X-Andrew-Authenticated-As: 32766 Return-path: Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Fri, 30 Nov 1990 02:36:51 -0500 (EST) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Fri, 30 Nov 1990 02:36:13 -0500 (EST) Subject: SPACE Digest V12 #594 SPACE Digest Volume 12 : Issue 594 Today's Topics: Re: Photon engine Galileo Update - 11/22/90 NASA receives award for minority business development program (Forwarded) Re: Magellan Update - 11/16/90 MONTHLY SOLAR TERRESTRIAL REVIEW Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription notices, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: 24 Nov 90 04:45:57 GMT From: mcgill-vision!thunder.mcrcim.mcgill.edu!clyde.concordia.ca!news-server.csri.toronto.edu!utgpu!utzoo!henry@bloom-beacon.mit.edu (Henry Spencer) Subject: Re: Photon engine In article <4948@bwdls58.UUCP> hwt@bwdlh490.BNR.CA (Henry Troup) writes: >|>only thing left behind with an expanding cloud of plasma. A 100 tonne >|>ship accelerating at 1 g requires a 3x10**11 watt powerplant. How >|>does that compare to the human species total power output these days? > >Well, it must be less than the power output of a shuttle at launch, right? Shuttle power output at launch is 15-20 gigawatts, I believe. However, the inequality you propose doesn't work. There is no unique answer to the question of power output for a given mass at a given acceleration. It depends on the exhaust velocity. A 100T ship at 1G (call it 10 m/s^2) requires a thrust of 1MN. Thrust is mass flow times exhaust velocity, by conservation of momentum. At an exhaust velocity of 3e8 m/s, naively (ignoring relativistic issues), we need 3.3e-3 kg/s of mass flow. Kinetic energy over time of that flow, with respect to the rocket, naively, is 0.5*mass_flow*ve^2, or about 15e13 W. Call it 150 terawatts. I'd have to hit the books to sort out the non-naive version of this, but it probably won't differ by more than a small integer, and it might even be the same. I don't have numbers handy for the whole species or total power, but the electrical power generating capacity of the US is circa 1 terawatt, I think. Handling 150TW would be, um, a challenge. For example, assume an efficiency of 50%. (That's awfully good for lasers, which are inherently pretty lossy devices.) That means our total power output actually has to be 300TW, and the missing 150TW comes out as heat. We have to get rid of that heat... somehow. The only long-term answer is radiators, but they're big and heavy. Ignoring practicalities, let us use evaporative cooling instead. We'll be generous and say our lasers can run at 2500K (2227C; if you want it in Fahrenheit, Rankine, or Reaumur, convert it yourself :-)). Assume our evaporative material is water, which has a high heat capacity, call its heat capacity a straight 4.2kJ/kgK, ignoring heats of melting and boiling, and assume we start with ice at roughly absolute zero. Then we are using a mere 15 kilotons of water per second to cool our 100T spacecraft. That won't work. :-) Another non-trivial consideration for photon rockets is how you power them. They are fiercely difficult to build. If you are burning up far more mass powering them than you are exhausting through them, better you should build a system with the same net mass flow and a lower exhaust velocity, by using all the mass as exhaust. Using fission or fusion to power a photon rocket is ridiculous, in particular. Fusion burns hydrogen to helium (ignoring lots of fine points), releasing quite a small fraction of the total mass as energy. Even with no losses, most of your fuel mass is going to run your fusion reactor, after which you are dumping the helium overboard at roughly zero velocity (compared to the exhaust velocity, any velocity you