The Exoplanet Hunter TESS Launched by Falcon 9

TESS taking off
The Falcon 9 taking off from SLC-40 at Cape Canaveral with TESS on board. Credit: SpaceX Flickr.

On April 18th, 2018 at 22:51 UTC a Falcon 9 took off from Launch Complex 40 at Cape Canaveral AFB. Aboard was NASA’s latest research satellite TESS. A mission that cost $337 million, Transiting Exoplanet Survey Satellite (TESS)  is the latest in a line of space based observatories that are set to launch this decade. Launched into an arching elliptical orbit that will take the spacecraft over two thirds of the distance to the moon. The first stage of the Falcon 9 landed on the autonomous drone ship Of Course I Still Love You to be refurbished and reused.

falcon 9 engines
The sheer power of the Falcon 9’s nine Merlin 1D engines produce an awesome inferno. You can clearly see the 45 written on the side as the booster designator. Credit @marcuscotephoto on Twitter.

After a 5 day checkout of the spacecraft, basically a hardware check, the ground controllers will switch on the TESS cameras. TESS is designed to scan around 85% of the sky during the two year mission, with astronomers estimating as many as 20,000 new planets could be found. It plans to build on discoveries made by NASA’s Kepler telescope which was launched in 2009 to find earth like planets. TESS carries four 16.8-megapixel cameras, and will look for dips in light coming from 200,000 preselected nearby stars. The four cameras cover a square in the sky that measures 24 x 24 degrees, wide enough to fit the Orion constellation into a single camera. the cameras together study a set area of sky for 27 days before staring at the next section.

TESS orbit
An illustration of the orbits that TESS will go through to get to the final orbit P/2. Credit: NASA.

The orbit TESS is being launched into is known as P/2, and requires time and finesse to reach. TESS will slingshot by the moon at a distance of around 5,000 miles (8,000 kilometers), using gravity to reshape its orbit, increasing the satellite’s orbital perigee, or low point, to the final planned altitude of around 67,000 miles. After the lunar flyby, the high point of the satellite’s elongated orbit will stretch well beyond the moon, and another thruster firing will nudge TESS into its final orbit in mid-June. Science data is planned to start in july, with the first year of the two year campaign aimed at the stars in the southern sky. TESS has been built to have enough fuel to last 20 or 30 years, assuming funding by NASA and the components on board continue to function correctly.

the TESS telescope
The TESS satellite before launch, the four cameras can be seen on the top of the spacecraft; Credit: NASA.

Each of TESS’s cameras have four custom built re-sensitive CCD sensors designed and developed by MIT’s Lincoln Laboratory. The sensors are claimed to be the most perfect CCD’s ever flown by a science mission. The lenses used by the cameras are only about 4 inches (10mm) wide, meaning it has a fairly low light collecting power compared to other space telescopes. The James Webb Space Telescope for example launching in 2020 had a 21.3ft (6.5m) primary mirror, although the satellite has cost over $8 billion to make. TESS is a bit like a finder telescope, it will lay a bedrock for future missions such as Webb and ground based observatories to make better readings. It gives a good idea of the best places to look, where the most likely exoplanets are.

launch of TESS
The Falcon 9 launching the Transiting Exoplanet Survey Satellite to an orbit of P/2. Credit: SpaceX Flickr.

TESS works by looking at a star, in this case mainly M-dwarf stars, which are cooler than our sun. They are also known as red dwarfs and make up most of the stars in our galaxy. When a planet goes in front of the star the light received by TESS “dips” and changes slightly in colour. This change in the light it receives can tell scientists alot about the size of a planet, and other things like density and velocity. They expect TESS to find between 500 and 1,000 planets that are between one and three times the size of Earth, and 20,000 planets the size of Neptune or Jupiter. The readings will give a good idea of where to focus on and ‘follow up’ on future missions. Then missions such as JWST can probe and use more complex tools to find information such as atmospheric composition, and whether they could be habitable.

long exposure TESS
A long exposure of the Falcon 9 taking off over the SpaceX hangar at Cape Canaveral. Credit: SpaceX Flickr.

