Status Report

NGST Weekly Missive 5 Jan 2001

By SpaceRef Editor

May 1, 2001

Filed under Goddard Space Flight Center, US

Hi Folks,

Sitting here, composing this message on the Saturday after New Year’s, I must admit that 2000 was one hell of an exciting
year on NGST! The Phase A studies are within a couple of months of wrapping up, and then the procurement of the decade
commences! With luck, we will know who gets to build NGST by late fall of next year (2001).

There are many interesting storylines running around regarding the much heralded Year 2000 NGST Rescope exercise, so I
thought I would offer you my perspective for my “year-end” message. I will try to address the “why, what and when.” Let
me refer you also to the 3-page handout prepared for the AAS – it’s at http://www.ngst.nasa.gov/cgi-bin/doc?Id=793

First the why – “why rescope now?” Well, reconciling the desired scientific performance and pre-flight performance
verification with the schedule and available resources is the natural outcome of a Phase A Study, as NASA defines it. Note
also that cost and schedule are invariably linked. Simply put, the rescope was triggered when it was clear from our in-house
estimates, briefed out at a November Project Cost Summit, that we could not afford the cost (and development schedule)
associated with the eight meter class observatory we had been talking about up to now. Approval to proceed into Phase B is
contingent upon achieving a baseline set of performance parameters at an affordable price. Additionally, in order to
commence the downselect procurement (RFP) in the spring, the federal acquisition regs require us to do this as well.

Next,the what – “exactly what is this rescope?” “Rescope” is an aerospace buzz word for a systems-level multi-variate
optimization. It is oftentimes preferred to the word “descope” at this point in a program because, unlike in a traditional
descope exercise, not everything is necessarily diminished in a rescope. This may seem like semantics, but in actuality, it’s
not. As an example, we decided not to carry forward a precursor flight experiment (Nexus) for cost and schedule reasons.
To mitigate risk as a result, we actually proposed improving the NGST wavefront control system as part of the rescope, in
order to ensure that the telescope is both testable on the ground and very stable in orbit. Overall, however, the net effect
was to achieve an acceptable level of performance at reduced cost.

Because of the competitive phase we are in, I directed the NASA Government Systems Engineering and Science IPTs to
conduct this re-optimization as a group, using information supplied by our contractors during Phase A, as well as material
obtained from the various cost studies undertaken by the government team and their NASA and DoD consultants. Frankly,
it was a systems engineering tour de force! Watching this effort unfold over that three week period in November, I realized
that collectively, the team (gov’t plus prime contractors) had done a first class job in Phase A, and they are to be
commended! By this I mean that the systems and science teams clearly understood the cost drivers and where the scientific
and technical breakpoints were. They were able to derive cost estimating relationships (CERs) for several of the most
technologically challenging elements of NGST, based on some actual data derived from our technology development
program. It really all came together during that 3 day cost summit! You know, as I sit here typing this, I realize that this is
one of those invaluable “lessons learned” for future technology-rich missions like NGST, namely, that the tech development
program should be initially architected to allow one to be able to derive valid (i.e., validated) CERs for cost-estimating
exercises during late formulation and prior to the costly implementation phase.

Back to the rescope. The team re-examined old (and new) constraints, chief of which was schedule for launching NGST. In
the early going, the mantra was “launch when the technology is ready.” Recently, however, the realization of the planned
deorbit of HST in 2010 and it’s linkage to NGST’s launch (and budget), added a certain perspective. That is, if NGST were
to slip into the next decade, then another HST servicing mission would probably be needed, and the resources for this
would come out of the funding line being used to manufacture NGST, thus delaying NGST even more.

Finally, the when – “when will the rescope be complete?” The rescope process and findings were briefed to the
NASA Administrator on the 18th of December. He spent an hour with John Mather and I, going over the 6 charts Joe Burt
and the systems group had prepared for him in great detail. He suggested that what we had done was the epitome of what’s
best about Better-Faster-Cheaper, and he congratulated us as we left his conference room. I believe he felt that NGST was
secure in this process, and one step closer to reality that day.

But it’s not quite done. Next we must engage our new Science Working Group, and ask them to verify that we went about
this in the right way, from the perspective of science performance. We have already begun the dialogue with a telecon on the
21st of December, and anticipate that this process will take a bit of time, but our goal is to be done by early March, so we
can put the finishing touches on the RFP, and get it out to the proposers by early April. Our International partners must also
weigh in and join the process, and they have already expressed enthusiasm for doing so. Meetings will commence in mid
January.

To sum up, you’re probably thinking that I have very cleverly avoided telling you the answers we derived during this
re-optimization. I’m not really trying to be coy, but I must not undercut Dan Blackwood’s Procurement Development Team
either, as we must still decide on some last minute details associated with the RFP. So let me just say the following. Our
particular attempt to get NGST back in an affordable part of the study phase space consisted of recognizing that we couldn’t
afford the money or time to polish 50 square meters of (8 m) mirror, and therefore we had to reduce the primary aperture by
about a third, adding that mass essentially back into the facesheet and reaction structure, to ensure ground verification of
performance in the presence of gravity (since we couldn’t afford a flight test. So we now talk about a “six meter class”
telescope, rather than an “8 meter class” one. The details of whether it’s 6.2, 6.5 or 6.8 meters must remain speculative until
we complete the RFP and the offerors hand in their technical and cost proposals for review.

Additionally, we opted to warm-bias the telescope temperature a bit, with the addition of active temperature control for
increased margin, and we souped-up the wavefront sensing and control system to further ensure testability and on-orbit
stability, respectively, while being careful not to preclude either of our detector options or the mid infrared instrumentation.
We looked at a variety of other things, including a Shuttle launch option to reduce cost and increase program robustness,
but will probably stick with the baseline expendable launcher approach for now. We traded field of view (FOV) of the
instruments, another big cost driver, recognizing that our previous baseline pixel count was unaffordable. The ISIM team
will be continue to review this and other things to reduce cost and mass, but they must work closely with our International
partners here.

So there you have it! Let me remind you, however, that the government rescope is but one solution, and not necessarily
optimal, in that many trades are clearly architecture-dependent. Thus, we must wait a while longer and see how our primes
choose to solve the problem, and at what cost. Till then, NGST is for all intents and purposes still the exciting observational
tool that it was when we started five years ago. It is still capable of detecting ‘first light’ in the universe; admittedly, it may
take a little longer to make those deep exposures, but it will be worth the wait! Even with it’s reduced aperture, wherever that
turns out, NGST still will provide orders of magnitude more sensitivity than the large ground-based telescopes on the
drawing board right now.

That’s it for the year 2000. I wish you, your colleagues, family and friends the best in the coming new year.

yours,

bernie

Bernard D. Seery

NASA/Goddard Space Flight Center

Next Generation Space Telescope Project Manager

Mail Code 431

Tel.#301-286-5712

FAX: 301-286-1670

Cell 301-980-2613

Pager: http://www.bam.com/send.htm

For Appointments, contact Gail at 301-286-8260