PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT PUBLICATION_DATE = 1999-09-07 NOTE = " E-mail and other messages concerning MGS Radio Science on or about 1997/016." END_OBJECT = TEXT END From trish@qmail.jpl.nasa.gov Thu Jan 16 01:49:52 1997 Message-Id: Date: 16 Jan 1997 01:45:34 -0800 From: "Trish Priest" Subject: USO Test #4 To: "Richard Simpson" , "Len Tyler" Cc: "Sami Asmar" , "Tom Thorpe" X-Mailer: Mail*Link SMTP-QM 3.0.2 Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; Name="Message Body" Content-Transfer-Encoding: quoted-printable Status: RO Mail*Link=AE SMTP USO Test #4 The 4th USO Test occurred on DOY 016 06:30 - 08:30 UTC. The test went smoothly. The DSP was put in run mode at 06:15. The spacecraft went TWNC ON at 06:30:58. On the SSI, the signal looked to be about 50 dB above the noise floor. The DSP idled at 08:30 UTC. Both open-loop and closed-loop data were taken. Spacecraft configuration: TWNC on, TLM on, RNG off Open-loop configuration: 5000 sps, 2.5kHz filter, -3750 Hz offset, 12-bits, Mode 2 Closed-loop configuration: Doppler samples at 10/1 The pass was long, so I took the opportunity to retransmit the data. A TOT query performed before the retransmission was complete returned 36002 sfdus (016-06:30 to 016-08:30). -Trish -------------------------------------------------------------------------- From trish@qmail.jpl.nasa.gov Thu Jan 16 12:56:56 1997 Message-Id: Date: 16 Jan 1997 12:53:21 -0800 From: "Trish Priest" Subject: TDF To: "Dick Simpson" Cc: "Joe Twicken" X-Mailer: Mail*Link SMTP-QM 3.0.2 Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; Name="Message Body" Content-Transfer-Encoding: quoted-printable Status: RO Mail*Link=AE SMTP TDF Hello, Dick, There should be a TDF on Oscar named 97015T016.sc94 for last night's USO Test. Let me know if there is an ODF as well, I did request it. -Trish -------------------------------------------------------------------------- From trish@qmail.jpl.nasa.gov Thu Jan 16 18:08:37 1997 Message-Id: Date: 16 Jan 1997 18:06:45 -0800 From: "Trish Priest" Subject: Stan To: "Dick Simpson" X-Mailer: Mail*Link SMTP-QM 3.0.2 Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; Name="Message Body" Content-Transfer-Encoding: quoted-printable Status: RO Mail*Link=AE SMTP Stan Hello, Dick, I figured out what Stan wanted, and we did some calculations. Sjogren is seeing some Doppler residuals with a 100 min period. It looks as though the HGA is moving toward and away from Earth by 8.3mm in each direction. Please let me know if you can see anything like this in the data. -Trish ---------------------------------------------------------------------- From rsimpson Thu Jan 16 20:18:42 1997 Date: Thu, 16 Jan 97 20:18:41 -0800 From: rsimpson (Richard Simpson) To: trish@qmail.jpl.nasa.gov Subject: Re: Stan Cc: rsimpson Status: R We barely have one cycle of spacecraft rotation in USO Test #4. We'll look for the Doppler; but from the amplitude fluctuations, I wouldn't be surprised if limit cycling is a larger contributer. I gather Stan doesn't see anything with a 6 minute period(?) -- which is very obvious in Figure 1 of the plot I attached to HEA7016A.TXT. Of course, some of that could be on the ground. ----------------------------------------------------------------------- From len@nova.stanford.edu Fri Jan 17 15:56:41 1997 Received: from [36.10.0.171] (exh2.Stanford.EDU [36.10.0.171]) by nova.stanford.edu (8.8.4/8.8.4) with SMTP id PAA15930; Fri, 17 Jan 1997 15:56:38 -0800 (PST) Message-Id: <199701172356.PAA15930@nova.stanford.edu> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 17 Jan 1997 16:02:01 -0800 To: trish@zygra.jpl.nasa.gov From: len@NOVA.Stanford.EDU (Len Tyler) Subject: USO test #4 Cc: joe, rsimpson, hinson@nova.stanford.edu Status: RO Hi Trish, Quick question... was conscan on for USO test #4? We are seeing an amplitude modulation with about a 7 minute period. Len ___________________________________________________________________ From trish@qmail.jpl.nasa.gov Fri Jan 17 16:41:47 1997 Received: from qmail.jpl.nasa.gov (qmail.jpl.nasa.gov [137.79.6.33]) by nova.stanford.edu (8.8.4/8.8.4) with SMTP id QAA29846; Fri, 17 Jan 1997 16:41:44 -0800 (PST) Message-ID: Date: 17 Jan 1997 16:40:17 -0800 From: "Trish Priest" Subject: Re: USO test #4 To: "Len