The Falcon 9 used was a v1.2 with designation F9-54. It used a brand new “Block 4” first stage. The booster designated B1045 has a clear 45 written on the side in some of the close up booster images. The fist stage boosted for 2 minutes and 29 seconds, then detaching and slowing itself down. The booster landed downrange on the autonomous drone ship “Of Course I Still Love You”. The first successful drone ship landing since October 2017. A total of 24 Falcon 9 or Falcon Heavy booster stages have now been recovered in 30 attempts. Four of which were on “Just Read The Instructions” off the coast of California, ten at Cape Canaveral Landing Zone 1 and 2, and nine on the autonomous drone ship “Of Course I Still Love You” off the Florida Coast. 18 first stages have been recovered, 11 of which have flown twice, five have been lost during their second flight. B1045 was the last brand new “Block 4” Falcon 9 booster.

TESS taking off
An awesome photo of a Falcon 9 taking off from across the water, a perfect day for pictures! Credit: SpaceX Flickr.

To find similar photos, and to buy reasonably priced prints of some of the above visit

The NOR Gate That Got Us To The Moon

Type G micrologic
The Fairchild Type ‘G’ Micrologic gate for the Apollo Guidance Computer – this is the flat pack verison

In a previous post I talked about how the going to the moon kick started the silicon age. If you haven’t read it, it is short but really interesting story about how NASA made Integrated circuits cheap, and partially funded what we now know as Silicon Valley. In this post I am going to take a slightly closer look at the circuit that ran the famous type “G” Micrologic gate that ran the Apollo Guidance Computer.

apollo 3 input NOR gate
The official NASA schematic of the Type G micrologic gate found in the Apollo Guidance Computer

As you can see in the above image, the circuit was not particularly complicated. You have to remember that this is very early logic, before CMOS or NMOS or any other fancy IC technologies. This is basically two 3 input NOR gates, they both run off the same power, with pin 10 at the top, and the negative which was likely ground being shared on pin 5. The output for the left NOR gate is pin 1, and the output for the right is pin 9. The three inputs for the left are pins 4, 2 and 3, with the right having pins 6, 7, and 8 as inputs. Simply put, the output is “pulled” high to power when all the inputs are OFF. The resistor between pin 10 and pin 1 (or 10 and 9) are a simple pull up resistor as you would find in most electronic circuits. As expected with a NOR gate, the output will be only be ON when all the inputs are OFF. When any of the inputs are ON the output of that gate will be pulled to ground. One two, or all the inputs can be on, but it just needs one to turn OFF the output. The resistors going into the base of the transistor are just to limit the current.

3 input NOR
My breadboarded version of the 3 input NOR gate, it is made with BC547 transistors and a DIP switch. the output has been inverted with the LED.

I made a simple recreation of this circuit using BC547 NPN transistors, but most NPN transistors would work, these were ones I found in my parts box. As you can see in the image above, I have made it on a breadboard, with the inputs being a DIP switch attached to the power (5V in this case). The base resistors for the transistors are 1K and the pull-up to 5V is a 10K. I recommend making up this circuit if you want to learn a bit more about logic, and is a cheaper method than going out to buy 74 series logic chips! As you can see in the images there are a number of states that I showed the circuit in, and notice that if any of the switches are on, the circuit turns on, this is slightly against what I mentioned earlier, but thats due to the output LED using the transistor as a current sink, not a source, so the output is inverted. Basically, when the output is 0 the LED turns on. The only time the LED is off (output high) is when no switches are on, meaning all the transistors are off.

apollo 3 input NOR gate
An image of the silicon die inside the Type G 3 input NOR gate. We will be going through how the layout works in a future post.

The final point for this post is why the circuit is actually quite efficient. Modern logic is amazingly low power compared to this. One of the biggest issues is that it is always taking power in some way. When the inputs are off, there is still some leakage through the pull up resistor, when an input is on, then there is current going through the resistor to ground. Also, by the nature of the transistors there is always parasitic leakages, and inefficiencies in the process. They are only small numbers, but the AGC used over 3000 of these circuits, so the small leakages soon add up to draw some hefty power needs, especially for battery powered operations.

