The U.S. $300-million Akatsuki spacecraft, whose name means "dawn" in Japanese, arrived at Venus at 6:49 p.m. ET Monday. The probe then fired its main thrusters so that Venus's gravity would capture the craft in an elliptical orbit.
During this maneuver, the Japan Aerospace Exploration Agency (JAXA) expected to lose contact with Akatsuki for 22 minutes, as the probe moved behind the planet. Instead, the blackout lasted for an hour and a half.
Communications with the probe were eventually resumed, but it's currently unclear whether Akatsuki successfully entered orbit around Venus.
"It is not known which path the probe is following at the moment," JAXA official Munetaka Ueno told the AFP news agency. "We are making maximum effort to readjust the probe."
JAXA scientists said they would know if the orbital insertion was successful sometime later on Tuesday, according to the Associated Press.
If the probe is in place, Akatsuki is the first Japanese spacecraft to circle another planet.
Akatsuki May Find Active Venus Volcanoes
In addition to being our nearest planetary neighbor, Venus could prove important for understanding climate on Earth.
The planet is about the same size and age as our world, but Venus is bone dry, and its atmosphere is much hotter, due to an abundance of carbon dioxide—the same greenhouse gas that is contributing to global warming on Earth.
Launched in May of this year, Akatsuki is designed to observe Venus's weather for two years. The probe will be orbiting at the same time as the European Space Agency's (ESA) Venus Express spacecraft, which has been sending back data since April 2006.
(Also see: "Solar Sail Hybrid Launches Today From Japan.")
While ESA is not directly involved in the JAXA mission, the two spacecraft will work well together, said Venus Express project scientist Håkan Svedhem.
"Venus Express [is] in a polar orbit, and Akatsuki in a close-to-equatorial orbit," Svedhem explained in an email. This means data from the two probes will offer scientists a more global view of Venus's weather patterns.
In fact, Akatsuki's instruments were designed to complement those on Venus Express, he added. The Japanese probe carries five cameras with wide- and medium-angle lenses, which will be able to spot things that Venus Express can't with its suite of spectrometers, plasma analyzers, and magnetometers.
One major mystery that Akatsuki could help solve is whether Venus is still volcanically active.
Earlier this year, Venus Express detected lightning storms in the planet's atmosphere. It's possible Venus's lightning originated in Earthlike storm clouds, or that the sparks might have been generated in the ash clouds of active volcanoes.
"What is the source and the mechanism of the lightning? That's one very exciting question" that Akatsuki could answer, said Adriana Ocampo, a Venus program scientist at NASA's headquarters in Washington, D.C.
In addition to ESA involvement, seven NASA scientists were chosen to work alongside the Akatsuki science team and help analyze data, said Ocampo, who sat on the NASA-JAXA selection committee.
NASA currently has no probes orbiting Venus, although the space agency has a proposal in the works for a lander to study the planet's surface.