# Operation ‘HI TIM’

Why writing a message to space turned out to be trickier than we’d thought…

It started over a cup of tea in the Royal Institution’s fourth-floor greenhouse. After going through the basic outline of the lectures, Kevin Fong and I sat and pondered how we might make year’s CHRISTMAS LECTURES memorable. We had a lot of great small-scale demos, but we needed a big stunt. So we sat and bounced ideas back and forth, racking our brains for something suitably impressive.

‘What if…’ I began, ‘we make something so big that it’s visible from space? What if we write a giant message on the ground?’

‘I love it.’ Kevin was on board.

Kevin was excited by the idea, but he was also cautious. He knew this would be a big job, there were a lot of unknowns, and the odds were long.

The first question, of course, was size: how big did the message need to be? My first, most ambitious thought was to make it visible with the naked eye. It turns out this is pretty difficult — the International Space Station (ISS) flies so high above the Earth (400km) that a square 150m across would appear as the barely visible speck to an unaided eye. And we didn’t want to make a speck; we wanted to write something legible.

Luckily for us, the astronauts on the ISS have cameras with very long lenses (up to a metre or more!). This allows them to take pictures with pixel resolutions down to 6m. That was a more manageable size that we could begin to work with. I was also heartened to find out that this kind of stunt had actually been done twice before — once in the spring of 2015 with cars in a desert and in the autumn of 2015 on the field of a university. So it was definitely possible.

We began operating on the assumption of 10m pixels and the next job was to decide what we were going to actually write. We wanted it to be a message from the whole nation to our first astronaut on the ISS, so we decided on ‘Hi Tim’. If the letters were five pixels high and each line was one pixel thick, that meant we could write the whole message in a space about 50m by 170m.

An important connection we needed to make was with the people who tell the astronauts what to take pictures of. This is the Crew Earth Observation team from Nasa. We asked our friends at the UK Space Agency to connect us through, and pretty soon we were talking about times and locations with the keeper of the target list. The only problem was that we didn’t have either.

This is when Assistant Producer Alex Collinge got roped into the secret project we were calling ‘Operation Hi Tim’. We started brainstorming places that might have large fields we could fill with a giant message to the space station. The top two contenders were Woolsthorpe Manor (Isaac Newton’s family home) and Chichester High School for Boys (Tim Peake’s secondary school). We chose Chichester because it turns out that the ISS’s orbit is such that the further south we could go, the better chance we would have. It also had the added bonus of involving young people and having a strong connection with Tim Peake.

So Alex and I got on the phone with the school. To our great surprise, not only would they be willing to have us come down and monopolise their sports fields, but they would also recruit a team of students to help us.

The next big question was: what are we going to physically make the message with? My initial thought was plastic sheeting of some sort. But that created more problems than it solved. I then thought about pitch-marking paint. It filled the criteria of easy to apply, high-contrast, and even allowed students to use the fields after they were painted.

So Alex and I got on the phone with the school again. We asked who usually paints their fields and we were put in touch with Burleys, the company responsible for landscaping at the school. Once we explained our ambitious scheme, to write a message to space, they were on board as well. Not only had they offered to generously donate their time and equipment to help us achieve our vision, but they also got Fleet involved, the company who supply pitch-marking paint. Fleet agreed to donate all the paint we needed to get the job done.

We got back to our Nasa contact and had Chichester High School added to the crew earth observation target list. To be precise, we’d do our painting on Friday 6 November at Latitude 50.827767, Longitude -0.777465.

The day arrived, and it was raining. Not ones to be discouraged, the team of boys and girls from Chichester High School bravely kept painting despite the weather. A team from Burleys and Fleet kept the line painting machines in good working order and always topped up with paint. Alex brought along his camera to capture the day’s work for the CHRISTMAS LECTURES.

After a wet day painting the field, Nick Brown, the head teacher at Chichester High School, said of the students’ commitment, ‘As Head of School, I was blown away by the resilience of our young people in the wet weather but also the sense of pride for their school and community.’

All we had to do now was wait. And hope.

The orbit of the ISS would prove to be the biggest challenge of this whole endeavour. The ISS lives 400km above the Earth’s surface and its orbit is tilted at about a 51 degree angle. It whips around the globe at 17500 miles per hour and completes one turn of the Earth every 90 minutes or so. In that time, the Earth will have rotated 22 degrees. The pattern this creates is a constantly shifting sine wave. With a target as relatively small and far north as the UK, we would only get a few passes every couple of days. Not only that, but those passes would need to happen during the day and on a day without clouds. To add to all of this, the crew would need to be willing and able to take the picture. There are all sorts of constraints on a crew member’s time, including science experiments, extravehicular activities, and even public relations, that mean they can’t always be sitting by the window with a camera. We knew the chances weren’t great, but we knew it was possible.

What we didn’t know was that the angle of the sun matters as well. It isn’t just that the ISS would have to be almost directly above Chichester on a sunny day in autumn, but it couldn’t be in the early morning or late afternoon. The alignment of all these variables just wasn’t in our favour and the ISS still hasn’t been able to take the picture as I write this, let alone in time for appearing in the CHRISTMAS LECTURES themselves. The target is still active and there is still a small hope of receiving the image.

We talked a lot about whether to include the story of the preparations of HI TIM in the Lectures themselves. The demo itself unlocks so much great science but in the end we decided that without the final shot as our pay off, it would be too underwhelming and feel like we’d wasted time in an already packed show.

James Alison, a Client Liaison Officer who worked on the project for Burleys, wrote of his company’s involvement, ‘the opportunity to be involved in a project like this doesn’t come around very often so we jumped at the chance. We immediately knew that the logistics and timescale of the project were challenging, however nothing compared to the challenge facing Tim!

It was a shame that the space station were unable to get photos of the message in the end — however we were still delighted to be a part of this ambitious project and work alongside the children at Chichester High School and the Ri.’

The whole experience was the strangest combination crash course in orbital dynamics and landscaping and we literally couldn’t have done it without the amazing contributions of Chichester High School, Burleys, and Fleet. It also goes to show that, where space is concerned, nothing is as easy as it looks.

While we couldn’t quite get the timing right for an ISS photo, we did get a great shot from a drone. We’d like to say, for the record, HI TIM!

Written by Jonathan Farrow, the 2015 CHRISTMAS LECTURES Assistant. You can watch the lectures in full on the Ri Channel.

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