Now that we are at the end of 2019, it is time to look back at this year’s material published on Drew Ex Machina and see which of the 37 new essays I posted during this site’s sixth year online, along with earlier published material, proved to be most popular to my readers. In addition to satisfying my curiosity, this exercise is an attempt to figure out what kinds of articles my readers prefer so that I can focus my attention on similar topics over the coming months when possible. What follows is a review of the Top Ten most popular articles on this site during 2019 based on a raw tally of their page views. If you are interested in checking out any of these articles for yourself, they can be accessed by clicking on the titles or the feature images in the reviews that follow.
The crew of Apollo 1 poses at LC-34 on January 17, 1967 – ten days before the pad fire which killed them. (NASA)
#10 The Future That Never Came: The Unflown Mission of Apollo 1
On January 27, 1967, NASA astronauts Gus Grissom, Ed White and Roger Chaffee perished in an accidental spacecraft fire during what should have been a routine countdown rehearsal for the Apollo 1 mission. This tragic accident brought NASA’s Apollo mission to a virtual halt as the accident was investigated casting doubts on the prospects of landing men on the Moon before the end of the decade. The #10 ranked article for 2019 took a close look at the preparations for this flight as well as the details of the plans for a two-week mission that was to have launched on February 21 had the pad fire not occurred.
This image shows the solar system’s eight recognized planets in order of increasing distance from the Sun to a common size scale. (Lunar and Planetary Institute)
#9 The Practical Limits of Trip Times to the Planets
Frequently the space-related media is filled with headlines about some new propulsion technology which can shorten trip times to the planets to even hours. Of course, such sensational claims deserve a sober review which was the purpose of the #9 ranked article on Drew Ex Machina in 2019. Dusting off some calculations I did as a physics undergrad decades ago, I demonstrated that any conventional cargo would be destroyed by the huge g-forces experienced during a putative half-hour trip to Mars. In fact, barring any unforeseen breakthroughs in physics which allows us to invent scifi tech such as “inertial dampers” or the like, we are not likely to ever see trip times to Mars for human passengers of less than a day. Still, if a propulsion technology is developed that permits the construction of my hypothetical “1-g ship”, calculations show that it would be possible to reach any point in the inner solar system in less than a week or any planet in the outer reaches of our system in just a couple of weeks – far faster than our current technology allows but still fast enough to open a whole universe of possibilities for the exploration (and exploitation!) of the solar system.
A view of LM-1 being prepared for the unmanned Apollo 5 mission. (NASA)
#8 Apollo 5: The First Flight of the Lunar Module
This past year saw the 50th anniversary celebrations of many key Apollo missions as NASA and its contractors worked hard to land on the Moon before the end of 1969. One of these important missions was the unmanned flight of Apollo 5 which tested the Lunar Module in space for the first time. The #8 most popular article during 2019 was a detailed account of this largely forgotten mission and the problems it encountered. Despite these issues, the flight was deemed a success bringing NASA one step closer to the goal of reaching the Moon.
A still from a video showing the Soyuz T-10-1 being engulfed in flames on the pad seconds before its LES was activated pulling the crew to safety. (RKK Energia)
#7 Soyuz T-10A: The First Crewed On-Pad Abort
One of the more dangerous phases in any space mission is launch. With rockets assembled from thousands of precisely engineered components filled with hundred of tons of volatile propellants, even the slightest problem can end in disaster. It is for this reason that all crewed spacecraft have launch abort options for most if not all phases of ascent into space. This need was dramatically demonstrated by the launch pad abort of Soyuz T-10A in 1983 when a pad fire broke out just seconds before launch. The crew of this mission survived because of the various safeguards built into their Soyuz spacecraft and launch vehicle.
The explosion of Atlas-Centaur 5 after its launch attempt on March 2, 1965. (NASA)
#6 The Launch of Atlas-Centaur 5
During the early years of the Space Age, Cape Canaveral witnessed some spectacular rocket failures as American engineers and scientists grappled with cutting edge technology. The #6 ranked article on Drew Ex Machina during 2019 took a close look at what was arguably one of the more spectacular failures from this time – Atlas-Centaur 5. Launched on March 3, 1965 for the fifth test flight of the cryogenic fueled Centaur, the Atlas’ MA-5 propulsion system failed just two seconds after liftoff resulting in a huge explosion fueled by the rocket’s propellant load of about one hundred tons of RP-1, liquid hydrogen and LOX. While a setback for the Atlas-Centaur program, the effects of the explosion were used to validate predictions of a hypothetical Saturn V launch failure so that facilities and personnel could be properly protected.