If you enjoyed this post, take a look at the rest of my blog, there is lots about space, electronics and random history. I am always open to ideas and feedback, and where is best to post links to my posts.

Why James Webb Was so Important

NASA Administrator James E. Webb
NASA Administrator James E. Webb. This was his official NASA photograph

There are not many people who know off the top of their head who James Webb is, even many lovers of space may not know who he was. Yet they are about to launch the James Webb Space Telescope into space to replace Hubble. James Webb wasn’t an engineer, or a physicist, or even really an academic; he was a lawyer and politician. He turned a small government research department into an organisation that had links to almost every state, and had control of 5% of the US federal budget. Webb’s NASA controlled the jobs of half a million workers across America, and he introduced new working practices and management techniques that are still used today.

If you were to go out and read the biographies of the astronauts, or histories of spaceflight, Webb doesn’t really come up. He was portrayed as just a bureaucrat in Washington, funnelling orders down the chain, living the politician life. In this new age of spaceflight, we see the Apollo years as some sort of poetic story, with NASA being the figurehead of the battle to win space against the evil russians. In 1961 though, America did not follow this narrative, nobody in America cared about space, least of all the brand new president, John F Kennedy. When he set up his first reshuffle of the cabinet they simply could not get anyone to run NASA, they asked 18 high level politicians, and everybody said no, space was a dead end job, and NASA was just a collection of squabbling mission centres. Eventually, JFK’s vice president, Lyndon B. Johnson suggested Jim Webb, a guy who had worked under the Roosevelt administration and had some experience with private businesses. When asked, by JFK personally, Webb agreed to run NASA, as long it was the way he wanted it. JFK, desperate for an administrator gladly agreed.

shaking hands with JFK
President Kennedy shakes hands with NASA Administrator James Webb

There had been heavy opposition to the idea of manned spaceflight. Up to this point, the head of the President’s Science Advisory Committee, Jerome Wiesner, had issued a critical report on project mercury. Kennedy, as a senator he had openly opposed the space program and wanted to terminate it. Kennedy put his vice president LBJ as the head of the National Aeronautics and Space Council because he had helped create NASA, but it was mainly to get him out of the way. Although Kennedy did try and reach out for international cooperation in space in his state of the union address in January 1961, he got nothing from Khrushchev. Kennedy was poised to dismantle the effort for space, purely because of the massive expense.

The space Council
Vice President Lyndon B. Johnson (seated, center) presides over a meeting of the National Aeronautics and Space Council.

He began his NASA administration on February 14th 1961. A month later on April 12th, Yuri Gagarin became the first man to orbit the earth. Reinforcing some fears that America was being left behind in a technological competition with the Soviet Union, America suddenly cared about space. Kennedy made a U-turn and space sped to the top of the list.  This lead to Kennedy making his famous speech on May 21st where he spoke those famous words “we will put a man on the moon before the decade is out”. Kennedy wanted to take lead in the space race. Suddenly, putting a man on the moon was the number one priority.

Kennedy Talking to Congress
MAy 1961, Kennedy proposes landing a man on the moon to congress. LBJ and Sam Rayburn sit behind him.

This meant that James Webb just got handed the opportunity to run the biggest single project the country had ever seen. Webb was told to go back to his engineers and figure out how much it will cost to get to the moon. His engineers came up with the number of $10 billion (a scary big number in the 1960’s), and sheepishly told Webb, expecting to be told to make cuts and slashes to the plan. Instead he told them to go higher, because he knew problems would come their way, and extra money will need to be spent, so they come back with the figure of $13 billion. Webb accepts the number, and goes to congress and tells them he needs $20 billion over the next 7 years. Jaws hit the floor, but he used this political knowledge to get a huge amount of leverage.

The key leverage he had was jobs, and he knew it. At its height, NASA employed half a million people in some form, that’s roughly the number of people living in Wyoming. The two biggest investments were in Cape Canaveral, FL and Houston, TX. The most controversial was the Manned Spaceflight Centre in Houston, donated by Rice University. Originally based in Langley Virginia, and named the Space Task Group, the senator didn’t care much for space. The entire operation was moved to Houston, LBJ’s home state. It was central, and had good universities surrounding it. There were many Texas based representatives in the space political landscapes at that time, such as Sam Rayburn, the speaker of the House of Representatives.