can get for that helium is zero). Building a fusion rocket would give similar performance with many fewer problems. Photon rockets make sense only if you can power them with total matter annihilation; even matter- antimatter reactions are better used as rockets than as a power source. (All the more so because we are not very far from being able to build antimatter rockets, while handling terawatts for a photon rocket is well beyond us.) -- "I'm not sure it's possible | Henry Spencer at U of Toronto Zoology to explain how X works." | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 26 Nov 90 16:58:03 GMT From: swrinde!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@ucsd.edu (Ron Baalke) Subject: Galileo Update - 11/22/90 GALILEO STATUS REPORT November 22, 1990 As of noon (PST) Wednesday, November 21, 1990, the Galileo spacecraft is 8,456,170 miles from the Earth and traveling at a heliocentric speed of 61,788 miles per hour; distance to the Sun is 99,324,410 miles (1.07 AU). The spacecraft is spinning at 3.15 rpm; downlink telemetry is at 7680 bps through the Low Gain Antenna. Round trip light time is 1 minute, 28 seconds. A SITURN to lead the sun was successfully performed on November 16. The turn, about 22 degrees, was the largest to date and resulted in the spacecraft leading the sun by about 12.5 degrees. Spacecraft performance during the activity was normal and without incident. The 21st RPM (Retro Propulsion Module) flushing activity was successfully performed on November 16. All thrusters were flushed during this activity except for the P-thrusters which were used later for the sun point activity. Successful flushing was directly confirmed and observed via high rate engineering data at 1200 bps (bits/second). Delayed Action Commands (DACs) were sent on November 16 to turn off the S-Band ranging channel to improve the RF downlink performance for subsequent Venus science data playback on for November 19, 20 and 21. A NO-OP command was sent on November 20 to reset the Command Loss Timer to 240 hours, the planned value for this mission phase. The PPR (Photopolarimiter Radiometer) instrument continued its calibration and checkout activities. Preliminary data indicates the instrument is working well. The Venus science data was played back from the spacecraft on November 19, 20, and 21. The data has been stored on the spacecraft since early February along with UVS (Ultraviolet Spectrometer) Lyman-Alpha data collected during cruise. The data was played back twice from Data Memory Subsystem (DMS) tape recorder. Data was returned from tracks 1 and 2 on November 19, then tracks 3 and 1 on November 20, and finally tracks 2 and 3 on November 21. Preliminary results indicate all Venus data was successfully returned and is presently being processed. Two delta DOR (Differential One-way Ranging) navigation activities were completed on November 19. The activities were successful using the 70 meter antenna pairs at Goldstone/Spain and Goldstone/Australia. A total of 25 of the planned 27 delta DOR activities are complete; 21 were successful. The NIMS (Near Infrared Mapping Spectrometer) instrument was powered on November 21. Several spacecraft heaters were configured to maintain acceptable power/thermal margins. Preliminary data indicates the NIMS instrument is functioning normally. The PCT (Photometric Calibration Target) heaters were powered off and the RCT-NIMS heater was powered on November 22 for power margin management and thermal control. Two non-interactive DACs were sent on November 21 to configure the PWS (Plasma Wave) instrument to gather calibration data from the magnetic field sensor; the commands went active later that day. The first command causes the PWS to inject a square