WASHINGTON – A delay in the launch of NASA’s Psyche asteroid mission forces another asteroid mission to take a turn to revise its plans.
Janus, a NASA small-scale mission selected in 2019, will launch two identical spacecraft as secondary payloads on the Falcon Heavy rocket whose primary payload is the Psyche. After a series of bypasses on Earth, each spacecraft Janus would fly with different binary asteroids, designated 1996 FG3 and 1991 VH.
But the mission’s chief investigator said on June 8 that the mission plan is no longer possible. Speaking at a meeting with NASA’s Small Bodies Assessment Group (SBAG), Dan Scheeres of the University of Colorado noted that the mission plan presupposed that Psyche was launched in August this year as previously planned. NASA announced it on May 23 The launch of the mission had been delayed until 20 September at the earliest to give more time to test the spacecraft’s software.
With the revised launch date, he said that it is no longer possible for the spacecraft to perform those Earth’s bypasses with the design of the existing spacecraft. “Those bypasses were crucial in setting up our bypasses of our target binaries, 1991 VH and 1996 FG3,” he said.
He said that it is possible for Janus to reach one of the original binary asteroid targets, 1996 FG3, if the mission starts between October 7 and 10. It would be near the end of the new launch window for Psyche, which closes on October 11. In that scenario, the mission would send both spacecraft to 1996 FG3, enabling them to reach their scientific goal thresholds.
“We have no opportunity to influence the launch dates or the direction of the launch vehicle, and that stems from our status as occupants,” he said.
The mission team is now looking for alternative asteroids that the spacecraft could visit if it could not fly through any of its original destinations. Scheeres said they have found “several asteroids” that the spacecraft can visit, depending on the day the mission starts. He did not reveal who is under consideration, but said that some violate current mission restrictions such as overtaking speed or communication data speed. “Many of these limitations can be met, it just takes a little more work,” he said.
These plans depend on Psyche’s ability to launch during the revised launch window. During an earlier presentation at the SBAG meeting, Carol Polanskey, a co-investigator on the Psyche assignment at Jet Propulsion Laboratory, said that work is continuing to upgrade the simulation environment needed for software testing.
“We have a new JPL flight software architecture that must be mixed with the traditional Maxar simulation capabilities,” she said. Maxar built the Psyche spacecraft. “It has turned out to be a little more challenging than we expected, so we have put a lot of resources into tackling this.”
She said the problem should be solved in the “near future” but was not more specific. “The project is very motivated to launch in that window,” she said. “We’re doing everything we can to get into the second launch.”
Should Psyche and Janus miss the second window, Polanskey suggested that the mission could return to its original plan to start in 2023 before moving up one year. “We have not really looked at what that would mean,” she said.
NASA selected Janus as one of three missions in its Small Innovative Missions for Planetary Exploration, or SIMPLEx, low-cost mission for planetary science, with a cost ceiling of $ 55 million each. All three have now suffered problems with their plans to launch as transportable payloads.
The launch of Psyche would originally include both Janus and Escape and Plasma Acceleration and Dynamics Explorers (EscaPADE), a small mission to study the interplay between the solar wind and Mars’ atmosphere. However, a change in launch vehicles for Psyche from Falcon 9 to Falcon Heavy changed the mission’s trajectory enough to no longer make it profitable to receive EscaPADE, and NASA paused work on the 2020 mission.
EscaPADE found new life in 2021 when NASA approved a revised plan for the mission with Photon spacecraft from Rocket Lab, with greater propulsion than the original design. The EscaPADE dual spacecraft is now scheduled to launch in 2024, although NASA has not announced how they will get to Mars.
The third SIMPLEx mission, the Lunar Trailblazer, is scheduled to be completed late this year, but will not start until early 2025 due to delays in the primary payload of its commuter mission, the Interstellar Mapping and Acceleration Probe (IMAP). Some lunar scientists have lobbied NASA to find an earlier trip for the missionwho will study the distribution of water on the moon, as it could support other robotic and human landing missions.
Scheeres said in a discussion at the SBAG meeting that the problems that Janus and other car sharing assignments face illustrate one of the disadvantages of that approach to starting assignments. “Having developed the spacecraft for a specific mission and then removing at least part of it, and perhaps all of it, highlights the fragility of having a very specific mission developed without control over launching conditions,” he said.
He suggested that shared payloads should have more to say about the launch date than they do today. “Maybe there should be some accommodation for small adjustments to launch dates,” he suggested.
However, there are no plans to remove Janus from the Psyche launch and find an alternative to space. A preliminary assessment, he said, found no other suitable assignments that could accommodate Janus as a carpool assignment and could better fulfill the mission’s scientific goals.
“It will not bring us any closer to the original binary asteroids,” he said when asked about the possibility of not postponing Psyche, “unless someone is willing to foster an independent launch for us, and I have not found any. recipient for it. “
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