Johnson Space Centre
Manned Spaceflight Centre, Texas, one of the biggest employers in Texas for a long time. with over 3000 federal workers, and 100 buildings

One thing that Webb understood was what NASA needed to run. He implemented a very flat organisational structure, with very few middle managers. Webb was the very top, controlling Washington. He also had the head of NACA (precursor to NASA) Hugh L. Dryden as an associate director. He had overseen the development of the x-15, and understood the technical needs of Apollo. Also Robert Seamans, also an associate director, acted as the general manager of NASA, and oversaw the everyday running of the program. Using a team of people, each with their own particular strengths helped NASA, especially in the early growth years, much more so than any one of them could achieve on their own.

Webb in a Gemini Trainer
Webb in a Gemini Trainer

Part of what James Webb did, to the dislike of congress, was to invest in academia, specifically universities. $30 million dollars a year was put into the Universities Development Fund. A fund designed to help students get into engineering, and to develop talent, skills, and academics that could not only work for NASA, but help the science behind it. As it was taken from a fund that congress had no control over, the money continued to help 7000-8000 students a year get through university at a time where NASA needed engineers. Webb believed that NASA was more than just the one shot to the moon, and frequently fought with the presidents on that fact. He wanted NASA, and space exploration to benefit science, engineering and even society. He believed that this project could fix other problems not even related to space, such as poverty and disease. The management style of NASA, and the way these big projects were handled showed the impossible could be achieved. He frequently lectured on this subject, and universities became an important part of NASA.

Webb, Vice President Lyndon Johnson, Kurt Debus, and President John F. Kennedy receive a briefing on Saturn I launch operations

There was huge pressure from washington to spend all of NASA’s budget purely on the Apollo moonshot. Webb was instrumental in making sure that NASA and spaceflight was more than that. be made sure other projects like the Mariner and Pioneer space programs happened, and that JPL still functioned even with a terrible track record at the time. At the time, the academic community worked with NASA, in large part because of the importance Webb put on furthering science. Webb would frequently lecture at universities, and teach about the management styles that made NASA was. Unfortunately, some in Washington didn’t care for the extra spending, especially the states that did not have a mission centre or any of the major manufacturing plants located there. So when the Apollo 1 fire happened, there were a small group that were willing to use it as a way to make changes.

Closeup of James E. Webb, National Aeronautics and space administration

The Apollo 1 fire was a very unfortunate accident, and a national tragedy. For some, it highlighted some major problems with the Apollo program and how it had been run by the major contractor North American Aviation. Committees were set up, and Webb suddenly went from running NASA to trying to defend it. During the inquests, NASA still ran, it continued to fix problems and aim for the moon. This was because James Webb was there defending it. Left to just take the heat, some believe (me included) NASA’s funding would have been significantly cut, and we may have never got to the moon. Webb stood up in Washington and fought hard for the continuation of the project, defending the decisions that his team had made. At the end of it, he had used up most of his political sway, and called in so many favours that NASA was safe for the time being, and that Apollo was possible.

Webb presents NASA’s Group Achievement Award to Kennedy Space Center Director Kurt H. Debus, while Wernher von Braun (center) looks on

At this point, Johnson had decided not to run for re-election, Webb felt that he should step down to allow Nixon to choose his own administrator. On October 7, 1968 he stepped down from office. To put that into perspective, Apollo 11 landed on the moon July 20th, 1969, barely a year later. Webb went on to be a part of many advisory boards and served as regent for the Smithsonian institute. He died in 1992, and was buried in Arlington National cemetery.

This post was inspired by reading the book: The Man Who Ran The Moon by Piers Bizony. For anyone interested in the subject of how Webb actually made his dealings, and a much more detailed account of how NASA became what it is, I recommend this book. He also did a Lecture on Webb that I found on YouTube where he tells the story really well.