wave signal tone into its magnetic field circuitry; the second command reconfigured the PWS back to the normal mode. The calibration was performed to verify instrument operation in presence of a known fixed source. Review of Venus data and recent (last week) data indicates the possibility of spacecraft generated time variable electric and magnetic fields. Commands were sent on November 21 to turn off the PLS (Plasma) instrument high voltage. This action drops the instrument power dissipation by about 1.2 watts and relaxes somewhat thermal concerns expressed by the Principal Investigator. The AC bus imbalance measurements dropped about 3 DN and about 47.5 volts. This measurement has been relatively stable since its inception and is likely indicative of a leakage resistance to chassis of about 100-500 ohms. During the past 2-3 weeks the DC measurement has gradually dropped from near 18.5 volts to its present value of about 2 volts. The gradual decline has not correlated with any spacecraft load switching event, thermal environment change or mechanical activity. The present reading can be indicative of a return leakage path to chassis of about 150 ohms. Tests to better characterize the PPS telemetry sensor performance are in process. All other power-related and spacecraft telemetry measurements are normal. ___ _____ ___ /_ /| /____/ \ /_ /| | | | | __ \ /| | | | Ron Baalke | baalke@mars.jpl.nasa.gov ___| | | | |__) |/ | | |___ Jet Propulsion Lab | baalke@jems.jpl.nasa.gov /___| | | | ___/ | |/__ /| M/S 301-355 | |_____|/ |_|/ |_____|/ Pasadena, CA 91109 | ------------------------------ Date: 29 Nov 90 23:24:20 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: NASA receives award for minority business development program (Forwarded) David Garrett Headquarters, Washington, D.C. November 26, 1990 (Phone: 202/453-8400) RELEASE: 90-154 NASA RECEIVES AWARD FOR MINORITY BUSINESS DEVELOPMENT PROGRAM NASA Administrator Richard H. Truly today accepted the "Government Agency of the Year Award" from the Black Business Association of Los Angeles for NASA's participation in minority business development. The award, given annually in conjunction with the association's trade mission to Washington, D.C., is presented to the government agency which has the most successful program designed to encourage minority business development. "NASA has earned this award for its aggressive and innovative approach to the small and disadvantaged business program. Our members currently hold contracts with NASA locations in excess of $50 million across the country, compared to $16 million 3 years ago," said Association Chairman Gene Hall. "We would like NASA to keep up the good work." Upon receiving the award, Truly acknowledged pride in being recognized for NASA's program to encourage development of small and disadvantaged businesses. He also pledged that NASA would continue to be a leader in this area as it looked for new ways to increase the participation of minority businesses in the nation's civil space program. Eugene Rosen, Director of NASA's Small and Disadvantaged Business Utilization Office, said, "our outreach efforts are increasing nationwide to small disadvantaged businesses to inform them of the possibilities of contracting with NASA. We also are in the process of installing a mentor program to encourage major corporations to assist small, disadvantaged businesses in becoming viable." The association, the second largest of its kind in the nation, has 450 members, 75 of them located outside of the Los Angeles area. ------------------------------ Date: 24 Nov 90 23:34:01 GMT From: ucselx!crash!adamsd@ucsd.edu (Adams Douglas) Subject: Re: Magellan Update - 11/16/90 In <1990Nov19.171957.13034@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >In article <1990Nov17.203838.10695@isc.rit.edu> swd0170@ritvax.isc.rit.edu writes: >>>... what does the science community hope to learn >>>by mapping Venus? >> The reason that we are mapping Venus is to answer many unanswered questions >>about the earth's origins... >[Enter cynic mode.] Nonsense. We are mapping Venus to learn more about >*Venus's* geology and origins. This will improve our knowledge of planets >in general, and thereby may eventually improve our understanding of Earth Hey, let's be totally honest. Besides the science, we're also mapping Venus because it's NEAT! Never lose that thought! -- ==================================================================== Adams Douglas 3206 Raintree Circle -sometime I'll think of a good quote for here- Culver City, CA 90230 crash!adamsd ------------------------------ Date: Sun, 25 Nov 90 18:50:35 MST From: std_oler%HG.ULeth.CA@vma.cc.cmu.edu (Cary Oler) Subject: MONTHLY SOLAR TERRESTRIAL REVIEW X-St-Vmsmail-To: ST%"space+@andrew.cmu.edu" --- MONTHLY SOLAR TERRESTRIAL REVIEW --- October 1990 Report Issued In-Part from Data Released by the Space Environment Services Center Boulder Colorado -------- MONTHLY ACTIVITY SUMMARY AND SOLAR CYCLE OUTLOOK NOVEMBER 1990 - MAY 1991 We are now in month 50 of solar cycle 22. Averaged activity levels and solar indices were up again in October compared to September, but not nearly enough to affect the prediction that July 1989 was in fact the solar maximum of cycle 22. The largest increase was observed in daily sunspot number and the monthly average was up almost 33 points over September values. The prediction model used for smoothed sunspot number shows that there is still a slight statistical possibility that solar maximum is yet to come. However, for this to be true, the activity and solar indices would have to reach the levels obtained in August 1990 and maintain that level for a number of months. If time proves July to be just a relative peak of activity and not the solar maximum, then the regression model predicts late spring 1991 as the next probably candidate. However, at this time we do not see any indication of the kinds of activity that would be necessary to unseat July 1989 as solar maximum of cycle 22. Flare activity ranged from low to high during October. There were a total of eleven M-class flares reported during the month. The two largest, an M8/1N Tenflare at 18:06 UT on 20 October and an M3/SF at 06:02 UT on 21 October, originated from Region 6311 which became quite active on 20-21 October, producing three M-class flares before it crossed the limb late on the 21st. There was a very slight proton enhancement at satellite altitudes which began around 09:00 UT on 23 October, reached a maximum of 4 pfu at the >10 MeV range at 14:25 UT on 23 October, and lasted about 36 hours. Although no solar event can be pinpointed as the cause of this proton enhancement, its signature suggests that it originated as an east limb event. Geomagnetic activity ranged from quiet to minor storm levels at mid latitudes and quiet to severe storm levels at high latitudes. The two most disturbed days were 10-11 October when mid latitudes experienced minor storm conditions and high latitudes experienced one day of severe storm and one day of major storm conditions. Although no individual event can be suggested as responsible for this activity, it is possible that the interplanetary magnetic field was aligned southward, allowing solar wind energy to be passed efficiently to the magnetosphere, in essence, enhancing the effects of earlier solar disturbances. Radio propagation conditions during the month ranged from very poor levels at high latitudes to very good levels at low