An artist’s depiction of Tau Ceti e and f (PHL@ UPR Arecibo)
#5 Habitable Planet Reality Check: Tau Ceti
Being the nearest single Sun-like star to our solar system, Tau Ceti has been of interest not only to scientists but fans of science fiction for decades. The #5 ranked article on Drew Ex Machina in 2019 took a fresh look at this system and updated information on its possible planetary system. An international collaboration of scientists working on various exoplanet surveys introduced a new data analysis technique which takes better account of the various sources of noise in precision radial velocity measurements allowing the detection of variations amounting to only a few tens of centimeters per second. Pooling radial velocity measurements for Tau Ceti from two long-term surveys, this group found evidence for the presence of four super-Earth-size exoplanet candidates including two first hinted in an earlier analysis from 2013 which some claimed were potentially habitable. While the prospects that these two exoplanets are potentially habitable are not very good (assuming that their existence is confirmed), these new results begin to hint at the potential discoveries and problems which await astronomers as they introduce a new generation of instruments capable of even higher precision measurements.
This is a view of the X-15 with its XLR-99 egine ignited after being dropped from its NB-52 carrier aircraft. (NASA)
#4 The First Reusable Spacecraft: The Origins & First Test Flights of the X-15
The rocket-powered X-15 is easily the most popular of all the X-series aircraft. During the course of this aircraft’s decade-long test program, it set a succession of records for speed and altitude qualifying eight of its pilots for USAF astronauts’ wings in the process. The #4 ranked article this year takes a close look at the origins of the X-15 program and the first test flights which were flown 60 years ago.
A vies of Saturn 500F at Pad A at dawn on June 22, 1966. (NASA/KSC)
#3 The Saturn 500F: The Moon Rocket that Couldn’t Fly
A half century ago, NASA was gearing up for the final push to land astronauts on the Moon. One of the key milestones to reach that goal was the completion of the facilities at Launch Complex 39 where the Apollo-Saturn V would be assembled, checked out and launched. On May 25, 1966 NASA rolled out a non-flight model of their Moon rocket called Saturn 500F to checkout the newly completed VAB and Pad A at LC-39. This post on Drew Ex Machina, which ranked #3 for 2019, tells the story of the Saturn 500F and the various tests that were performed during the summer of 1966. Immediately following the disassembly of Saturn 500F, work began on the first Saturn V flight article for the Apollo 4 test flight of November 1967.
The Apollo 9 LM, Spider, as viewed after undocking from the CSM, Gumdrop, on March 7, 1969. (NASA)
#2 Apollo 9: Giving the “Spider” Wings
With so much focus on the anniversary of the Apollo 11 Moon landing, some of earlier test flights which made this mission possible did not get the attention they deserve. This probably explains the popularity of the #2 post in 2019 which gave details of the Apollo 9 mission. Launched on March 3, 1969, this ten-day mission tested the Apollo Lunar Module in space for the first time with a crew on board as well as continue testing of other systems needed to land on the Moon. The success of this mission continued to pave the path for the successful Apollo 11 mission four month later.
Apollo 6 shown during its ascent as debris is seen coming off of its spacecraft launch adapter (SLA). (NASA)
#1 Apollo 6: The Saturn V that Almost Failed
Space enthusiasts fondly remember the Saturn V rocket which sent nine Apollo crews to the Moon including a dozen astronauts who actually landed on the lunar surface between July 1969 and December 1972. Retired after thirteen flights when it launched NASA’s Skylab space station into Earth orbit on May 14, 1973, it is frequently claimed that the Saturn V had a perfect flight record – an unequaled achievement for what was the largest launch vehicle of its day. While it is certainly true that no Saturn V suffered a catastrophic failure, which resulted in the total loss of a mission, NASA’s famous Moon rocket did experience its share of problems.
The most popular article on Drew Ex Machina for the second year in a row related the details of the unmanned Apollo 6 mission. Launched on April 4, 1968, the second Saturn V to fly experienced more than its share of problems during its flight culminating with the failure of the S-IVB third stage to reignite to send the spacecraft on a simulated trajectory to the Moon. Fortunately, the causes of the failures were quickly assessed, and fixes confidently identified eliminating the need for a third unmanned test flight of the Saturn V and keeping NASA’s schedule on track to land on the Moon before the end of 1969.
I would like to take this opportunity to thank the almost 92,000 people from around the globe who have taken time in 2019 to read these Top Ten as well as the other 289 essays on Drew Ex Machina. The many comments and feedback on this site as well as in other forums have also been greatly appreciated. I intend to continue posting interesting essays on space-related topics during 2020 and hope that all of you continue reading and enjoying them.
Happy New Year! Drew LePage
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