Ashima Research Concedes to Roffman Critiques
ASHIMA CONCESSION FOR POSTING INCORRECT DATA FOR THE FIRST 268 SOLS AND THE ROFFMAN RESPONSE TO IT:
For the first 268 sols of data collected by REMS we’ve archived the XML data files published by CAB without any modifications. We also collected these files into a rems_climate file that powers our mobile HTML5 app.
We’ve known about a few small flaws in the data stream for a while, including the lack of wind data, occasional copy-paste errors and changes in the language used for terrestrial dates (the files are manually updated). However, this is not the ‘science’ data (which can be found on NASA’s Planetary Data System) and this site is not maintained by/for the REMS science team. So, while we can guess at corrections to the data, we don’t add or create data without a very good reason.
Last month, spaceappschallange launched a project called “Wish You Were Here” to provide an “interesting representation of weather on Mars” using the REMS public feed. This led to most (if not all) of the participating groups to base their projects on our archived data feed and blame us for the errors they found. A few even tried to correct the data and added in new and interesting errors while doing so.
We can’t fix all of the data, but the data we release now contains a few extra values related to time on Mars that we calculate using our Python tools that we also use in our Data Assimilation project. The new data does not replace the old data, which still exists in the files, but we’ve added some fields to provide our best estimates of the timing data. Some of the projects formed in the spaceappschallange have archived our dataset, so it might take them a while to update, but the data is live in our weather app right now!
In detail, we have:
1. Calculated the sunrise and sunset times at MSL in Mean and True Solar Times. These values are much better than the fixed values provided by the original data, but still rely on some assumptions. We assume that the mission Sol in question is referenced correctly in the original data and calculate the Mars Solar Date and J2000 ephemeris offset using this data. Once this date is found we (mathematically) look for the sunrise and sunset, noting the times it happens. Times are now given in a 24 hour clock format.
2. Calculated the Heliocentric Longitude, Ls. These calculated values rely on the same assumption about Sol number as the sunrise/sunset calculation. It turns out the original data is pretty close to our calculated values so we think the original data is correct. The difference between the two is in the origin of those values used to calculate Ls. Our Ls comes directly from the Sol number. The original CAB Ls may have a better source for this value in the raw data, or they may start from the “posted” Earth date.
3. Removed the wind speed and direction data.
4. Normalized the ‘posted’ or ‘terrestrial date’ to an ISO standard format. In our weather app (that has been running since MSL landed!) we present the date in a format determined by your Locale settings.
(As a reminder, neither the original nor calculated data provided by the app should be relied on for mission planning, weather forecasting, or conspiracy theories. NASA provides many free tools to find the time on Mars with extremely good accuracy if you need it.)
THE ROFFMAN REPLY ON JUNE 7, 2013:
Well it took you long enough to remove the winds and to agree (within a minute or two) with our day length calculations. In fact, it took so long that we had asked Guy Webster to fire you guys (and, of course, the REMS Team who are the main source of your errors for these many, many, many months). By now we have filled the Internet with reports criticizing the hell out of Ashima, and, due to your retreat, we are in the process of updating it all with your new positions. What would have helped immensely to avoid all this would have been honest answers to our criticisms of your now admitted mistakes way back in September, 2012. We wrote in to your blog in good faith, and you deleted everything we had – thus greatly enhancing the conspiracy explanation for the junk you posted. In short, if you had displayed courteous manners back then we would not be where we are now in our relationship. One way to turn the relationship around is to acknowledge all the mistakes that the Roffman team brought to your attention and detailed on our DavidARoffman.Com site, rather than allude to nobody in particular who tracked your errors.
Update of April 2, 2014: Ashima should respond to our new site at MarsCorrect.com.