latitudes. The most disturbed period occurred in conjunction with the minor geomagnetic storm of 10-11 October. Significant auroral flutter and fading caused poor HF propagation over most paths. SIX MONTH SOLAR CYCLE OUTLOOK Prediction models indicate another small increase in the raw solar indices for November, still not enough to affect July 1989 as solar maximum. A drop in December and a leveling off through the first couple of months of the new year are also predicted. No great deviation from the activity levels of the last two months are foreseen at this time. Radio propagation conditions over the next six months look relatively good. No significant changes in overall conditions are expected, excluding the normal seasonal variations. Approximately one minor to major geomagnetic storm can be expected every month or two. Therefore, between 3 to 5 significant periods of degraded propagation conditions should be anticipated over the next six months, provided current models are accurate in predicting pulses of solar activity and recurrent phenomena. The occurrence of SIDs/SWFs should persist throughout the next six months. Present solar models suggest that December through January will likely be the least productive months in terms of solar flare and SID/SWF activity. Also, a decline in MUF is anticipated for December and the first part of the new year, coinciding with decreased levels of ionospheric ionization. VHF propagation should remain mostly normal throughout the next six months, with decreased probabilities of DX contacts in December and January. Reduced MUF will also make DX openings on 50 MHz somewhat unlikely during these months of expected decreased solar activity. Although reduced MUF's are anticipated, there remains a moderate probability for some potential auroral backscatter communications on VHF bands during periods of minor to major geomagnetic and auroral storming. Middle and high latitudes will benefit the most during these periods. RECENT SOLAR INDICES (PRELIMINARY) OF THE OBSERVED MONTHLY MEAN VALUES Updated for October, 1990 Sunspot Numbers Radio Flux Geomagnetic ------------------------------------ ------------- ----------- Observed Ratio Smooth Values Ottawa Smooth Smooth SESC RI RI/SESC SESC RI 10 cm Value Ap Value ------------------------------------ ------------- ----------- YEAR = 1988 Nov: 153.8 125.1 .82 168.3 130.2 156.2 177.5 12 16.1 Dec: 229.5 179.2 .78 180.1 137.4 199.8 184.8 13 16.5 YEAR = 1989 Jan: 203.2 161.6 .80 189.2 141.9 235.4 190.2 19 16.7 Feb: 211.0 164.5 .78 196.0 144.7 222.4 194.0 15 17.0 Mar: 176.8 131.0 .74 204.1 149.4 205.1 199.7 41 17.6 Apr: 172.3 129.3 .75 209.9 153.1 189.6 204.4 23 18.2 May: 207.0 138.4 .67 216.4 156.5 190.1 209.3 16 18.8 Jun: 297.3 196.0 .66 220.1 157.9 239.6 213.1 17 19.2 Jul: 193.9 126.8 .65 221.1 158.1 181.9 212.6 8 19.1 Aug: 243.0 166.8 .69 221.5 157.4 217.1 209.7 20 19.3 Sep: 240.7 176.8 .74 221.3 156.3 225.9 207.2 17 18.8 Oct: 217.4 158.5 .73 223.2 157.1 208.7 206.3 21 18.3 Nov: 255.0 173.0 .68 223.4 157.3 235.1 206.1 19 18.4 Dec: 217.8 166.1 .76 217.3 153.3 213.0 203.3 16 18.4 YEAR = 1990 Jan: 239.3 179.4 .75 212.4 150.3 210.1 200.4 14 18.6 Feb: 184.7 128.4 .71 213.9 152.5* 178.3 200.5* 23 18.8 Mar: 198.6 140.8 .71 212.7 151.7* 188.8 198.6* 23 18.6 Apr: 196.1 139.8 .71 210.5 149.0* 185.3 195.3* 27 18.2* May: 187.7 132.0 .70 189.7 16 Jun: 168.9 105.2 .62 170.9 16 Jul: 204.3 147.0 .72 180.7 14 Aug: 269.4 199.9* .74* 221.6* 19 Sep: 186.4 124.7* .67* 175.8* 14 Oct: 219.0 145.2* .66* 180.6* 14* * = Preliminary estimates The lowest smoothed sunspot number for Cycle 21, RI = 12.3, occurred in September 1986. The preliminary sunspot maximum for this cycle (cycle 22) remains July 1989, with a peak smoothed sunspot number of 