News Summary

• Portal Space Systems announced a $50 million Series A funding round Thursday that values the company at $250 million.
• The company is developing a technology called solar thermal propulsion.
• Its engines would instead concentrate the heat of the sun, using that to heat propellant and move the spacecraft along at high speed.
• The technology has been the subject of investigation in government research labs since the 1960s, most recently as a concept for sending a probe into interstellar space, but has yet to make it into orbit.