NASA Actually Canceled The Dawn Mission In 2006
NASA’s Dawn Mission to Asteroid Belt Comes to End
“NASA’s Dawn spacecraft has gone silent, ending a historic mission that studied time capsules from the solar system’s earliest chapter. Dawn missed scheduled communications sessions with NASA’s Deep Space Network on Wednesday, Oct. 31, and Thursday, Nov. 1. After the flight team eliminated other possible causes for the missed communications, mission managers concluded that the spacecraft finally ran out of hydrazine, the fuel that enables the spacecraft to control its pointing. Dawn can no longer keep its antennae trained on Earth to communicate with mission control or turn its solar panels to the Sun to recharge.”
Dawn Mission Cancelled, earlier post (2006)
“Upon returning to her office from this morning’s hearing, Mary Cleave cancelled the Discovery “Dawn” mission. Curiously, with several hours during the hearing to do so, she did not bother to mention to the House Science Committee that she was about to do this.”
– Congress Hears About Dawn Mission Cancellation, earlier post (2006)
– Letter from PSI Director Sykes to House Science Committee Chair Boehlert Regarding Cancellation of NASA’s Dawn, earlier post (2006)
– Cancellation of Dawn Mission on Hold Pending Review By NASA Administrator , earlier post (2006)
– NASA Reinstates the Dawn Mission, earlier post (2006)
It’s worth mentioning that the mission was seriously over budget when it was cancelled. It was reinstated when the spacecraft builder (OSC) offered to do the job at cost (waiving profits.) And the mission still ended up about 20% over budget at launch. Some people (myself included) have said missions like MSL and JWST shouldn’t be forgiven for poor management and cost overruns, based on spectacular scientific success. In the end, I think Dawn’s results are enough to forgive a 20% cost overrun. But it was looking to be much worse when it was cancelled, and cost caps do need to have some teeth or they aren’t credible.
Ended up being a solid mission but I really regret that the magnetometer didn’t fly.
I wonder how much would be saved by reusing basic designs. Dawn seems to be well designed and I wonder how it would cost to build 3-4 duplicates that could be sent to other target regions.
A pair of “Dawn Class” spacecraft to explore the Jupiter Trojans for example, one craft each sent to the L4 and L5 groups. If Jupiter migrated from the inner Solar System as models show it might have taken some of the Trojans with it. If so they would provide insight on what the planetary disk in the inner Solar System was like before the inner planets formed. Similarly there are some interesting features of the Mars Trojans that would probably be worth studying.
If NASA was able to break out of its “marketing myopia” of an agency that builds launch vehicles (SLS) for space exploration and just focused on space exploration it could do a lot of interesting research.
It would probably be quite expensive to duplicate the Dawn bus – you’re talking about a 15-20 year old design, using parts that had heritage back then, so they’re probably 25 years old. You’d almost certainly wind up redesigning some pieces of the spacecraft to use currently available parts. Once you start down that “let’s just fix up X”, you might be better off with a clean sheet design that can leverage 20 years of semiconductor development.
True, but remember, this is NASA and NASA likes the reliability of Legacy Hardware. Look at the engines used on the SLS with heritage dating from the 1970’s. So twenty year old technology would mean it is just getting proven in the NASA world.
Now if I was doing it I would use a BFR to launch four spacecraft, a pair to each group of Trojans, that would use state of the art technology, including electric propulsion systems. I would also have the BFR crew deploy and test them at the EM L-1 to make sure everything worked before sending them off. But that is how it would work under the new space paradigm, not the one NASA works under.
And a Dawn copy wouldn’t be viable for a Trojan asteroid mission. It didn’t have enough fuel and at 5.2 AU, solar power would be down a factor of four from what it is at Ceres.
However, if someone wanted to fly a main belt asteroid mission, copying an existing spacecraft and using electric propulsion, why not copy Psyche? Since they are only at PDR, calling that “existing” is a little bit of a stretch. But Psyche is build around a SSL 1300 communications satellite bus. That series has a very long history, lots of heritage and has been incrementally updated over the years, so it’s quite modern. It’s also a flexible design, intended to be customized based on the customer’s needs.
NASA threatens cancellations but seldom pulls the trigger. One painful part of the development struggle for Dawn was that NASA deselected the magnetometer instrument, which was the PI’s primary area of expertise. That seemed to be a cruel message. So we’re missing that data on Vesta and Ceres and will have to wait for the Psyche mission to reach a metallic asteroid in 2026.
I hope Psyche has a good solution, but both Dawn and Psyche used/will use electric propulsion. That produces huge magnetic fields even when the thruster is off (for the Kaufman thrusters they use; a Hall effect one might not be quite as bad when off.) That’s a disaster for scientific, magnetic field measurements. The Deep Space 1 mission did produce some ways of dealing with that, but the results weren’t widely communicated. (And that’s partly my fault, since I was involved with DS1.)
Did that play a role in the magnetometer descope on Dawn? I always thought that was basically punishment for the PI’s project busting the budget.
As far as I know, the reasoning behind the descopes isn’t publicly available. But I doubt if it was personal. I can see how that might be tempting, but I don’t believe it. They also descoped the laser altimeter and reduced the time in orbit around Vesta.
Usually, descopes are intended to get the biggest improvement in cost and/or schedule for the least harm to the mission’s science on science. These days, Discovery proposals are required to include descope plans, but I’m not sure if that was true back when Dawn was selected.
Anyway, in the case of magnetometers, things get complicated. Yes, I think good measurements from a spacecraft with three Kaufman ion thrusters would be challenging, and I’m sure someone pointed that out. But even without thrusters, the resources required for a magnetometer are debatable. The instruments themselves are usually low mass, power and cost. Except for the boom, which is usually billed to the spacecraft not the instrument, and all the requirements placed on every other spacecraft system for magnetic cleanliness. That can be a significant impact.
As a couple of random notes, I was poking around a little and learned (or relearned) that 1) The Dawn and Kepler missions not only ended within a few days of each other, they were also selected at the same time (December, 2001.) And 2) Psyche is using Hall effect rather than Kaufman thrusters. That might be better for magnetic cleanliness. I’m not sure but I think they use fewer or no fixed magnets, so they might not be a problem when the thruster is off.
Dawn mission had this great guy, Marc Rayman. At one time he had a blog where the public could post questions and Marc would answer. It was fascinating to hear from the scientists running the mission. Also it was great to see what other people were asking. Details about reaction wheels and cameras and navigation. It got shut down and I thought that was too bad.
Who shut it down as it sounds like a really good model for NASA outreach?
JPL media relations sometimes gets upset about scientists and engineers not going through them (or involving them) when talking to the public. I know of one occasion where they complained about a scientist in the UK giving the BBC a sound bite about a JPL project he was involved in. They were at least somewhat satisfied when they were told (1) we don’t pay him, his own government does, (2) talking to the press is something his funding agency expects him to do and (3) the BBC needed something on short notice, to fill about thirty seconds of empty air time, and with the time zone differences, he couldn’t have contacted them, even if it had occurred to him.
Marc Rayman was doing more or less the same sort of things during the Deep Space 1 mission. Blogs and web pages weren’t quite as sophisticated back then, but he did a nice job of it.
The DS1 mission outreach was great.
*Sigh* Cassini and now Dawn. I know that no mission is forever but I guess hearing of these probes’ EOLs makes me feel old in a way.
No, what makes you feel old is when you hire a student to work on the project, and he mentions that he remembers hearing about the spacecraft arriving at Saturn. When he was in fourth grade.