Pioneer Non-Anomaly

Artist depiction of Pioneer spacecraft in deep space.

Artist depiction of Pioneer spacecraft in deep space. Image Credit: NASA

Pioneer 10 and 11 launched in 1972 and 1973, respectively, and were Earthkind’s  first explorers of the outer planets and emissaries to deep space.  Pioneer 10 became the first spacecraft to pass through the asteroid belt and observe Jupiter up-close, providing us with details of the gas giant’s interior, atmosphere, magnetic fields, and some of the most breath-taking images of Jupiter we had ever seen. Pioneer 11 wasn’t far behind, and after making its own observations of Jupiter, it went on to Saturn to open our eyes to the mighty ringed planet in the same way Pioneer 10 had done for Jupiter. (But this isn’t a story about the accomplishments of the Pioneer program; I’ll save that for another day.)

In addition to all of the data and images sent back, however, those two Pioneers also sent back a mystery. As early as 1980, it was noticed that the spacecrafts were experiencing an acceleration force toward the sun of .000000000874 m/s2 (meters per second, per second)1. To be clear, this does not mean the Pioneers are heading back towards the Sun. Pioneer 10 and 11 are cruising away from the Sun at a speed of around 132,000 kilometers per hour (82,000 miles per hour) and 175,000 kilometers (110,000 miles per hour), respectively, and this force is 10 billion times smaller than the acceleration we feel from the Earth’s gravitational pull. Nonetheless, the force is real and our instruments and techniques are precise enough to notice.

Many plausible causes were considered to explain the anomaly, including:

perturbations from the gravitational attraction of planets and smaller bodies in the solar system; radiation pressure, the tiny transfer of momentum when photons impact the spacecraft; general relativity; interactions between the solar wind and the spacecraft; possible corruption to the radio Doppler data; wobbles and other changes in Earth’s rotation; outgassing or thermal radiation from the spacecraft; and the possible influence of non-ordinary or dark matter.

In 1994, a thorough, long-term, collaborative study was undertaken to try and solve the anomaly. Initial results from that study were released in 1998, with a detailed analysis following in 2002. All known systematics were tested and calculated, yet that 8.74±1.33×10−10 m/s2 deceleration force2 remained. The origin of the anomaly was still unaccounted for, though the leading theory was that it was the result of anisotropic thermal radiation (don’t let the big words intimidate you, this just means heat was being radiated from the Pioneers in a certain direction). In 2004, another paper was published, proposing a deep space mission to solve the anomaly once-and-for-all.

But now, that expensive deep-space mission won’t be necessary, according to a paper just submitted by astrophysicist Slava Turyshev and his team of scientists and engineers, with thanks, in no small part, to The Planetary Society and its members.3

With funds provided by The Planetary Society, Turyshev and his team were able to collect and compile great volumes of data from the two Pioneer missions. The data had to come from a variety of different sources and came in any number of formats, media, and condition. According to Bruce Betts, Director of Projects at The Planetary Society:

“This was not an easy (or quick) task. These missions lasted for more than 30 years. Imagine all the people, computing formats, and hardcopy and electronic storage devices involved over that period, and you’ll start to get an idea of the problem.”

Boxes of Pioneer data tapes.

Boxes of data tapes from the Pioneer missions. Image Credit: The Planetary Society

Think of what you would have to go through if I handed you a 5.25″ floppy disk that contained… well, it couldn’t contain much compared to the amount of data we exchange today, but whatever it was, it was something you needed. Imagine trying to find the hardware to read the disk, and then the intermediary hardware and software that would be required to get the data from the disk onto one of today’s modern machines so you could even utilize it. If you consider how much technology has changed between now and floppy disks, you can only begin to imagine how much it has changed since the 1970s and how cumbersome compiling all of this data, let alone securing it, must have been. I digress.

Once Turyshev and his team were able to assemble the more-complete data picture, they were able to isolate the source of acceleration: that anisotropic thermal radiation. Again, Bruce Betts:

Why was the thermal emission from the spacecraft anisotropic and slowing the spacecraft down? First of all, because the Pioneer spacecraft were spin-stabilized and almost always pointed their big dishes towards Earth. Second of all, because two sources of thermal radiation (heat) were then on the leading side of the spacecraft. The nuclear power sources, more formally Radioisotope Thermoelectric Generators (RTG), emitted heat towards the back side of the dishes. When the dishes reflected or re-radiated this heat, it went in the direction of travel of the spacecraft. Also, the warm electronics box for the spacecraft was on the leading side of the spacecraft, causing more heat to spill that direction. Photon pressure, the same type of thing used in solar sailing, then preferentially pushed against the direction of travel, causing a tiny, but measurable, deceleration of the spacecraft – the Pioneer Anomaly.

