Thursday, 6 August 2015


In a jar of cookies, there are calories.

Wednesday, 29 October 2014

October 2014 Antares launch failure: Some history

On October 28, the Antares rocket, an unmanned launch vehicle carrying non-critical supplies to the International Space Station (ISS), crashed seconds after lift-off at the NASA Mid-Atlantic Regional Spaceport on Wallops Island, Virginia. This was the fifth Antares launch since April 2013, and its first failed launch. It was carrying its heaviest payload yet of 2,290 kg for ISS crew, including 30 small satellites, consumables and spare parts. It is estimated that Orbital Sciences, the company that owns and manages Antares, incurred a loss of $200 million because of this launch failure.

It is unclear what caused the failure. From video footage taken near the launchpad, the first stage of the rocket is seen firing as the rocket lifts off. Within the next 10 seconds, however, sparks fly out of the lower end, a column of fire engulfs the rocket and it crashes almost perpendicularly to the ground. Like the video embedded above (taken from an airborne Cessna 177) shows, there are two distinct explosions. The first one is due to the first stage exploding and the second coincides with the rocket's crash. At a press conference, it was announced that Orbital Sciences, NASA and FAA will be conducting an investigation, in which time Orbital Sciences will be 'locked out' of revealing specific details of the failure.

In the meantime, a tweet by astronomer Pamela Gay indicates the launch was deliberately aborted after lift-off (after visual confirmation of some issue).

According to a factsheet available on the Orbital Sciences website, Antares has been designed to achieve a launch reliability of 95% or higher. It'd be meaningless to assess Antares's reliability after five launches (just as meaningless as reconsidering the future of commercial spaceflight a few hours after one failure). That chart below shows how the most reliable rockets are ones that have been services for many decades. The takeaway is not that they were in service because of high reliability but the other way round: that engineers were able to perfect each design only after multiple tests and launches.

Like the chart below shows, the more reliable rockets (darker dots) are also the ones that have been in services for longer (size).

The history of spaceflight is dotted with tens of failures, some more catastrophic than the rest. Failures - including during planning, manufacturing or testing - are not uncommon because spaceflight is an inherently difficult endeavor [scroll to page 42] due to its scale and complexity. In fact, every successful launch ought to be widely celebrated because failure comes way easier, and the success is singular testimony to how many hurdles have been overcome. Even if decade-long space programs have managed to institutionalize legacy processes, every new launch is still a potential disaster. Of 6,854 launches in the history of spaceflight (1957-2013), 549 have failed. That's a big number. And while commercial spaceflight can be tracked back to the 1960s, it's become more regular and visible only in the last four years.

The October 28 Antares launch was the third in a series of eight that Orbital Sciences has to execute per an ISS-resupply agreement with NASA.According to the factsheet, Antares is a two-stage rocket with an optional third stage. The first stage, comprising two Aerojet Rocketdyne AJ26-62 engines, is powered by oxygen and kerosene. The first of two explosions visible in videos is the kerosene burning up, with the remainder oxygen dissolving into the atmosphere. The second stage is the real bad news: it consists of one ATK Castor 30B motor powered by solid fuel, which has much higher energy density and is toxic, too. Its explosion is likely to have caused significant damage to the Wallops launchpad, which is the only facility that Antares can be launched from (similarly, SpaceX launches from the Kennedy Space Center, Florida).

On October 16, Orbital Sciences announced to shareholders that it had upgraded its second stage engine (although it didn't name the new engine). However, if preliminary reports are to be believed, then the first stage Aerojet A26-62 engines are the problem. These engines are derived from the Soviet-era NK-33 engines that were used on the N-1F launcher family in the 1970s. The N-1 was abandoned after all four of its launches failed. In fact, an A26 also failed during a test in May 2014, and before that in June 2011. However, this is only speculation; let's wait for the investigation to conclude before we come to conclusions because NASA also tested many of the A26s and had approved them for use.