Tyler" , joe@nova.stanford.edu, rsimpson@nova.stanford.edu, hinson@nova.stanford.edu X-Mailer: Mail*Link SMTP-QM 3.0.2 Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; Name="Message Body" Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nova.stanford.edu id QAA29846 Status: R Reply to: RE>USO test #4 Hello, Len, I will have to check the LMC log. The keyword file that goes to the station asks them to make sure that CONSCAN is off for the test, but I forgot to check personally. I will from now on. -Trish ___________________________________________________________________ From joe Fri Jan 17 15:43:29 1997 Received: from neptune.stanford.edu. (neptune.Stanford.EDU [36.10.0.149]) by nova.stanford.edu (8.8.4/8.8.4) with SMTP id PAA32130; Fri, 17 Jan 1997 15:43:27 -0800 (PST) Date: Fri, 17 Jan 1997 15:43:27 -0800 (PST) From: Joe Twicken Message-Id: <199701172343.PAA32130@nova.stanford.edu> To: hinson@nova.stanford.edu, len@nova.stanford.edu, rsimpson@nova.stanford.edu, trish@qmail.jpl.nasa.gov Subject: MGS USO Test #4 (97/016) Status: RO I have processed the ODS data from 97/016. This ODS was recorded at DSS 15. The data were acquired as part of USO Test #4. This is the first open-loop data we have recorded and examined since the MGS HGA was deployed. The SNR was approximately 54 dB/Hz during the Test. The ODS was acquired at DSS 15 from 06:15:00 to 08:30:00 at 5000 samples per second (1250 samples/second for each of 4 A/D's). I used the spk_c_961111-970321 SP-kernel file to steer the data. This file was created on 97/008. The ODS file contained 40501 1666-byte records. There were no missing or duplicate records. The POCA file was fixed with our "salvagePoca" program. No hand modification of the POCA file was required. An amplitude modulation with a period of about 7 minutes (4+ cycles in 30 minutes) is clearly evident in all the carrier amplitude estimates. I do not know the source of this amplitude modulation. The spacecraft spin is clearly evident in the carrier frequency estimates. I did not compensate for the spin when estimating Allan deviation. There also appear to be two set of frequency spurs related to the carrier. In the steered data, these sets of spurs appear at 30 and 50 Hz from the carrier. I estimated the USO frequency to be 8423152915.99 Hz. The best linear fit to the USO frequency since 96/323 has a slope of 0.24 Hz/day. The Allan deviation for this recording is shown below. The SNR during the acquisition of data was approximately 54 dB/Hz. I did not compensate for the spacecraft spin cycle. The estimates for 97/016 are: t (sec) AD ------ ---------- 1.6384 2.6285e-13 3.2768 2.1063e-13 6.5536 1.5100e-13 26.2144 1.3857e-13 Plots, as usual, are in the notebook in room 222... Joe ----------------------------------------------------------------------- From trish@qmail.jpl.nasa.gov Mon Jan 20 15:50:09 1997 Message-Id: Date: 20 Jan 1997 15:47:17 -0800 From: "Trish Priest" Subject: CONSCAN To: "Dick Simpson" Cc: "Joe Twicken" , "Len Tyler" X-Mailer: Mail*Link SMTP-QM 3.0.2 Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; Name="Message Body" Content-Transfer-Encoding: quoted-printable Status: RO Mail*Link=AE SMTP CONSCAN Hello, According to the LMC log for USO Test #4, CONSCAN was not turned on until after the USO test. -Trish __________________________________________ From: Joseph Beerer on Mon, Jan 20, 1997 4:33 PM Subject: MGS RST Rpt HEA7018A.TXT To: Adams, William R Cc: Neuman, James C (MSMAIL) Bill, USO Test 4 showed HGA phase center motion larger than expected, although I don't believe any requirement was violated. Below is Richard Simpson's description of results. Do you have any idea what would cause motion of this magnitude? Joe ------------------------------------------------------------------------ From tthorpe@jpl.nasa.gov Tue Jan 21 15:21:03 1997 Date: Tue, 21 Jan 97 15:21:02 -0800 Received: from [137.78.144.51] by eis-msg-003.jpl.nasa.gov (Netscape Mail Server v2.02) with ESMTP id AAA17398 for ; Tue, 21 Jan 1997 15:20:47 -0800 X-Sender: tthorpe@pop.jpl.nasa.gov Message-Id: Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: rsimpson@magellan.Stanford.EDU (Richard Simpson) From: Tom Thorpe Subject: RE: MGS RST Rpt HEA7018A.TXT Status: R >Mime-Version: 1.0 >Date: Tue, 21 Jan 1997 08:50:30 +0100 >To: