By Kenneth Chang
Beresheet, the plucky robotic spacecraft built by an Israeli nonprofit, remains on track for landing on the moon next week. On Thursday, after already travelling more than 3.4 million miles, it is to pull off a crucial bit of gymnastics — swinging from a highly elliptical orbit around Earth to one around the moon.
“This is actually the most critical manoeuvre our spacecraft will do during the mission,” said Ido Anteby, chief executive of the nonprofit, SpaceIL. “Except, of course, the landing.”SpaceIL will broadcast coverage of the event from its control center in Israel on its Facebook page beginning at 9:30 am Eastern time.
Since launching in February, Beresheet, which means “Genesis” or “in the beginning” in Hebrew, has fired its engine several times to nudge its looping orbit higher and higher. On March 19, a 60-second burn pushed the highest point of Beresheet’s orbit to more than a quarter-million miles above Earth, or slightly beyond the orbit of the moon.
This trajectory has been carefully choreographed so that on Thursday, the spacecraft will near that highest point again as the moon passes by, its gravity grabbing Beresheet and flinging it away from Earth.
At 10:15 am Eastern time (5:15 pm in Israel), the engine is to fire again, for about five minutes, slowing the spacecraft’s speed from about 5,300 mph, relative to the moon, to 4,700 mph.
“If we don’t hit the brakes, it will slingshot away forever,” said Opher Doron, the space division general manager at Israel Aerospace Industries, which partnered with SpaceIL in building the spacecraft.
This Thursday, #Beresheet will reach the moon’s orbit & perform a Lunar Capture: a maneuver entering the #moon‘s gravity & will begin circulating towards its planned landing. #SpaceIL & @ILAerospaceIAI are practicing scenarios & simulations in the hybrid lab. #IsraelToTheMoon
— Israel To The Moon (@TeamSpaceIL) April 1, 2019
If Beresheet misses that rendezvous, it probably will not have another chance. “It’s not a complex manoeuvre,” Doron said. “It’s just not a time to have a sudden small problem. We’ll be nervous.”
If the manoeuvre works, Beresheet will be reined into an elliptical orbit around the moon, passing within 310 miles of the surface and swinging out as far as 6,200 miles away.
Over the next week, it will fire its engine again to pull into a circular orbit 124 miles above the moon’s surface. If all continues to go to plan, Beresheet is to attempt a soft landing on April 11. To date, that is a feat that has only been accomplished by the governmental space agencies of the United States, the former Soviet Union and China.
SpaceIL’s original goal was to win the Google Lunar X Prize competition, which offered $20 million for the first privately financed venture to put a robotic spacecraft on the moon. But the prize expired last year before any of the teams could claim it.
SpaceIL pushed on, with the hope that its mission would inspire Israeli students to pursue careers in science and engineering.
Doron said Beresheet has done just that. On Purim, a Jewish holiday where people dress up in costumes much like on Halloween, “Everywhere you went, people were dressed up as Beresheet — or astronauts,” Doron said. “The main parade had a huge float made of balloons shaped like Beresheet. It’s an amazing impact.”
The X Prize Foundation announced last week that it would give a special $1 million Moonshot Award to SpaceIL if the landing succeeds.
Not everything has gone perfectly for Beresheet. Its computer has crashed several times. Its star trackers, used to help the spacecraft’s navigation, have been blinded, even when not looking directly at the sun.
Engineers have not figured out the causes of all of the glitches, but they have figured out how to work around them. “The spacecraft is working,” Anteby said. “We are happy with what we have.”
The landing itself, aiming for a lava plain known as the Sea of Serenity, will be the trickiest part of the mission.
“Would you fly in a helicopter with the windows closed, landing just by a laser sensor that has never been tested before, without maps?” he asked. “I doubt you would fly on that helicopter. That’s what we’re trying to do.”