TROPICS Mission Launches to Resume Sunday

That is, Sunday evening, east coast USA time.  To be more precise, launch is set to be No Earlier Than 9:00 PM ET Sunday evening.  That's 0100 UTC Monday.  The launch window is two hours (9-11 ET) and is to be from Rocket Labs' own launch facility, launch complex LC-1B, on the Māhia Peninsula, New Zealand.  The mission is named "Rocket Like A Hurricane."  

We've been tracking the TROPICS missions since March of '21 (second part of that post) when we first heard of it.  As I've said virtually every time I do a summary of it, TROPICS is the kind of name that's almost legally required to be an acronym, in this case: Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (they went with TROPICS instead of TROPSSICS). 

Originally, the launch contract was awarded to Astra and the program was envisioned to use three pairs of radar satellites.  Astra's first launch failed and the contract was moved to Rocket Lab, primarily because they're a much more reliable launch provider.  It was hoped they would meet NASA’s requirement to have TROPICS operational in time for this year’s Northern Hemisphere storm season, which officially begins June 1. At this point, the second launch is scheduled for two weeks from this one, approximately May 22.  I don't know how much time is required to check out the system once the four satellites are on orbit, but that's only 10 days before the start of the season.  

The mission imposes tight requirements on the launch provider.  The four CubeSats require launching to specific orbits at an altitude of 341 miles (550 kilometers) and inclination of about 30 degrees, and need to be deployed into their operational orbits within a 60-day period. Their ability to do this was another one of the requirements that led to selecting Rocket Lab rather than a ride sharing mission on a larger rocket. 

Artist’s illustration of two TROPICS satellites collecting data on hurricanes. Credit: NASA

A concern I've had since the Astra flight is that in a system designed around three pairs of satellites, does losing one pair impact the mission significantly.  

In a pre-launch media briefing, Will McCarty, program scientist, NASA Earth Science Division, told Spaceflight Now that having four instead of the originally planned six satellites would make a difference, but not impact the overall quality of data.

“Falling back to four, we lose about 10-15 minutes of revisit time, but we will still be a lot better than our minimum requirement of 60 minutes,” McCarty said. “The observations from TROPICS will complement those of existing weather satellites and help give us a broader understanding of the entire Earth system.