158.1. DAILY SOLAR DATA FOR OCTOBER, 1990. ENERGITIC EVENT SUMMARY (MINOR AND MAJOR FLARES) _____________________________________________________________________________ | Date | Time (U.T.) | X-Ray | Optical Information | Sweep Freq. | | | Begin Max End | Class | Type Location Region | Intensity | |------|-----------------|-------|------------------------------| II III IV V| |08 Oct| 0652 0706 0729| M1.5 | Uncorrelated event. | | | | | |09 Oct| 0853 0911 1028| M1.6 | 1F S18E71 6314 | | | | | |10 Oct| 1753 1804 1824| M1.1 | SN S17E60 6314 | | | | | |11 Oct| 0735 0741 0749| M1.0 | 1N N09E44 6312 | | | | | |15 Oct| 0129 0135 0147| M2.8 | 1N S21E41 6321 | | | | | |16 Oct| 1716 1728 1733| M1.4 | Uncorrelated event. | | | | | |20 Oct| 1753 1806 1812| M8.5 | 1N N15W82 6311 | | 1 | | 2| |21 Oct| 0312 0320 0325| M1.0 | SF N16W92 6311 | | | | | | | 0553 0602 0629| M3.0 | SF N14W89 6311 | | 1+| | | | | 0949 1008 1106| M1.7 | SF N18E23 6327 | | 2 | | | |22 Oct| 0611 0641 0740| M2.9 | SF S08W50 6322 | | 1+| | | |______|_________________|_______|______________________________|_____________| NOTES: - Xray Flare Classes (weak to strong): C, M, X (with sub-categories rated from 0.0 to 9.9 in each class). - Optical Flare Classes (weak to strong): S, 1, 2, 3, 4 (with an attached figure identifying brightness: F-Faint, N-Normal, B-Brilliant). - Locations are given in latitude and longitude as measured from the central solar meridian. - Sweep Frequency Intensity represents the intensity of detected solar radio frequency bursts (bursts sweep over large frequencies). Type II and IV almost always represent ejection of solar material through the solar corona and into interplanetary space. Intensities are rated from 1 to 3+. GENERAL DAILY SOLAR STATISTICS _____________________________________________________________________________ | | Radio Flux | | Sunspot | Flares | | | Ottawa | Sunspot | Area | X-Ray Optical | |Date | 10.7 cm | Number | mil.sq.km. | C M X | S 1 2 3 | |-------|-------------|-----------|------------|--- --- --- | --- --- --- --- | |01 Oct | 158 | 169 | 2,730 | 3 0 0 | 12 1 0 0 | |02 Oct | 161 | 182 | 3,450 | 6 0 0 | 20 2 0 0 | |03 Oct | 177 | 180 | 4,710 |10 0 0 | 25 2 0 0 | |04 Oct | 184 | 208 | 5,130 | 8 0 0 | 16 1 0 0 | |05 Oct | 169 | 214 | 3,780 | 6 0 0 | 9 1 0 0 | |06 Oct | 169 | 181 | 3,270 | 5 0 0 | 6 2 0 0 | |07 Oct | 168 | 208 | 3,870 |12 0 0 | 10 0 0 0 | |08 Oct | 179 | 229 | 4,440 | 7 1 0 | 12 1 0 0 | |09 Oct | 182 | 224 | 4,380 | 8 1 0 | 13 3 0 0 | |10 Oct | 192 | 216 | 5,520 | 5 1 0 | 18 0 0 0 | |11 Oct | 202 | 278 | 6,000 |11 1 0 | 14 1 0 0 | |12 Oct | 200 | 267 | 5,550 |10 0 0 | 25 0 0 0 | |13 Oct | 207 | 297 | 5,430 | 8 0 0 | 20 1 0 0 | |14 Oct | 220 | 287 | 5,970 | 5 0 0 | 23 2 0 0 | |15 Oct | 232 | 368 | 6,300 |14 1 0 | 34 2 0 0 | |16 Oct | 226 | 361 | 5,790 | 4 1 0 | 25 0 0 0 | |17 Oct | 193 | 283 | 6,450 |10 0 0 | 26 2 0 0 | |18 Oct | 195 | 260 | 5,730 |12 0 0 | 13 3 1 0 | |19 Oct | 221 | 257 | 5,430 | 8 0 0 | 25 0 0 0 | |20 Oct | 200 | 276 | 4,350 |16 1 0 | 6 2 0 0 | |21 Oct | 187 | 185 | 1,980 | 4 3 0 | 15 3 1 0 | |22 Oct | 169 | 221 | 1,860 | 4 1 0 | 13 1 0 0 | |23 Oct | 164 | 181 | 1,620 | 9 0 0 | 12 2 0 0 | |24 Oct | 157 | 180 | 2,070 | 8 0 0 | 12 0 0 0 | |25 Oct | 163 | 183 | 2,310 |10 0 0 | 20 2 0 0 | |26 Oct | 154 | 171 | 2,010 | 7 0 0 | 16 2 0 0 | |27 Oct | 164 | 139 | 1,680 | 3 0 0 | 6 0 0 0 | |28 Oct | 152 | 158 | 2,940 | 2 0 0 | 10 0 0 0 | |29 Oct | 156 | 155 | 3,270 | 7 0 0 | 9 0 0 0 | |30 Oct | 154 | 126 | 2,910 | 7 0 0 | 10 0 0 0 | |31 Oct | 143 | 109 | 2,640 | 5 0 0 | 10 0 0 0 | |_______|_____________|___________|____________|____________|_________________| ** End of Report ** ------------------------------ End of SPACE Digest V12 #594 *******************