Thomas.E.Thorpe@jpl.nasa.gov, > Patricia.Priest@jpl.nasa.gov, > Pasquale.B.Esposito@jpl.nasa.gov >From: Joseph Beerer >Subject: RE: MGS RST Rpt HEA7018A.TXT > >>Conversion: Allowed >>Priority: normal >>Disclose-Recipients: Prohibited >>Alternate-Recipient: Allowed >>Date: 20 Jan 1997 18:27:19 -0700 >>From: "Adams, William R (MSMAIL)" >>To: "Joseph Beerer" (Return requested) >>cc: "Neuman, James C (MSMAIL)" (Return requested= ), >> "/s=3Dtrish@zygra.jpl.nasa.gov/"@SMTP.den.mmag.mmc.com (Return >>requested) >>Subject: RE: MGS RST Rpt HEA7018A.TXT >>MIME-Version: 1.0 >> >> >>Ok, It's difficult to respond to something like this when the >>conclusion is buried in a bunch of experimental detail that I don't >>follow. They seem to be saying that the HGA is moving back and fourth >>along the range track (apart from our overall range rate) in a >>sinusoidal fashion with an amplitude of 34 cm. >> >>I hope somebody's made a factor of 10 or 100 error here, because that >>number (if purely due to pointing error) is absurd! The previous >>estimate passed along to me by Trish Priest with Bill Sjogren's name >>attached to it was 8 to 9 mm! This is much more believable than a >>significant fraction of a meter. However, it's still too large to >>attribute to pointing error on the the S/C X-Axis. We would be seeing >>much more variation in X-Band downlink signal level if our pointing >>error was on the order of 0.5=83 ( HGA phase center is about 0.5m from >>COM; diameter of rotation is thus about 1m). >> >>By the way, if they meant =B10.34cm instead of 34.0 cm than the estimate >>is very close to Sjogren's. >> >>An alternative (or additional) explanation might be found in the >>varying solar pressure as we rotate about the Earth vector. But I >>only think that's likely because I don't know the numbers. It may be >>just as unbelievable.... Have they talked to Pat Esposito about this? >> >>Also the USO is varying in temperature about 0.8=83 C peak-to-peak with >>each rotation, and is 5=83 C cooler than on 96/323. >> >>I'm much more interested in the amplitude variation of the carrier. >>I'd like to be told if this 7 minute periodic variation continues or >>is determined to be a spacecraft artifact. I'm currently seeing >>variations in BVR agc telemetry with a period exactly half that, but >>only when ranging is on. The 3.5 minute period corresponds well with >>ranging code cycle time. But how the hell is that suppressing my >>downlink carrier!? >> >>Glad to see I'm not the only one with questions... >> >>Bill Adams ------------------------------------------------------------------------- From rsimpson Tue Jan 21 16:11:57 1997 Date: Tue, 21 Jan 97 16:09:23 -0800 From: rsimpson (Richard Simpson) To: tthorpe@jpl.nasa.gov Subject: RE: MGS RST Rpt HEA7018A.TXT Cc: adams@pogo.den.mmc.com, jbeerer@pop.jpl.nasa.gov, len@nova, rsimpson, sbutman@pop.jpl.nasa.gov, trish@zygra.jpl.nasa.gov Status: R Thanks for the relay of the correspondence. I wasn't claiming that the HGA was wobbling by +/-34 cm every hour -- simply that if we took the one-way Doppler residuals and interpreted them to be motion of that type we would get +/-34 cm. Since the inferred velocity is at least an order of magnitude larger than what Sjogren is seeing in two-way Doppler, I think other explanations are needed (such as thermal or magentic field influences on the USO) -- my last couple sentences in that paragraph. I hope the Project isn't spending all of its time investigating a problem that most likely doesn't exist! I put this into the report because there was a request from Stan Butman (via Trish Priest) that we take a look. The results do NOT fit with the other data, so the short answer is that we do NOT see the motion resulting from the HGA offset. On the other hand there is both a Doppler signature (from something else) and an amplitude signature with a much shorter period that we need to understand. --------------------------------------------------------------------- From hinson@nimbus.Stanford.EDU Wed Jan 22 12:14:20 1997 Received: (from hinson@localhost) by nimbus.Stanford.EDU (8.8.4/8.8.3) id MAA08781; Wed, 22 Jan 1997 12:14:19 -0800 (PST) Date: Wed, 22 Jan 1997 12:14:19 -0800 (PST) From: Dave Hinson Message-Id: <199701222014.MAA08781@nimbus.Stanford.EDU> To: rsimpson@magellan.Stanford.EDU