Aerojet Rocketdyne says development of its AR1 engine remains on schedule after successful tests.

The company announced last week that it had completed a series of hot-fire tests that validate the preburner design for the AR1, keeping the program on schedule to be flight-ready by 2019.

Aerojet is developing the AR1 for potential use in United Launch Alliance’s Vulcan vehicle, although ULA executives said as recently as last month that Blue Origin’s BE-4 engine remains the front-runner for that rocket. [Aerojet Rocketdyne]

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The U.S. Air Force’s X-37B spaceplane landed in Florida Sunday morning to end a record-breaking mission. The spaceplane landed at the Shuttle Landing Facility at the Kennedy Space Center shortly before 8 a.m. Eastern. The Air Force called this latest mission a success, but disclosed few details about the mission or its payload, beyond a Hall effect thruster and a NASA materials science experiment. The X-37B spent 718 days in space, the longest to date of the four X-37B missions. A fifth mission is scheduled for launch later this year. [SpaceNews]

The James Webb Space Telescope has arrived at NASA’s Johnson Space Center for its next round of testing. NASA said late Sunday that the telescope assembly had been shipped from the Goddard Space Flight Center to JSC, using a C-5 cargo plane that flew from Joint Base Andrews to Ellington Field in Houston. At JSC, the JWST telescope assembly will undergo a series of thermal vacuum tests slated to run for 100 days. [NASA]

NASA will hold off on reviews of the next flagship astronomy mission after JWST to conduct an independent study. NASA recently announced it was establishing an independent panel to review work on the Wide Field Infrared Survey Telescope (WFIRST), which is in its early phases of development. The panel was recommended last year by the National Academies midterm review of the astrophysics decadal survey, which made WFIRST its top priority flagship mission. NASA will postpone upcoming project reviews, including a decision to move to Phase B of development, until any recommendations made by that review can be implemented. [SpaceNews]

NASA received a dozen proposals for its next New Frontiers planetary science mission. The proposals, due to NASA late last month, are for missions that fit six themes, from a lunar sample return to missions to Saturn and its potentially habitable moons Enceladus and Titan. NASA expects to select several proposals for Phase A studies later this year, and select one mission in 2019 for launch in the mid-2020s. New Frontiers is a program for medium-sized planetary missions, and includes New Horizons, Juno and OSIRIS-REx. [NASA]

A judge has dismissed some charges in a former employee’s lawsuit against SpaceX. A judge last week dropped a defamation allegation in a suit Jason Blasdell filed against the company last year, but let stand claims of wrongful termination and retaliation. Blasdell alleged that he was fired from his job as a technician at SpaceX after informing management of safety issues there. The company has called those claims baseless and sought to have the entire case dismissed. The case will go to trial later this month in Los Angeles Superior Court. [City News Service]

In the 1960s, NASA used deaf men to study motion sickness. The agency recruited 11 men through Gallaudet University who lost their hearing due to spinal meningitis, which meant they did not have a functioning vestibular system. NASA subjected the men to various tests, from centrifuges to parabolic aircraft flights, to study ways to protect astronauts from hearing sickness. The deaf men, without a vestibular system, would not get sick, even in circumstances where others did. [Washington Post]

You, too, can float in weightlessness with Captain Kirk, for a price. Actor William Shatner will fly on a Zero-G Corporation aircraft in August, flying parabolic arcs that provide brief periods of weightlessness. Tickets for the flight will cost nearly $10,000 a person, double the usual rate. “I’ve always wondered what it would be like to actually explore the final frontier, and now I have the opportunity to experience zero gravity firsthand,” Shatner, who previously denied reports he was interested in flying on a suborbital space tourism spacecraft, said in a statement. []

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...