According to Space News, the new investment, which the company calls a Series B-1 round, comes from a mix of new and existing investors. The company's investors include venture capital firms Founders Fund and Social Capital, as well as software company Autodesk. Several individual investors also participated in the latest round.

Moon Express Chief Executive Bob Richards said one of the company's co-founders, billionaire Naveen Jain, played a key role in the round. 'He not only participated at a significant financial level, but also gave other investors the confidence through his commitment that they should invest as well,' Richards said in an interview. He did not disclose how much of the $20 million round he contributed.

The new round brings the total Moon Express has raised to $45 million. Richards said the company is looking to raise an additional $10 million as a 'contingency' and to support future missions. 'This is not a stunt,' he said. 'We're not putting all our eggs in one basket.'

The company is developing a small lunar lander called the MX-1E. The spacecraft is designed to land on the moon and then 'hop' to another landing site, fulfilling the requirement of the Google Lunar X Prize to travel at least 500 meters across the surface after landing. That initial mission will carry scientific and commercial payloads from several customers.

Richards said Moon Express is currently focusing on the spacecraft's key technology, its propulsion system. The company previously tested that propulsion technology in tests at NASA's Kennedy Space Center, but Richards said the company is making changes to improve its performance.

That additional performance is needed since the spacecraft will launch on Electron, a small launch vehicle being developed by U.S.-New Zealand company Rocket Lab, which can only take the lander into low Earth orbit. Earlier mission concepts called for launching on a larger vehicle that could place the spacecraft into a geostationary transfer orbit. 'We need that extra punch from our own engine in order to get to the moon,' Richards said.

That work is now being done at Launch Complex 17, a former Delta 2 launch site at Cape Canaveral. While the agreement with the U.S. Air Force to use the site was signed last July, Richards said the company only recently finalized all the paperwork with the 45th Space Wing needed to conduct engine tests and begin other work at the site.

Moon Express is also hiring again. Richards said the company currently has 23 employees, but is current seeking to hire 10 engineers and several administrative and management staff. 'By the time we're launching we're going to be 40 to 50 people' at the company, he said

The company's current schedule calls for integrating the spacecraft in July, and then shipping it to Rocket Lab's New Zealand launch site in October. The launch, scheduled for late this year, will be the seventh or eighth operational flight of the Electron, Richards said, shortly after a NASA mission under a Venture Class Launch Services contract Rocket Lab received in late 2015.

Although Rocket Lab has yet to launch an Electron -- its first test flight is scheduled for no earlier than February -- Richards believed the company would be ready in time for Moon Express, which faces a deadline of the end of this year to win the $20 million Google Lunar X Prize before the prize expires. Several other teams in the competition also have plans to launch missions late this year.

'We have high confidence that Rocket Lab will be ready to receive us with an operational vehicle,' he said. 'We hope they get to an operational status as quickly as they hope they will.'