The next 5 million(ish) kilometers rest squarely on NASA’s New Horizons shoulders. No more engine burns. Yesterday, the hardy spacecraft entered Encounter Mode (or EM). Any problems that pop up between now and the Ultima Thule flyby on New Year’s Day will be diagnosed and fixed by New Horizons’ onboard computer. Without radioing back home to Earth
This way, the spacecraft can fix any last minute issues and quickly get back to its mission of gathering science.
Usually, when New Horizons has an issue, it stops its flight plan and radios mission control. But if that were to happen when the spacecraft was on its closest approach, the folks back on Earth wouldn’t have time to send instructions back to the spacecraft. New Horizons would cruise right past Ultima Thule without even looking.
Encounter Mode gives the team the best chance at gathering all the science they can. New Horizons used the same mode during the Pluto flyby. Luckily, everything went smoothly, and the world was stunned by incredible pictures of the dwarf planet. The New Horizons team is crossing their fingers for a repeat performance on the first day of 2019.
If New Horizons delivers again, we’ll get stunning images of the “most well-preserved sample of a planetary building block ever explored,” as mission leader Alan Stern puts it. That’s because Ultima Thule isn’t big enough to have any mechanism for resurfacing. It should be much more crater-riddled than Pluto. But who knows what New Horizons will see in just a few days. Maybe Ultima Thule will shock us with rings, or an atmosphere.
As for when all of us will see what New Horizons saw? The first image should be released on January 2 according to Stern. A week later, even better images and the answers to if Ultima Thule has company in the form of satellites, rings, or an atmosphere.
The best images from the flyby should be incredible. Back in 2016, I wrote about what we could expect New Horizons’ cameras to deliver. Below is a simulated image showing expected resolution using Mars’ moon Phobos as a fill-in (it’s similar in size to Ultima Thule)
Earlier this month, Stern also touched on the challenges and what these images could show us:
“Early next year, megapixel images will be sent, and if they contain the target – shooting at this resolution while speeding by at over 32,000 miles per hour is a stretch goal – they will reveal Ultima’s geology in exquisite detail.”
While it’ll take New Horizons about 20 months to beam back all the data it gathers on New Year’s Day, we thankfully won’t have to wait long for the first images. And what images they may be!