At the end of the day, there are a few take-home lessons to be learned. First, Occam’s Razor proved itself once again (some of the suggestions to account for the Pioneer Anomaly were the need to invoke a new type of exotic physics). The second is that you can’t just apply Occam’s Razor and say that anisotropic thermal radiation is the simplest theory and therefore correct, you have to painstakingly collect all of the data needed to prove it — and more importantly, you have to have the experts that are willing to put forth the years decades of research to solve the mystery. Finally, you take in the account that this was made possible with the help of citizen scientists and those of us that contribute to furthering our understanding of the Universe, through means such as The Planetary Society4.

This new paper will undoubtedly generate more discussion about the Pioneer Anomaly and others will work to verify or disprove its results, but at this point it seems pretty safe to say that one of space physic’s mysteries is no more.


  1. 8.74±1.33×10−10 m/s2
  2. In physics, acceleration is a change in velocity over time. It does not only apply to an increase in speed. Traveling in your hot-rod sports car, as you step on the gas and race up to 100 miles per hour, you’re experiencing acceleration. When you notice a brick wall rapidly closing in from ahead of you and you stand on the brakes, you’re experiencing a negative acceleration. Acceleration is just a change from a constant velocity.
  3. Are you a member of The Planetary Society? I am. You should be, too! Sign up!
  4. Again, join!

F-1 Rocket Engine Recovery

They took rocket-grade kerosene and liquid oxygen, and turned it into 1.5 million pounds of thrust, 32 million horsepower, and made it possible to take the Apollo astronauts to the Moon. I’m talking about the Rocketdyne F-1 rocket engines used in the first stage of Saturn V — the only vehicle to take humans outside of low-Earth orbit.

Following launch, five F-1 engines would burn for about 2-and-one-half minutes, boosting the Saturn V and its payload to an altitude of nearly forty miles, and 55 miles downrange from Cape Kennedy. At that point, the first stage (S-1C) containing the F1 engines would separate from the rest of the Saturn V and fall back to Earth, crashing into the Atlantic Ocean where they would rest forever.

Separation of Apollo first stage from other two stages of the Saturn V.

Separation of the first (S-1C) stage containing the F-1 engines from the other two Saturn V stages, during Apollo 11.

(Image Credit: NASA)

At least, forever was how long we thought they would sit there….

Amazon.com founder, Jeff Bezos, recently announced that a “team of undersea pros” that he funded had found the most famous F-1 engines of all; the ones from Apollo 11 that launched humanity to the Moon, where the first humans would walk on another world. But finding them is just the start, Bezos Expeditions is planning on actually recovering one or more of the F-1s.

“We don’t know yet what condition these engines might be in – they hit the ocean at high velocity and have been in salt water for more than 40 years. On the other hand, they’re made of tough stuff, so we’ll see”, Bezos said in the announcement. He also pointed out that regardless of how long the engines have spent 14,000 feet below the surface of the Atlantic, they are still the sole property of NASA. He also stated that he had requested that NASA make available for display at the Museum of Flight in Seattle, Washington, the second F-1 his group manages to salvage (the first presumably would go to the Smithsonian).

NASA followed the announcement with a press release of their own, in which NASA Administrator Charles Bolden expressed his support for the project, and acknowledged the request to house a second (or the first, if the Smithsonian declines it) F-1 at Bezos’ requested facility.

“NASA does retain ownership of any artifacts recovered and would likely offer one of the Saturn V F-1 engines to the Smithsonian Institution’s National Air and Space Museum in Washington under long-standing arrangements with the institution as the holder of the national collection of aerospace artifacts.

“If the Smithsonian declines or if a second engine is recovered, we will work to ensure an engine or other artifacts are available for display at the Museum of Flight in Seattle, as Jeff requested in his correspondence with my office.”

As of yet, there hasn’t been an announced timeline, cost, or specific details released about the project; however, I personally suspect Bezos will have no problem pulling together the resources needed to tackle the feat.

