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06 February 2004

Resources for Analyzing Data from Interplanetary Space Missions

by Reginald Smith

It seems everyone today has Mars fever. The casual observer may assume that this recent upsurge in interest in the Red Planet began with the landing of NASA’s most recent rovers, Spirit and Opportunity. However, it has been evident to me that the public interest in Mars was rising even before recent events. Just witness the worldwide wonder at the close approach of Mars last August. From the US to Europe to Asia to Africa it can be argued that this new excitement is more than just a fad.

The biggest beneficiaries of this recent popularity have been astronomy and amateur astronomers. Amateur astronomers have long been the most organized, and arguably the most impressive, single segment of the amateur science community. For centuries, they were the vanguard of humanity’s search for meaning in the cosmos. In many respects they still are. However, the game has significantly changed since the launching of Sputnik on October 4, 1957 and the beginning of the age of direct exploration of heavenly bodies.

Since Sputnik only orbited the Earth though, one can argue that true interplanetary exploration did not begin until Pioneer 5 and Luna 1, which respectively investigated solar phenomena and the moon in 1959. Since then, space probes have been regularly sent to investigate the planets and other large bodies of our solar system. These missions have each gathered massive amounts of data and sent it back to Earth for detailed inspection. From this data, discoveries such as the solar wind, planetary moons, and the environments of our neighbors in the solar system were discovered.

Until recently, the huge volumes of data generated by these probes could only be dealt with by those with massive computing power reserved only for governments and large corporations. The information revolution, however, has put such power in the hands of every household. Clearly then, the amateur scientist could hope to participate in the investigation of the cosmos.

Forrest Mims discussed in an earlier SAS E-Bulletin how one could ask valid scientific questions from the photos being sent back from Mars by the two rovers. What is probably surprising to most is that the data from these missions is often publicly available, even in raw form (though the Mars rover data will likely not be publicly available for several months). One does not have to be content with just analyzing photos released in major newspapers by NASA or the ESA. With a lot of motivation, patience, and diligence one can obtain and analyze data from these space probes and perhaps even make discoveries that were lost in the mounds of data.

Sources of Space Probe Data

With the power of the Internet, one does not have to look for data at an academic library. You can also request CD-ROMs from NASA that include data from most space probe missions. Much data is easily available for present and past missions of NASA, the European Space Agency (ESA), and even Russian space probe missions.

NASA’s Planetary Data System (PDS)

http://pds.jpl.nasa.gov/scientist.html

The Planetary Data System (PDS) is NASA’s warehouse of almost all of the publicly available data from its interplanetary and Earth scientific missions. The data sets are divided several ways, including the type of data collected (including atmospheric, geological, planetary rings, planetary plasma interactions, small bodies, and of course, images), the target bodies of the data, and the space probe mission, which obtained the data. In addition, there is a plethora of free software available that helps prospective researchers analyze the data more efficiently. There is a lot on this site, and it is worth spending time looking at the information available.

NASA’s National Space Science Data Center (NSSDC)

http://nssdc.gsfc.nasa.gov/

This is another way to get into the archive of NASA’s space data, although most of what it does seems to be overlapped by the PDS. One great bonus is that you can find information on data sets from non-NASA space missions, including many Russian ones. It is a good resource to supplement any search for data.

ESA’s Science Operations and Data Systems Division

http://www.rssd.esa.int/index.php?project=RR

This is the closest I could find to a companion page of NASA’s PDS for the European Space Agency’s interplanetary missions. The ESA likes to organize its data sets by missions, so choose the field of interest from the task bar at the top (Astrophysics, Planetary Exploration, etc.) and find the probe mission that has information for which you are looking.

Russia’s Space Research Institute

http://www.iki.rssi.ru/eng/index.htm

This is the central location for information about the Russian probes and their data sets. It is also a good jumping off point for finding information on the Russian space program in general. Most of these data sets are most easily available through the NSSDC.

Analyzing Data

Let’s say you have some data. Now the hard part begins. It is no trivial matter to sort through data, and many a researcher or grad student has spent hours agonizing over data interpretations. There are several clear steps one should take in analyzing this information.

1. Make sure you know the format of the data. Data can be in various formats and have different tags depending on which file type it is and what it is trying to represent. Make sure you know what software you need to analyze the data. Much of the software is free and available from sources like the PDS.

2. Make sure you know how "clean" the data is. NASA releases data sets with various amounts of "cleaned" data to the public. Clean data has usually been processed to eliminate spurious information, noise, etc. and placed in a format that will make a researcher’s job easiest. Data certified this way has usually been looked over by a panel of experts and is definitely much better than "raw" data.

3. Understand the instruments taking the measurements and what their results mean. Before you interpret any data in an experiment, you must be familiar with the apparatus. Space data is no exception. First, you should know what the instrument was monitoring, such as the strength of magnetic fields, optical spectra, and so forth. This will help you appreciate what the data can tell you and what it cannot tell you.

4. For your first study, agree with the experts. Once you decide to tackle a data set it is a good idea to go to the nearest academic library and find peer reviewed publications that have used the data you are studying. The purpose is to find results made by researchers familiar with the data and try to replicate them. It is one thing to interpret data and another thing to interpret it correctly. The best task you can accomplish is trying to back track a researcher’s steps and get the same results. That way, you can get valuable experience manipulating the data and get a good feel on how to interpret the readings.

5. Consult with experts if necessary. Often, experts are very friendly and helpful if you come to them with concise and clearly defined questions, and you show you know what you are trying to do. Do not hesitate to ask for help. Valuable sources can be researchers who have published findings based on the data and researchers that worked with the space probe data. Flattery also never hurts, if you know about research they have done. Referencing their work is always appropriate, and telling them how great and helpful it was could go a long way.

6. Be conservative when extrapolating from your results. When you come to a possible conclusion, it may be exciting but it definitely should be realistic. It is not likely that you will find definitive evidence of life on Mars going back through old Viking data (though you may find new and interesting results). It is best to conservatively report what you have found in terms of recognized scientific laws and processes, unless you are extremely sure the evidence points in a different direction. If this is the case, you would be wise to look at all other explanations and provide convincing counterevidence for their involvement.

7. If you have good results, share them with the world. If you find results that are new and noteworthy, by all means begin the task of publishing them. The peer review process can be rigorous and occasionally discouraging. If you know your work represents solid science, consider posting it on www.Arxiv.org, submit it to a journal, and send it to experts in the field to get their opinions of your results.

Thanks to the Internet, all of this wonderful information is at our fingertips. I will be honest. This is not an afternoon amateur science exercise. Often it will require you to look at texts from a variety of fields, including space physics, geosciences, and even measuring instruments. However, to a dedicated amateur scientist, I am sure a treasure trove of discoveries awaits you in the data from these valuable missions.