You can eliminate some time periods right away using the orbit data, since the bow shock will only be observable over certain parts of the orbit. However, detecting features like the bow shock is not always easy to automate, so some poor graduate student probably had to spend a lot of time making plots of the data and going through them by hand to find candidates for events showing the type of shock structures described in the article. Also, the Cluster mission is actually 4 satellites, so to do a study like this, the scientists actually had to look at the magnetic and electric fields, particles, and plasma waves observed by all four satellites and compare the observations by the four satellites.

Once the data analysis was finished, the scientists may have done some modeling to compare with the theory. I wouldn't know for sure what they did to compare with the theory unless I actually read the article they published in the scientific journal.

When all of the analysis and modeling was complete, the scientists had to write the paper and submit it for publication. The peer review process for scientific publications can take up to a year.

So to make a long story short, results from spacecraft data that require sophisticated data analysis probably won't appear in a scientific journal until a few years after the data were actually recorded by the spacecraft. You might see pretty pictures taken by the Hubble Space Telescope or the Mars rovers posted on the Internet within a few days or weeks of when they were recorded, but it still can take months or even years to do any serious scientific analysis of these images.