Bezos ended the announcement with a quote that echoes my own heart when it comes to NASA’s ability to inspire:

NASA is one of the few institutions I know that can inspire five-year-olds. It sure inspired me, and with this endeavor, maybe we can inspire a few more youth to invent and explore.

Good luck, Bezos Industries. Thanks for taking the public treasure that NASA is and multiplying its inspiration for generations to come.


NASA's Shorty Award

Shorty Awards Logo

Last week, the ceremony for the 4th Annual Shorty Awards was held in New York City. The Short Awards, nicknamed Shorties “… honor the best of social media, recognizing the people and organizations producing real-time short form content across Twitter, Facebook, Tumblr, YouTube, Foursquare, and the rest of the social Web.”

Each year in January, the nomination period opens and people are urged to nominate social media accounts (people, agencies, groups, etc.) that they feel are particularly inspiring or important in a variety of different categories, such as Science, Travel, Art, Actresses, Government, and many more.

They’re like the Oscars or Emmy’s of the Social Media world.

I’m happy to report that in the category of Government, @NASA took this year’s Shorty.

“The Obama administration has placed a high priority on openness and on-line communications, and @NASA is honored to be recognized for its social media efforts with a Shorty Award,” said David Weaver, NASA’s associate administrator for communications. “We are inspired by the social media community and their passion for sharing our compelling story of reaching for new heights and keeping America the world leader in space exploration.”

While it is evident that the US Government has been making leaps and bounds in attempts to exist in an online world with the rest of us, I think NASA is being entirely too humble. And evidence of my claim comes from another Shorty Award:  Best Social Media Manager, awarded to Stephanie Schierholz, the social media manager for none other than NASA.

Not only has NASA set an example for how government can properly use social media, it has set an example for how the social media industry itself can properly use social media.

It is especially refreshing that, during a time in which the American political institution has relegated itself into a malignant mass of bemusement that is quickly making the case that its greatest efficiency is its ability to divide its populace, NASA still stands out as a bipartisan non-partisan example of what makes this country worth the effort one must muster to endure these very trying times. NASA continues to be one of the All-American beacons that inspires the world along with the nation that supports its existence.


ATREX – Observing the Air Up There

I suspect we might hear about strange sky phenomena and UFOs occurring over the US Eastern Seaboard tomorrow, thanks to NASA’s ATREX mission.
After previously being scrubbed, the next launch attempt has been set for the wee hours (2am – 5am EST, or what I might consider late tonight) of March 27. ATREX, or the Anomalous Transport Rocket Experiment, is designed to study ultra-high altitude, high-speed wind patterns that have been observed on the very edge of space1. Data suggests that 200 – 300 mile-per-hour winds occur at an altitude of 62 – 68 miles; though little is yet understood about the phenomena. The atmosphere at that height is incredibly thin, and it essentially takes a rocket to get there.

The project will complete its test with the use of five of what are referred to as sounding rockets, launched within minutes of each other. These sounding rockets are smaller than those that are used to achieve orbit or carry heavier payloads, but will work just fine for this experiment. After reaching an altitude of 50 miles, the rockets will release a chemical tracer that will be observed from camera facilities both North (New Jersey) and South (North Carolina) of the Wollops Flight Facility in Virginia. The chemical, trimethylaluminium, was selected due to its reaction to oxygen; it glows and produces aluminium dioxide, carbon dioxide, and water vapor (each already present in our atmosphere).

Diagram of ATREX mission
(Graphic showing various aspects of the ATREX mission. Click for larger version.)
[Credit: NASA/Goddard Space Flight Center]

If you’re not on the US East Coast, but still want to try and watch the show, NASA has a webcast available here: http://sites.wff.nasa.gov/webcast/ and a UStream will carry it here: http://www.ustream.tv/channel/nasa-wallops

For more information, you can follow the Wollops Flight Facility on Twitter, and check out the video below.


  1. For an important point of clarification, when I use the term “edge of space”, I mean it literally. You will often hear about an amateur balloon going to space, or a sky-dive from or near space, but those are exaggerations in my opinion. In my book, we’re talking at least 50 miles (the point at which NASA gives you astronaut wings) or better yet, the Kármán line.