Friday, 17 October 2014

State support for power production in the EU

Ozone depletion is impact by long and far the most impacted by various power production modes over their lifetimes, on average. However, the rest of the segregation misses the point on climate change (0.043 EUR) for two reasons. One, changes like ozone depletion, land transformation and water acidification also contribute to climate change. Two, incentives in terms of carbon cuts are not included in the data.

These conclusions are from a report compiled by energy consulting group Ecofys for the European Union. It also goes on to assert that the cost of nuclear power and solar power are starting to converge, at 100 EUR/MWh and 100-115 EUR/MWh, respectively. However, this assertion glazes over the significant tax support solar power development receives from EU states.

The most significant amount of support, comes unsurprisingly from Germany, which has 19 nuclear power plants slated for decommissioning. The countries that come second and third are Spain and France. Support from Italy, on the other hand, saw a drastic 448% drop from 2011 to 2012. Data from countries apart from the ones shown wasn't available.

A harmonograph

Monday, 15 September 2014

Suicide notes

From a recent report titled 'Preventing suicide: A global imperative', authored by the World Health Organization:
These numbers are from 172 WHO Member States with populations of 300,000 or more. These estimates represent the best estimates of WHO, computed using standard categories, definitions and methods to ensure cross-country comparability, and may not be the same as official national estimates. The estimates are rounded to the appropriate number of significant figures.

Compare them to what they were in 2000 with the map below.

Exactly 50 of the 172 countries saw an increase in suicide rate per 100,000 people between 2000 and 2012. Of them, the top 10 were South Korea, Bolivia, Suriname, Angola, Turkmenistan, Montenegro, Burundi, Cyprus, Malawi and Equatorial Guinea.

The WHO concedes that the numbers reported here may not be the same as national estimates, which means the efficacy and/or methodology of federal methods to register cases of suicide could vary from country to country. The report maps this variation out. As you can see, almost all of Africa has unreliable data; Middle East countries with autocratic governments and western South American nations have vital registration systems in place; and, surprisingly, most of South East Asia has only sample registration of data - at least probably because of logistical issues in heavily populated India and China.

From the report, again:
There are several important caveats that need to be considered when evaluating these suicide mortality data. Of the WHO 172 Member States for which estimates were made, only 60 have good-quality vital registration data that can be used directly to estimate suicide rates. The estimated suicide rates in the other 112 Member States (which account for about 71% of global suicides) are necessarily based on modelling methods. As might be expected, good quality vital registration systems are much more likely to be available in high-income countries. The 39 high-income countries with good vital registration data account for 95% of all estimated suicides in high-income countries, but the 21 LMICs [low- and middle-income countries] with good vital registration data account for only 8% of all estimated suicides in LMICs.
For India-specific data, there is a report from 2012 from the office of the Registrar General of India, which estimates that 134,600 killed themselves in that year - a value that a study in The Lancet pegs at 187,000. Either way: an image from this study shows which states have the highest suicide rates (ASR = age-standardized suicide death rate per 100,000 people) by gender.

While 75% of the world's suicides occur in LMICs, most of India's suicides seem to be happening in the better-off southern states.

Saturday, 30 August 2014

Counting (war)heads

On a map of where the warheads are supposedly deployed. Note: In northwest India, India and Pakistan seem to have a or some warheads in the same location. That location is Punjab, and Google Maps has plotted the Pakistani side of Punjab on the Indian side. Another curious datapoint is Amur, France, where apparently a Russian warhead rests.

Wednesday, 6 August 2014

Female parliamentarians

Visit my blog for more on this.

Wealth and religion

Tirupati's biggest sources of income

Its other sources of income:

In the world at large, religion and wealth share a negative relationship. Specifically, countries with higher GDP have lower religiosity. See here for more.

Saturday, 2 August 2014

The Big Mac Index

Data available here - thanks to The Economist.

"The difference between the price predicted by the [black line at '0'] for each country, given its income per person, and its actual price gives a supersized measure of currency under- and over-valuation."

Price of a Big Mac in the local currency