The Beresheet spacecraft executed a perfectly choreographed space hop on Thursday evening, to allow the car-sized spacecraft to jump from an orbit around Earth to one around the Moon.
If the maneuver is confirmed to have been successful, Israel will have become the seventh country in the world to bring a spacecraft into lunar orbit. Confirmation is expected within the next few hours.
In order for the spacecraft to successfully enter into an orbit around the Moon, Beresheet needed to slow down from 8,500 kilometers per second to 7,500 kilometers per second. Although that still seems fast to mere humans, according to engineers, it is the orbital equivalent of slamming on the brakes. The engineers accomplished this by turning the spacecraft so that its engines thrust it in the opposite direction, slowing down the speed.
It took about nine minutes for eight different engines to slowly maneuver the spacecraft in the right direction, and a little less than six minutes for the engines to slow the spacecraft down to the correct speed.
On Thursday, engineers said they believed that the Moon’s gravity had successfully captured the spacecraft, though it will take a few hours for them to be sure that the craft is heading in the right direction. About 25 engineers at the control room in Yehud, a suburb of Tel Aviv where Israel Aerospace Industries is housed, burst into applause at the end of the planned maneuver.
“After six weeks in space, we have succeeded in overcoming another critical stage by entering the moon’s gravity,” said SpaceIL CEO Ido Antebby. “This is another significant achievement our engineering team achieved, while demonstrating determination and creativity in finding solutions to unexpected challenges. We still have a long way until the lunar landing, but I‘m convinced our team will complete the mission to land the first Israeli spacecraft on the moon, making us all proud.”
Amusingly, though the engineers successfully executed the spacecraft’s maneuver, the press team had difficulty pulling off the powerpoint presentation explaining next week’s lunar landing for journalists, and were forced to abandon the effort midway, turning the presentation off.
Thursday was the longest period that engineers have activated the engines since the spacecraft’s launch on February 22.
Engines have so far been fired seven times to widen the elliptical orbits. Beresheet has made 12.5 trips around the Earth since launching on February 22. The lunar orbits are much smaller, and some will take no longer than 14 hours. In the coming week, the spacecraft will make smaller and smaller circles around the Moon until it reaches an altitude of around 15 kilometers above the surface. The landing gear will then engage to hopefully bring the spacecraft to rest in the Sea of Serenity.
In total, the spacecraft has traveled around 5.5 million kilometers and still has about a million left to go. This is the slowest and longest trip a spacecraft has made to the Moon. The distance from the Earth to the Moon is an average about 385,000 kilometers (239,000 miles).
By utilizing the gravitational pull of the earth and the Moon and only activating the engines at the nearest and farthest points on the ellipses, engineers were able to drastically reduce the amount of fuel needed on the spacecraft. Fuel still accounts for the majority of Beresheet’s weight. At launch, the spacecraft weighed a total of 600 kilograms (1,300 pounds), of which about 440 kilograms (970 pounds) were fuel.