The Corned Beef Sandwich Incident

Today marks the anniversary of one of NASA’s more “corny” moments. It was on this day in 1965 that… well, let me explain:

Project Gemini was the bridge between the Mercury and Apollo NASA space programs. Mercury proved NASA had the capability to put humans into Earth orbit, and Gemini set out with a new set of goals, including: putting multiple astronauts into orbit aboard the same craft, learning how to walk in space, practicing rendezvous and docking between crafts, and testing the influence of long-term spaceflights. All of these were necessary to begin the Apollo program with its goal to put a man on the Moon (and bring him back home safely!) before the end of the decade.

Gemini 3 Mission Patch

Gemini 3 Mission Patch / Source: NASA

Following two unmanned Gemini missions, Gemini III was the first manned mission in the program and carried Command Pilot Virgil I. “Gus” Grissom and Pilot John W. Young. Gus Grissom became the first human to fly into space twice, while John Young took his rookie flight.

The Gemini III capsule1 orbited the Earth three times on March 23, 1965, over the course of just under five hours.

Then, at 1 hour, 52 minutes, and 26 seconds into the mission… it happened.


Grissom: What is it?
Young: Corn beef sandwich.
Grissom: Where did that come from?
Young: I brought it with me. Let’s see how it tastes. Smells, doesn’t it?
Grissom: Yes, it’s breaking up. I’m going to stick it in my pocket.
Young: Is it?
Young: It was a thought, anyway.
Grissom: Yep.
Young: Not a very good one.
Grissom: Pretty good, though, if it would just hold together.


John Young, through the aid of fellow astronaut Wally Schirra, had smuggled aboard a corned beef sandwich. Young and Grissom shared a few bites, but it began to crumble and little bits of it began to float around inside the capsule. It was quickly stowed away to prevent the pieces from shorting out any sensitive electronic equipment.

After Gemini III returned to Earth, Young, Grissom, and Schirra, and NASA caught flack for the incident from members of Congress that were looking for an excuse to cut agency funding.

Young elaborated in his 2012 memoir, Forever Young: “A couple of congressmen became upset, thinking that, by smuggling in the sandwich and eating part of it, Gus and I had ignored the actual space food that we were up there to evaluate, costing the country millions of dollars.”

A Congressional Committee even held a hearing over the ordeal.

According to CollectSpace.com: Congressman George Shipley of Illinois explained his concerns to NASA administrator James Webb, associate administer for manned spaceflight George Mueller and director of the Manned Spacecraft Center (now Johnson Space Center) Robert Gilruth, during the hearings: “My thought is that … to have one of the astronauts slip a sandwich aboard the vehicle, frankly, is just a little bit disgusting.

The reply came from Mueller:

“We have taken steps … to prevent recurrence of corned beef sandwiches in future flights.”

Gemini 3 Crew: John Young (L) and "Gus" Grissom (R)

Gemini 3 Crew: John Young (L) and “Gus” Grissom (R) / Source: NASA



And there you have it: the story of the first corned beef sandwich in space. Sometimes a sandwich is just a sandwich, and other times it threatens humanity’s greatest space program.

(This post was originally published on March 23, 2011. It has been slightly modified from its original version.)


  1. Nicknamed by Grissom, “Molly Brown”, after a popular Broadway musical, “The Unsinkable Molly Brown”. NASA PR was originally not impressed with the nickname, but backed off any attempts to ditch the moniker when they discovered Grissom’s back-up name for the capsule was “Titanic”.

NuSTAR Update

Artist's concept of NuSTAR on orbit. Image Credit: NASA/JPL-Caltech

In anticipation of an upcoming launch, I recently provided an overview of NASA’s next on-orbit telescope, NuSTAR. At that time, the launch date had not yet been set. A news release was issued today, postponing the launch:

The planned launch of NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) mission has been postponed after a March 15 launch status meeting. The launch will be rescheduled to allow additional time to confirm the flight software used by the launch vehicle’s flight computer will issue commands to the rocket as intended.

The time required to complete the software review has moved NuSTAR beyond the March timeframe currently available on the range at Kwajalein. In the interim, NASA will coordinate with the launch site to determine the earliest possible launch opportunity. This is expected to be within the next two months.

(emphasis mine)

At this point, I’m not entirely sure what might have caused the delay. While NASA is calling it a postponement, they had never officially announced the launch date — though it was implied that it would be in March. In any case, I’d much rather them spend a couple of extra months increasing their confidence in a flawless launch and operations than face the potential consequences of hasty action.