Subject: USO temperature sensitivity Cc: joe@neptune.Stanford.EDU, len@nova.Stanford.EDU X-Sun-Charset: US-ASCII Status: R I found some plots that characterize the sensitivity of USO frequency to temperature variations. It's a bit complicated because the rate of change of frequency with temperature also depends on temperature. For this type of USO, delta-f/f is typically about 4.e-12 per K. A change in temperature of 0.5 K would cause a change in USO frequency of about 0.017 Hz. This is about the right size to explain the 100-minute oscillation in frequency observed in USO test #4. ------------------------------------------------------------------------ From rsimpson Wed Jan 22 12:43:33 1997 Date: Wed, 22 Jan 97 12:43:32 -0800 From: rsimpson (Richard Simpson) To: hinson@nimbus.Stanford.EDU Subject: Re: USO temperature sensitivity Cc: rsimpson Status: R That's good detective work. The remaining question is where the temperature is measured for the 4e-12 sensitivity relative to where the temperature is being measured on the spacecraft. -------------------------------------------------------------------------- From adams@pogo.den.mmc.com Fri Jan 24 10:54:10 1997 Received: by pogo.den.mmc.com (1.37.109.4/16.2) id AA13059; Fri, 24 Jan 97 11:54:01 -0700 From: Bill R Adams Subject: Re: MGS RST Rpt HEA7018A.TXT To: rsimpson@magellan.Stanford.EDU (Richard Simpson) Date: Fri, 24 Jan 1997 11:54:01 -0700 (MST) In-Reply-To: <9701220009.AA14686@magellan.Stanford.EDU> from "Richard Simpson" at Jan 21, 97 04:09:23 pm X-Mailer: ELM [version 2.4 PL25] Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Content-Length: 2822 Status: R Hi! So the magnitude is 34 and not 0.34 huh? Yeah, that's gotta be something other than pure pointing. Hopefully whomever relayed my message back to you also included the other effects I suggested, i.e. USO temperature and varying solar pressure on the spacecraft. As far as the 7 minute amplitude variation goes. I took a look at that the other day. I appears that it started about a half an hour before configuring for the USO test and continued for an about 90 minutes after. It was present in both the uplink and the downlink agc telemetry which points to a station problem, as our donwlink carrier power is not nominally dependent on the uplink carrier power. If you can send me a fax number I will gladly forward you a plot. We are coincidentally (I hope) also experiencing some anomalous agc telemetry with ranging and other effects with command uplinks and the transition between one and two way communication with the stations. The numbers we're looking at right now don't make sence, frankly. Anything unusual you see in the downlink will be interesting to us as well. Bill Adams --------------------------------------------------------------------- From rsimpson Fri Jan 24 11:14:58 1997 Date: Fri, 24 Jan 97 11:12:25 -0800 From: rsimpson (Richard Simpson) To: adams@pogo.den.mmc.com Subject: Re: MGS RST Rpt HEA7018A.TXT Cc: rsimpson Status: R No no no no ... we don't think the magnitude is 34. But if you do the simple-minded analysis, 34 is what you get. One of our people went back to some of the old thermal cal data on the USO; if you believe that, thermal effects can account for all the variation we see (within a factor of 2). I'm not sure how the thermal cal was done relative to how the spacecraft USO temperature is being measured. But that looks more promising than attributing the 0.01 Hz fluctuations to motions of the spacecraft. The bottom line for now is that any spacecraft motion effects are buried under several other things. Even Bill Sjogren at JPL says he can't see the rotation in two-way data any longer; it's either gotten smaller or other noise has gotten larger (he argues for a combination of both). The 7-minute oscillations remain a puzzle here. So, if you can send the plot, we can be equally well-informed data-wise. We double checked; Trish Priest looked at the LMC log from the station and concluded that CONSCAN had been commanded off, then we looked at DSN monitor data and concluded that the system at least THOUGHT CONSCAN was off. CONSCAN is our nominal culprit, though these oscillations are more regular than what you usually see from CONSCAN. I don't have any other theories at the moment. Regards, Dick